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Solution and solid state photochemistry of some bridgehead substituted dibenzobarrelene diesters : x-ray… Pokkuluri, Phani Raj 1990

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SOLUTION AND SOLID STATE PHOTOCHEMISTRY OF SOME BRIDGEHEAD SUBSTITUTED DIBENZOBARRELENE DIESTERS: X-RAY CRYSTALLOGRAPHY OF STARTING MATERIALS AND PHOTOPRODUCTS By PHANI RAJ POKKULURI B.Sc, Nagarjuna University, India, 1982 M.Sc. , Indian Institute of Technology, Kanpur, India, 1984 M.Sc. The University of British Columbia, 1987 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (DEPARTMENT OF CHEMISTRY) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA December 1990 © Phani Raj Pokkuluri, 1990 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of C H E M l S T f t V The University of British Columbia Vancouver, Canada Date DE-6 (2/88) My Father and Mother ABSTRACT The solid state and solution phase photochemistry of three bridgehead-substituted dibenzobarrelene-11,12-diesters and a 2,3-naphthobarrelene diester derivative were investigated. These compounds were expected to undergo the di-7r-methane rearrangement via their t r i p l e t excited states, and a rearrangement to a cyclooctatetraene (COT) derivative via their singlet excited states. A l l compounds investigated underwent smooth photoreactions in the solid state to produce the same products as observed in the corresponding solution phase photolyses. One exception to this was a bridgehead dimeth-yl-substituted dibenzobarrelene diester. In this case an unusual photo-product which was characterized as a dibenzopentalene derivative, was obtained in the solid state along with lesser amounts of the normal-solution products. The mechanism proposed for the formation of this prod-uct involves a 1,4-biradical intermediate which undergoes a novel double 1,2-ester migration. It was recognized that this biradical intermediate could also undergo fragmentation to produce a cyclooctatetraene (COT) derivative which differs in i t s symmetry from that of the COT expected based on the mechanism proposed by H. E. Zimmerman for similar transfor-mations observed in the cases of benzo- and naphthobarrelenes. Thus, there are two structures possible for the COT formed which cannot be dis-tinguished based on their spectral properties. For this reason, single crystal X-ray diffraction analysis of the COTs formed in each case was performed. Of the four COT structures determined by X-ray crystallogra-phy, three COTs had structures that were consistent with the fragmentation - iv-mechanism, while one had a structure consistent with the Zimmerman mecha-nism. In light of the possible unusual photorearrangements observed, i t was thought desirable to establish the molecular structures of a l l photo-products obtained. To this end, crystal and molecular structures of 11 photoproducts were determined. Also, in an attempt to establish structure-reactivity relationships, crystal and molecular structures of four start-ing materials were determined. A bridgehead chloromethyl-substituted dibenzobarrelene diester was also found to produce dibenzopenatalene-like photoproducts in the solid state or in chloroform solution; these photoproducts were also character-ized based mainly on X-ray crystallography. These results add to the gen-erality of the. unusual photobehavior of some dibenzobarrelene derivatives. In the solution phase photolysis of a bridgehead dichloro-substituted dibenzobarrelene diester, a novel cyclic peroxide product was obtained. This was rationalized as being derived from photolysis of the primary di-7r-methane photoproduct followed by trapping of the resulting 1,3-biradical by traces of molecular oxygen present in the reaction mixture. Thus, in the present study i t was found that bridgehead substituted dibenzobarrelene derivatives undergo di-7r-methane rearrangement via their T^ states as expected, but that their states may undergo unusual rear-rangements to produce cyclooctatetraene derivatives with unexpected struc-tures, and dibenzopentalene derivatives in some cases. - V-TABLE OF CONTENTS Page ABSTRACT i i i L I ST OF TABLES v i i i L I ST OF FIGURES x i L IST OF SCHEMES x i i i ACKNOWLEDGEMENTS xv INTRODUCTION 1 CHAPTER 1. PHOTOCHEMICAL INTRODUCTION 2 The di-7r-me thane rearrangement 9 Reaction multiplicity 10 Reaction Regioselectivity 10 Photochemistry of Barrelene, Benzobarrlene and Naphthobarrelene 12 The photochemistry of Dibenzobarrelene and its Derivatives . . . 14 Objectives of Present Research 20 CHAPTER 2 . CRYSTALLOGRAPHIC INTRODUCTION 23 Data collection 23 Data Reduction 26 Structure Solution 27 Structure Refinement 32 Treatment of Disorder 35 Structure Completion 35 RESULTS AND DISCUSSION 36 SYNTHESIS OF STARTING MATERIALS 37 PART I. PHOTOCHEMICAL DISCUSSION 39 - v i -CHAPTER 3. THE PHOTOCHEMISTRY OF 9,10-DIMETHYLDIBENZOBARRELENE DIESTER 9 40 Discussion of Solution Photolysis Results 42 Discussion of Solid State Photolysis Results 43 A Possible Mechanism of the Formation of 16 44 Origin of Biradical 17 48 Unique Reactivity of 9 in the Solid State 49 Single Crystal Versus Powder Reactivity 53 The Structure of Photoproduct 14 53 CHAPTER 4. THE PHOTOCHEMISTRY OF 9 -PHENYLDIBENZOBARRELENE DIESTER 10 56 Discussion of the Photolysis Results 57 Why only path b? 59 Structure of COT 20 . . . 60 CHAPTER 5. ADDITIONAL EXAMPLES OF COT STRUCTURES 62 CHAPTER 6. UNUSUAL REARRANGEMENTS OF 9 -CHLOROMETHYL-DIBENZOBARRELENE DIESTER 26 66 CHAPTER 7. THE PHOTOCHEMISTRY OF 9,10-DICHLORODIBENZO-BARRELENE DIESTER 11 70 Discussion of the Photolysis Results 72 Solid State Photochromism of Compound 11 74 CHAPTER 8. THE PHOTOCHEMISTRY OF A 2,3-NAPHTH0BARRELENE DIESTER 12 81 Discussion of the Photolysis Results 83 A Comment on the Solid State Reactivity of 12 84 PART II. CRYSTALLOGRAPHIC DISCUSSION 85 - v i i -CHAPTER 9 . CRYSTAL AND MOLECULAR STRUCTURES OF BRIDGEHEAD SUBSTITUTED DIBENZOBARRELENE DIESTER DERIVATIVES 86 CHAPTER 1 0 . CRYSTAL AND MOLECULAR STRUCTURES OF THREE SEMIBULLVALENE DERIVATIVES 93 CHAPTER 1 1 . CRYSTAL AND MOLECULAR STRUCTURES OF DIBENZO-CYCLOOCTATETRAENE DERIVATIVES 97 CHAPTER 1 2 . CRYSTAL AND MOLECULAR STRUCTURES OF UNUSUAL REARRANGEMENT PRODUCTS 101 EXPERIMENTAL 106 PHOTOCHEMICAL WORK 107 CRYSTALLOGRAPHIC WORK 127 REFERENCES 219 APPENDIX 224 - v i i i -LIST OF TABLES Table Caption Page 1 Photoproduct ratios of 9 as a function of medium . . . . 41 2 Results of volume analysis 50 3 Product ratios from photolysis of compound 10 as a function of medium 57 4 Some important geometrical data observed in the molecular Structures of compounds discussed in chapter 9 89 5 Short intermolecular contacts observed in the crystal structures of compounds discussed in chapter 9 90 6 Some important geometric parameters observed in the molecular structures of compounds discussed in chapter 10 94 7 Short intermolecular contacts observed in the crystal structures of compounds discussed in chapter 10 95 8 Some of the main geometrical data observed in the molecular structures of COTs 98 9 Short intermolecular contacts observed in the crystal structures of compounds discussed in chapter 11 . . . . 99 10 Some of the important geometric parameters of compounds discussed in chapter 12 102 11 Short intermolecular contacts observed in the crystals of compounds discussed in chapter 12 103 12 Data collection parameters and crystal data for compounds of chapter 9 128 13 Atomic coordinates and B gq values of compound 9 . . . . 132 - ix-14 Bond lengths involving non-hydrogen atoms of compound 9 133 15 Bond angles involving non-hydrogen atoms pf compound 9 . . 134 16 Atomic positions and B eq values of compound 10 . . . . 137 17 Bond lengths involving non-hydrogen atoms of compound 10 138 18 Bond angles involving non-hydrogen atoms of compound 10 139 19 Atomic positions and B eq values of compound 11 141 20 Bond lengths involving non-hydrogen atoms of compound 11 142 21 Bond angles involving non-hydrogen atoms of compound 11 143 22 Atomic coordinates and B eq values of compound 26 . . . . 146 23 Bond lengths involving non-hydrogen atoms of compound 26 147 24 Bond angles involving non-hydrogen atoms of compound 26 148 25 Data collection parameters and crystal data for compounds of chapter 10 150 26 Atomic coordinates and B eq values of compound 19 . . . . 153 27 Bond lengths involving non-hydrogen atoms of compound 19 154 28 Bond angles involving non-hydrogen atoms of compound 19 155 29 Atomic positions and B eq values of compound 33 . . . . 159 30 Bond lengths involving non-hydrogen atoms of compound 33 160 31 Bond angles involving non-hydrogen atoms of compound 33 121 32 Atomic positions and B gq values of compound 38 163 33 Bond lengths involving non-hydrogen atoms of compound 38 165 34 Bond angles involving non-hydrogen atoms of compound 38 166 35 Data collection parameters and crystal data for compounds of chapter 11 169 36 Atomic coordinates and B gq values of compound 15 . . . . 173 37 Bond lengths involving non-hydrogen atoms of compound 15 174 -x-38 Bond angles involving non-hydrogen atoms of compound 15 175 39 Atomic positions and B eq values of compound 20 178 40 Bond lengths involving non-hydrogen atoms of compound 20 180 41 Bond angles involving non-hydrogen atoms of compound 20 182 42 Atomic positions and B gq values of compound 23 186 43 Bond lengths involving non-hydrogen atoms of compound 23 187 44 Bond angles involving non-hydrogen atoms of compound 23 188 45 Atomic positions and B gq values of compound 25 . . . . 190 46 Bond lengths involving non-hydrogen atoms of compound 25 191 47 Bond angles involving non-hydrogen atoms of compound 25 192 48 Data collection parameters and crystal data for compounds of chapter 12 194 49 Atomic positions and B gq values of compound 16 198 50 Bond lengths involving non-hydrogen atoms of compound 16 199 51 Bond angles involving non-hydrogen atoms of compound 16 200 52 Atomic positions and B eq values of compound 29 203 53 Bond lengths involving non-hydrogen atoms of compound 29 205 54 Bond angles involving non-hydrogen atoms of compound 29 207 55 Atomic positions and B eq values of compound 30 211 56 Bond lengths involving non-hydrogen atoms of compound 30 212 57 Bond angles involving non-hydrogen atoms of compound 30 213 58 Atomic coordinates and B gq values of compound 34 . . . . 216 59 Bond lengths involving non-hydrogen atoms of compound 34 217 60 Bond angles involving non-hydrogen atoms of compound 34 218 -xi-LIST OF FIGURES Figure Caption Page 1 ORTEP diagram of compound 16 , the major solid state photoproduct of 9 44 2 ORTEP diagram of COT 15 46 3 A packing diagram of starting material 9 52 4 ORTEP diagram of photoproduct 19 59 5 ORTEP diagram of COT 20 61 6 ORTEP diagram of COT 23 63 7 ORTEP diagram of COT 25 64 8 ORTEP drawing of the molecular structure of 29 67 9 ORTEP drawing of the molecular structure of 30 67 10 Packing diagram of compound 26 69 11 An ORTEP diagram of photoproduct 33 71 12 An ORTEP diagram of photoproduct 34 71 13 Solid state UV-VIS spectrum of irradiated 11 in a KBr pellet 75 14 ESR spectra of irradiated 11 . 76 15 Another photochromic dibenzobarrelene derivative, 36 . . 77 16 An ORTEP diagram of the molecular structure of 12 . . . . 82 17 An ORTEP diagram of the molecular structure of 38 . . . . 82 18 ORTEP diagram of compound 9 86 19 ORTEP diagram of compound 10 87 20 ORTEP diagram of compound 11 87 - x i i -21 ORTEP diagram of compound 26 87 22 Definitions of parameters p, e and <f>i, <j>2 88 23 Packing diagram of compound 10 91 24 Packing diagram of compound 11 91 25 Packing diagram of compound 19 95 26 Packing diagram of compound 33 96 27 Packing diagram of compound 38 96 28 Packing diagram of COT 15 99 29 Packing diagram of COT 20 100 30 Packing diagram of COT 23 100 31 Packing diagram of COT 25 100 32 Packing diagram of compound 16 104 33 Packing diagram of compound 29 104 34 Packing diagram of compound 30 104 35 Packing diagram of compound 34 105 - x i i i -LIST OF SCHEMES Scheme Page 1 4 2 5 3 8 4 9 5 11 6 12 7 13 8 14 9 15 10 17 11 17 12 20 13 37 14 40 15 42 16 45 17 47 18 48 19 55 20 56 21 58 22 60 23 62 -xiv-24 25 26 27 28 29 30 31 64 66 68 70 72 79 81 83 -XV-ACKNOWLEDGEMENTS I would like to thank my research supervisors, Professors John R. Scheffer and James Trotter for their guidance through these years, and for a l l their suggestions in preparing this thesis. They were more than kind to read this thesis as quickly as possible. I express deep appreciation for a l l the help Dr. Steve Rettig has offered me over the years in unravelling the mysteries of the 'black box'-thanks Steve, for teaching me some of the 'tricks' to get around the limited software a b i l i t i e s . 1 also like to thank Prof. G. Herring for his help in obtaining the ESR spectra. Now, thanks to a l l my friends for everything they have done for me. I enjoyed working in the two groups - a l l beers and pot-luck dinners we had. Special thanks to Johnathan for helping me put everything together in the last minute rush - I was getting a bit tired. Finally, I thank the Department of Chemistry for teaching assistance, and a l l the departmental staff for their help in various aspects. -1-INTRODUCTION -2-CHAPTER 1. PHOTOCHEMICAL INTRODUCTION Not too long ago recrystallization to remove impurities was the only use scientists had in the preparation of molecular crystals of organic compounds. The potential use of organic crystals as reaction media, not only to get a better insight into structure-reactivity relationships, but also to discover new reactions, has been recognized for approximately 30 years. Solid state organic chemistry, though s t i l l considered to be in its infancy, has established i t s e l f as a f i e l d of rapidly growing interest and diversity. Organic photochemistry in 'organized media',-'- of which the crystalline state is one, also includes polymers, inclusion complexes, surface adsorbed species, micelles, etc. The reasons for choosing the crystalline medium over other organized media are f a i r l y obvious - such as, highest degree of order and the availability of X-ray crystallography, a powerful structural tool which can provide intimate details of molecular conforma-tion and three dimensional arrangement. Magic angle spinning ± JC NMR, and FT-IR are two other techniques that further enhance the structural infor-mation one can obtain from the solid state. A serious limitation to the use of the crystalline medium is the d i f f i c u l t y of not knowing a pr i o r i how a given molecule aggregates i t s e l f in the crystal. Serious efforts are being made in this area, termed "crystal engineering", to produce 'tailor-made' packing motifs by con-t r o l l i n g the molecular structure, through synthesis and growth condi-tions.-^ Several intermolecular interactions have been recognized to play an important role in the molecular packing of organic solids. The role of hydrogen bonding as a powerful organizing force in molecular crystals and biopolymers has long been noted. Etter and co-workers have worked out several patterns of hydrogen bonding, and have successfully exploited their use in preparing acentric organic solids for applications in non-linear optics.^ Of other relatively weak intermolecular interactions recognized, CI...CI and C-H...0 interactions are found to direct packing in several planar aromatic compounds.-* The design of organic crystals so as to satisfy certain molecular and bulk requirements is invaluable in the development of various electrooptic devices;^ however, this thesis is con-cerned mainly with photochemical reactions in the crystalline medium. Therefore, a brief introduction is given here to the topic of solid state organic photochemistry.^ The f i r s t principle of solid state chemical reactivity was proposed by by Kohlschutter in 1918.^ The so-called "topochemical postulate" is an intuitive concept that recognizes the restrictions of the solid state to the atomic and molecular motions thought to be necessary for chemical reactivity. It suggests that only reactions requiring a minimum of such motions would be permitted in the solid state. Many years later, Schmidt and co-workers refined this view after their intensive and pioneering work on the crystalline photodimerization reactions of trans-cinnamic acid derivatives.^ They proposed that the packing of the molecules in the crystal lattice, which determines the distance and orientation of the reactive centers with respect to each other, is the dominant factor in controlling solid state reactions. The views of Schmidt and co-workers laid a good foundation for solid state organic chemistry. In later years, however, various researchers have proposed different concepts to explain solid state reactivity (some of which are general and some of which per-tain to a given situation), such as 'reaction cavity', 'steric compression control', 'free volume' and 'local stress'. The reaction cavity concept developed by Cohen^ considers a reacting molecule in a crystal as an entity lying in a cavity formed by the pres-ence of i t s neighbors. The shape of the cavity is determined by the pack-ing of the crystal, and movement of the reacting molecule is expected to exert 'pressure' on the walls of the cavity. Thus only motions that do not exert more than tolerable pressure (some movement is necessary for any molecular reorganization) would be allowed. In cases where two pathways of reaction are available, only the pathway leading to minimal disruption of the cavity would be feasible (Scheme 1). RE ACTA NTS " £ £ 7 ™ " PRODUCTS r & Path II is not favored in the solid state Scheme 1 Steric compression control, a term coined by Scheffer et a l . , 1 is more specific and pertains to an intermolecular contact thought to be responsible for the difference in photobehavior of compound 1 (and several other related compounds investigated) in solution and the solid state (Scheme 2). In solution, a minor high energy conformer is thought to be involved in a relatively faster intramolecular [2+2] dimerization to -5-Scheme 2 produce product 4, but compound 1 is locked in the minimum energy conformation in the crystal (organic molecules usually crsytallize in their lowest energy conformations-^) preventing any possibility of forming 4. Surprisingly, however, crystals of 1 upon photolysis result in an unexpected hydrogen abstraction-initiated product 3. Surprising because previous work had shown that compounds analogous to 1 upon photolysis transfer a hydrogen (H5 in this case) to the /3-carbon of the excited enone system resulting in a more stable radical (due to conjugation with the carbonyl group) center at the a-carbon. In the case of 1, a product initiated by hydrogen abstraction by the a-carbon (even though i t results in a less stable biradical) is formed in the solid state. A closer look at the packing diagrams derived from X-ray crystallography revealed an answer to this puzzle. It turns out that in the crystals of 1, the methyl group present on the /J-carbon has a close contact with another methyl group from one of the neighboring molecules which prevents the downward movement of the former methyl group necessary for the process of pyramidalization of the /3-carbon accompanying hydrogen abstraction. There i s , however, no such steric impediment in pyramidalizing the a-carbon, and this explains the observed product 3. This hypothesis is corroborated by additional calculations and computer simulation studies. An indirect verification of this comes from a later paper by Gudmundsdottir and Scheffer,^ who investigated the photobehavior of 1 in solid polymer films. It was expected that polymer films would be a medium roughly intermediate between solution and the pure crystalline state, as the three dimensional regularity of the crystals is lost while maintaining a higher viscosity and conformational r i g i d i t y . Thus, i f the steric compression referred to above is responsible for the unusual photobehavior of 1 in the crystalline state, then in polymer films i t should react normally to give product 2, resulting from hydrogen abstraction by the y3-carbon because specific intermolecular contacts are no longer operative. Such is indeed what was observed (Scheme 2). Gavezzotti designed a relatively accurate method of calculating vol-umes, by which crystal structures of photoreactive solids can be investi-gated for differences in available 'free space' (or void space which is not occupied) around the reactive centers.^ Owing to the presence of relatively stationary neighbors, in the i n i t i a l stages of a reaction i t is possible that the volume of free space (which is different in different directions due to the anisotropic environment) might force the reaction to proceed in a given pathway rather than in any otherwise equally possible pathway(s). This method of 'volume analysis' has proven to be quite suc-cessful in explaining solid state reactivity in some cases. In their efforts to understand the decomposition reactions of some diacyl peroxide crystals, McBride et a l . ^ have exposed another important aspect of solid state photochemistry. These authors' work shows that dif-ferences in the 'local stress' caused by the primary photochemical reac-tion influences the further consequences of the reactive intermediates formed. In the cases of several peroxide crystals investigated by using ESR among other techniques, and Gavezzoti's volume analysis, i t was found that the stress caused by the liberation of CO2 molecules in the primary step is what controls product formation and not the i n i t i a l average struc-ture of the crystal. To relieve the stress, in some instances rather drastic molecular rotations are found to be necessary which are consistent with the observed photoproducts. In this way, motions that are larger than thought to be possible within the reaction cavity can in fact occur. Thus, the effects of the crystalline medium on photoreactivity may be divided into two broad categories. A primary effect controls the confor-mation of a reacting molecule. In solution, due to conformational f l e x i -b i l i t y , reactions often occur from higher energy conformations, while in the solid state such f l e x i b i l i t y is lost, and reaction is limited to one lowest energy conformation; there are examples, however, of a given crys-ta l composed of two low energy conformations which may react differ-e n t l y . 1 6 A secondary effect restricts the motions required for a given reac-tion, through intermolecular steric effects which are dependent on the packing of the crystal. Most of the concepts that were discussed above f a l l into this category. A few chosen examples showing different photo-reactivity in solution and the solid state are given in Scheme 3. -8-Scheme 3 The Di-jr-Methane Rearrangement As i t s name implies, the di-7r-methane rearrangement is the rearrange-ment of a system of two 7r-bonds connected via a 'methane' (or saturated) carbon atom. When such a system is electronically excited i t is found to produce a vinyl-substituted cyclopropane system. The di-7r-methane rear-rangement1'' is one of the most thoroughly investigated photochemical reac-tions in solution (largely by H.E. Zimmerman and co-workers), and has more 1 Q recently been explored in the solid state. ° The mechanism proposed by Zimmerman for the simplest case of 1,4-pentadiene is shown in Scheme 4. Scheme 4 This is a general rearrangement in the sense that i t is applicable to both acyclic and cyclic di-jr-methane systems, and the individual 7r-bonds may also be part of a conjugated system (e.g. aromatic ring). The mecha-nism of Zimmerman is largely accepted, although the discrete existence of the i n i t i a l 1,4-biradical s t i l l remains questionable, 1^ especially in cases where one of the 7r-bonds is part of an aromatic ring. It is reasonable to assume, that the radical structures shown in Scheme 4 are points on the energy surface of the reaction in going from starting diene -10-to the product vinyl cyclopropane; they may represent energy minima in some cases. The various reaction characteristics like multiplicity, regioselectivity, etc. have been thoroughly studied and understood. 1^ Reaction Multiplicity Acyclic di-7r-methane systems undergo the rearrangement via their low-est singlet excited (S^) states, while their bicylcic counterparts rear-range via their lowest t r i p l e t excited (T^) states. This has been rationalized as described below.^ In acyclic di-7r-methane systems, the t r i p l e t excited states undergo a facile bond-rotation (known as the 'free-rotor effect', leading to cis-trans isomerization) which supersedes the rates of di-7r-methane rearrange-ment, whereas the rates of the rearrangement are higher than that of bond-rotation in singlet excited states. In bicyclic systems, due to r i g i d i t y the free rotor effect is not effective and the di-7r-methane rearrangement can occur from the t r i p l e t excited states. The reason that these systems do not undergo the rearrangement via their singlet excited states has been attributed to other facile rearrangements (usually electrocyclic) that are available which are more effective in deactivation. Reaction Regioselectivity When the two 7r-bonds are not symmetrically substituted, an interesting situation arises in which the di-7r-methane rearrangement may produce two different products that are regioisomers. The regioselectivity of the reaction as a function of various electron donating and withdrawing " sub--11-stituents has been studied and correlated with the s t a b i l i t i e s of the biradical species involved in each case.^ In general, the rearrangement proceeds in such,a way as to produce a more stable biradical, and when one of the 7T-bonds is part of an aromatic ring, the rearrangement proceeds in a way to regenerate aromaticity. Electron-donating groups are found to become part of the vinyl bond in the fi n a l product, whereas electron-with-drawing substituents form part of the cyclopropane ring. Some examples ill u s t r a t i n g these ideas are represented in Scheme 5. Scheme 5 -12-Photochemistry of Barrelene, Benzobarrelene and Naphthobarrelene It is interesting to note that the mechanism shown in Scheme 4 is derived from deuterium labeling studies on the di-vr-methane rearrangement of barrelene to semibullvalene (Scheme 6).^1 Since barrelene is a b i c y l i c system, i t undergoes the di-?r-me thane rearrangement via . It is known that direct irradiation of barrelene results in the formation of cyclooc-tatetraene (COT) via S^  (Scheme 6),^1 but to the author's knowledge no deuterium labeling studies on this transformation have been reported. semibullvalene (• represent* H Ubel, deuterium elsewhere) via Si barrelene COT Scheme 6 -13-The photochemistry of benzobarrelene and naphthobarrelene derivatives has been extensively investigated by deuterium labeling experiments by Zimmerman et al.^2.23 These compounds present an interesting situation because they consist of two different di-»r-methane systems, known as 'vinyl-vinyl' or 'benzo-vinyl' depending on which of the two jr-bonds is involved in the reaction. The formation of semibullvalene derivatives has been rationalized in terms of the mechanism proposed in Scheme 4. In these cases, i t is the f i r s t step of 2,4-bonding (known as vinyl-vinyl or benzo-vinyl bridging) that decides the f i n a l product (Scheme 7). not observed Scheme 7 -14-The mechanism thought to be followed for the formation of the corre-sponding cyclooctatetraene derivative in these cases is shown in Scheme 8. The mechanism involves an intramolecular [2+2] cycloaddition between the aryl-vinyl bonds resulting in a quadricyclane (not isolated), which under-goes thermal reorganization to form a COT with the labeling pattern shown in Scheme 8. In the case of benzobarrelene, a minor amount of another COT derivative is formed (not shown in Scheme 8) which is consistent with the same mechanism except that the i n i t i a l cycloaddition is vinyl-vinyl in nature. • represents H label deuterium elsewhere Scheme 8 The Photochemistry of Dibenzobarrelene and i t s Derivatives In 1966 Ciganek reported the di-jr-methane rearrangement of dibenzo-barrelene and some of i t s derivatives in solution, in which he noted the interesting regioselectivity observed which depended on the position of the substituent in the starting material.^ Following this work, several -15-researchers studied the t r i p l e t photochemistry of various dibenzobarrelene 9 5 derivatives of general structure 5 (Scheme 9) . J C0 2 Me 67: 33 Scheme 9 -16-The Zimmerman mechanism applied to these systems is shown in Scheme 9. The regioselectivities observed as a function of the nature of the bridgehead substituents have been rationalized in terms of the effect of X on the cyclopropyldicarbinyl biradical involved.^5 i t should be noted that the f i r s t step of the reaction (called benzo-vinyl bridging) is the product-determining step, as the opening of the 1,4-biradical would be expected to result only in regeneration of aromaticity. It was found that electron-donating and electronegative groups destabilize biradical B', and hence disfavor path b, while electron-withdrawing groups in principle stablize biradical B' and favor path b. Alkyl substituents present at the bridgehead position apparently favor path a for steric reasons. Opposing electron-withdrawing and electronegativity effects may operate simultaneously in determining the regioisomer formed in some cases (e.g., when X is NO2, the electron-withdrawing nature of this group in principle favors path b, whereas i t s high electronegativity destabilizes biradical B', and as a result only path a is observed). Direct irradiation of dibenzobarrelene was reported to produce diben-9 6 zocyclooctatetraene by Rabideau et a l , there were no reports of any deuterium labeling experiments on this transformation. Several deriva-tives of dibenzobarrelene were also found to produce corresponding COTs via their S^  states (Scheme 10).,26,27 These compounds were assumed to rearrange to COTs in much the same way as the benzobarrelene studied by Zimmerman, and the structures of COTs formed were not proved. -17-Scheme 10 Over the past few years in our laboratory, pioneering work on the solid state di-7r-methane rearrangement has produced several fascinating results. This research not only showed that dibenzobarrelene and it s various ester derivatives rearrange nicely to the corresponding semibull-valene derivatives in the crystalline phase, but also provided structure-reactivity correlations through X-ray crystallography. The general structure of the compounds investigated is that of 6 (Scheme 1 1 ) . ^ a C 0 2 R ' Scheme 11 -18-In these cases, regioisomers become possible owing to the loss of symmetry caused by the different substituents R and R'. It is readily apparent that in these compounds, benzo-vinyl bridging can occur in four different ways to afford each regioisomer as a pair of enantiomers. In one study, while keeping R = CC^ Me as a constant, R' was varied (CC^Et, CC^iPr, CC^tBu). In solution, there was a slight regioselectivity favor-ing 8 in which the smaller ester alkyl group occupies a more sterically congested position. In the solid state, in general, the regioselectivity was much higher (e.g., when R = CC^ Me, R' = CC^iPr, the 7 :8 ratio was 97:3) and accompanied by a reversal of solution regioselectivity in some cases. Attempts to rationalize these results from two different points of view are discussed below. The solid state conformation of a l l of these compounds was such that one of the ester carbonyl groups was more in-plane with the central vinyl double bond than the other (a primary crystal lattice effect). This means that (assuming Zimmerman's mechanism) benzo-vinyl bridging should occur at the vinyl carbon bearing the less-conjugated ester group in order to leave a radical at a center where i t may be stabilized through conjugation with the more-conjugated ester. Here an important assumption is made, which is that the excited state conformation is the same or close to that of the ground state of the reactant. However, the observed photoproducts did not follow the pathway predicted by the conjugative radical stabilization argument. A more successful hypothesis was found to be the one that takes into account the intermolecular steric interactions involved during the reaction (secondary crystal lattice effect). It was intuitively expected that unfavorable contacts may develop during the benzo-vinyl bridging process, -19-which causes rather drastic motions of the attached ester group. Packing potential energy calculations performed, using the non-bonded contacts that were developed by a computer simulation of the benzo-vinyl bridging processes, indicated that the increase in potential energy of the lattice was considerably smaller for the pathway observed experimentally in a l l cases studied of compounds of general structure 6. One exception was found with a compound of structure 5 when X = Me (Scheme 9), in which case the observed major product in the solid state was the one consistent with o o the conjugation effect. It was argued that in this particular case, the perfect conjugation and non-conjugation of the two ester groups with the central double bond may be responsible for the apparent anomaly. Probably one of the most interesting results obtained in our labora-tory concerns the mapping of the absolute steric course of a reaction in O Q the solid state. * Fortuitously, a compound of structure 6 with R = R' = C02iPr, was found to crystallize in a chiral space group (P2^2^2^). It was expected that the irradiation of such crystals may convert the dissym-metric influence of the lattice into permanent molecular chirality in the semibullvalene derivative that would be formed (which contains four chiral centers, but would be racemic i f formed in the absence of any chiral influence). Indeed, such an influence of the lattice was found and the semibullvalene derivative was formed in 100% enantiomeric excess. The opportunity created by this result was exploited by correlating the abso-lute configurations of the starting material and the photoproduct, which resulted in understanding the exact pathway followed (with reasonable con-fidence) by the rearrangement in the solid state. -20-Objectives of Present Research It was observed earlier that compounds of general structure 5 (Scheme 9) with X = Me,^ 0 a n d x = C l ^ 1 crystallize in conformations in which the ester carbonyl group adjacent to the bridgehead substituent is almost completely out of the plane of the central double bond, whereas the other ester carbonyl group is essentially in-plane with i t . In the present research, the solution and solid state photochemistry of compounds of gen-eral structure I (Scheme 12) was investigated. E 9: Rx = R2 = Me 1 0 : Rj_ - Ph, R2 = H 1 1 : Ri = R2 = CI R i E = COOMe Ph 12 Scheme 12 The crystal and molecular structures of the starting materials and their photoproducts were determined. Some of the questions to which answers were sought include the following: 1. How does bridgehead substitution affect the conformation of the ester groups with respect to the central double bond? -21-2. How does the crystal structure of the dichloro derivative differ from that of the dimethyl derivative? Since the size of the chloro and methyl groups is considered to be approximately the same, this may provide some understanding of the electronic versus steric factors that govern the crystallization process. 3. What are the molecular structures of the photoproducts? In the l i t -erature, the stuctures of the di-w-methane products (A and B, Scheme 9) formed from compounds of structure 5 are normally based on their 1H NMR spectra, and there were no reports of any additional structural proof. Thus, i t was thought to be desirable, especially in cases where there were no bridgehead protons, to prove the photoproduct structures by X-ray crys-tallography . 4. Do these compounds undergo rearrangement to the corresponding COTs? If so, would their structures be consistent with those derived from Zimmer-man's work on the corresponding transformation observed in cases of benzo-and naphthobarrelenes? The acetone-sensitized photolysis of bridgehead phenyl derivative 10 has been reported earlier by Iwamura et a l . ^ c The direct irradiation results were, however, not known. Hence this compound was investigated under direct photolysis conditions to determine whether formation of a COT derivative occurs, and in the solid state to derive any possible structure-reactivity relationships. Finally, the photochemistry of one additional compound 12 (Scheme 12) was investigated. This compound presents an interesting situation as there are three different pathways (a total of six including enantiomeric pathways) via which i t could undergo di-7r-methane rearrangement. It could also in principle produce a COT via S^ , in which case the structure of the COT may be compared to the known COT from naphthobarrelene i t s e l f . Also, any differences in photoreactivity in solution and the solid state may be explained by information obtained by X-ray crystallography. In a broad sense, the crystal and molecular structures of organic materials are needed for a larger data base which may help in a better understanding of the forces that govern crystal packing, and they may also help in a better understanding of chemical reactions at the molecular level by providing structure-reactivity relationships. CHAPTER 2. CRYSTALLOGRAPHIC INTRODUCTION As pointed 'out in the previous chapter, the use of X-ray crystal structure analysis has proven to be of immense help in gaining apprecia-tion for the chemical phenomena occurring in the solid state. Principles of X-ray diffraction by single crystals, and use of the technique in obtaining a clear three-dimensional picture of the contents of a crystal are well-established.32-36 Therefore, the intention of this chapter is mainly to introduce a general description of an 'X-ray experiment' (choos-ing a crystal to structure completion), and is largely restricted to the methods used for obtaining crystal and molecular structures reported in this thesis. Data Collection A crucial step in an X-ray crystal structure analysis is to measure the intensities of reflections that are diffracted by a crystal immersed in the X-ray beam. A l l structures reported in this thesis result from such intensity measurement data sets obtained at 21 ±1°C using a Rigaku AFC6 diffractometer equipped with a sealed tube X-ray source. The radia-tion used was graphite-monochromated CuKQ (average A = 1.54178 A). A crystal is normally chosen from i t s external quality and in some cases precession photographs are taken to assess the diffracting a b i l i t y of the crystal. A crystal of suitable dimensions is mounted on an AFC6 goniometer (glued to a glass fiber) in a general orientation, and centered in the X-ray beam. The incident beam collimator is 1 mm in diameter and crystal to detector distance is 28.5 cm. Data collection procedures are -24-controlled by the software called TEXRAY supplied by Molecular Structure Corporation.-^ After the crystal is mounted and centered, AUTO mode of data collection is initiated which through various preliminary steps proceeds to collect the intensity data.t First, the reciprocal lattice is searched systematically for strong reflections, up to 25 in number. Each reflection is centered and the intensity profile is plotted on a line printer which can be used to assess the crystal quality. If the reflections are s p l i t or are unreasonably broad, the crystal under examination is discarded and a different one mounted at this stage. Otherwise, the AUTO mode proceeds to the next routine of indexing the reflections in the working l i s t . A primitive unit c e l l and the corresponding orientation matrix are calculated. In case of d i f f i c u l t y in indexing a l l the reflections, AUTO mode w i l l stop and the reflections are indexed manually, or i f necessary, a different crystal is chosen and the whole process is restarted. The next routine, DELAUNAY, reduces and transforms the primitive c e l l to highest symmetry possible. In the next step, Laue symmetry is determined by the measure-ment of equivalent reflections (this routine is skipped for t r i c l i n i c c e l l s; equivalent reflections are empirically corrected for absorption based on a ^-scan). Based on Laue symmetry, c e l l centering and other previously chosen variables, data collection parameters are selected. Data collection limits for the indices are selected to obtain a unique set of data based on the •f Specific details of data collection, structure solution and refinement for each compound are presented and discussed in the Experimental section. -25-Laue group. Systematically absent reflections other than those arising from c e l l centering are measured. Three standard reflections are chosen based on their intensity and spatial distribution in \- Scan width in w (expressed as A + Btan0 ; the f i r s t part is dependent on the mosaic spread of the crystal, while the second part is dependent on variation in KQ^-KQ2 spli t t i n g of the radiation used which is in turn 0-dependent) is deter-mined by scanning the standard reflections. Both horizontal and vertical apertures of the detector are fixed at 6.0 mm by manually insertable s l i t s . u-2d scan type is used for a l l data collections reported in this thesis. The scan speed is chosen by the program based on average intensity of the reflections present in the working l i s t , and is fixed at 8, 16 or 32° min-"1 in w. Usually, the AUTO mode is interrupted at this stage, and i f necessary, the limits of data collection in h,k,l are adjusted so as to avoid high negative values for x a t higher 26 (an inherent d i f f i c u l t y with four-circle diffractometers). Data is normally collected in four shells of 26 (shell 1: 3.40-85.00; shell 2: 105.00; shell 3: 125.00; shell 4: 155.00°). Weak reflections with I < 40.0CT(I) are rescanned up to a maximum of 8 rescans and the counts are accumulated to improve the counting s t a t i s t i c s . Reflections are tagged unobserved i f I < 3cr(I). Stationary background measurements are made at the beginning and end of each scan, and the scan to background counting time is in the ratio of 2:1. The standard reflections are moni-tored after every 150 reflections collected, for crystal orientation and decay. If the deviation in any of the angular settings is greater than a preset maximum value, a l l the reflections in the working l i s t are recen-tered and a new orientation matrix is calculated. The intensity values are saved for any decay correction to be applied to the data. -26-At the end of the data collection, more accurate c e l l dimensions are calculated using the positions of strong reflections with high 28 values. Up to 13 reflections from the data collected (along with their equivalent Friedel reflections) satisfying the requirements for F 0^ s (> 50.0) and 28 (50.0-150.0°) are centered accurately and used in obtaining high angle c e l l parameters. Next, three strong reflections with x near 90° are used for ip-scans. The last step in this procedure is a constrained least-squares refinement (not applicable for t r i c l i n i c cells) which is performed to yield the f i n a l c e l l parameters. Data Reduction At the completion of the AUTO mode, the raw intensity data are auto-matically processed by the TEXSAN software provided by the Molecular Structure Corporation.-^ Intensities are corrected for background, and the standard deviations, CT(I)'S, are calculated by the following expressions: I = C - 2(b x + b 2) a 2(I) = [ C + 4(b x + b 2) + ( p i ) 2 ] where, C is total scan counts, b^ and b 2 are background counts, and p is a factor used to correct for the underestimation of a(I)'s for the strong reflections. A value of 0.03 or 0.05 is assigned to p for the structures reported in this thesis. The corrected intensities are then used to cal-' culate observed structure factor amplitudes, |F Q|. • |F G| = y u / L p ) where, Lp stands for Lorentz-polarization correction factors. -27-A Wilson a n a l y s i s ^ of the intensities is performed to estimate an overall temperature factor and a scale factor which is later used as the starting value for the scale factor in the least-squares refinement of the t r i a l structure. Based on the N(Z) t e s t , ^ any systematic absences in various classes of reflections collected, and on the Laue group determined earlier, an attempt is made to select the best possible space group. If the space group selection is successful, the direct methods program, MITHRIL,^1 w i l l automatically be executed. If the space group is not selected or i f the data are in a non-standard setting for the space group selected, MITHRIL w i l l not be executed. If the data should be trans-formed, a transformation matrix is provided. In such cases, MITHRIL is executed manually. Based on the three \j>-scans obtained earlier, an aver-age V-scan curve is calculated which is used in calculating transmission factors for an empirical absorption correction. Structure Solution A l l structures reported in this thesis are solved by direct methods using MITHRIL, as mentioned earlier. An attempt is therefore made here to outline br i e f l y the process of solving a structure by direct methods mainly from the point of view of MITHRIL. Because of some fundamental assumptions made regarding the electron density distribution in the unit c e l l , direct methods is most useful in solving "equal atom' structures. MITHRIL (Multan with Interactive f a c i l i t i e s , Triplet checking, Higher invariants, Random phasing, Intelligent control of flow and options and Linear equations phasing) is a series of computer programs designed to derive the phases for each reflection and to calculate an E-map (usually -28-for the 'best' phase set) for peak interpretation. First step in this procedure is to 'normalize' the observed structure factor amplitudes to give |E|'s, the normalized structure factor amplitude for each reflection by |E|2 - k 2 | F | 2 / e Z i f l 2 where k is a scale-factor, e is an integer, and f^ is the scattering fac-tor for atom i corrected for thermal motion. At this stage, i t is assumed a l l atoms have an isotropic (or spherical) thermal motion, in which case, f t - f j / exp (-B sin 20 /A 2) (1) 9 9 9 where B is the isotropic temperature factor equal to 87rzuz, and u z is the mean-square amplitude of vibration of the atom under consideration. There are methods to estimate the values for k and B (e.g. Wilson analysis), and e is normally 1 except for some special class of reflections in some space groups (e.g. in P2]_/c, e = 2 for hOl and OkO reflections and 1 for a l l others). After the |E|'S are calculated and tabulated in decreasing order, a s t a t i s t i c a l analysis, known as E-statistics, is done to estimate whether the space group is centric or acentric. This can be added as a double check to the N(Z) test performed in the data reduction stage. The program then proceeds to make a l i s t of what are called " t r i p l e t s " (not to be confused with t r i p l e t excited states of molecules which are also referred by the same name) using a number of reflections (normally decided by the program, but can also be specified by the user) above a -29-preset minimum value of |E|. A 'triplet' is set of three reflections whose indices sum to zero, such as, hi + h2 + (hi + h2 ) = 0 where hi = h^,k^,l^ and h2 = h2.k2.l2- The corresponding phase relation-ship, also known as a S2 relationship, is ^hl + **h2 + ^(hl+h2) = ^(hl , h 2 ) where <£(hl h2) l s t* i e phase of the relationship which is constant regardless of the choice of 'origin' to which the individual phases are being referred and is usually zero. Each such relationship can be given a weight «(hl h2) which i s , in general, proportional to the product of the IEI's that make up the relationship. A special case of the above relationship, called relationship, arises when two of the three reflections involved are the same. In such cases, the phase of a reflection can be estimated directly from the inten-sity data with a given probability that the assigned phase is correct. After a complete l i s t of S2 relationships is made, the program con-verges into a set of reflections that participate in a large number of £2 relationships. Based on the number of E2 relationships and their corre-sponding weights (K'S) in which a given reflection (hi) participates, a weight a^i can be estimated that the assigned phase for the reflection is correct. In general, three strong reflections with high weight (a's) are used to define the origin, and in non-centrosymmetric cases an additional reflec-tion may be used to fix the enantiomorph. In addition, any relation--30-ships developed, and a few more (usually 4-6) reflections are chosen as a 'starting set' of reflections. Each reflection in the starting set is assigned a phase, and the unknown phases for a l l other reflections in the data set are derived from the 'weighted tangent formula'. z 2 h 2 w h 2 w h i + h 2 * h l , h 2 s i n <*h2 + *h i+h2> tan<£hl = Z h 2 wh2 Whi+hl * h l , h 2 c o s ^ h 2 + ^h l+h2 ) where w^  is the weight with which each phase <j>^_ is estimated. Thus, a complete set of phases, known as a 'phase set' is obtained. The process then goes back to the starting set and some Of the phases are permuted between the possible values. For each such permutation, a phase set is derived making up a series of 'phase sets' possible, of which one might be the correct solution to the 'phase problem'. For centrosymmetric space groups, the phase value for the starting reflections can take either 0 or 7 r , whereas in non-centrosymmetric cases, the phase values can be any-where between 0 and 2n. Therefore, in the latter cases, since an infinite number of possible permutations exist, a procedure called 'magic integer method'^ is used to assign the i n i t i a l phases in the starting set. Each phase set is evaluated normally in terms of ^Karle ( r e l i a b i l i t y index), V° (psi-zero) test, and 'absolute figure of merit' for internal consistency making use of the 'Sayre r e l a t i o n s h i p ' . ^ 2 • ^ Each of these test results are appropriately weighed and a combined figure of merit (CFOM) is calculated for every phase set. In general, the phase set that has the best CFOM is expected to be the correct solution. The last stage of the direct methods program is calculation of an E-map, which is a Fourier synthesis, to obtain an electron density map of the unit c e l l using |E|'S (rather than |F j 's and hence the name) and a's, the corresponding phases from the best phase set using the expression: P(x,y,z) = (V)" 1 ESE |E| e i Q e -2*i(hx+ky+lz) where V is the volume of the unit c e l l . The 'peaks' in such a map are interpreted as atoms with the help of chemical knowledge available about the compound under investigation. A meaningful solution is said to be obtained i f some (or al l ) of the peaks correspond to a chemically reason-able fragment (or molecule). The approximate atomic positions obtained from the E-map constitutes a ' t r i a l structure' which is subsequently improved as described in the next section. If MITHRIL is not successful with default parameters, in general i t is found to be successful when the number of |E|'S to be used in t r i p l e t calculation is increased. Another option also used for solving some structures is the HARD option, which invokes the calculation of higher invariants (quartets and quintets where four and five reflections, respec-tively, whose indices sum to zero are utilized). By default, quartets are always calculated in MITHRIL i f the space group is symmorphic (i.e., no translational symmetry elements present). In these cases, additional figures of merit (NQEST, NQINT) are calculated and are used in obtaining CFOM. If only a partial-structure is found in an E-map from MITHRIL, another program (DIRDIF) is used to expand i t to a ' t r i a l structure'. DIRDIF is a direct methods phase refinement and extension program which uses the starting phases from the known molecular fragment to calculate the dif-ference structure factors, and is followed by a Fourier synthesis by which an electron denisty map is calculated. Thus, the known molecular fragment is expanded further to a size at which i t can be used as a ' t r i a l struc-ture' in the refinement process described below. Structure Refinement When the approximate positions of a l l or most of the non-hydrogen atoms are available from MITHRIL or DIRDIF, a process known as "least-squares refinement" is used to refine the various variables that describe the structure in order to obtain a better f i t between the observed struc-ture factors and those calculated for the model structure. A l l structures reported in this thesis are refined by full-matrix least-squares ^ method and the function minimized is 2 w ( |F 0| - k|F c| ) 2 where w is the weight given to each reflection and is derived from the counting s t a t i s t i c s : w = 1 / a2 (F Q), and k is a factor used to scale the calculated structure factors to match the observed structure factors. The variables that are normally refined are the positional parameters (x,y,z) and thermal parameters for each atom along with the scale factor. In the i n i t i a l stages of refinement, each atom is assumed to have an iso-tropic thermal motion and the corresponding scattering factors are cor-rected accordingly [Eq. (1)]. Once the t r i a l structure is complete (except for hydrogen atoms), a l l non-hydrogen atoms are refined allowing anisotropic or ellipsoidal thermal motion. The scattering factor expres-sion for anisotropic thermal motion is f = f° exp(-27r2 EjEj hihj a^aj*) Thus for an isotropic refinement, each atom has four variable parame-ters, and nine variables for anisotropic refinement. Neutral atom scat-tering factors are taken from Cromer and Waber.^ Anomalous dispersion terms are included in the scattering factor calculation (f° + A f + A f ' ) for a l l non-hydrogen atoms;^ the values for A f and Af' ' are those of Cromer.^ If found necessary, an empirical secondary extinction correc-tion is applied, in which case an additional parameter, g (extinction coefficient) in the following expression is refined. ^ | F o C o r r e c t e d | _ | ^ e x t | ( 1 + g | F | 2 L p ) In general, a "difference Fourier map" is computed after every few cycles of refinement. It is an electron density map based on the differ-ence between the observed and calculated structure factors. P o(x,y,z) - p c(x,y,z) = (V)~l EXE ( |F o| - | F c | ) e i a e - 2 7 r i ( h x + k y + l z > where a is the phase of F c. Using such a map any 'missing' atoms in the model structure are located, and is also helpful in the later stages of refinement to locate any hydrogen atoms or a possible disorder in the structure. -34-Hydrogen atoms that are not found in difference maps are calculated and placed in idealized positions (C-H distance = 0.95 A) and are not ref-ined. They are given isotropic thermal parameters which are 20% greater than the B eq (defined below) of the atom to which they are bound. B e q - (8* 2 / 3) 23 Uij a i * a j * (a^aj) The refinement is considered 'converged' when the shift in any of the parameters being refined is negligible compared to it s standard deviation. Finally, the 'trueness' of the model structure is estimated based on a few derived quantities shown below. (1) The R-factor, R - [ S |F Q|- |F C| ] / [ S |F Q| ] (2) The weighted R-factor, R„ = [ 2 w( |F O| - |F C| ) 2 / E w |F Q| 2 ] 1 / 1 (3) The goodness of f i t , S = [ £ w( |F 0| - |F C| ) 2 / (n-m) ] 1 / 2 where n and m are the number of observations and variables, respec-tively . (4) The residual peaks in the AF-map The closer the R-values to zero, the better the model structure describes the 'true' structure, while S is ideally equal to 1. The resid-ual electron density peaks (+ve or —ve) in the fi n a l AF-map indicate any electron density that is not accounted for by the calculated structure. For an organic structure, residual peaks between +0.25 and -0.25 eA-^ are normally expected. -35-Treatment of Disorder Often, a minor disorder in the structure is observed in the later stages of refinement, and is normally treated as follows. The highest residual peaks found on the AF-map are included in the model as s p l i t atoms (C or 0 as the case may be) with the occupancies distributed between the disordered atoms. In general, the occupancies are not refined but are given fixed values (say 80:20 or 70:30) depending on the B eq values of the atoms in question. The model is then refined further allowing anisotropic thermal motion of the disordered atoms with higher occupancy (> 70%) and isotropic thermal motion of their counterparts. This usually decreases the R-values, but does not always result in a meaningful geometry in the disordered atoms. Structure Completion After the refinement is converged, a l l bond lengths, angles are derived from the atomic positions, and their standard deviations are estimated from the errors associated with the corresponding parameters used.^ Molecular structures are drawn using 50% probability ellipsoids (ORTEP);50 packing diagrams are drawn using PLUTO.51 -36-RESULTS AND DISCUSSION -37-SYNTHESIS OF STARTING MATERIALS A l l the starting materials were prepared by the Diels-Alder addition reaction between dimethyl acetylenedicarboxylate and the corresponding substituted anthracene (Scheme 13). 5 2 Attempts to make bridgehead 9: R1 = R2 - Me 10: Ri = Ph, R2 = H 11: Rx = R2 = CI 12: R1 - R2 - Ph 13: R1 = Ph, R2 = H Scheme 13 -38-diphenyl-substituted dibenzobarrelene diester were not successful, as the Diels-Alder addition was found to occur only across the 1,4-positions of 9,10-diphenylanthracene producing 12. In the case of the Diels-Alder reaction with 9-phenylanthracene, a minor product (13) is also formed, which is consistent with 1,4-addition (Scheme 13). No solvent was used in carrying out the Diels-Alder reaction in the case of 9,10-dimethyl- and 9-phenylanthracene. For 9,10-dichloro- and 9,10-diphenylanthracene, i t was found that the yields were slightly better when o-xylene was used as a refluxing solvent. A l l starting materials were ful l y characterized by spectroscopic and analytical data, and molecular structures were confirmed by X-ray crystal-lography (see Experimental section). -39-PART I. PHOTOCHEMICAL DISCUSSION The photochemical results obtained are discussed in this part of the thesis. Only those crystallographic diagrams that are required by the nature of the discussion are presented here, but the actual discussion of a l l crystal and molecular structures determined is contained in Part II. -40-CHAPTER 3. THE PHOTOCHEMISTRY OF 9,10-DIMETHYLDIBENZOBARRELENE DIESTER 9t Tho photochemistry of compound 9 was investigated in solution and in the solid state, and was found to exhibit unique differences as a function of medium. In acetone, a solvent and a t r i p l e t energy sensitizer, mainly one product was obtained which was characterized as the semibullvalene derivative, 14 (Scheme 14). In acetonitrile (direct irradiation), 14 and E Me E 9 Me Me 14 acetonitrile or benzene Crystal 14 + 15 (COT) + 14+15 16 Scheme 14 t Dimethyl 9,10-dimethyl-9,10-dihydro-9,10-ethenoanthracene-11,12-dicarboxylate. -41-an additional product 15 , a cyclooctatetraene (COT) derivative were formed. Some additional minor products were also formed in both solvent media (as indicated by GC), but were not isolated. In the crystalline state, however, a new product 16 is formed as a major product along with the solution products 14 and 15 which were produced in minor amounts. The product ratios in various media along with their absolute error limits are presented in Table 1. Sums of a l l unidentified peaks observed on GC are given in the column of 'unknown' in Table 1. The product ratios in solution were found to be sensitive to both the solute concentration as well as the percent conversion to products. Control experiments indicated that photoproduct interconversion was not occurring under the photolysis conditions used, hence we may conclude that compounds 14, 15 and 16 are primary photoproducts of 9. As w i l l be discussed later, i t was the structure of the solid state product 16 that provided an important clue to some startling results obtained in the photochemistry of bridgehead substituted dibenzobarrelene diester derivatives. Table 1. Photoproduct ratios of 9 as a function of medium. Medium 14 15 16 Unknown (%) Acetone 89 0 0 11 ±2 Acetonitrile 27 51 0 21 ±3 Benzene 40 32 0 28 ±5 Crystal 12 7 80 1 ±2 Powder 27 12 50 10 ±2 -42-Discussion of Solution Photolysis Results The formation of compound 14 can easily be envisaged in terms of the di-7r-methane rearrangement of 9 via it s t r i p l e t excited state. This is consistent with the fact that 14 is formed exclusively in the presence of a sensitizer. Since 9 is symmetrically substituted, the di-7r-methane reaction is expected to produce only one semibullvalene derivative (14) as a racemate (Scheme 15). M e Scheme 15 -43-Application of Zimmerman's mechanism of COT formation from benzo- and naphthobarrelenes to compound 9 would produce a COT with mirror symmetry as shown in Scheme 15. The COT is formed only when irradiated in the absence of a t r i p l e t sensitizer indicating that i t is singlet-derived. Discussion of Solid State Photolyis Results As shown in Scheme 14, the solid state photolysis of 9 produced a new product (16) as the major product. Compound 16 was isolated from prepara-tive photolyses in the solid state. Mass spectrometry indicated that 16 is isomeric with the starting material, IR spectroscopy indicated that its ester carbonyl groups were saturated, and the NMR spectrum indicated that the compound is symmetric, as only one methyl (6H) and one ester methyl (6H) signal were observed. Based on literature precedent, compounds similar to 9 are expected to undergo only the di-7r-methane rearrangement and a rearrangement to a COT derivative under the photolysis conditions used. So i t was not possible to characterize the solid state product based only on i t s spectral data. Since compound 16 was crystalline, single crystal X-ray diffraction analysis was used as the definitive step in it s characterization. Following several attempts to solve the structure by direct methods (see Experimental section for details), photoproduct 16 was found to have an interesting pentalene-like structure with the indicated stereochemistry as shown in Scheme 14. The ORTEP drawing of compound 16 is presented in Figure 1. -44-Figure 1. ORTEP diagram of compound 16, the major solid state photoproduct of 9. A Possible Mechanism for the Formation of 16 The structure of 16 presented an interesting puzzle as to how i t may be formed from compound 9. Inspection of the structure of 16 provided a mechanism which is reasonably convincing in rationalizing i t s formation (Scheme 16). A biradical 17 which contains a pentalene-like skeleton can be formed from 9 by two 1,2-aryl shifts to the two different carbon atoms of the central double bond as shown by the arrows in Scheme 16. It is apparent that biradical 17 is quite stable, as i t is bis-benzylic and the radical centers in i t are tertiary in nature. Then, sequential 1,2-ester migration (involving the carbonyl group of the ester) to the radical sites would give 16 with the observed stereochemistry. The 1,2-ester migration involves the formation of an intermediate cyclopropyloxy radical, and hence cannot migrate to a different face of the dibenzopentalene. Aldehydes, ketones and thioester groups are known to undergo 1,2-migration to adjacent radical sites;however, the present example seems to be a M » 3 C C 0 C M « 2 C H 2 . — C — M « 8 C C 0 C H 2 C M « 2 M« 2 C C H 2 Scheme 16 The possible involvement of biradical 17 in the photorearrangement to 16 suggested the intriguing possibility that a COT may arise by the frag-mentation of 17 (see Scheme 16). The striking feature of such a possibil-ity is that the COT thus formed would have C 2 symmetry and not the C g symmetry expected from the 2n+2n mechanism of Zimmerman (see Scheme 15). This means that the actual structure of 15 may be either of the two COT -46-structures which are d i f f i c u l t to distinguish based on the spectral data. Again, a solution to this problem was sought in the determination of the crystal structure of 14. Single crystal X-ray analysis proved unambi-guously that the structure of the COT formed from 9 is of C 2 symmetry (shown in Scheme 16) and not the one shown in Scheme 15. The ORTEP draw-ing of compound 15 is shown in Figure 2. Since the X-ray analysis was Figure 2. ORTEP diagram of COT, 15. performed on the COT isolated from the solution photolysis, i t leaves open the possibility that the COT formed in the solid state may be a different one. Comparison of the GC retention times (DB-1 and DB-17 columns), including co-injection of an authentic sample of COT isolated from solu-tion along with the solid-state photolysis mixture, indicates that both COTs are the same. Additional corroboration came from the NMR spectrum of the solid-state mixture, in which the methyl groups of the COT appear at the same frequency as those of the COT isolated from solution. The reluctance of compound 9 to undergo 2n+2ir photocycloaddition to produce a cage compound may reasonably be attributed to steric factors -47-resulting from the presence of two bridgehead methyl substituents; the st a b i l i t y of biradical 17 may be the driving force for the alternative rearrangement pathway observed. In this context, i t is worth mentioning that while analysing the deuterium labeling pattern observed for the minor COT formed from benzobarrelene (the structure of the major COT formed is shown in Scheme 8, p. 14), Zimmerman and co-workers considered the possibility that the labels were 1,5-related as shown in Scheme 17, ^  however, the authors ruled this out by arguing that the deuterium labels, via vinyl-vinyl [2+2] Scheme 17 which are 1,4-related in the starting material, cannot be converted into a 1,5-relationship in the product. The present studies with compound 9, however, suggest such a conversion is possible. The generality of the formation of a COT with the unexpected structure was tested by studying a few more examples of bridgehead substituted dibenzobarrelene diesters. These w i l l be discussed in later chapters of this thesis. -48-Origin of Biradical 17 Since both compounds 15 and 16 are not formed in the photolysis of 9 in the presence of a t r i p l e t energy sensitizer, i t is reasonable to assume that biradical 17 is singlet-derived. A lik e l y pathway by which 17 may be formed is shown in Scheme 18. Zimmerman et a l . have considered double bridging on opposite sides of the central double bond in the case of bar-relene as one of the possible routes of the di-jr-methane rearrangement (Scheme 18).^1 On the basis of HUckel calculations, they concluded that E / E 9 Me Me Me E Products E Me 17 barrelene Scheme 18 semibullvalene -49-such double bridging would have a slightly higher energy barrier i f i t 01 H were to be a concerted rather than a stepwise process. •LD Similar argu-ments may be extended to the present case, which means that biradical 17 probably arises from a stepwise process as shown in Scheme 18. The two biradical structures prior to the formation of 17 are not necessarily intermediates, but are points on the energy surface leading to biradical 17, which may be regarded as an intermediate that leads to the products. As mentioned earlier in the Introduction (p. 9), controversy exists in these systems as to whether the f i r s t step of the reaction is benzo-vinyl bridging or a direct 1,2-aryl migration. It is also not clear i f disrup-tion of two aromatic rings simultaneously as shown in Scheme 18, is ener-getically favorable. Unique Reactivity of 9 in the Solid State If a common biradical is involved in the formation of both compounds 15 and 16, the question then arises as to why 16 is formed only in the crystalline state and not even a trace (as indicated by GC and NMR spectroscopy) is formed in solution phase. Experience in such a situation v suggests that this difference may be due to some unique features of 9 in the solid state, and its rationalization was approached from different points of view as discussed below. Recently, Zimmerman and Zuraw^6 have used the differences in volumes (AV) between starting material, the intermediate biradical species, and the f i n a l products in attempting to rationalize the formation of solid state products different from those formed in solution. They found that the volume change both in going from starting material to intermediate -50-biradical species as well as biradical to product was less for products formed in the solid state, as would be expected based on topochemical restrictions. With these ideas in mind, the molecular volumes of starting material 9, the two photoproducts (15 and 16) as well as the biradical 17 (generated by MM2 calculations 5^) were calculated using the program, MOLENC.58 The van der Waals radii used for C, 0 and H were 1.75, 1.40, 1.17 A, r e s p e c t i v e l y , a n a a n rj-H bond distances were taken as 1.11 A. It was anticipated that i f the volume change in going from 9 to 16 is smaller than that in going from 9 to 15, then the formation of 16 may be favored in the solid state owing to topochemical restrictions. The molecular volumes calculated indicate such is indeed the case; however, the difference in volume change (between 9 to 16 and 9 to 15) is very small (Table 2). It is not clear i f this small difference is significant enough to cause such a dramatic difference in reactivity. Table 2. Results of volume analysis. Species Volume (A 3) Volume Change (AV, A 3) 9-16 9 -+ 15 17-16 17 - 15 9 313.32 17 312.21 16 314.42 +1.10 - +2.21 15 318.56 +5.24 - +6. .35 In another attempt using the Best Molecular F i t (BMFIT) program, u the molecular structures of the starting material 9 and the two photoproducts -51-15 and 16 (one at a time) were superimposed in order to determine which of the photoproducts has better congruence with the structure of the starting material. This is a r i g i d atom-to-atom overlap of the structures in the sense that the conformations of the two molecules under investigation are fixed, while the program determines their best spatial overlap. The cor-responding atoms (hence the atomic numbering should correspond on a one-to-one basis) of the two molecules are matched and the extent of overlap is estimated as a sum of the squares of the distances between respective atoms, £A 2, a smaller value for which indicates a better overlap (i.e., a better f i t in shape) of the two structures. The program also tests the mirror image of the structure of the second molecule (in this case either 15 or 16) in determining the best f i t . A limitation of this approach is that the product structures used are derived from the X-ray crystal struc-tures of the pure products, which may not be the conformations in which they were formed in the lattice of the starting material during the pho-toreaction. The BMFIT analysis has proved to be successful in explaining the solid state regioselectivities of the di-7r-methane reactions of sev-eral dibenzobarrelene diesters (6, Scheme 11) studied in our labora-tory, ^ a but in the present case i t does not seem to be consistent with the observed results. In fact, the structures of the COT 15 and 9 have a better f i t compared to the solid state product 16 and 9 as indicated by the values of ZA^ of 64.8 and 67.1 A , respectively. Once again the differences are small and the significance of such an interpretation is questionable. Kinetic Factors. If biradical 17 exhibits different reactivity in solu-tion and the solid state, i t may reflect the fact that its conversion to -52-COT in solution is much more rapid than in the solid state. In other words, the biradical may be longer lived in the solid state and be capable of exploring alternative reaction pathways, such as double ester migration leading to 16. The difference in the rate of fragmentation of 17 in the solid state may be attributed to topochemical factors, because (specula-tively) i t appears that the structure of 16 resembles closely that of 17 (in the sense that planarity of the molecular frame is retained), whereas the structure of 15 does not. It is reasonable to assume that fragmenta-tion of the 1,4-biradical 17 may be d i f f i c u l t in the solid state because of poor orbital overlap which requires much molecular motion to overcome. A careful examination of stereo packing drawings and intermolecular con-tact distances of the lattice of the starting material failed to reveal any specific details that may help rationalize the unusual photobehavior. A packing diagram of compound 9 is shown in Figure 3. Figure 3. A packing diagram of starting material 9. -53-Single Crystal Versus Powder Reactivity As indicated in Table 1, i t was observed that, in general, the photo-product selectivity in the solid state is lowered when powdered material was irradiated. In several runs, the percent of product 16 formed in single crystals varied between 70-90 % depending on the size and quality of the crystals used; in contrast, 16 is formed in 45-55 % in photolyses using powdered material. This can be taken as added support for the sug-gestion that 16 is formed in the solid state owing to some unique features related to the bulk structure of the starting material. Also, the percent conversion for a given length of irradiation was typically lower (< 5%) in single crystal irradiations compared to that in powdered samples (5-10%), and melting was not observed in any of the solid state irradiations. Sim-i l a r behavior observed in the analogous case of 9-methyl dibenzobarrelene diester 2** (compound 22, p. 62) was attributed to a lower reaction selecti-vity at the surface of the crystal compared to that in the bulk, and since surface area increases when the crystal is powdered, the selectivity is lost to some extent. The Structure of Photoproduct 14 Compound 14, thought to be triplet-derived, was characterized based on it s spectral data, and is assigned the semibullvalene structure shown in Scheme 14. The assignment of the structure is based largely on i t s NMR spectrum, in which two non-equivalent methyl signals and two non-equivalent ester methyl signals were observed. The argument that com-pound 14 may have a structure resulting from the direct coupling of the -54-radical centers in biradical 17 can be dismissed because such a structure would be symmetric to NMR spectroscopy (i.e., would give rise to only one (6H) methyl signal and one (6H) ester methyl signal). The 1 3C NMR spectrum of compound 14 also supports the assigned structure. It should be mentioned here that the possibility of a structure for 14 that results from radical closure after one ester migration cannot be ruled out com-pletely; however, such a structure is not very l i k e l y owing to i t s ring strain. Also, compound 14 is not likely to come from biradical 17 because 17 is singlet-derived and 14 is not. Additional support for the di-7r-methane rearranged structure of 14 comes from the similar behavior of other compounds discussed in the next chapters. Several attempts to obtain good quality single crystals of this material for X-ray analysis were not successful. Thus, i t is reasonable to conclude that the t r i p l e t excited state of 9 is behaving as expected by undergoing the di-7r-methane rearrangement, whereas the singlet excited state is behaving unexpectedly by rearranging to an abnormal COT and to an unusual ester migration product in the solid state. The dibenzobarrelene derivative 18 (Scheme 19), an analogue of com-pound 9, was reported earlier to produce a COT which was assigned a struc-ture based on the 2n+2n mechanism.^1 Following our suggestion, these authors reinvestigated the structure of the COT formed by X-ray diffrac-tion methods and found i t to be of C 2 symmetry analogous to 15 and not the earlier assumed structure.^ 2 Compound 18 was also found to rearrange to a dibenzopentalene derivative (Scheme 19) analogous to 16. These results provide additional support for the involvement of 1,4-biradicals such as 17, and for the generality of the unexpected photorearrangemehts of -55-compound 9. Scheme 19 -56-CHAPTER 4. THE PHOTOCHEMISTRY OF 9-PHENYLDIBENZOBARRELENE DIESTER l o t Acetone-sensitized photolysis of compound 10 was reported by Iwamura et a l . 2 - * 0 to produce only one of the two possible di-7r-methane regioisomers, 19 (Scheme 20); there were no reports of any COT formation from 10. In the present study, compound 10 was photolysed in acetone, benzene, acetonitrile and in the solid state. In our hands, triplet-sensitized photolysis pro-duced mainly one product (19, the same as reported by Iwamura et al . ) , whereas in the direct irradiation in solution (and in the solid state) an additional product (20, Scheme 20), spectroscopically consistent with a COT structure, was obtained. The product ratios observed in various media are presented in Table 3. or benzene ( or solid state 19 + 20 (COT) Scheme 20 f Dimethyl 9-phenyl-9,10-dihydro-9,10-ethenoanthracene-ll,12-dicarboxy-late. -57-Table 3. Product ratios from photolysis of compound 10 as a function of medium. 19 20 (%) Acetone 97 3 ±2 Acetonitrile 27 73 ±3 Benzene 47 53 ±2 Crystal 48 52 ±3 Discussion of the Photolysis Results In acetone (a tr i p l e t energy sensitizer), the photoproduct obtained was characterized as di-7r-methane regioisomer 19. In the case of com-pound 10, which unlike 9 is not symmetrically substituted, the di-7r-methane rearrangement can proceed, in principle, in two different ways. The f i r s t step of vinyl-benzo bridging can occur at a vinyl site adjacent to the bridgehead phenyl group or away from i t . In the literature, characteriza-tion of such regioisomers from bridgehead-substituted dibenzobarrelene diesters has been based largely on NMR, in which the chemical shifts of the methine protons are dependent on their locations. J It was observed 8 that the methine hydrogens on the 4b and 8b carbons of dibenzosemibullval-ene derivatives resonate at S 5.0-5.1 and 4.2-4.5 ppm, res p e c t i v e l y . 2 5 0 Compound 19 showed a one proton signal at <5 5.08 ppm, which is consistent with the product formed via path b (Scheme 21). In light of possible unusual photorearrangements (described in the previous chapter), i t was -58-4b (5 5.0-5.1 ppm) not observed norcaradiene cycloheptatriene Scheme 21 thought desirable to prove the structure of 19 by X-ray crystallography. Single crystal X-ray analysis proved the structure to be that consistent with di-7r-methane rearrangement via path b. This also provides a general support of the expected methine hydrogen resonance in NMR spectra of simi-lar compounds. An ORTEP drawing of the molecular structure of photopro-duct 19 is shown in Figure 4. -59-Figure 4. ORTEP diagram of photoproduct 19. Why only path b? As alluded to in the Introduction (p. 16), the di-7r-methane rearrange-ment regioselectivity observed from compounds analogous to 10 is inter-preted in terms of the effect of the bridgehead substituent on the strength of the new bond formed (in the cyclopropyldicarbinyl biradical) close to i t , in the same way as a substituent R (Scheme 21) affects the equilibrium between norcaradiene and cycloheptatriene. In the latter case, i t was known that electron-accepting groups (like Ph, CN etc.) strengthen the opposite bond in the cyclopropyl ring and hence favor the equilibrium towards norcaradiene, whereas electron-donating groups weaken the same bond and hence favor cycloheptatriene. ^  Iwamura et a l . 2 - ^ c have rationalized the exclusive formation of 19 from 10 by arguing that vinyl-benzo bridging is favored close to the bridgehead phenyl group. In addi-tion, the 1,3-biradical formed via path b is more stable than that formed via path a because of the stabilization offered by the phenyl substituent in the former case. Traces of COT 20 formed in acetone (Table 3) may be -60-attributed to partial direct excitation of the starting material. Structure of COT-20 On direct irradiation, a product 20 spectroscopically consistent with a COT structure is formed via the singlet excited state (since i t is not formed in the presence of a t r i p l e t energy sensitizer) of 10. Again, the actual structure of the COT may be either that derived by the 2n+2n mecha-nism or that from the fragmentation of biradical 21 (Scheme 22) which are d i f f i c u l t to distinguish based on spectral data. Hence, a single crystal X-ray structure determination was carried out which proved the structure E 10 E=C02Me via [2+2] E not observed Scheme 22 of 20 to be that derived from the fragmentation of biradical 21. An ORTEP -61-diagram of COT 20 is given in Figure 5. Based on GC retention times, the COT formed in both the solution and the solid state photolysis of 10 are the same. Figure 5. ORTEP drawing of COT 20 This provides another example of the unexpected behavior of the sing-let excited state of a bridghead-substituted dibenzobarrelene in producing an abnormal COT while reacting as expected via the t r i p l e t excited state. It can also be taken as additional support for the assignment of the di-7r-methane rearranged structure for compound 14 formed in the t r i p l e t sensit-ized photolysis of 9. The reasons for not obtaining any ester migration product from 10 similar to that observed in the solid state photolysis,of 9 are not clear. CHAPTER 5. ADDITIONAL EXAMPLES OF COT STRUCTURES As discussed in the previous chapters, two bridgehead-substituted dibenzobarrelene diesters were found to react via their states to give abnormal COTs that are not expected based on previous studies with benzo-and naphthobarrelenes. It was therefore intriguing to ask whether a l l dibenzobarrelenes behave similarly, or is the unexpected behavior specific to some cases. In order to help answer this question, two more COTs that were prepared earlier in our laboratory, and which were characterized assuming a structure based on the 2n+2n mechanism, were reinvestigated by X-ray diffraction methods. One of the two COTs was obtained from the bridgehead methyl-substituted dibenzobarrelene diester 22 (Scheme 23). 3^ X-ray diffraction analysis of not observed Scheme 23 COT 23 formed from compound 22 showed that 23 is derived from the fragmen-tation of a bis-benzylic 1,4-biradical. GC retention times and NMR spectroscopy indicate that the same COT is formed in both the solution and solid state. An ORTEP drawing of COT 23 is given in Figure 6. Compound o o 22 also undergoes normal di-7r-methane rearrangement via T]_, and as for compound 10, none of the ester migration product was observed. Figure 6. ORTEP drawing of COT 23. Another COT available in the laboratoryt was that formed from com-pound 24 (Scheme 24). 6^ The two possible structures of COT 25 are shown in Scheme 24. Based on X-ray crystallography, the actual COT formed was found to be that consistent with a 27r+27r mechanism (a normal COT) . An ORTEP drawing of the molecular structure of 25 is given in Figure 7. f COT 25 was prepared and crystallized by M. Garcia-Garibay under the supervision of Prof. J. R. Scheffer at UBC.64 -64-not observed Scheme 24 Figure 7. ORTEP diagram of COT 25. The fact that compound 24 produces a normal COT via the 2n+2n mecha-nism proves that not a l l dibenzobarrelenes show similar chemical behavior via their singlet excited states. In other words, there are at least two different pathways by which COTs may be formed from dibenzobarrelene derivatives. Thus, four bridgehead-substituted dibenzobarrelene diesters (compounds 9, 10, 18, 22) produce an abnormal COT and one (compound 24) produces a normal COT. An examination of the substituent pattern in the structures of these starting materials indicates that the difference in the behavior of these compounds may be a result of differences in the steric crowding that would be present in a cage compound resulting from intramolecular 2n+2n cycloaddition. Compound 9 and 18 contain four, and compounds 10 and 22 contain three substituents on the barrelene unit, respec tively, and do not undergo 2n+2n cycloaddition; in contrast, compound 24, containing only two substituents on the barrelene unit, undergoes such an addition and proceeds to give a normal COT. Clearly, more examples are needed to confirm such an explanation based on steric effects. Finally, one interesting point of observation is that not a l l dibenzo-barrelene derivatives produce COTs under direct irradiation conditions. 9 f\ While unsubstituted dibenzobarrelene i t s e l f produces a COT via S^ , there does not seem to be any correlation between the number or the positions of various substituents present in dibenzobarrelene and a COT formation via their states. This may be a simple consequence of the relative differ-ence between the rate of the reaction to produce COT and other deactiva-tion modes available to the states of respective molecules. -66-CHAPTER 6. UNUSUAL REARRANGEMENTS OF 9-CHLOROMETHYLDIBENZOBARRELENE DIESTER 26t Compound 26 undergoes a normal di-w-methane rearrangement when photo-lysed in acetone, whereas in the solid state or in chloroform solution irradiation gives two additional products that were characterized as 6 S dibenzopentalene derivatives 29 and 30 (Scheme 25). J The molecular E E E CH2CI 29 30 Scheme 25 | Dimethyl 9-chloromethyl-9,10-dihydro-9,10-ethenoanthracene-ll,12-dicarboxylate. The synthetic and photochemical work presented in this chapter were done by J. Chen under the supervision of Prof. J.R.Scheffer at UBC, and w i l l be discussed in detail in the Ph. D. thesis of J. Chen. The X-ray crystallographic work was done by me. -67-structures of compounds 29 and 30 (stereoisomers of one another) are based mainly on X-ray crystallography, and their ORTEP drawings are presented in Figures 8 and 9, respectively. Figure 8. ORTEP drawing of the molecular structure of 29. Figure 9. ORTEP drawing of the molecular structure of 30. The most interesting feature of these unusual products is that their formation may be rationalized by postulating a biradical intermediate similar to biradical 17 proposed in the formation of dibenzopentalene derivative 16 from compound 9. A mechanistic rationale for the formation -68-of photoproducts 29 and 30 (not formed in t r i p l e t sensitized photolysis) is depicted in Scheme 26. Compound 26 rearranges via S^ to biradical 31, Scheme 26 which undergoes homolysis of the C-Cl bond to produce a chlorine atom plus radical species 32 having an exocyclic methylene group. Recombination of the radical pair thus produced would result in epimers 29 and 30. Prece-dent to such /?-carbon-chlorine bond fission of 1,4-biradicals is found in the work of P. J. Wagner.^ In the crystal lattice of 26, there is a short intermolecular CIO...CI contact of 4.28 A (sum of the van der Waals radii for C and CI is 3.55 A), which is interpreted as an indication of -69-the likelihood of an intermolecular chlorine atom transfer to the second-ary radical site at CIO in species 32.^ This is also a probable cause for the formation of epimers 29 and 30 in a higher yield in the solid state compared to that in solution. A packing diagram of compound 26 is shown in Figure 10. In this case, neither an ester migration product nor a COT were observed. However, these results add to the generality of the unusual behavior of states of some dibenzobarrelene derivatives. Figure 10. Packing diagram of compound 26. -70-CHAPTER 7. THE PHOTOCHEMISTRY OF 9,10-DICHLORODIBENZOBARRELENE DIESTER l i t The photochemistry of compound 11 was investigated in acetone, aceto-n i t r i l e , benzene and in the solid state. In acetone, mainly one product (33, Scheme 27) was isolated; however, preparative photolysis in acetoni-t r i l e gave 33 plus an additional product, 34. Since spectral data were E CI 34 Scheme 27 t Dimethyl 9,10-dichloro-9,10-dihydro-9,10-ethenoanthracene-11,12-dicarboxylate. not sufficient to characterize these products unambiguously, single crys-ta l X-ray analyses were carried out, which proved the structure of photo-product 33 to be a dibenzosemibullvalene derivative, and that of 34 to be an unusual peroxo-ring compound shown in Scheme 27. The molecular formula of 34 is confirmed by elemental analysis and chemical ionization mass spectrometry. ORTEP drawings of 33 and 34 are given in Figures 11 and 12, respecitively. In none of the media investigated was any formation of a COT or dibenzopentalene derivatives observed. Figure 11. An ORTEP diagram of photoproduct 3 3 . Figure 12. An ORTEP diagram of photoproduct 34 . Discussion of the Photolysis Results Formation of product 33 can be rationalized readily in terms of the di-7r-methane rearrangement of 11 via (Scheme 28) which, like compound 9, is expected to produce only one semibullvalene derivative as a race-mate. Compound 34 is thought to be a secondary photoproduct and i t s for-mation may be explained as shown in Scheme 28. It seems li k e l y that com-pound 33 once formed undergoes a photochemical bond fission of the strained CI 35 Scheme 28 cyclopropane ring to produce a 1,3-biradical species 35 (stabilized through conjugation with the aromatic rings) which is trapped by traces of molecular oxygen present in the photolysis mixture. The X-ray crystal structure of 34 proves that i t cannot be a result of trapping the 1,3-biradical species formed along the di-7r-methane rearrangement pathway, as such a product would have a peroxo-ring connected to different carbon atoms. This hypothesis was supported by independent photolysis of com-pound 33, from which a product was isolated which shows identical IR and NMR spectra to that of product 34 isolated from the photolysis of 11. An additional product was also obtained in minor amounts in the photolysis of 33, which was not characterized. As expected, analytical photolysis of 11 when carefully degassed pro-duces only 33 and no traces of 34 were found on GC. Also, analytical photolysis of 33 when carefully degassed does not show any reaction (as indicated by GC). In both cases, however, when the solution was not degassed formation of 34 was observed. Similar results were obtained by M.V. George and co-workers 6 2 in the photolysis of dibenzobarrelene derivative 18 (Scheme 19, p. 55). They postulated an intermediate peroxo-ring compound (not isolated) analogous to 34 which undergoes further rearrangements to give an unusual photopro-duct. They also found that this reaction did not occur when the photoly-sis was carried out in deoxygenated solutions. In the solid state (in both nitrogen atmosphere and in a i r ) , photoly-sis of 11 leads to exclusive formation of compound 33 (< 10% conversion) which suggests that the oxygen addition to the product formed in the lat-tice of 11 is not effective. Crystals of photoproduct 33 were found to be photostable to Pyrex-filtered irradiation (A > 290 nm). -74-Solid State Photochromism of compound 11 Compound 11 was found to be photochromic in the solid state. Single crystals or microcrystalline powders of 11 when irradiated (Pyrex f i l t e r , A > 290 nm) develop a purple-blue color which can be removed by allowing the crystals to stand in the dark at room temperature over a period of time. Heating the crystals speeds up the decolorization reaction. It is a reversible process which can be repeated several times without destroying the quality of the crystals. However, irradiated crystals or powdered samples l e f t exposed to ordinary laboratory light (visible) develop a slight yellow coloration. Also, prolonged irradiation (UV) in the solid state produces a brown or yellow coloration accompanied by some photoreaction to products (indicated by GC) with no signs of melting or cracking. Single crystals showed a more intense purple color compared with the powdered samples for the same duration of irradiation; however, the purple crystals upon powdering were found to be largely white, indicating that the coloration developed is restricted to the f i r s t few layers of the crystal. GC analysis of the purple crystals showed very l i t t l e or no photoreaction. The photochromic behavior was independent of whether the crystals were irradiated in a nitrogen atmosphere or in air. The same behavior was also observed when crystals were photolysed while being immersed in a solvent (hexane) in which they were insoluble. Thus, i t is clear that the purple color is due to the formation of some species induced by the UV-radiation in the solid state of compound 11, as no such phenomenon was observed in solution. The question then is what is the species responsible for this photochromic behavior, and since this -75-behavior is limited to the solid state, is there another crystalline modification that is not photochromic? Compound 11 was found to form crystals of two different morphologies -needles (grown from ethanol:petroleum ether:ethylacetate) and hexagonal plates (grown from petroleum ether:ethylacetate). However, the mps, FT-IR spectra, and the unit c e l l dimensions (within experimental error) were identical for both types of crystals. They also exhibited similar photo-chromic and photochemical behavior. To date, some attempts to unravel this puzzling behavior of compound 11 have been made, and in light of similar photochromic behavior observed with other compounds being investigated in our laboratory, speculations on the origin of the purple color are in order. The solid state UV-VIS spectrum of compound 11 obtained in a KBr pel-let (4 mg of compound 11 and 152 mg of KBr were used to make the pellet) after irradiation indicates a minor absorption band (A = 0.12 at 582 nm, Figure 13) which is consistent with the observed purple color. This band, although weak, was absent before irradiation and is not observed when the U c u o w < 1 . 6 0 6 A 6 0 6 0 A 1 9 9 . 9 4 8 6 ' . 0 6 6 0 ' . 7 0 6 . 6 ' A (nm) Figure 13. Solid state UV-VIS spectrum of irradiated 11 in a KBr pellet. -76-purple color fades. The FT-IR spectrum of irradiated 11 in a KBr pellet was identical to that of pure 11. Attempts to observe photo-emission from the purple crystals were not successful, probably owing to the small concentration of the colored species; however, attempts to observe an ESR signal were successful. ESR spectra of irradiated compound 11, both as a crystalline sample and powder sample at room temperature are shown in Figure 14. Also given in Figure 14 is the ESR spectrum of a powdered sample of 11 at 77K. The g-values observed (given in Figure 14) indicate that the radical species is organic in nature. 6^ The observation that the intensity of the ESR signal decreases with time and is absent when the purple color fades, supports the idea that the radical species responsible for the ESR signal are also the colored species (assuming the decay rates for both phenomena are equal). The ESR and the optical absorption data suggest that a radical species which absorbs in the vis i b l e around 582 nm is responsible for the photochromic behavior of compound 11. Similar ESR signals were observed with other photochromic compounds being investigated in our laboratory. Compound 26 (Scheme 25, p. 66) and another dibenzobarrelene derivative, compound 36 (Figure 15) exhibit sim-i l a r photochromic behavior. 6^ These compounds also turn deep purple upon E=C02Me Figure 15. Another photochromic dibenzobarrelene derivative, 36 . irradiation in the UV, fading with time in the dark. One important obser-vation with compound 26 is that i t forms crystalline dimorphs, one of which is not photochromic. It was also observed that in this case, photo-chromic crystals can be converted into non-photochromic crystals and vice-versa by suitable recrystallization conditions. This strongly suggests that crystal packing is a dominant factor in determining whether a given dimorph is photochromic or not, and the fact that these dimorphs Can be -78-interchanged stands against the argument that an impurity present in the crystal may be responsible for the photochromism. Photochromic crystals of 26, when used to make thin polymer films which were irradiated, did not exhibit photochromism as one would expect i f crystalline packing effects are required for such a behavior. Owing to the nature of the photochemical reactions these compounds undergo, i t is rather tempting to speculate that the radical species responsible for the photochromism is one of the biradicals involved in the di-7r-methane rearrangement pathway. From the structures of the d i - 7 r -methane biradical species (shown in Scheme 28 for the case of compound 11), one would not expect that these species absorb at longer wavelengths of the visible spectrum in order to show the purple color. It seems more like l y that the purple colored species is a radical ion, as radicals that can be expected from these systems are not likely to have such longer wavelength absorption bands. The photochromic behavior of compound 37 (Scheme 29), was thoroughly investigated by Zweegers et a l . and others.^ Crystals of 37, when irra-diated with UV-radiation turn from colorless to deep purple, and revert to colorless in the dark or upon heating. The irradiated crystals were also found to give rise to an ESR signal; in this case, however, i t was found that the decay rates of the optical absorption (around 530 nm) and the ESR signal were different. These authors propose, as shown in Scheme 29, two -79-Cl Scheme 29 colored species. different species, one of which is responsible for the ESR signal and the other for the color. Homolytic fission of the C-Cl bond gives a radical pair which is observed in the ESR spectrum, and a heterolytic fission of the same bond of the parent molecule results in the formation of a carbe-nium ion which is believed to be the colored species. The recombination of the species produced by irradiation gives the starting material. It is also proposed that the recombination of C l — and the carbenium ion produced in the photochromic crystals is hindered by a short intermolecular 0 ... CI contact, which is absent in non-photochromic modifications of crystal-line 37. Application of these mechanisms to the present case of compound 11 is problematic, as such homolytic or heterolytic C-Cl cleavage results in a radical or a positive charge present at a bridgehead carbon atom; however, -80-such a mechanism can be proposed for compound 26, which contains a chloro-methyl group. The facts that compound 36, which does not have a chlorine substituent, also exhibits similar photochromic behavior, and the ESR spectra observed in the case of irradiated 36 closely resembles that of irradiated 11, suggest that the photochromic behavior may not necessarily involve a mechanism that exploits the presence of a chlorine atom in the parent molecule. On the other hand, each of these compounds may have a different source for the photochromism observed. Thus, the picture that emerges from a l l of these observations is that some specific effects of the crystalline state are present which, probably coupled with some unimolecular phenomenon, makes these compounds photo-chromic in the solid state. The actual reasons are far from clear, and more work is required before a detailed explanation can be given. -81-CHAPTER 8. THE PHOTOCHEMISTRY OF A 2,3-NAPHTHOBARRELENE DIESTER 12t Compound 12 was prepared while attempting the synthesis of 9,10-diphenyl dibenzobarrelene diester (see p. 37). The photochemistry of 12 was investigated in acetone, acetonitrile, benzene and the solid state. In a l l media, only one product (38, Scheme 30) was obtained. In prepara-tive photolysis in acetonitrile, traces (about 5%) of an additional peak on GC were observed; this material was not isolated. However, analytical photolyses under carefully degassed conditions did not show any peaks on GC other than product 38. The structures of both 12 and 38 were confirmed by X-ray crystal structure analysis, and the respective ORTEP drawings are shown in Figures 16 and 17. Scheme 30 t. Dimethyl 9 ,10-diphenyl-l ,4-dihydro-l ,4-ethenoanthracene-ll, 12-dicarboxylate. -82-Figure 16. An ORTEP diagram of the molecular structure of 12. t Figure 17. An ORTEP drawing of the molecular structure of 38. f The molecular structure of compound 12 is well-determined by the X-ray analysis, however, the crystal structure is ambiguous and more work is required to determine the crystal structure completely. -83-Discussion of the Photolysis Results An examination of the structure of 12 reveals the presence of three different di-w-methane systems: a combination of unsubstituted and diester-substituted vinyl bonds, and the aromatic double bond. Formation of semibullvalene derivative 38 can be rationalized by the di-w-methane rear-rangement involving the two vinyl bonds (Scheme 31). Scheme 31 Formation of only 38 from 12 is consistent with the results obtained 9 3 by Zimmerman et a l . J in the case of 2,3-naphthobarrelene i t s e l f , in which case they found that di-7r-methane rearrangement occurs only via vinyl-vinyl bridging and not via naphtho-vinyl bridging, and no formation of COT was observed under unsensitized irradiation. However, 1,2-naphthobarrelene undergoes the di-7r-methane rearrangement preferentially via naphtho-vinyl bridging, although some of the products derived from vinyl-vinyl bridging -84-were also observed; 1,2-naphthobarrelene also produces a COT exclusively via 2n+2n cycloaddition involving the naphtho-vinyl bonds under direct ir r a d i a t i o n . 2 ^ These differences led to the suggestion that the bridging reactivity decreases in the following order: a-naphtho-vinyl > vinyl-vinyl > /J-naphtho-vinyl bridging The reason for not observing any COT from 2,3-naphthobarrelene was attrib-uted to the fact that intersystem crossing was efficient in deactivating the excited singlet states. 2-^ Compound 12, being a derivative of 2,3-naphthobarrelene, exhibits similar photochemical behavior. Benzosemibullvalene derivatives analagous to 38 are known to undergo a reversible photochemical 1,3-sigmatropic s h i f t ; ^ however, Pyrex-filtered irradiation of 38 in acetonitrile showed only traces of a new peak on GC, and the NMR spectrum of the photolysis mixture (after extensive i r r a -diation) showed no signals other than those due to the starting material. This could mean that 38 is photostable to radiation of A > 290 nm, or that the photostationary state favors the starting material almost exclusively. A Comment on the Solid State Reactivity of 12 Unlike the dibenzobarrelene diesters investigated, i t was observed that the photochemical reaction of 12 in the solid state was relatively faster (% conversion versus irradiation time) and also proceeds to high conversions. Irradiation (Pyrex f i l t e r ) of crystals of 12 overnight gave conversions of up to 40-60% after which the crystals are opaque and fra-gile, but no melting was observed. In the case of the compounds discussed in earlier chapters, similar irradiation of crystals would result in typi-cally < 5% conversion with no melting observed. -85-PART II. CRYSTALLOGRAPHIC DISCUSSION A brief discussion of a l l the crystal and molecular structures determined is presented here. Compounds are divided into separate classes based on their general structure, and their crystal and molecular struc-tures are compared. The actual details of data collection, structure solution, and the tables of atomic coordinates (including B eq values), bond lengths, angles, etc. are given in the Experimental section. The bond lengths and angles involving hydrogen atoms, and a l l anisotropic thermal parameters are submitted in the Appendix section. The observed and calculated structure factors for a l l structures are also given in the Appendix. -86-CHAPTER. 9 CRYSTAL AND MOLECULAR STRUCTURES OF BRIDGEHEAD SUBSTITUTED DIBENZOBARRELENE DIESTER DERIVATIVES A brief discussion of crystal and molecular structures of bridgehead substituted dibenzobarrelene diesters (compounds 9, 10, 11, and 26), whose photochemistry was discussed in previous chapters is presented here. Compounds 9 and 10 crystallized in space group PI with two molecules per unit c e l l , while compounds 11 and 26 were found to crystallize in space groups P2^/a and F2-±/c, respectively, with Z = 4. The molecular conformations of compounds 9, 10, 11 and 26 are given in Figures 18-21. Figure 18. ORTEP diagram of compound 9. -87-igure 21. ORTEP diagram of compound 26. -88-Some of the main features of the geometric parameters observed in the molecular conformations of compounds discussed in this chapter are sum-marized in Table 4. The angles p and e are the external and internal angles (see Figure 22) between the bonds connecting the benzene rings with the barrelene unit, respectively, and are systematically distorted from their normal values of 120°. The mean values of p and e reported in Table 4 are in good agreement with those observed by Wireko^1 and others.^ 2 These angular distortions are commonly observed when a benzene ring is fused to a cycloalkane, and especially so in cases of smaller alkane 73 rings.' J 1 9: Ri = R2 = Me 10: Rx •= Ph, R2 = H 11: Rx = R2 = CI 26: Ri = CH2C1, R2 = H Figure 22. Definitions of parameters p, e and <f>^, ^2. -89-Table 4. Some important geometrical data observed in the molecular structures of compounds discussed in chapter 9. Parameter 9 10 11 26 C = C (bridge, A) 1.335(2) 1.336(3) 1.337(4) 1.337(3) C—C (aromatic, A) 1.386 1.386 1.381 1.385 C-C-C (aromatic , °) 120.0 120.0 120.0 120.0 P (°) 125.9 126.4 127.6 126.4 e (°) 114.0 113.4 112.4 113.2 <t>l (°) 88.5(3) -72.9(4) -129.6(4) -111.5(3) 4>2 (°> -151.4(3) -31.8(4) -104.2(4) 20.2(4) Another striking feature of these compounds in the solid state is the conformation of the two ester carbonyl groups with respect to the bridge double bond. It was observed earlier, when a bridgehead substituent is present in the barrelene unit of these compounds, the ester carbonyl adjacent to this substituent is forced out of the plane of the central double bond, while the other ester carbonyl is more or less in-plane with the same double bond. U ' J This is measured in terms of the torsion angles (<£^  and (f>2> Figure 22) involving the ester carbonyl and the central double bond. A value close to 0 or 180° for the torsion angle suggests conjugation of the enone system, whereas a value close to 90 or 270° suggests non-conjugation. As can be seen in Table 4, compounds 10 and 26 for which <f>2 is closer to 0° and is closer to 90°, indicates the effect of the bridgehead substituent on the conformation of the nearest ester -90-group. However, the bond lengths observed in the ene-dioate system do not confirm any conjugation or non-conjugation, as pointed out by Wireko.^1 The bond lengths and angles of the aromatic rings are within expected values and their mean values are given in Table 4. A l l other bond lengths and angles are as normally expected. The packing diagrams of compounds 10 and 11 are presented in Figures 23 and 24, while those of compounds 9 and 26 are given in Figures 3 (p. 52) and 10 (p. 69), respectively. A few intermolecular contacts that are smaller than the sum of the van der Waals radii of the atoms involved were observed in a l l compounds presented in this chapter and the shortest of those are given in Table 5. Table 5. Short intermolecular contacts observed in the crystal structures of compounds discussed in chapter 9. Contact distance (A) Nature of contact 9 10 11 26 C . . . 0 C . . . H 2.87(3) 0 . . . H 2.49(5) CI. . . H H . . . H 2.33(4) 3.107(4) 2.79(3) 2.89(5) 2.88(5) 2.51(5) 2.52(3) 3.04(5) 2.97(3) 2.35(6) - 2.30(6) -91-Figure 24. Packing diagram of compound 11. In case of compound 26, some intramolecular contacts close to the sum of the van der Waals r a d i i were observed in v o l v i n g the two methylenic hydrogens of the bridgehead chloromethyl group and the nearest aromatic hydrogens. They are H8 ... H17A = 2.45; H8 ... H17B = 2.41; HI ... H17A = 2.48; HI ... H17B = 3.76 A. This suggests, as can be seen i n the ORTEP drawing of compound 26 (Figure 21) that the conformation of the chloro-methyl group is such that i t s methylene hydrogens are closer to one aromatic ring than the other. Also, one of these methylene hydrogens is 2.68 A away from the nearest carbonyl oxygen (of the same molecule) suggesting a weak hydrogen bond. -93-CHAPTER 10. CRYSTAL AND MOLECULAR STRUCTURES OF THREE SEMIBULLVALENE DERIVATIVES A brief discussion of crystal and molecular structures of the d i - 7 r -methane rearrangement products (compounds 19, 33 and 38) of compounds 10, 11 and 12 is given here. The primary interest in performing X-ray analysis of these compounds was to confirm their molecular structures. Compounds 19 and 38 crystallized in racemic space groups P2^/n (Z = 4) and C2/c (Z = 8), while compound 33 was found to crystallize in chiral space group P2]^2^2^ with four molecules per unit c e l l . The semibullvalene unit of these compounds contains four chiral centers, but as pointed out in discussion of the photochemical results, these compounds are expected to be formed as racemates. Only compound 33 was found to crystallize in a chiral space group with only one of the two enantiomers present in the crystal. The absolute configuration in this case was not experimentally determined; however, the data were refined in both possible enantiomorphs, and the one which gave a lower R-value was taken as the correct enantiomer present in the crystal (see Experimental section). The molecular conformations of compounds 19, 33 and 38 were presented earlier in Figures 4 (p. 59), 11 (p. 71) and 17 (p. 82). Some of the main features of the molecular structures of these compounds are summarized in Table 6. The angles p and e for these compounds were found to be farther from 120° than the same in cases of dibenzobarrelene derivatives, which is consistent with the fact that benzene rings are fused to smaller five-carbon rings in the dibenzosemibullvalene derivatives. It is known in the literature that when there is conjugation between cyclopropane and a -94-Table 6. Some important geometric parameters observed in the molecular structures of compounds discussed in chapter 10. Parameter 19 33 38 C-C (cyclopropane, A) 1.540 1.529 1.523 C-C (aromatic, A) 1.386 1.386 1.386 c-c--C (aromatic, °) 120.0 120.0 120.3 P D 129.0 128.7 130.0 e (°) 110.1 109.9 108.6 w-acceptor substituent the distal bond is shortened, while the vic i n a l bonds are lengthened.^ The bond lengths of the cyclopropane ring in present cases are slightly different from each other but do not show any systematic effects indicative of conjugation with the ester carbonyl groups. The mean C-C (cyclopropane) and C-C (aromatic) bond lengths are given in Table 6. In case of compound 38 (a naphthosemibullvalene derivative), the isolated C=C bond length is 1.330(9) A. The mean C—C bond length invol-ving only naphthalene skeleton is 1.397 A, and mean C-C bond length involving only the phenyl substituents is 1.376 A, although the mean C-C bond length including a l l aromatic rings is a normal 1.386 A. The mean C-C bond length connecting naphthalene and phenyl substituents is 1.502 A which is significantly higher than C-C (aromatic) and suggests non-conjugation. The mean internal angle involving the isolated C=C bond in the semibullvalene unit is 111.5° which is comparable to the e values. -95-The packing diagrams of compounds 19, 33 and 38 are given in Figures 25-27, and the short intermolecular contacts observed are summarized in Table 7. Table 7. Short intermolecular contacts observed in the crystal structures of compounds discussed in chapter 10. Contact distance (A) Nature of contact 19 33 38 c . . C 3 419(3) 3 487(7) 3 31(1) c . . CI - 3 367(4) -c . . 0 - - 2 971(8) c . . H 2 83(3) 2 8 (1) 2 68(5) 0 . . H 2 43(2) 2 4 (1) 2 57(6) H . . H 2 34(5) 2 39(7) -Figure 25. Packing diagram of compound 19. -96-Figure 27. Packing diagram of compound 38. -97-CHAPTER 11. CRYSTAL AND MOLECULAR STRUCTURES OF DIBENZOCYCLOOCTATETRAENE DERIVATIVES The crystal and molecular structures of the cyclooctatetraene deriva-tives (compounds 15, 20, 23 and 25) formed in the photolysis of dibenzo-barrelene derivatives discussed in earlier chapters are b r i e f l y discussed here. As pointed out in the photochemical discussion of these compounds, i t was necessary to establish the molecular structures of COTs formed in each case in order to distinguish the two possible routes of their forma-tion. COTs 15 and 25 crystallized in space group P2]_/n with Z = 4, and COT 23 crystallized in Pna2^ with Z = 4; whereas, COT 20 was found to crystallize in PI with two independent molecules in the asymmetric unit of the crystal. The molecular structures of COTs 15, 20, 23, and 25 were shown in Figures 2 (p. 46), 5 (p. 61), 6 (p. 63) and 7 (p. 64) in the section of Photochemical Results and Discussion. Some of the main structural features observed in a l l four COTs are summarized in Table 8. As known in the l i t e r a t u r e , ^ the cyclooctatetra-ene ring was found to be in a 'tub' shape (cis-fused to the benzene rings) with approximately equal geometry in a l l four compounds whose structures were determined. The various bond lengths of the dibenzocyclooctatetraene skeleton (i.e., C=C, C-C of the eight memebered ring and C-C of aromatic rings, mean values of which are given in Table 8) suggest the absence of conjugation between the benzene rings and the two double bonds of the eight membered ring. This non-conjugation is known to be a consequence of the tub shape. Unlike dibenzobarrelene and dibenzosemibullvalene derivatives, the -98-values of p and e observed for the dibenzocyclooctatetraene derivatives (Table 8) are not far from their expected values of 120°, which is rea-sonable as the benzene rings in these cases are connected to larger eight membered rings. However, i t is worth noting that in the dibenzo-COTs the values of p are less than 120° and the e values are slightly larger than 120°; whereas the trend in compounds of previous chapters was to have a systematically higher values for p and lower values for €. Table 8. Some of the main geometrical data observed in the molecular structures of COTs. Parameter 15 20t 23 25 C = C (COT, A) 1.340 1.339 (1.335) 1.341 1.335 C-C (COT, A) 1.489 1.485 (1.483) 1.482 1.481 C-C (aromatic, A) 1.386 1.383 (1.383) 1.387 1.388 C-C-C (aromatic, °) 120.0 120.0 (120.0) 120.0 120.0 P (°) 119.0 118.9 (118.9) 118.6 119.0 e (°) 122.0 122.1 (122.0) 122.3 122.0 f The values given in parantheses are for the second molecule in the asymmetric unit. The packing diagrams of COTs 15, 20, 23 and 25 are given in Figures -99-28-31; short intermolecular contacts observed are summarized in Table 9. Table 9. Short intermolecular contacts observed in the crystal struc-tures of compounds discussed in chapter 11. Contact distance (A) Nature of contact 15 20 23 25 c . . . C 3, .468(4) - 3 .42(1) 3. .408(3) c . . . . H 2, .81 (3) 2.82 2 .78 2. .86 (4) 0 . . . . H 2, .52 (3) 2.45(2) 2 •49(5) 2, .57 (2) H . . . . H 2, .38 - 2 .40 2. .42 (4) Figure 28. Packing diagram of COT 15. -100-Figure 31. Packing diagram of COT 25. -101-CHAPTER 12. CRYSTAL AND MOLECULAR STRUCTURES OF UNUSUAL REARRANGEMENT PRODUCTS A brief discussion of crystal and molecular structures of dibenzopen-talene derivatives (compounds 16, 29 and 30) and the unusual peroxo-ring derivative (compound 34) is presented here. The X-ray crystallographic analysis of compounds discussed in this chapter is the primary source of their molecular structure determination. Some of the main features of molecular geometry of these compounds are summarized in Table 10. Compound 16 was found to crystallize in space group C2/c with Z = 8. The structure was solved in space group Cc, and later refined in space group C2/c with two independent molecules each containing a crystallo-graphic 2-fold axis at positions (0, y, 1/4) and (0, y, 3/4). Thus there are two independent half-molecules present in the crystal accounting for Z = 8. The molecular conformation of compound 16 is shown in Figure 1 (p. 44). The dibenzopentalene skeleton of the molecule is nearly planar; one half of the molecule is related to the other by a C 2 axis perpendicular to the molecular frame and passing through the mid-point of the central C = C double bond of the pentalene. Compound 29 was found to crystallize in space group PI with Z = 4. The conformation of one of the independent molecules is shown in Figure 8 (p. 67). The second molecule was found to be disordered in one of the ester methyl groups, but otherwise has geometry nearly identical to that of the other molecule. Compound 30 was formed in the photolysis of compound 26 as a minor product. Due to the d i f f i c u l t y in i t s separation from the major epimer 29, the best batch of crystals of 30 was only 85% pure (as . shown by GC) -102-with the remaining 15% being compound 29. One of these crystals was used for data collection and the structure was solved in space group Pc. How-ever, the structure was refined later in space group P2^/c (Z = 4); see the Experimental section for details. Probably owing to the impurity of the crystal the structure was found to be disordered (R = 0.103). The molecular geometry of 30 is comparable with that of i t s stereo isomer 29 except the terminal exo.cyclic C = C double bond length was determined as 1.473(8) A much higher than that found in compound 29 (Table 10). The 1H NMR spectrum of 30 does not show any methyl resonance other than the two ester methyl groups present, and this rules out the possibility of this long bond being a C—C single bond. Thus the molecular structure of 30 though poorly determined from X-ray analysis is consistent with the spec-t r a l data. An ORTEP drawing of compound 30 is shown in Figure 9 (p. 67). Table 10. Some of the important geometric parameters of compounds dis-cussed in chapter 12. Parameter 16 29 30 34 C = C (isolated, A) 1.328(9) 1.330(3) [1.473(8)] 1.324(9) 1.333(3) C-C (aromatic, A) 1.376 1.384 1.381 1.378 1.386 1.382 C-C-C (aromatic, A) 120.0 120.0 120.0 120.0 120.1 120.0 p (°) 129.6 127.9 128.6 127.7 129.6 128.0 « (°) 109.3 111.5 110.7 111.5 108.9 111.4 -103-Compound 34 crystallized in space group PI with Z = 2. The molecular structure of 34 is shown in Figure 12 (p. 71). The peroxide is part of a puckered five membered ring with an 0-0 bond length of 1.464(4) A. The p and e values of these compounds (Table 10) compare well among themselves as well as with those of dibenzobarrelene and dibenzosemibull-valene derivatives. The external and internal angles involving the iso-lated double bond of the dibenzopentalene derivatives are f a i r l y distorted from normal 120° (like p and e) but their mean angle is 120° in cases of compounds 16 and 29, whereas i t is 118.7° in compound 30. The packing diagrams of compounds discussed in this chapter are given in Figures 32-35 and the short intermolecular contacts are summarized in Table 11. Table 11. Short intermolecular contacts observed in the crystals of com-pounds discussed in Chapter 12. Contact distance (A) Nature of contact 16 29 30 34 C . CI . CI . CI . C . 0 . H . . C . CI . c . H . H . H . H 3.434(8) 3.216(8) 3.459(8) 2.69 2.64 2.48 2.98(3) 2.91(3) 2.60(3) 3.445(7) 2.70(7) 2.76 2.66(5) 3.496(7) 3.364(3) 3.335(6) 2.97 2.59 -104-Figure 34. Packing diagram of compound 30 -105-gure 35. Packing diagram of compound 34. -106-EXPERIMENTAL -107-PHOTOCHEMICAL WORK General Melting Points. Melting points were determined on a Fisher-Johns melting point apparatus and are not corrected. Infrared Spectra. A Perkin-Elmer 1710 Fourier transform infrared spec-trometer was used for obtaining spectra in KBr pellets. A pellet typi-cally contained 2-3 mg of sample and 100-150 mg of KBr and was made using a Perkin-Elmer evacuated die 186-0002 and a Carver laboratory press model B. Nuclear Magnetic Resonance Spectra. A l l NMR and 1 3C NMR spectra were recorded on a Varian XL-300 spectrometer at 300 and 75.4 MHz respectively using deuterochloroform as solvent. Signal positions are reported in units of S, parts per million downfield from tetramethylsilane, which was the internal standard used. Multiplicity, number of protons and assign-ment are given in parentheses following 6. For 1 3C NMR spectra, the sig-nals were assigned based in part on the attached proton test. Mass Spectra. Both low resolution and high resolution mass spectra were recorded on a Kratos MS 50 mass spectrometer. A Kratos MS 80 mass spec-trometer coupled with a Karlo-Erba gas chromatograph was used for GC-MS s tudy. Ultraviolet spectra. A l l electronic absorption spectra reported were -108-recorded on a Perkin-Elmer A-4B UV-VIS spectrophotometer. Absorption maxima (^max) a r e given in nanometers, and the molar absorptivities are expressed as L mole - 1 cm-1. Elemental Analysis. A l l elemental analyses reported were performed by Mr. P. Borda, Department of Chemistry, UBC. Gas Chromatography. A Hewlett-Packard 5890 A capillary gas chromatograph attached to a Hewlett-Packard 3392 A integrator was used for a l l gas chromatographic analyses. A fused s i l i c a DB-1 column (15 m x 0.2 mm) was used for most analyses. In some cases, however, for comparison purposes, a DB-17 column was also used. A l l retention times (RT) reported were measured in minutes. General conditions: Column head pressure = 15 psi. DB-1 (one of the following conditions used). (i) Isothermal at 200 °C. ( i i ) I n i t i a l temp = 235 °C, i n i t i a l time <= 8 min, rate = 10°/ m i n> f i n a l temp = 250 °C, f i n a l time = 5 min. ( i i i ) I n i t i a l temp = 250 °C, i n i t i a l time = 8 min, rate = 10°/min, f i n a l temp = 270 "C, f i n a l time = 10 min. DB-17 Isothermal at 250 °C. Column Chromatography. For purification and separation purposes, s i l i c a gel 60 (230-400 mesh, E. Merck) was used in column chromatography.^6 Chemicals and Solvents. A l l substituted anthracene derivatives and -109-dimethyl acetylenedicarboxylate were obtained from Aldrich Chemical Co., Inc. and were used as recieved. A l l solvents were obtained from BDH Chemicals and were used as recieved. Petroleum ether used was low boiling (35-60 °C). Unless otherwise mentioned, spectral grade BDH solvents (ace-tone and acetonitrile) were used for preparative photolyses. Analytical photolyses were performed in spectral grade BDH solvents (acetone, aceto-n i t r i l e and benzene). For absorption spectra measurements spectral grade acetonitrile was used. Photolysis Procedures. A l l analytical and preparative photolyses were performed using a Hanovia 450 W medium pressure mercury lamp placed in a water-cooled Pyrex immersion well (thickness = 4 mm, transmits A > 290 nm). For analytical photolyses in presence of a sensitizer, a PRA/MODEL UV-12 pulsed nitrogen laser (A = 337 nm, pulse rate = 20-30 per sec) or a Hanovia lamp with a uranium glass f i l t e r (thickness = 2 mm, transmits A > 340 nm) were used. A l l photolyses were done at room temperature. For preparative photolysis, in general, the compound under investiga-tion was dissolved in the solvent and purged with nitrogen for at least 1/2 hr prior to the photolysis and purging was continued during the photolysis. For analytical photolysis, the samples were degassed by several freeze-thaw-pump cycles and sealed under nitrogen atmosphere prior to the photolysis. X-ray analysis. The molecular structures of a l l starting materials and photoproducts except compound 14 were confirmed by single crystal X-ray diffraction analysis. See the crystallographic experimental section for details. -110-Preparation of Starting Materials Synthesis of Dimethyl 9.10-dimethyl-9.10-dihydro-9,10-ethenoanthracene- 11.12-dicarboxylate ( 9 ) : In a round-bottomed flask f i t t e d with a reflux condenser and a drying tube, 0.75 g (3.6 mmoles) of 9,10-dimethylanthrac-ene and 0.82 g (5.8 mmoles) of dimethyl acetylenedicarboxylate were heated together at 200 °C for 45 min. The brown mass obtained was subjected to s i l i c a gel flash chromatography and elution with 8% (V/V) ethyl acetate in petroleum ether gave the Diels-Alder adduct as a solid which was recrystallized from chloroform-diethyl ether (0.77 g, 61%). MP: 190-1 °C. IR: 1726 (ester carbonyl stretch), 1622 (C=C stretch) cm-1. 1H NMR: 6, 2.27 (s, 6H, bridgehead methyl hydrogens), 3.71 (s, 6H, ester methyl hydrogens), 7.03-7.09 (m, 4H, aromatic) and 7.31-7.37 (m, 4H, aro-matic) . 1 3C NMR: 5, 13.60 (bridgehead CH3), 49.73 (bridgehead C), 51.99 (ester CH3), 120.80, 124.93 (aromatic C-H), 147.40, 150.16 (quaternary aromatic and vinylic C), 166.00 (carbonyl C). MS: m/e (relative intensity): 348 (M+, 8.8), 316 (5.9), 288 (78.0), 273 (5.4), 257 (8.9), 242 (5.1), 229 (100), 215 (38.2), 202 (13.4), 189 (9.3), 121 (5.1), 113 (4.7), 101 (6.3), 59 (9.1), 44 (6.7). Exact mass calculated ( C22 H20°4) : 348.1362; measured: 348.1366. Elemental Analysis: (C22H20°4) calculated: C, 75.84; H, 5.79. Found: C, 75.89; H, 5.82. UV (acetonitrile): 278 (e = 1851), 271 (e = 1984) nm. - I l l -Synthesis of Dimethyl 9-phenyl-9.10-dihydro-9.10-ethenoanthracene-ll.12- dicarboxvlate (10): In a round-bottomed flask f i t t e d with a reflux con-denser and a drying tube, 9-phenylanthracene (1.39 g, 5.47 mmoles) and dimethyl acetylenedicarboxylate (1.02 g, 7.18 mmoles) were heated together at 200 °C for 1 hr. GC analysis of the reaction mixture showed 9% of unreacted 9-phenylanthracene and two products at retention times 6.03 min (66%) and 7.70 min (25%). The reaction mixture was flash chromatographed over s i l i c a gel. Unreacted 9-phenylanthracene was eluted with 8% (V/V) ethyl acetate in petroleum ether and the products with 10-12% (V/V) ethyl acetate in petroleum ether. Although this did not afford a good separa-tion of the two products, upon standing overnight, the fractions gave nice crystals of the product with RT 6.03 min (0.25 g) which was subsequently characterized as compound 10. The fractions containing both products were concentrated under reduced pressure and the o i l obtained was dissolved in diethyl ether and allowed to crystallize. This yielded nice colorless crystals (0.68 g). Careful examination of these crystals revealed two morphologies, and the GC analysis of them separately showed that they belong to the two products and are about 99% pure. The stout prisms are of 10 and the thin rectangular plates are of compound 13. These crystals were hand separated and recrystallization from diethyl ether-ethyl acetate gave 0.33 g of 10 (total yield 27%) and 0.15 g of 13 (7%). Dimethyl 9-phenyl-9,10-dihydro-9,10-ethenoanthracene-ll,12-dicarboxylate (10). MP: 176-8 °C. IR: 1742, 1721 (ester carbonyl stretches), 1632 (C=C stretch) cm-1. 1H NMR: S, 3.67 and 3.78 (two s, 3H each, ester methyl hydrogens), 5.70 -112-(s, 1H, bridgehead methine), 6.93-7.78 (m, 13H, aromatic). 1 3C NMR: 6, 51.34 (bridgehead C-H), 52.20, 52.52 (ester CH3), 123.77, 124.78, 124.93,- 125.44, 127.65, 128.39, 130.38 (aromatic C-H), 134.82, 144.55, 145.24, 146.02, 154.27 (quaternary aromatic and vinylic C), 164.07, 168.17 (carbonyl C). MS: m/e (relative intensity): 397 (M+l, 7.4), 396 (M+, 26.8), 364 (11.5), 336 (79.0), 305 (31.8), 293 (25.0), 278 (100), 265 (6.9), 252 (28,0), 200 (6.9), 152 (7.3), 138 (32.5), 126 (21.1), 113 (22.1), 100 (10.3), 91 (9.6), 77 (16.5), 59 (98.9), 44 (46.1). Exact mass calculated ( C 2 6 H 2 0 0 4 ) : 396.1362; measured: 396.1363. Elemental Analysis: (C26H20O4) calculated: C, 78.77; H, 5.09. Found: C, 78.58; H, 5.04. Dimethyl 9-phenyl-1,4-dihydro-1,4-ethenoanthracene-11,12-dicarboxylate (13). MP: 218-21 °C. IR: 1732, 1722 (ester carbonyl stretches), 1642 (C=C stretch) cm - 1. -^H NMR: 6, 3.74 and 3.80 (two s, 3H each, ester methyl hydrogens), 5.07 (dd, J = 6 Hz and 3 Hz, 1H, bridgehead methine), 5.39 (dd, J = 6 Hz and 3 Hz, 1H, bridgehead methine), 6.78-6.85 (m, 1H, vi n y l i c ) , 6.98-7.05 (m, 1H, vi n y l i c ) , 7.28-7.78 (m, 10H, aromatic). 1 3C NMR: 5, 47.55, 49.55 (bridgehead C-H), 52.15, 52.36 (ester CH3), 121.22, 125.82, 125.86, 125.91, 126.41, 127.53, 127.61, 128.21, 128.33, 130.33, 130.77, 137.95, 138.78 (aromatic and vinylic C-H), 130.78, 131.36, 134.33, 137.85, 138.71, 140.62, 145.97, 147.91 (quaternary aromatic and vinylic C), 165.81, 166.45 (carbonyl C). -113-MS: m/e (relative intensity): 397 (M+l, 21.4), 396 (M+, 74.0), 364 (16.3), 336 (80.7), 322 (5.9), 309 (23.3), 305 (49.6), 293 (11.3), 276 (100), 265 (17.0), 252 (98.8), 239 (19.4), 226 (13.3), 215 (10.2), 200 (14.4), 182 (7.0), 138 (32.2), 126 (26.4), 125 (26.2), 119 (11.0), 113 (16.4) 59 (12.0). Exact mass calculated (C26H20°4): 396.1362; measured: 396.1363 Synthesis of Dimethyl 9.10-dichloro-9.10-dihydro-9.10-ethenoanthracene- 11.12-dicarboxvlate (11): In a round-bottomed flask f i t t e d with a reflux condenser and a drying tube, 5.01 g (20.3 mmoles) of 9,10-dichloroanthra-cene and 3.07 g (21.6 mmoles) of dimethyl acetylenedicarboxylate were placed. The contents of the flask were refluxed in 10 mL of o-xylene for a period of 5 days. GC analysis indicated a product peak at 13.04 min (49%) in addition to the unreacted starting material. Owing to the high boiling nature of the solvent used, rotary evaporation was not attempted. Instead, the contents of the flask were poured onto a packed s i l i c a gel column and the unreacted starting material was eluted with petroleum ether, and elution with 10% (V/V) ethyl acetate in petroleum ether gave the adduct as a yellow solid which was further purified by washing with several 5 mL portions of methanol. The resulting solid was colorless and weighed 2.15 g (27%). MP: 204-5 °C (recrystallized from petroleum ether-ethyl acetate). IR: 1734 (ester carbonyl stretch), 1616 (C=C stretch) cm - 1. XH NMR: 5, 3.78 (s, 6H, ester methyl hydrogens), 7.18-7.24 (m, 4H, aro-matic), 7.73-7.79 (m, 4H, aromatic). 1 3C NMR: 6, 52.70 (ester CH3), 70.5 (bridgehead C), 121.42, 126.41 (aromatic C-H), 141.48, 146.30 (quaternary aromatic and vinylic C), 163.10 -114-(carbonyl C). MS: m/e (relative intensity): 390 (M+2, 34.9), 389 (M+l, 13.8), 388 (M+, 55.2), 353 (17.3), 325 (100), 294 (72.4), 270 (27.6), 250 (46.3), 246 (41.1), 236 (26.4), 215 (11.0), 200 (67.9), 176 (31.7), 149 (8.4), 108 (56.5), 100 (1.0), 91 (77.2), 83 (9.5), 55 (23.3), 41 (20.4). Exact mass calculated (C20H14CI2O4): 388.0270; measured: 388.0275. Elemental Analysis: (C20H14CI2O4) calculated: C, 61.71; H, 3.63; CI, 18.22. Found: C, 61.58; H, 3.70; CI, 18.09. UV (acetonitrile): 276 (e = 1061) nm. Synthesis of dimethyl 9.10-diphenvl-l.4-dihvdro-l.4-ethenoanthracene-ll.  12-dicarboxylate (12): In a round-bottomed flask f i t t e d with a reflux condenser and a drying tube, 9,10-diphenylanthracene (1.02 g, 3.09 mmoles) and dimethyl acetylenedicarboxylate (1.02 g, 7.18 mmoles) were refluxed in 10 mL of o-xylene for 4.5 days. The reaction was monitored by GC which indicated the development of a new peak at RT 13.54 min (31%). The reaction was stopped, and after cooling the mixture to room temperature, about 25 mL of petroleum ether was added and the flask and i t s contents were l e f t at -10°C overnight. The product with RT 13.54 min was precipitated and collected, and this process was repeated with the f i l t r a t e u n t i l most of the product was separated.^ The solid thus obtained (0.83 g, 92% pure by GC) was flash chromatographed over s i l i c a gel by using 10% (V/V) ethyl acetate in petroleum ether. Removal of solvent gave a yellow solid (0.29 g, 20%), which upon several washings with methanol followed by recrystallization from diethyl ether-ethanol, gave colorless hexagonal plates. These were later characterized as compound 12; none of -115-the adduct corresponding to 9,10-addition was isolated. MP: 241-3 °C. IR: 1732, 1721 (ester carbonyl stretches), 1645 (C=C stretch) cm - 1. 1H NMR: 5, 3.75 (s, 6H, ester methyl hydrogens), 5.13-5.18 (m, 2H, bridge-head methine), 6.81-6.87 (m, 2H, vin y l i c ) , 7.28-7.73 (m, 14H, aromatic). 1 3C NMR: rS, 47.60 (bridgehead C-H) , 52.24 (ester CH3) , 125.78, 126.54, 127.63, 128.33, 128.42, 130.47, 130.92, 138.59 (aromatic and vinylic C-H), 130.37, 133.70, 137.82, 138.17, 146.97 (quaternary aromatic and vinylic C) , 165.81 (carbonyl C). MS: m/e (relative intensity): 473 (M+l, 11.5), 472 (M+, 31.8), 440 (11.0), 412 (32.2), 381 (16.5), 353 (22.0), 330 (100), 313 (12.9), 300 (6.9), 276 (11.6), 252 (50.2), 169 (8.9), 163 (15.9), 156 (15.2), 150 (12.8), 106 (24.4), 91 (61.0), 77 (11.0), 69 (9.0), 51 (8.7), 43 (31.6). Exact mass calculated (C32H24O4): 472.1675; measured: 472.1667. UV (acetonitrile): 330 nm (sh, e = 861). PHOTOCHEMISTRY OF DIMETHYL 9,10-DIMETHYL-9,10-DIHYDRO-9,10-ETHENOANTHRA-CENE-11.12-DICARB0XYLATE (9) Preparative Photolysis of 9 in Acetone: Compound 9 (0.25 g, 0.72 mmoles) was photolyzed for 40 min in 300 mL of spectral grade acetone using the standard procedure described earlier. GC analysis of the reaction mixture indicated mainly the presence of two new peaks at RT 7.47 and 7.87 min and traces of some other products. Solvent evaporation in vacuo gave an o i l which was dissolved in diethyl ether and the solvent was allowed to evaporate slowly. The yellow solid obtained from . this -116-treatment was washed with diethyl ether until a l l the color was removed. The resulting white solid (75 mg, 30%) was characterized as compound 14 and found to decompose on the GC column to show two peaks. Repeated attempts to obtain single crystals of this material for X-ray analysis were not successful. Dimethyl 4b.8b.8c.8d-tetrahydro-4b.8b-dimethyldibenzo f a.f1cyclopropa fcdl- pentalene-8c.8d-dicarboxylate (14). MP: 162-5 °C. IR: 1723 (ester carbonyl stretch) cm-1. LH NMR: 6, 1.90 and 1.98 (two s, 3H each, methyl hydrogens), 3.76 and 3.88 (two s, 3H each, ester methyl hydrogens), 7.04-7.59 (m, 8H, aromatic). 1 3C NMR: 5, 13.87 and 15.47 (CH3), 51.68 and 52.36 (ester CH3), 52.8, 56.3, 56.6, 61.44 (quaternary sp 3 C), 119.13, 119.26, 124.36, 125.69, 126.94, 127.19, 127.51, 127.63 (aromatic C-H), 133.60, 138.33, 152.54, 152.67 (quaternary aromatic C), 167.67, 168.80 (carbonyl C). MS: m/e (relative intensity): 348 (M+, 7.5), 316 (4.1), 289 (14.5), 288 (43.7), 273 (7.6), 257 (5.0), 242 (4.7), 229 (100), 215 (39.4), 202 (9.7), 189 (4.4), 106 (5.0), 94 (3.4), 59 (2.7). Exact mass calculated ( C22 H20°4) : 348.1362; measured: 348.1364. Elemental Analysis: (C2 2H 20 04) calculated: C, 75.84; H, 5.79. Found: C, 75.61; H, 5.89. Preparative Photolysis of 9 in Acetonitrile: Compound 9 (0.22 g, 0.63 mmoles) was photolyzed for 5 1/2 hr in 300 mL of reagent grade acetonitrile using the standard procedure. GC analysis of the mixture -117-indicated new peaks at RT's 4.59 (47%), 6.82 (10%), 7.52 (20%), 7.93 (6%) and a few other smaller peaks. Evaporation of the solvent in vacuo l e f t an oily foam which upon scratching with 5 mL of diethyl ether gave a brown solid which did not show any peaks on GC. The solid was f i l t e r e d off and the f i l t r a t e was found to contain a l l the photoproducts as shown by GC. Removal of solvent gave an o i l which was flash chromatographed over s i l i c a gel by using 8% (V/V) ethyl acetate in petroleum ether. Although this did not result in complete separation, a few fractions contained the photo-product with RT 4.59 in about 95% GC purity. Removal of solvent from these fractions gave an o i l which crystallized. Recrystallization from diethyl ether gave nice prisms (55 mg, 25%) which were subsequently characterized as compound 15. Attempts to isolate the photoproduct with RT 6.82 were not successful. The peaks at 7.52 and 7.93 correspond to 14 isolated from the photolysis in acetone. Dimethyl 5.11-dimethyldibenzo[a.e1cvclooctene-6.12-dicarboxylate (15). MP: 132-4 °C. IR: 1713 (ester carbonyl stretch), 1642 (C=C stretch) cm - 1. 1H NMR: 6, 2.40 (s, 6H, methyl hydrogens), 3.71 (s, 6H, ester methyl hydrogens), 7.01-7.16 (m, 8H, aromatic). 1 3C NMR: 5, 22.63 (CH3), 51.93 (ester CH3), 125.73, 126.85, 127.35, 127.92 (aromatic C-H), 129.87, 135.64, 142.99, 149.73 (quaternary aromatic and vinylic C), 168.20 (carbonyl C). MS: m/e (relative intensity): 348 (M+, 9.5), 317 (6.2), 288 (100), 257 (8.8), 245 (4.2), 229 (96.6), 215 (55.2), 202 (12.6), 189 (5.9), 113 (23.5), 100 (20.0), 94 (4.0), 88 (9.4), 75 (5.5), 59 (3.7), 44 (5.9), 32 -us -es. 8). Exact mass calculated (C 22H20°4) : 348.1362; measured: 348.1361. Elemental Analysis: (C2 2H2o04) : calculated: C, 75.84; H, 5.79. Found: C, 75.84; H, 5.73. ' Preparative Photolysis of 9 in the Solid State: Compound 9 (0.3 g, 0.9 mmoles) was photolyzed in the form of polycrystalline samples between Pyrex plates (2.5x7.5 cm) for 24 hr (5% conversion by GC). The reaction mixture was dissolved in chloroform-diethyl ether and the unreacted start-ing material was crystallized out. Then the starting material was photo-lyzed again in the crystalline form as described above. This process was repeated several times un t i l enough photolysis mixture was obtained to chromatograph. An o i l (0.2 g) containing approximately 50% unreacted 9 and the photoproducts was subjected to s i l i c a gel flash chromatography by using 8% (V/V) ethyl acetate in petroleum ether. This resulted in the separation of photoproducts from the unreacted 9. The resulting mixture ( o i l , 0.1 g), rich in the solid state product (RT 5.26 min), was subjected to conventional gravity s i l i c a gel column chromatography and elution with 4% (V/V) ethyl acetate in petroleum ether gave products with RT's 4.50 (15) and 5.26 min (16) as a mixture (21:78 by GC) in the form of a colorless solid. Repeated fractional crystallization from petroleum ether-diethyl ether yielded nice needles (20 mg, 7%) of the product with RT 5.26 which was later characterized as compound 16. -119-Dimethyl 5.10-dimethyl-5.10-dihydroindeno[2.1-alindene-5.10-dicarboxylate mi. MP: 158-60 °C. IR: 1733 (ester carbonyl stretch) cm-1. 1H NMR: 6, 1.79 (s, 6H, methyl hydrogens), 3.68 (s, 6H, ester methyl hydrogens), 7.24-7.66 (m, 8H, aromatic). 1 3C NMR: 5, 22.26 (CH3), 29.77 (quarternary sp 3 C), 52.76 (ester CH3), 120.31, 123.89, 125.85, 128.01 (aromatic C-H). Other carbon signals were not observed as the concentration of the solution was very low. MS: m/e (relative intensity): 348 (M+, 49.6), 289 (12.9), 273 (4.0), 257 (18.6) , 245 (18.0), 230 (100), 215 (96.4), 202 (10.2), 189 (7.4), 169 (12.7) , 113 (11.4), 101 (11.7), 94 (3.4), 88 (5.2) 69 (17.5), 44 (14.3), 32 (4.0). Exact mass calculated (C 22H20°4) : 348.1362; measured: 348.1370. PHOTOCHEMISTRY OF DIMETHYL 9-PHENYL-9,10-DIHYDRO-9,10-ETHENOANTHRACENE-11,12-DICARBOXYLATE (10) Preparative Photolysis of 10 in Acetonitrile: Compound 10 (0.45 g, 1.14 mmoles) was photolyzed in 300 mL of spectral grade acetonitrile using standard procedure unt i l a l l the starting material was reacted (13 hr). GC analysis showed new peaks at RT's 3.68, 3.75, 4.20 and 7.26 min. Sol-vent removal gave an o i l which was subjected to s i l i c a gel flash chroma-tography by using 8% (V/V) ethyl acetate in petroleum ether. The fract-ions containing the product with RT 3.7 min were collected and solvent removal under pressure gave a white solid which upon recrystallization from chloroform-diethyl ether gave colorless needles (40 mg, 9%) which -120-were later characterized as compound 20. The fractions showing GC peaks at RT's 4.20 and 7.26 were combined and upon removal of solvent gave a colorless solid which was recrystallized from chloroform-diethyl ether to give nice prisms (21 mg, 5%); these were subsequently characterized as compound 19. This compound was found to decompose on GC to show two peaks at RT 4.20 and 7.26 min. Dimethyl 5-phenvldibenzo[a.e1cyclooctene-6.12-dicarboxvlate (20). MP: 193-6 °C. IR: 1719 (ester carbonyl stretch), 1636 (C=C stretch) cm - 1. XH NMR: 6, 3.43 and 3.80 (two s, 3H each, ester methyl hydrogens), 6.88-7.59 (m, 13H, aromatic), 8.19 (s, 1H, v i n y l i c ) . 1 3C NMR: 5, 51.93, 52.37 (ester CH3), 126.96, 127.15, 127.45, 127.52, 127.92, 128.01, 128.10, 128.56, 128.63, 129.09, 129.56, 141.87, 141.92, 142.03 (aromatic and vinylic C-H), 132.83, 134.61, 135.52, 136.14, 136.59, 139.68 141.30, 146.89 (quaternary aromatic and vinylic C), 166.93, 168.85 (carbonyl C). MS: m/e (relative intensity): 397 (M+l, 14.4), 396 (M+, 50.7), 365 (5.3), 336 (43.6), 305 (47.1), 293 (19.4), 278 (100), 276 (57.0), 265 (5.1), 250 (5.1), 236 (7.6), 215 (7.3), 201 (7.3), 152 (2.9), 138 (23.7), 125 (9.9), 112 (3.6), 83 (7.2), 59 (5.5), 44 (3.4). Exact mass calculated ( C26 H20°4) : 396.1362; measured: 396.1352. Elemental analysis: (C26H20O4) calculated: C, 78.77; H, 5.09. Found: C, 78.63; H, 5.02. -121-Dimethyl 4b.8b.8c.8d-tetrahydro-8b-phenyldibenzo\a.f1cvclopropa Tcdl- pentalene-8c.8d-dicarboxylate (19). MP: 201-3 °C. IR: 1745 and 1715 (ester carbonyl stretches) cm - 1. 1H NMR: 6, 3.52 and 3.71 (two s, 3H each, ester methyl hydrogens), 5.08 (s, 1H, cyclopropylcarbinyl methine), 6.61-7.84 (m, 13H, aromatic). 1 3C NMR: 6, 51.91, 51.94 (ester CH3), 58.47 (sp 3 C-H), 63.35, 68.16 (quaternary sp 3 C), 120.73, 121.32, 126.37, 126.52, 126.97, 127.06, 127.51, 127.75, 127.93, 130.96 (aromatic C-H), 133.66, 135.41, 139.69, 148.41, 150.14 (quaternary aromatic C), 168.08, 168.40 (carbonyl C). MS: m/e (relative intensity): 397 (M+l, 1.0), 396 (M+, 3.0), 365 (2.3), 336 (72.7), 305 (12.5), 293 (25.4), 278 (100), 265 (8.3), 252 (4.1), 230 (5.7), 200 (3.8), 189 (2.3), 168 (2.6), 152 (7.1), 138 (25.5), 125 (7.2), 113 (3.0). Exact mass calculated (C26H20O4): 396.1362; measured: 396.1360. PHOTOCHEMISTRY OF DIMETHYL 9,10-DICHLORO-9,10-DIHYDRO-9,10-ETHENOANTHRA-CENE-11,12-DICARB0XYLATE (11) Preparative Photolysis of 11 in Acetonitrile: Compound 11 (1.24 g, 3.19 mmoles) was photolyzed for 30 hr in 300 mL of spectral grade acetonitrile using the standard procedure. GC analysis of the reaction mixture revealed new peaks at RT 10.94 (70%), 12.56 (14%), 13.69 (10%) and few other smaller peaks. S i l i c a gel flash chromatography of the mixture by using 10% (V/V) ethyl acetate in petroleum ether afforded the major prod-uct in the form of a yellow solid (0.15 g) which was purified by several -122-washings with methanol and recrystallized from ethanol-chloroform to give pure crystals of compound 33 (0.13 g, 10%). The remaining fractions were combined and upon solvent removal gave a white solid (47 mg, 4%); recrys-t a l l i z a t i o n from acetonitrile-diethyl ether gave nice needles which were later characterized as compound 3 4 . This compound decomposes on the GC column to show mainly peaks at RT 12.56 and 13.69 in addition to few other smaller peaks. Dimethyl 4b.8b.8c.8d-tetrahvdro-4b.8b-dichlorodibenzo[a.f1cyclopropa[cdl- pentalene-8c.8d-dicarboxylate ( 3 3 ) . MP: 178-91 °C (decomp). IR: 1744, 1728 (ester carbonyl stretches) cm-1. NMR: 5, 3.88 and 3.94 (two s, 3H each, ester methyl hydrogens), 7.18-7.77 (m, 8H, aromatic). 1 3C NMR: 5, 52.49, 52.96 (ester CH3), 58.3, 58.6, 62.5, 71.8 (quaternary sp 3 C), 119.87, 120.52, 125.00, 126.07, 126.11, 128.79, 129.07, 129.12, 129.64 (aromatic C-H), 130.00, 132.10, 147.68, 148.36 (quaternary aro-matic C), 162.88, 165.23 (carbonyl C). MS: m/e (relative intensity): 390 (M+2, 15.2), 389 (M+l, 5.8), 388 (M+, 23.5), 353, (18.0), 325 (75.4), 294 (95.2), 272 (12.3), 263 (28.6), 251 (58.7), 236 (46.9), 200 (100), 187 (14.5), 171 (41.0), 112 (17.9), 100 (32.3), 87 (10.2), 83 (20.1), 71 (37.6), 57 (68.7), 43 (53.6). Exact mass calculated (C20H14CI2O4): 388.0270; measured: 388.0270. Elemental analysis: (C20H14CI2O4) calculated: C, 61.71; H, 3.63; CI, 18.22. Found: C, 61.62; H, 3.67, CI, 18.06. -123-Compound 34 MP: 177-91 °C (decomp). IR: 1760, 1752 (ester carbonyl stretches), 1435, 1283, 1250 cm - 1. -^H NMR: 5, 3.78 and 3.92 (two s, 3H each, ester methyl hydrogens), 7.34-7.88 (m, 8H, aromatic). 1 3C NMR: 5, 52.77, 53.40 (ester CH3), 79.63 (quaternary sp 3 C), 123.71, 124.02, 124.56, 125.67, 130.58, 130.81, 131.62, 133.14 (aromatic C-H), 133.69, 137.13, 144.65, 144.70 (quaternary aromatic C), 165.15, 165.85 (carbonyl C). Other quaternary sp 3 carbon signals were not observed. MS: m/e (relative intensity): 390 (M+2-02, 2.2) 388 (M+-02, 3.3), 350 (12.4), 326 (2.5), 292 (32.6), 291 (100), 263 (25.4), 247 (26.2), 233 (33.1), 204 (23.4), 193 (12.1), 176 (62.3), 163 (14.0), 150 (14.0), 88 (30.6), 75 (14.4), 69 (10.9), 57 (15.4), 55 (12.6), 44 (13.9), 36 (28.5). Chemical Ionization MS: 421 (M+l). Elemental analysis: (C^H^C^Og) calculated: C, 57.03; H, 3.35; CI, 16.83. Found: C, 57.03; H, 3.41; CI, 16.69. PHOTOCHEMISTRY OF DIMETHYL 9,10-DIPHENYL-l,4-DIHYDR0-1,4-ETHENOANTHRACENE-11,12-DICARBOXYLATE (12) Preparative Photolysis of 12 in Acetonitrile: Compound 12 (0.18 g, 0.38 mmoles) was photolyzed for 1 hr in 300 mL of spectral grade acetonitrile using the standard procedure. GC analysis indicated traces of unreacted 12 and new peaks at RT's 16.25 (93%) and 18.39 (5%). Removal of solvent gave an o i l which when dissolved in diethyl ether-petroleum ether and allowed to evaporate gave a solid (0.18 g) which was subjected to s i l i c a -124-gel flash chromatography. Elution with 10% (V/V) ethyl acetate in petroleum ether yielded the major product as a yellow solid (60 mg, 33%). This was later characterized as compound 38. Compound 38 MP: 209-11 °C. IR: 1725 (ester carbonyl stretch) cm-1. *H NMR: 5, 3.65 and 3.74 (two s, 3H each, ester methyl hydrogens), 4.27 (s, 1H, cyclopropyl methine), 4.50 (d, J = 6 Hz, 1H, cyclopropylcarbinyl methine), 5.45 (d, J = 9 Hz, 1H, vin y l i c ) , 5.68-5.72 (m, 1H, v i n y l i c ) . 1 3C NMR: 6, 15.18, 48.76, 48.83, 55.88 (sp 3 C-H), 52.14, 52.41 (ester CH3), 57.94, 65.25, 65.72, 65.77 (quaternary sp 3 C), 120.35, 125.23, 125.60, 125.87, 126.12, 127.56, 127.63, 128.09, 128.33, 128.67, 128.87, 129.99, 130.05, 130.37, 130.55, 136.78 (aromatic and vinylic C-H), 131.70, 131.86, 132.21, 133.04, 137.22, 137.85, 144.76 (quaternary aromatic C), 168.33, 169.0 (carbonyl C). MS: m/e (relative intensity): 473 (M+l, 14.8), 472 (M+, 43.4), 440 (36.0), 413 (52.3), 381 (30.5), 354 (44.5), 326 (12.4), 276 (20.6), 206 (5.9), 175 (14.4), 162 (10.2), 70 (11.7), 57 (13.6), 43 (100), 40 (30.4). Exact mass calculated (C32H24O4): 472.1675; measured: 472.1677. -125-Product Ratio Determination. In solution: Typically 15-20 mg of the com-pound under investigation was dissolved in 10.0 mL of acetone, acetonitr-i l e and benzene. Then the solutions were placed in a 3 mm Pyrex tube, degassed by several freeze-thaw-pump cycles and sealed under a nitrogen atomosphere. These were photolysed and analysed by GC (the percent conversions were normally kept at <20% to minimize any secondary photo-reactions). The product ratios reported are averages of at least three photolysis runs. In the solid state: Single crystal and polycrystalline materials of each compound under investigation were placed in 3 mm Pyrex tubes, degassed and sealed under a nitrogen atmosphere. Then the samples were photolysed and analysed by GC. The typical conversions were < 5% and, in general, the polycrystalline samples gave higher conversions for a given time of irradiation. In none of the solid state irradiations was any melting observed. Photoproducts from the solid state, in general, were not isolated but were assumed to be the same as their solution counterparts based mainly on their GC retention times (DB-1 and DB-17), and in some cases by their NMR spectra. Sensitization Studies. A l l starting materials were systematically inves-tigated for their t r i p l e t state photoreactivity in acetone (solvent and tr i p l e t sensitizer) and in acetonitrile solution using xanthone as a sen-s i t i z e r . Control Experiments. Analytical photolyses of the photoproducts isolated in each case were performed and analysed by GC in order to determine i f there was any product interconversion under the photolysis conditions used. -127-CRYSTALLOGRAPHIC WORK DIBENZOBARRELENE DIESTER DERIVATIVES The data collection parameters and crystal data for the compounds discussed in chapter 9 are presented in Table 12, followed by a brief description of the structure determination for each compound. -128-Table 12. Data collection parameters and crystal data for compounds of chapter 9. Compound 9 Compound 10 Compound 1] Formula C22 H20°4 C26 H20°4 C20 H14 C 12°4 F.W. 348.40 396.44 389.23 F(000) 368 416 800 Dc (g cm - 3) 1.31 1.32 1.46 Radiation CuKQ CuKQ CuKQ M (cm - 1) 6.86 6.77 35.41 2^max (°) 154.7 154.9 120.1 w-scan width (°) 1.15+O.3Otan0 O.89+O.3Otan0 1.15+O.3Otan0 Scan speed (° min - 1)t 32 32 32 Orientation check 150 150 150 Space group Pi PI P2i/a a (A) 8.6950(6) 10.713 (1) 14.767(1) b (A) 13.6328(8) 11.9911(9) 8.243(2) c (A) 8.2727(6) 8.1772(9) 15.130(1) a (°) 98.512(6) 95.711(8) 90 j8 (°) 113.341(6) 105.142(8) 105.358(5) 7 (°) 80.965(6) 79.612(7) 90 V (A 3) 885.2(1) 995.9(2) 1775.9(5) Z 2 2 4 t A maximum of 8 rescans i f I < 40.0a(I). -129-Table 12 (continued). Compound 26 Formula C21 H17 C 1 04 F.W. 368.82 F(000) 768 Dc (g cm-3) 1.400 Radiation CuKQ fi (cm - 1) 21.44 2Vax (°) 155.0 w-scan width (°) 1.05+0.3Otan0 Scan speed (° m i n - 1 ^ 32 Orientation check 150 Space group P21/c a (A) 10.0865(6) b (A) 16.207 (1) c (A) 11.2329(9) cc (°) 90 P (°) 107.636(6) 7 (°) 90 V (A 3) 1749.9(2) Z 4 t, A maximum of 8 rescans i f I < 40.0CT(I). -130-Compound 9 A crystal with approximate dimensions of 0.4 x 0.2 x 0.4 mirr was used for data collection. A t r i c l i n i c c e l l with Z = 2 (assuming a density of 1.31 g cm - 3) was indicated by the preliminary reflections. Of 3835 reflections collected (range of h,k,l: -11 to 11, -17 to 17, 0 to 10), 3582 were unique and 3046 were observed. Final c e l l parameters were determined using 25 well-centered reflections with 109.93 < 26 < 118.79°. The inten-si t i e s of three standard reflections (0,0,2; 0,3,1; -2,1,2) monitored during the data collection did not indicate any significant change (no deacy correction was applied). Lp corrections were made. An empirical absorption correction was applied (transmission factors: 0.79 to 1.00), and equivalent reflections were merged. Based on E-statistics, and the successful solution and refinement of the structure, the space group was determined to be PI. The structure was solved by direct methods. MITHRIL with standard default options failed to produce a meaningful solution, but when used with the HARD option gave the correct solution. The t r i a l structure (with the positions of a l l non-hydrogen atoms from the best E-map) was refined i n i t i a l l y with isotropic thermal parameters and later on with anisotropic thermal parameters. A l l hydrogen atoms were found in subsequent AF-maps and were refined isotropically. An extinction correction was applied (final coefficient = 0.808xl0~4). Five reflections (0,1,0; 1,-6,-4; 0,15,-3; 8,6,-8; 2,-15,1) with AF/aF > 20.0 were removed from refinement in later cycles. The residual electron density (of 0.460 eA - 3) in the difference map indicated a possible disorder in one of the ester groups. The two highest -131-residual peaks were included in the model structure as disordered oxygens (03', 04') with an occupancy factor of 0.1 each and were refined isotro-pically, while the original oxygen atoms (03, 04) were given 0.9 occupancy and were refined anisotropically. The refinement converged at R = 0.057, Rw = 0.092 (S = 3.05; including zeros: R = 0.068, R^,, - 0.094) for 324 variables. The largest parameter shift in the f i n a l cycle was O.OICT, and the highest and lowest residual electron density peaks in the AF-map were 0.32 and —0.31 eA — 3. The f i n a l atomic positions and isotropic or equivalent isotropic thermal parameters are given in Table 13, while the bond lengths and bond angles involving non-hydrogen atoms are given in Tables 14 and 15, respec-tively . -132-Table 13. Atomic coordinates and B e q values of compound 9. atom X y z B(eq) 01 0 .3043(2) 0 .3878(1) 0 .3091(2) 4.65(6) 02 0 .3247(2) 0 .3144(1) 0 .0567(2) 5.07(7) 03 0 .5739(2) 0 .4745(1) 0 . 2 8 4 2 ( 3 ) 5.00(8) 04 0 . 8 3 3 9 ( 3 ) 0 . 4 3 0 4 ( 2 ) 0 .3031(5) 8.1(1) 03' 0 .586(2) 0 .449(1) 0 .212(2) 3.5(3) 04' 0 .836(2) 0 .456(1) 0 .405(2) 2.9(2) CI 0 .5920(3) 0 .1787(2) 0 .7230(3) 4.28(8) C2 0 .6923(4) 0 . 1 9 6 6 ( 2 ) 0 .9018(3) 5.3(1) C3 0 .8436(4) 0 .2341(2) 0 .9512(3) 5.1(1) C 4 A 0 .8027(2) 0 .2341(1) 0 .6474(2) , 3.20(6) C4 0 . 9 0 1 0 ( 3 ) 0 . 2 5 2 9 ( 2 ) 0 .8259(2) 4.20(7) C5 0 . 9 6 0 6 ( 3 ) 0 . 0 9 1 0 ( 2 ) 0 .3360(3) 3.95(7) C6 0 .9306(3) -0 . 0 0 0 0 ( 2 ) 0 .2362(3) 4.71(8) C7 0 .7770(3) -0 .0354(2) 0 .1849(3) 4.87(9) C8 0 .6489(3) 0 .0201(2) 0 .2316(3) 4.04(7) C 8 A 0 .6791(2) 0 .1111(1) 0 .3314(2) 3.24(6) C9A 0 . 6 4 8 4 ( 2 ) 0 .1973(1) 0 .5970(2) 3.24(6) C9 0 .5544(2) 0 . 1 8 1 0 ( 1 ) 0 .3960(2) 3.13(6) C10A 0 .8348(2) 0 .1469(1) 0 .3830(2) 3.09(6) CIO 0 .8487(2) 0 .2493(1) 0 .4920(2) 3.11(6) C l l 0 .5478(2) 0 .2820(1) 0 .3306(2) 2.97(6) C12 0 .6960(2) 0 .3170(1) 0 .3775(2) 2.94(6) C13 0 .3822(2) 0 .3300(1) 0 .2147(2) 3.31(6) C14 0 .1514(3) 0 .4477(3) 0 .2106(5) 6.3(1) C15 0 .7139(2) 0 .4124(1) 0 .3226(2) 3.52(6) C 1 6 0 .5733(5) 0 .5688(2) 0 .2283(5) 6.1(1) C17 0 .3836(3) 0 .1435(2) 0 .3388(3) 4.36(8) C18 1 .0207(2) 0 .2862(2) 0 .5506(3) 4.23(8) H i 0 .480(3) 0 .154(2) 0 .678(3) 4.9(5) H2 0 .645(4) 0 .183(2) 0 .986(4) 6.3(6) H3 0 .912(4) 0 .250(3) 1 .076( 4 ) 7.0(7) H4 1 .009(4) 0 .279(2) 0 .859(4) 5.3(6) H5 1 .076(3) 0 .114(2) 0 .377(3) 4.8(5) H6 1 .026(3) -0 .040(2) 0 .198(4) 5.5(6) H7 0 .745(3) -0 .095(2) 0 .102(4 ) 5.5(6) H8 0 .543(3) -0 .004(2) 0 .199(3) 4.2(5) H14C 0 .063(6) 0 .403(4) 0 .136(6) 10(1) H 1 4 B 0 .171(6) 0 .462(4) 0 .103(7) 11(1) H 1 4 A 0 .090(6) 0 .474(4) 0 .278(7) 12(1) H16B 0 .608(4) 0 .568(3) 0 .134(5) 7.2(8) H16C 0 .434(8) 0 .595(5) 0 .175(8) 15(2) H16A 0 .655(6) 0 .610(4) 0 .324(7) 11(1) H17C 0 .305(4) 0 .196(2) 0 .380(4) 5.8(6 ) H17A 0 .329(3) 0 .137(2) 0 .201(4) 5.2(6) H17B 0 .398(3) 0 .077(2) 0 .394(4) 5.6(6) H18A 1 .042(3) 0 .298(2) 0 .447(3) 3.9(4) H 1 8 B 1 .113(4) 0 .238(2) 0 .635(4) 5.8(6) H18C 1 .027(3) 0 .352(2) 0 .614(4) 5.3(6) -133-Table 14. Bond lengths involving non-hydrogen atoms of compound 9. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.326(2) C5 C6 1.385(3) 01 C14 1.448(3) C5 C10A 1.385(2) 02 C13 1.199(2) C6 C7 1.375(4) 03 C15 1.322(3) C7 C8 1.397(3) 03 C16 1.429(3) C8 C8A 1.384(3) 04 C15 1.183(3) C8A C10A 1.394(3) 03' C15 1.22(2) C8A C9 1.534(2) 03' C16 1.60(2) C9A C9 1.534(2) 04' C15 1.20(1) C9 C17 1.517(3) CI C9A 1.384(3) C9 C l l 1.538(2) CI C2 1.395(3) CI OA CIO 1.540(2) C2 C3 1.372(4) CIO C18 1.521(3) C3 C4 1.385(3) CIO C12 1.545(2) C4A C4 1.390(2) C l l C12 1.335(2) C4A C9A 1.390(3) C l l C13 1.489(2) C4A CIO 1.538(2) C12 C15 1.488(2) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are g i v e n i n p a r e n t h e s e s . -134-T a b l e 15 . Bond a n g l e s i n v o l v i n g non--hydrogen atoms o f compound 9. a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 3 ( 2 ) C5 C 1 0 A C8A 1 2 0 . 0 ( 2 ) C15 03 C16 1 1 8 . 1 ( 2 ) C5 C 1 0 A CIO 1 2 5 . 8 ( 2 ) C15 0 3 ' C16 1 1 3 ( 1 ) C8A C 1 0 A CIO 1 1 4 . 2 ( 1 ) C9A C I C2 1 1 9 . 3 ( 2 ) C18 CIO C4A 1 1 3 . 3 ( 2 ) C3 C2 C I 1 2 0 . 0 ( 2 ) C18 CIO C 1 0 A 1 1 3 . 4 ( 1 ) C2 C3 C4 1 2 1 . 0 ( 2 ) C18 CIO C12 1 1 6 . 5 ( 2 ) C4 C4A C9A 1 1 9 . 8 ( 2 ) C4A CIO C 1 0 A 1 0 4 . 0 ( 1 ) C4 C4A C IO 1 2 5 . 9 ( 2 ) C4A CIO C12 1 0 3 . 9 ( 1 ) C9A C4A CIO 1 1 4 . 3 ( 1 ) C10A CIO C12 1 0 4 . 4 ( 1 ) C3 C4 C4A 1 1 9 . 3 ( 2 ) C12 C l l C13 1 2 5 . 3 ( 2 ) C6 C5 C 1 0 A 1 1 9 . 8 ( 2 ) C12 C l l C9 1 1 5 . 8 ( 1 ) C7 C6 C5 1 2 0 . 3 ( 2 ) C13 C l l C9 1 1 8 . 8 ( 1 ) C6 C7 C8 1 2 0 . 5 ( 2 ) C l l C12 C15 1 2 3 . 1 ( 1 ) C8A C8 C7 1 1 9 . 1 ( 2 ) C l l C12 CIO 1 1 4 . 3 ( 1 ) C8 C8A C 1 0 A 1 2 0 . 3 ( 2 ) C15 C12 CIO 1 2 2 . 6 ( 1 ) C8 C8A C9 1 2 6 . 1 ( 2 ) 02 C13 01 1 2 4 . 8 ( 2 ) C 1 0 A C8A C9 1 1 3 . 6 ( 1 ) 02 C13 C l l 1 2 3 . 8 ( 2 ) C I C9A C4A 1 2 0 . 6 ( 2 ) 01 C13 C l l 1 1 1 . 4 ( 1 ) C I C9A C9 1 2 5 . 7 ( 2 ) 04 C15 0 3 ' 1 1 0 . 3 ( 7 ) C4A C9A C9 1 1 3 . 7 ( 1 ) 04 C15 03 1 2 2 . 2 ( 2 ) C17 C9 C8A 1 1 4 . 2 ( 2 ) 04 C15 C12 1 2 5 . 4 ( 2 ) C17 C9 C9A 1 1 4 . 3 ( 2 ) 0 4 ' C15 0 3 ' 1 2 4 ( 1 ) C17 C9 C l l 1 1 4 . 1 ( 1 ) 04 ' C15 03 1 1 1 . 0 ( 6 ) C8A C9 C9A 1 0 4 . 5 ( 1 ) 0 4 ' C15 C12 1 2 0 . 7 ( 6 ) C8A C9 C l l 1 0 4 . 5 ( 1 ) 0 3 ' C15 C12 1 1 4 . 4 ( 7 ) C9A C9 C l l 1 0 4 . 1 ( 1 ) 03 C15 C12 1 1 2 . 2 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -135-Compound 10 •3 A crystal having approximate dimensions of 0.03 x 0.1 x 0.4 mirr was used for collecting data. The preliminary reflections indicated a t r i -c l i n i c c e l l with Z = 2, assuming a density of 1.32 g cm . A total of 4357 reflections in the h,k,l limits of -14 to 14, -15 to 15, 0 to 10 was collected, of which 4066 were unique, and 3069 were observed. Carefully centered reflections (25 with 87.38 < 28 < 96.69°) were used to determine the f i n a l c e l l parameters. The intensities of the standard reflections (-3,-2,1; -2,-2,2; -1,1,2) were roughly constant during the data collection (decay correction was not applied). Lp corrections were made, and an empirical absorption correction was applied (transmission factors: 0.89 to 1.00). Equivalent reflections were merged. Based on E-statistics, and successful structure solution and refine-ment, the space group was determined as PI. The structure was solved using direct methods. MITHRIL with standard default options did not produce a meaningful solution, but when executed with the HARD option gave the positions of a l l non-hydrogen atoms in the best E-map. The t r i a l structure was i n i t i a l l y refined isotropically and later with anisotropic thermal parameters. A l l hydrogen atoms were found in difference maps and were refined isotropically. A secondary extinction correction was applied (final coefficient = 0.437xl0 — 4). The refinement converged at R = 0.060, R w = 0.095 (S = 2.83; including zeros: R = 0.081, Rw = 0.097) for 352 variables with largest parameter shift being 0.01a. The maximum and minimum residual peaks in the AF-map were 0.25 and —0.30 eA~3. The f i n a l atomic positions and isotropic or equivalent isotropic -136-thermal parameters are presented in Table 16. The bond lengths, bond angles involving non-hydrogen atoms are given in Tables 17, 18. -137-Table 16. Atomic positions and B e g values of compound 10. atom X y z B(eq) 01 0.1263(2) 0.0189(2) 0.8578(3) 5.0(1) 02 0.1627(2) 0.0159(2) 0.6005(3) 4.8(1) 03 0.5514(2) 0.1036(2) 0.7838(3) 4.8(1) 04 0.4368(2) -0.0302(2) 0.8041(3) 5.3(1) CI 0.1086(3) 0.4623(2) 0.7151(3) 3.6(1) C2 0 . 1 6 5 5 ( 3 ) 0 . 5 4 6 4 ( 3 ) 0.6702(4) 4.5(1) C3 0.2994(3) 0.5420(3) 0.7148(4) 4.6(1) C4 0.3798(3) 0.4539(3) 0.8078(3) 4.0(1) C4A 0.3237(2) 0.3706(2) 0.8531(3) 3.3(1) C5 0.4078(3) 0.2805(3) 1.2764(4) 4.3(1) C6 0.3433(4) 0.2820(3) 1.4039(4) 5.0(1) C7 0.2113(4) 0.2791(3) 1.3620(4) 4.8(1) C8 0.1395(3) 0.2778(3) 1 . 1 9 3 K 3) 3.9(1) C8A 0.2024(2) 0.2795(2) 1.0654(3) 3.3(1) C9 0.1421(2) 0.2738(2) 0.8704(3) 3.0(1) C9A 0.1883(2) 0.3733(2) 0.8071(3) 3.1(1) C10A 0.3377(2) 0.2787(2) 1 . 1 0 8 8 ( 3 ) 3.4(1) CIO 0.3959(2) 0.2702(2) 0.9562(3) 3.4(1) C l l 0.2237(2) 0.1650(2) 0.8119(3) 3.2(1) C12 0.3530(2) 0.1644(2) 0.8524(3) 3.4(1) C13 0.1687(3) 0.0589(2) 0.7404(3) 3.5(1) C14 0.0669(7) -0.0831(4) 0.8089(8) 7.5(3) C15 0.4488(3) 0.0675(2) 0.8115(3) 3.6(1) C16 0.6516(4) 0.0173(4) 0.7384(7) 6.0(2) C17 -0.0066(2) 0.2854(2) 0.8127(3) 3.2(1) C18 -0.0710(3) 0.2256(2) 0.6691(3) 3.7(1) C19 -0.2069(3) 0.2432(3) 0.6142(4) 4.3(1) C20 -0.2808(3) 0.3234(3) 0.6979(4) 4.9(1) C21 -0.2191(3) 0.3858(3) 0.8352(4) 5.0(1) C22 -0.0836(3) 0.3674(3) 0.8916(4) 4.0(1) H i 0.015(3) 0.461(3) 0.683(4) 3.5(6) H2 0.104(4) 0.608(3) 0.606(5) 6.1(9) H3 0.340(4) 0.601(3) 0.683(5) 6.0(8) H4 0.477(3) 0.455(3) 0.839(4) 4.6(7) H5 0.504(4) 0.280(3) 1.295(5) 5.8(8) H6 0.397(3) 0.280(3) 1.527(5) 4.9(7) H7 0.165(4) 0.282(4) 1.455(6) 7(1) H8 0.051(3) 0.268(3) 1.167(4) 4.2(7) H10 0.490(2) 0.271(2) 0.983(3) 2.4(5) H 1 4 C 0.140(6) -0.14K 5) 0.783(7) 10(2) H 1 4 B -0.012(8) -0.071(7) 0.71(1) 15(3) H14A 0.074(9) -0.113(8) 0.92(1) 18(3) H 1 6 C 0.729(6) 0.053(5) 0.763(7) 10(1) H16B 0.624(5) -0.026(4) 0.634(7) 8(1) H 1 6 A 0.676(6) -0.048(6) 0.831(8) 12(2) H18 -0.020(3) 0.167(3) 0.605(4) 4.2(6) H19 -0.247(3) 0.196(3) 0.513(4) 4.4(7) H20 -0.378(4) 0.334(4) 0.660(5) 7(1) H21 -0.262(3) 0.448(3) 0.894(4) 5.1(7) H22 -0.043(3) 0.413(3) 0.986(4) 3.4(6) -138-Table 17. Bond lengths involving non-hydrogen atoms of compound 10. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.326(3) C8 C8A 1.386(3) 01 C14 1.453(4) C8A C10A 1.399(3) 02 C13 1.198(3) C8A C9 1.556(3) 03 C15 1.329(3) C9 C17 1.523(3) 03 C16 1.448(4) C9 C l l 1.542(3) 04 C15 1.195(4) C9 C9A 1.551(3) CI C9A 1.389(4) C10A CIO 1.521(3) CI C2 1.392(4) CIO CI 2 1.527(4) C2 C3 1.377(5) C l l C12 1.336(3) C3 C4 1.388(5) C l l C13 1.500(4) C4 C4A 1.380(4) C12 C15 1.480(4) C4A C9A 1.396(3) C17 C22 1.387(4) C4A CIO 1.511(4) C17 C18 1.399(4) C5 C10A 1.381(4) C18 C19 1.391(4) C5 C6 1.390(4) C19 C20 1.377(4) C6 C7 1.371(5) C20 C21 1.371(5) C7 C8 1.394(4) C21 C22 1.387(4) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -139-Table 18 . Bond angles in v o l v i n g non-hydrogen atoms of compound 10 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 4 ( 3 ) C5 C I OA C IO 1 2 5 . 5 ( 2 ) C15 03 C16 1 1 6 . 5 ( 3 ) C8A C 1 0 A C IO 1 1 3 . 6 ( 2 ) C9A C I C2 1 1 9 . 3 ( 3 ) C4A C IO C 1 0 A 1 0 5 . 7 ( 2 ) C3 C2 C I 1 2 0 . 9 ( 3 ) C4A C IO C12 1 0 6 . 5 ( 2 ) C2 C3 C4 1 2 0 . 2 ( 3 ) C I OA C IO C12 1 0 4 . 7 ( 2 ) C4A C4 C3 1 1 9 . 0 ( 3 ) C12 C l l C13 1 2 0 . 4 ( 2 ) C4 C4A C 9 A 1 2 1 . 3 ( 2 ) C12 C l l C9 1 1 5 . 1 ( 2 ) C4 C4A C IO 1 2 6 . 1 ( 2 ) C13 C l l C9 1 2 3 . 8 ( 2 ) C9A C4A C IO 1 1 2 . 6 ( 2 ) C l l C12 C15 1 2 3 . 7 ( 2 ) C 1 0 A C5 C6 1 1 9 . 6 ( 3 ) C l l C12 C IO 1 1 4 . 3 ( 2 ) C7 C6 C5 1 1 9 . 8 ( 3 ) C15 C12 C IO 1 2 1 . 9 ( 2 ) C6 C7 C8 1 2 1 . 1 ( 3 ) 02 C13 01 1 2 4 . 5 ( 3 ) C8A C8 C7 1 1 9 . 5 ( 3 ) 02 C13 C l l 1 2 6 . 6 ( 2 ) C8 C8A C I OA 1 1 9 . 1 ( 2 ) 01 C13 C l l 1 0 8 . 9 ( 2 ) C8 C8A C9 1 2 7 . 7 ( 2 ) 04 C15 03 1 2 4 . 1 ( 2 ) C10A C8A C9 1 1 3 . 1 ( 2 ) 04 C15 C12 1 2 5 . 2 ( 2 ) C17 C9 C l l 1 1 7 . 9 ( 2 ) 03 C15 C12 1 1 0 . 7 ( 2 ) C17 C9 C9A 1 0 9 . 8 ( 2 ) C22 C17 C18 1 1 7 . 1 ( 2 ) C17 C9 C8A 1 1 6 . 3 ( 2 ) C22 C17 C9 1 1 9 . 8 ( 2 ) C l l C9 C9A 1 0 5 . 4 ( 2 ) C18 C17 C9 1 2 2 . 7 ( 2 ) C l l C9 C8A 1 0 2 . 0 ( 2 ) C19 C18 C17 1 2 1 . 2 ( 3 ) C9A C9 C8A 1 0 4 . 0 ( 2 ) C20 C19 C18 1 2 0 . 1 ( 3 ) C I C9A C4A 1 1 9 . 2 ( 2 ) C21 C20 C19 1 1 9 . 4 ( 3 ) C I C9A C9 1 2 6 . 4 ( 2 ) C20 C21 C22 1 2 0 . 5 ( 3 ) C4A C9A C9 1 1 4 . 4 ( 2 ) C17 C22 C21 1 2 1 . 5 ( 3 ) C5 C 1 0 A C8A 1 2 0 . 9 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -140-Compound 11 A crystal with approximate dimensions of 0.3 x 0.2 x 0.3 mm3 was used for data collection. Preliminary reflections indicated a monoclinic c e l l with Z = 4 (based on a density of 1.46 g cm J ) . In h,k,l limits of 0 to 17, 0 to 9, -17 to 17, 2974 reflections were collected of which 2851 were unique and 2041 considered observed. Least squares refinement of 25 well-centered reflections (63.04 < 29 < 79.75°) gave the f i n a l c e l l parameters. Three standard reflections (3,-1,-2; 3,-1,-4; 4,1,-3) did not show any significant variation in their intenstities (no decay correction was applied). Lp corrections were made, and an empirical absorption cor-rection was applied (transmission factors: 0.56 to 1.00). Based on systematic absences (hOl: h ^ 2n; OkO: k ¥• 2n), and success-ful structure solution and refinement, the space group was found to be P21/a. The structure was solved using direct methods. The best E-map gave a l l 26 non-hydrogen atoms which were included in the model structure and refined i n i t i a l l y with isotropic thermal parameters and then with aniso-tropic thermal parameters. A l l hydgrogen atoms were located in subsequent difference Fourier syntheses and were refined isotropically. A secondary extinction correction was applied (final coefficient = 0.980xl0-^). The refinement converged at R = 0.046, R^  = 0.064 for 292 variables (S = 1.62; including zeros: R = 0.066, R^, = 0.071). In the f i n a l cycle, the largest parameter shift was 0.01a, and residual peaks in the AF-map were between 0.32 and -0.34 eA - 3. The f i n a l atomic positions and isotropic or equivalent isotropic ther-mal parameters are given in Table 19, while the bond lengths, bond angles -141-involving non-hydrogen atoms are given in Tables 20 and 21, respectively. Table 19. Atomic positions and B e q values of compound 11. atom X y z B(eq) C L l 0.31594(7) 0.0278(1) 0.14796(7) 5.37(5) CL2 -0.02635(6) -0.0346(1) 0.30044(7) 4.97(5) 01 0.3442(1) -0.2035(3) 0.4054(2) 3.6(1) 02 0.3945(2) 0.0245(3) 0.3539(2) 4.8(1) 03 0.1938(2) - 0 . 0 5 4 0 ( 3 ) 0.4767(1) 3.6(1) 04 0.1338(2) -0.2909(3) 0.4158(2) 4.3(1) CI 0 . 2 0 2 3 ( 3 ) 0 . 3 3 0 2 ( 5 ) 0.1856(3) 4.6(2) C2 0.1520(4) 0.4662(5) 0 . 2 0 3 0 ( 3 ) 5.9(2) C3 0.0752(4) 0.4495(6) 0.2373(3) 5.4(2) C4A 0.0941(2) 0.1633(4) 0.2385(2) 3.2(1) C4 0.0462(3) 0.2981(5) 0.2553(3) 4.4(2) C5 -0.0184(3) -0.1858(5) 0.1150(3) 4.4(2) C6 -0.0178(4) - 0 . 2 5 5 6 ( 6 ) 0.0330(3) 6.0(2) C7 0.0588(4) -0.2426(6) -0.0005(3) 6.2(2) C8A 0.1380(3) -0.0865( 4 ) 0.1301(2) 3.4(1) C8 0.1370(4) -0.1589(6) 0.0474(3) 4.7(2) C9 0.2166(2) 0.0139(4) 0.1926(2) 3.2(1) C9A 0.1723(2) 0.1782(4) 0.2035(2) 3.4(1) CI OA 0.0589(2) -0.1000(4) 0.1634(2) 3.3(1) CIO 0.0719(2) -0.0136(4) 0.2546(2) 3.0(1) C l l 0.2387(2) -0.0640(4) 0.2879(2) 2.7(1) C12 0.1624(2) -0.0827(4) 0.3187(2) 2.7(1) C13 0.3352(2) -0.0760(4) 0.3506(2) 3.1(1) C14 0.4270(3) -0.2004(7) 0.4838(3) 4.8(2) C15 0.1617(2) -0.1572(4) 0.4087(2) 2.8(1) C16 0.2011(4) -0.1185(7) 0.5681(3) 5.1(2) H i 0.254(3) 0.335(5) 0.168(3) 4(1) H2 0.172(3) 0.560(6) 0.194(3) 7(1) H3 0.035(3) 0.550(6) 0.254(3) 7(1) H4 - 0 . 0 1 K 3) 0.286(6) 0.281(3) 7(1) H5 -0.071(2) -0.176(4) 0.135(2) 3.3(8) H 6 -0.066(3) -0.317(5) 0.003(3) 6(1) H7 0.049(3) -0.293(6) -0.062(4) 8(1) H8 0.180(3) -0.143(5) 0.030(3) 4(1) H 1 4 B 0.485(3) -0.200(5) 0.465(3) 6(1) H14C 0.430(4) -0.290(6) 0.509(4) 8(2) H 1 4 A 0.447(4) -0.100(8) 0.537(4) 11(2) H16A 0.222(4) -0.046(6) 0.604(4) 7(2) H16B 0.250(4) -0.199(8) 0.581(4) 9(2) H16C 0.130(5) -0.155(8) 0.568(4) 12(2) -142-Table 20. Bond lengths involving non-hydrogen atoms of compound 11. atom atom d i s t a n c e atom atom d i s t a n c e C L l C9 1.774(3) C5 C6 1.371(7) CL2 CIO 1.775(3) C5 C10A 1.377(5) 01 C13 1.323(4) C6 C7 1.361(7) 01 C14 1.461(4) C7 C8 1.376(7) 02 C13 1.197(4) C8A C8 1.384(5) 03 C15 1.322(4) C8A C9 1 . 5 3 K 5) 03 C16 1.458(4) C8A C10A 1.394(5) 04 C15 1.191(4) C9 C9A 1.532(5) CI C2 1.407(7) C9 C l l 1.533(4) CI C9A 1.379(5) C10A CIO 1.520(4) C2 C3 1.375(7) CIO C12 1.537(4) C3 C4 1.370(6) C l l C12 1.337(4) C 4 A C4 1.377(5) C l l C13 1.492(4) C 4 A C9A 1.397(5) C12 C15 1.497(4) C4A CIO 1.528(5) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are g i v e n i n p a r e n t h e s e s . -143-Table 21. Bond angles involving non-a t o m a t o m a t o m a n g l e C13 01 C14 1 1 4 . 8 ( 3 ) C15 03 C16 1 1 5 . 2 ( 3 ) C2 C I C9A 1 1 8 . 3 ( 5 ) C I C2 C3 1 2 1 . 3 ( 4 ) C2 C3 C4 1 1 9 . 9 ( 4 ) C4 C4A C9A 1 2 1 . 0 ( 3 ) C4 C4A C IO 1 2 6 . 7 ( 3 ) C9A C4A C IO 1 1 2 . 3 ( 3 ) C3 C4 C4A 1 1 9 . 7 ( 4 ) C6 C5 C5 CI OA 1 1 9 . 6 ( 5 ) C6 C7 1 2 0 . 6 ( 5 ) C6 C7 C8 1 2 0 . 6 ( 4 ) C8 C8A C9 1 2 8 . 1 ( 4 ) C8 C8A C 1 0 A 1 1 8 . 9 ( 4 ) C9 C8A C 1 0 A 1 1 3 . 0 ( 3 ) C7 C8 C8A 1 1 9 . 9 ( 5 ) CL1 C9 C8A 1 1 1 . 6 ( 2 ) CL1 C9 C9A 1 1 3 . 8 ( 2 ) CL1 C9 C l l 1 1 3 . 2 ( 2 ) C8A C9 C9A 1 0 5 . 6 ( 3 ) C8A C9 C l l 1 0 7 . 0 ( 3 ) C9A C9 C l l 1 0 5 . 1 ( 3 ) C I C9A C4A 1 1 9 . 7 ( 4 ) rogen atoms of compound 11 . a t o m a t o m a t o m a n g l e C I C9A C9 1 2 7 . 8 ( 4 ) C4A C9A C9 1 1 2 . 4 ( 3 ) C5 C I OA C8A 1 2 0 . 4 ( 3 ) C5 C 1 0 A C IO 1 2 7 . 7 ( 4 ) C8A C I OA C IO 1 1 1 . 9 ( 3 ) CL2 C IO C4A 1 1 2 . 8 ( 2 ) CL2 CIO C 1 0 A 1 1 2 . 9 ( 2 ) CL2 C IO C12 1 1 2 . 5 ( 2 ) C4A CIO C 1 0 A 1 0 6 . 4 ( 3 ) C4A C IO C12 1 0 5 . 5 ( 3 ) C I OA CIO C12 1 0 6 . 2 ( 2 ) C9 C l l C12 1 1 2 . 7 ( 3 ) C9 C l l C13 1 2 3 . 8 ( 3 ) C12 C l l C13 1 2 1 . 5 ( 3 ) C10 C12 C l l 1 1 4 . 2 ( 3 ) C10 C12 C15 1 2 0 . 8 ( 3 ) C l l C12 C15 1 2 5 . 0 ( 3 ) 01 C13 02 1 2 4 . 9 ( 3 ) 01 C13 C l l 1 1 1 . 8 ( 3 ) 02 C13 C l l 1 2 3 . 1 ( 3 ) 03 C15 04 1 2 5 . 8 ( 3 ) 03 C15 C12 1 1 1 . 0 ( 3 ) 04 C15 C12 1 2 3 . 2 ( 3 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -144-Compound 26 o A crystal having approximate size of 0.40 x 0.20 x 0.40 mirr was used for data collection. A monoclinic unit c e l l with Z = 4 was suggested by the preliminary reflections collected (D c = 1.40 g cm J ) . Of 3826 reflections collected (h,k,l limits: -13 to 13, 0 to 20, 0 to 14), 3634 reflections were unique and 2569 were observed. Least squares f i t of 24 well-centered high angle reflections (82.95 < 29 < 110.78°) gave the fi n a l c e l l parameters. The standard reflections (-1, —4, 0; —1, —3,2; 1, -4, 0) monitored during data collection did not indicate any need for decay correction. Lp corrections were made. Following an empirical absorption correction (transmission factors: 0.75 to 1.00), the equivalent reflec-tions were merged. Based on systematic absences (hOl: 1 ^  2n; OkO: k ^ 2n), E-statistics and successful structure solution and refinement, the space group was determined as P2^/c. The best E-map from MITHRIL gave the positions of 24 non-hydrogen atoms which were refined isotropically. This resulted in location of the remaining two ester methyl carbons in the difference map. A l l non-hydrogen atoms were then refined with anisotropic thermal motion. In the subsequent difference maps a l l hydrogen atoms were located which were refined with isotropic thermal parameters. A secondary extinction cor-rection was applied (final coefficient = 0.757 x 10 — 5). The refinement converged with a maximum parameter shift of O.Olu at R = 0.042, Rw = 0.062 and S = 1.83 for 304 variables. Including zeros the R-values were, R = 0.067, R w = 0.064. The maximum and minimum peaks in the fi n a l difference map were 0.21 and -0.27 eA~3, respectively. -145-The f i n a l atomic coordinates and the corresponding B eq values are l i s t e d in Table 22; while the bond lengths and angles are provided in Tables 23 and 24. -146-Table 22. Atomic coordinates and B e a values of compound 26. atom X y z B(eq) CI 0 .33401(8) 0 .15087(4) 0 .79413(7) 5.48(3) 0( 1) 0 .0914(2) 0 .2224(1) 0 .5350(2) 4.68(7) 0( 2) 0 .0206(2) 0 .2581(1) 0 .6987(2) 6.3(1) 0( 3) 0 .1443(2) 0 .4669(1) 0 .4089(2) 4.63(7) 0( 4) -0 .0151(2) 0 .3881(1) 0 .4553(2) 6.19(9) C( 1) 0 .5804(2) 0 .2729(1) 0 .7746(2) 4.16(9) C( 2) 0 .6887(3) 0 .2864(2) 0 .7243(3) 4.8(1) C( 3) 0 .6881(3) 0 .3533(2) 0 .6492(3) 4.9(1) C( 4) 0 .5791(2) 0 .4093(2) 0 .6230(2) 4.4(1) C( 4A) 0 .4685(2) 0 .3951(1) 0 .6691(2) 3.56(8) C( 5) 0 .3302(3) 0 .5517(2) 0 .8214(3) 4.9(1) C( 6) 0 .3225(3) 0 .5628(2) 0 .9417(3) 5.9(1) C( 7) 0 .3176(3) 0 .4960(3) 1 .0143(3) 6.0(1) C( 8) 0 .3224(3) 0 .4153(2) 0 .9712(2) 4.9(1) C( 8A) 0 .3307(2) 0 .4045(1) 0 .8521(2) 3.84(8) C( 9A) 0 .4679(2) 0 .3267(1) 0 .7437(2) 3.43(7) C( 9) 0 .3367(2) 0 .3213(1) 0 .7865(2) 3.55(8) C( 10A) 0 .3346(2) 0 .4726(1) 0 .7777(2) 3.89(8) C( 10) 0 .3406(2) 0 .4492(1) 0 .6486(2) 3.74(8) C( 11) 0 .2135(2) 0 .3268(1) 0 .6650(2) 3.55(8) C( 12) 0 .2154(2) 0 .3932(1) 0 .5949(2) 3.65(8) C( 13) 0 .0970(2) 0 .2663(2) 0 .6364(2) 4.09(9) C( 14) -0 .0202(4) 0 .1636(3) 0 .4921(4) 7.1(2) C( 15) 0 .1015(2) 0 .4141(1) 0 .4797(2) 3.97(8) C( 16) 0 .0453(3) 0 .4878(3) 0 .2899(3) 5.9(1) C( 17) 0 .3332(3) 0 .2477(2) 0 .8700(2) 4.4(1) H( 1) 0 .584( 3 ) 0 .223(2) 0 .829(3) 5.1(6) H( 2) 0 .764(3) 0 .250(2) 0 .739(3) 6.4(7) H( 3) 0 .768(4) 0 .361(2) 0 .618(3) 6.8(8) H( 4) 0 .575(3) 0 .456(2) 0 .569(3) 5.5(6) H( 5) 0 .335(3) 0 .594(2) 0 .766(3) 7.0(8) H( 6) 0 .321(3) 0 .618(2) 0 .964(3) 7.2(8) H( 7) 0 .312(3) 0 .500(2) 1 .092(3) 6.5(7) H| 8) 0 .326(3) 0 .367(2) 1 .029(3) 5.3(7) H( 10) 0 .335(3) 0 .498(2) 0 .596(2) 4.2(5) H( 14C) -0 .044(5) 0 .152(3) 0 .401(5) 11(1) HI 14A) -0 .110(6) 0 .194(3) 0 .498(4) 11(1) H( 14B) -0 ,025(5) 0 .131(3) 0 .557(4) 10(1) H( 1 6 A ) 0 .092(4) 0 .501(3) 0 .240(4) 10(1) HI 16C) -0 .022(5) 0 .518(3) 0 .310(4) 9(1) H( 16 B) -0 .016(5) 0 .436(3) 0 .250(4) 11(1) H| 17A) 0 .415(3) 0 .246(2) 0 .946(3) 5.1(6) HI 17B) 0 .245(3) 0 .248(2) 0 .900(2) 4.7(6) -147-Table 23. Bond lengths involving non-hydrogen atoms of compound 26. atom atom d i s t a n c e atom atom d i s t a n c e CL C17 1.788(3) C5 C10A 1.379(3) 01 C13 1.328(3) C6 C7 1.364(5) 01 C14 1.442(3) C7 C8 1.401(4) 02 C13 1.195(3) C8 C8A 1.378(3) 03 C15 1.326(3) C8A C9 1.546(3) 03 C16 1.446(3) C8A C10A 1.391(3) 04 C15 1.200(3) C9A C9 1.541(3) CI C2 1.392(3) C9 C l l 1.545(3) CI C9A 1.389(3) C9 C17 1.524(3) C2 C3 1.372(4) C10A CIO 1.517(3) C3 C4 1.388(4) CIO C12 1.523(3) C4 C4A 1.384(3) C l l C12 1.337(3) C4A C9A 1 .39K 3) C l l C13 1.489(3) C4A CIO 1.519(3) C12 C15 1.486(3) C5 C6 1.388(5) D i s t a n c e s are i n angstroms. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are given i n parentheses. -148-Table 24 . Bond angles involving non-hydrogen atoms of compound 26 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 9 ( 2 ) C9A C9 C l l 1 0 4 . 9 ( 2 ) C15 03 C16 1 1 6 . 5 ( 2 ) C9A C9 C17 1 1 4 . 7 ( 2 ) C2 CI C9A 1 1 8 . 9 ( 2 ) C l l C9 C17 1 1 5 . 2 ( 2 ) C I C2 C3 1 2 1 . 0 ( 2 ) C5 C 1 0 A C8A 1 2 0 . 9 ( 2 ) C2 C3 C4 1 2 0 . 3 ( 2 ) C5 C 1 0 A CIO 1 2 6 . 0 ( 2 ) C3 C4 C4A 1 1 9 . 2 ( 2 ) C8A C I OA CIO 1 1 3 . 1 ( 2 ) C4 C4A C9A 1 2 0 . 6 ( 2 ) C4A C IO C 1 0 A 1 0 6 . 1 ( 2 ) C4 C4A C IO 1 2 6 . 2 ( 2 ) C4A C IO C12 1 0 6 . 2 ( 2 ) C9A C4A CIO 1 1 3 . 2 ( 2 ) C 1 0 A C IO . C12 1 0 5 . 0 ( 2 ) C6 C5 C I OA 1 1 9 . 0 ( 3 ) C9 C l l C12 1 1 4 . 5 ( 2 ) C5 C6 C7 1 2 0 . 1 ( 3 ) C9 C l l C13 1 2 1 . 6 ( 2 ) C6 C7 C8 1 2 1 . 5 ( 3 ) C12 C l l C13 1 2 3 . 7 ( 2 ) C7 C8 C8A 1 1 8 . 2 ( 3 ) CIO C12 C l l 1 1 3 . 9 ( 2 ) C8 C8A C9 1 2 6 . 6 ( 2 ) C10 C12 C15 1 2 2.6 ( 2 ) C8 C8A CI OA 1 2 0 . 3 ( 2 ) C l l C12 C15 1 2 3 . 4 ( 2 ) C9 C8A C 1 0 A 1 1 3 . 1 ( 2 ) 01 C13 02 1 2 5 . 1 ( 2 ) C I C9A C4A 1 1 9 . 9 ( 2 ) 01 C13 C l l 1 1 1 . 3 ( 2 ) C I C9A C9 1 2 6 . 9 ( 2 ) 02 C13 C l l 1 2 3 . 6 ( 2 ) C4A C9A C9 1 1 3 . 2 ( 2 ) 03 C15 04 1 2 4 . 3 ( 2 ) C8A C9 C9A 1 0 5 . 1 ( 2 ) 03 C15 C12 1 1 1 . 3 ( 2 ) C8A C9 C l l 1 0 3 . 5 ( 2 ) 04 C15 C12 1 2 4 . 4 ( 2 ) C8A C9 C17 1 1 2 . 2 ( 2 ) CL C17 C9 1 1 2 . 9 ( 2 ) Angles are i n degrees. Estimated standard deviations i n the le a s t s i g n i f i c a n t figure are given i n parentheses. -149-SEMIBULLVALENE DERIVATIVES The data collection parameters and crystal data for the compounds discussed in chapter 10 are presented in Table 25, followed by a brief description of the structure determination for each compound. -150-Table 25. Data collection parameters and crystal data for compounds of chapter 10. Compound 19 Compound 33 Compound 38 Formula F.W. F(000) Dc (g cm"3) Radiation /i (cm - 1) 2^max (°) to-scan width (°) Scan speed (° min - 1)t Orientation check Space group a (A) b (A) c (A) a (°) )8 (°) 7 ( ° ) v (A3) z C26 H20°4 396.44 832 1.337 CuKQ 6.85 155.3 O.94+O.3Otan0 8 150 P21/n 10.206(3) 16.485(1) 11.758(4) 90 95.48(2) 90 1969.2(8) 4 C20 H14 C 12°4 389.23 800 1.45 Cutf a 35.26 155.2 1.00+0.3Otan0 8 150 P2 12 12 1 10.420(3) 17.652(1) 9.697(2) 90 90 90 1783.6(5) 4 C32 H24°4 472.54 1984 1.30 CuKQ 6.44 155.4 O.89+O.3Otan0 8 150 C2/c 29.368(1) 13.378(2) 13.186(2) 90 111.519(6) 90 4819.8(4) f A maximum of 8 rescans i f I < 40.0CT(I). -151-Compound 19 A crystal of approximate 0.3 x 0.1 x 0.4 mm-3 size was chosen for data collection. A monoclinic c e l l with Z = 4 (assuming a density of 1.337 g cm-3) was indicated by preliminary reflections. In the h,k,l range of 0 to 13, 0 to 21, -15 to 15, 4426 reflections were collected of which 4195 were unique and 2882 observed. Final c e l l parameters were determined using a least-squares refinement of 21 well-centered reflections (50.00 < 28 < 87.48°). The standard reflections (1,-4,-2; 3,-5,-2; 1,-2,3) did not exhibit any significant change in their intensities (no decay correction was necessary). Lp corrections were made. An empirical absorption cor-rection was made (transmission factors: 0.84 to 1.00). Equivalent reflec-tions were merged. Based on systematic absences (hOl: h+1 2n; OkO: k * 2n), and suc-cessful structure solution and refinement, the space group was determined as P21/n. The structure was solved by direct methods. The best E-map gave 29 non-hydrogen atoms which were used as a t r i a l structure for refinement with isotropic thermal parameters. This resulted in locating the remain-ing one cyclopropyl carbon atom. The model was then refined anisotropi-cally. A secondary extinction correction was applied (final coefficient = 0.533xl0 —. A l l hydrogen atoms were found in subsequent difference maps and were refined isotropically. The refinement converged at R = 0.039, R w = 0.056 for 352 variables (S = 1.69; including zeros: R = 0.074, Rw = 0.059) with the largest parameter shift being 0.01a. The f i n a l dif-ference map showed electron density fluctuations between 0.21 and -0.18 eA - 3. -152-The f i n a l atomic coordinates tropic thermal parameters are given bond angles are presented in Tables and their isotropic or equivalent iso-in Table 26. The bond lengths and 27 and 28, respectively. -153-Table 26. Atomic coordinates and B e q values of compound 19. a t o m x y z B ( e q ) 0 ( 1 ) 0 . 4 9 7 8 ( 1 ) 0 . 2 8 8 6 7 ( 8 ) 0 . 3 7 8 4 ( 1 ) 3 . 4 3 ( 5 ) Oi 2 ) 0 . 3 0 4 3 ( 1 ) 0 . 3 4 0 8 6 ( 8 ) 0 . 3 0 9 6 ( 1 ) 4 . 1 1 ( 6 ) 0 ( 3 ) 0 . 5 2 9 9 ( 1 ) 0 . 1 1 1 4 ( 1 ) 0 . 4 4 2 5 ( 1 ) 4 . 2 1 ( 6 ) 0 ( 4 ) 0 . 6 8 7 6 ( 1 ) 0 . 1 3 9 2 ( 1 ) 0 . 3 3 1 2 ( 1 ) 5 . 5 5 ( 8 ) C( 1 ) 0 . 3 9 2 7 ( 2 ) 0 . 1 5 9 0 ( 1 ) - 0 . 0 6 4 3 ( 2 ) 3 . 8 3 ( 9 ) C( 2 ) 0 . 3 5 2 6 ( 2 ) 0 . 0 9 7 7 ( 2 ) - 0 . 1 4 0 7 ( 2 ) 4 . 5 ( 1 ) C( 3 ) 0 . 3 2 2 0 ( 2 ) 0 . 0 2 1 1 ( 1 ) - 0 . 1 0 3 2 ( 2 ) 4 . 1 ( 1 ) C( 4 A ) 0 . 3 7 1 6 ( 2 ) 0 . 0 6 4 3 ( 1 ) 0 . 0 8 9 2 ( 1 ) 2 . 7 4 ( 6 ) C( 4 ) 0 . 3 2 9 3 ( 2 ) 0 . 0 0 3 9 ( 1 ) 0 . 0 1 2 7 ( 2 ) 3 . 4 6 ( 8 ) C( 5 ) 0 . 1 3 1 4 ( 2 ) 0 . 0 3 8 1 ( 1 ) 0 . 2 4 7 2 ( 2 ) 3 . 2 7 ( 8 ) 6 ) 0 . 0 0 9 9 ( 2 ) 0 . 0 7 4 0 ( 1 ) 0 . 2 5 8 2 ( 2 ) 3 . 6 3 ( 8 ) C( 7 ) - 0 . 0 0 1 7 ( 2 ) 0 . 1 5 7 2 ( 1 ) 0 . 2 6 2 1 ( 2 ) 3 . 4 0 ( 8 ) C( 8 A ) 0 . 2 2 8 9 ( 2 ) 0 . 1 7 1 7 ( 1 ) 0 . 2 4 7 2 ( 1 ) 2 . 5 2 ( 6 ) C( 8 ) 0 . 1 0 7 3 ( 2 ) 0 . 2 0 7 5 ( 1 ) 0 . 2 5 6 2 ( 2 ) 3 . 0 3 ( 7 ) c( 9 A ) 0 . 4 0 2 9 ( 2 ) 0 . 1 4 1 4 ( 1 ) 0 . 0 5 1 9 ( 1 ) 2 . 8 0 ( 7 ) C( 9 ) 0 . 4 5 4 8 ( 2 ) 0 . 1 9 4 2 ( 1 ) 0 . 1 4 9 1 ( 1 ) 2 . 6 3 ( 6 ) C( 1 0 ) 0 . 3 7 8 3 ( 2 ) 0 . 0 6 4 2 ( 1 ) 0 . 2 1 8 5 ( 2 ) 2 . 7 0 ( 6 ) C( 1 0 A ) 0 . 2 4 0 2 ( 2 ) 0 . 0 8 7 4 ( 1 ) 0 . 2 4 2 8 ( 1 ) 2 . 6 1 ( 6 ) c( 1 1 ) 0 . 3 6 2 2 ( 2 ) 0 . 2 0 9 5 ( 1 ) 0 . 2 4 9 2 ( 1 ) 2 . 5 2 ( 6 ) C( 1 2 ) 0 . 4 6 1 4 ( 2 ) 0 . 1 4 1 0 ( 1 ) 0 . 2 5 3 6 ( 1 ) 2 . 6 0 ( 6 ) C( 1 3 ) 0 . 3 8 3 2 ( 2 ) 0 . 2 8 6 7 ( 1 ) 0 . 3 1 4 1 ( 1 ) 2 . 7 2 ( 6 ) C< 1 4 ) 0 . 5 2 7 1 ( 3 ) 0 . 3 6 2 3 ( 2 ) 0 . 4 4 2 4 ( 2 ) 4 . 7 ( 1 ) C( 1 5 ) 0 . 5 7 4 5 ( 2 ) 0 . 1 3 2 4 ( 1 ) 0 . 3 4 3 3 ( 2 ) 2 . 9 2 ( 7 ) C( 1 6 ) 0 . 6 2 7 7 ( 3 ) 0 . 1 0 4 4 ( 2 ) 0 . 5 3 9 1 ( 2 ) 6 . 1 ( 1 ) C( 1 7 ) 0 . 5 5 2 1 ( 2 ) 0 . 2 5 7 9 ( 1 ) 0 . 1 2 1 6 ( 1 ) 2 . 7 8 ( 7 ) C( 1 8 ) 0 . 6 7 9 7 ( 2 ) 0 . 2 3 5 5 ( 1 ) 0 . 1 0 4 1 ( 2 ) 3 . 3 5 ( 8 ) C( 1 9 ) 0 . 7 6 7 3 ( 2 ) 0 . 2 9 1 8 ( 1 ) 0 . 0 6 8 0 ( 2 ) 3 . 8 3 ( 9 ) C( 2 0 ) 0 . 7 2 8 8 ( 2 ) 0 . 3 7 0 8 ( 1 ) 0 . 0 4 8 4 ( 2 ) 3 . 8 5 ( 8 ) C | 2 1 ) 0 . 6 0 2 7 ( 2 ) 0 . 3 9 3 7 ( 1 ) 0 . 0 6 5 0 ( 2 ) 4 . 1 ( 1 ) c 2 2 ) 0 . 5 1 4 2 ( 2 ) 0 . 3 3 7 8 ( 1 ) 0 . 1 0 1 1 ( 2 ) 3 . 6 1 ( 8 ) H( 1 ) 0 . 4 1 4 ( 2 ) 0 . 2 1 1 ( 1 ) - 0 . 0 8 9 ( 2 ) 4 . 2 ( 5 ) H 2 ) 0 . 3 4 3 ( 3 ) 0 . 1 1 3 ( 2 ) - 0 . 2 2 4 ( 3 ) 6 . 6 ( 7 ) H( 3 ) 0 . 2 9 5 ( 3 ) - 0 . 0 2 2 ( 2 ) - 0 . 1 6 1 ( 2 ) 5 . 7 ( 6 ) H< 4 ) 0 . 3 0 4 ( 2 ) - 0 . 0 5 0 ( 1 ) 0 . 0 4 1 ( 2 ) 4 . 3 ( 5 ) H 5 ) 0 . 1 4 0 ( 2 ) - 0 . 0 2 2 ( 1 ) 0 . 2 4 4 ( 2 ) 4 . 2 ( 5 ) H 6 ) - 0 . 0 6 8 ( 2 ) 0 . 0 3 8 ( 1 ) 0 . 2 6 5 ( 2 ) 4 . 0 ( 5 ) H| 7 ) - 0 . 0 8 7 ( 2 ) 0 . 1 8 1 ( 1 ) 0 . 2 7 0 ( 2 ) 4 . 9 ( 5 ) H 8 ) 0 . 0 9 9 ( 2 ) 0 . 2 6 6 ( 1 ) 0 . 2 6 2 ( 2 ) 3 . 5 ( 4 ) H 1 0 ) 0 . 4 1 6 ( 2 ) 0 . 0 0 9 ( 1 ) 0 . 2 5 4 ( 2 ) 3 . 4 ( 4 ) H( 1 4 C ) 0 . 4 5 2 ( 4 ) 0 . 3 7 5 ( 2 ) 0 . 4 8 0 ( 4 ) 1 2 ( 1 ) H 1 4 B ) 0 . 5 3 4 ( 3 ) 0 . 4 0 9 ( 2 ) 0 . 3 9 2 ( 3 ) 8 . 0 ( 9 ) H 1 4 A ) 0 . 6 0 6 ( 3 ) 0 . 3 4 7 ( 2 ) 0 . 4 8 9 ( 2 ) 5 . 7 ( 6 ) H 1 6 C ) 0 . 5 7 1 ( 4 ) 0 . 0 9 0 ( 2 ) 0 . 6 0 3 ( 4 ) 1 2 ( 1 ) H 1 6 B ) 0 . 6 7 8 ( 4 ) 0 . 1 6 1 ( 2 ) 0 . 5 4 4 ( 3 ) 1 0 ( 1 ) H 1 6 A ) 0 . 6 9 9 ( 3 ) 0 . 0 7 1 ( 2 ) 0 . 5 1 8 ( 2 ) 6 . 4 ( 7 ) H 1 8 ) 0 . 7 0 9 ( 2 ) 0 . 1 7 8 ( 1 ) 0 . 1 1 4 ( 2 ) 4 . 5 ( 5 ) H 1 9 ) 0 . 8 5 7 ( 3 ) 0 . 2 7 7 ( 2 ) 0 . 0 5 9 ( 2 ) 6 . 3 ( 7 ) H 2 0 ) 0 . 7 9 5 ( 2 ) 0 . 4 1 3 ( 1 ) 0 . 0 2 9 ( 2 ) 4 . 7 ( 5 ) H 2 1 ) 0 . 5 7 7 ( 2 ) 0 . 4 5 3 ( 1 ) 0 . 0 5 3 ( 2 ) 4 . 9 ( 5 ) H 2 2 ) 0 . 4 2 1 ( 2 ) 0 . 3 5 6 ( 1 ) 0 . 1 1 1 ( 2 ) 4 . 4 ( 5 ) -154-Table 27. Bond lengths involving atom atom d i s t a n c e 01 C13 1.332(2) 01 C14 1.444(2) 02 C13 1.199(2) 03 C15 1.337(2) 03 C16 1.444(3) 04 C15 1.182(2) CI C2 1.387(3) CI C9A 1.390(3) C2 C3 1.383(3) C3 C4 1.388(3) C4A C4 1.383(3) C4A C9A 1.392(2) C4A CIO 1.515(3) C5 C6 1.392(3) C5 C10A 1.382(2) C6 C7 1.377(3) C7 C8 1.395(3) C8A C8 1.388(2) -hydrogen atoms of compound 19. atom atom d i s t a n c e C8A C10A 1 .395(2) C8A C l l 1 .495(2) C9A C9 1 .493(2) C9 C l l 1 .599(2) C9 C12 1 .506(2) C9 C17 1 .502(2) CIO C10A 1 .514(2) CIO C12 1 .558(2) C l l C12 1 .515(2) C l l C13 1 .489(2) C12 C15 1 .494(2) C17 C18 1 .388(2) C17 C22 1 .388(3) C18 C19 1 .384(3) C19 C20 1 .373(3) C20 C21 1 .373(3) C21 C22 1 .386(3) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -155-Table 28. Bond angles involving non-hydrogen atoms of compound 19 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 3 ( 2 ) C4A C IO C12 1 0 3 . 6 ( 1 ) C15 03 C16 1 1 6 . 1 ( 2 ) C 1 0 A C IO C12 1 0 3 . 7 ( 1 ) C2 C I C9A 1 1 8 . 3 ( 2 ) C5 C I OA C8A 1 2 1 . 0 ( 2 ) C I C2 C3 1 2 1 . 3 ( 2 ) C5 C 1 0 A C IO 1 2 8 . 6 ( 2 ) C2 C3 C4 1 2 0 . 5 ( 2 ) C8A C I OA C IO 1 1 0 . 0 ( 1 ) C4 C4A C9A 1 2 1 . 3 ( 2 ) C8A C l l C9 1 2 1 . 6 ( 1 ) C4 C4A C IO 1 2 9 . 2 ( 2 ) C8A C l l C12 1 0 7 . 1 ( 1 ) C9A C4A C IO 1 0 9 . 2 ( 1 ) C8A C l l C13 1 1 6 . 8 ( 1 ) C3 C4 C4A 1 1 8 . 4 ( 2 ) C9 C l l C12 5 7 . 8 ( 1 ) C6 C5 C 1 0 A 1 1 8 . 6 ( 2 ) C9 C l l C13 1 1 6 . 5 ( 1 ) C5 C6 C7 1 2 0 . 5 ( 2 ) C12 C l l C13 1 2 3 . 9 ( 1 ) C6 C7 C8 1 2 1 . 3 ( 2 ) C9 C12 C IO 1 0 6 . 1 ( 1 ) C8 C8A C 1 0 A 1 2 0 . 3 ( 2 ) C9 C12 C l l 6 3 . 9 ( 1 ) C8 C8A C l l 1 2 9 . 8 ( 2 ) C9 C12 C15 1 2 7 . 1 ( 1 ) C10A C8A C l l 1 0 9 . 7 ( 1 ) C10 C12 C l l 1 0 4 . 6 ( 1 ) C7 C8 C8A 1 1 8 . 3 ( 2 ) C IO C12 C15 1 1 8 . 3 ( 1 ) C I C9A C4A 1 2 0 . 1 ( 2 ) C l l C12 C15 1 2 4 . 3 ( 2 ) C I C9A C9 1 2 8 . 2 ( 2 ) 01 C13 02 1 2 3 . 9 ( 2 ) C4A C9A C9 1 1 1 . 5 ( 1 ) 01 C13 C l l 1 1 2 . 7 ( 1 ) C9A C9 C l l 1 1 7 . 7 ( 1 ) 02 C13 C l l 1 2 3 . 4 ( 2 ) C9A C9 C12 1 0 5 . 7 ( 1 ) 03 C15 04 1 2 3 . 2 ( 2 ) C9A C9 C17 1 1 5 . 9 ( 1 ) 03 C15 C12 1 0 9 . 6 ( 1 ) C l l C9 C12 5 8 . 3 ( 1 ) 04 C15 C12 1 2 7 . 1 ( 2 ) C l l C9 C17 1 1 9 . 8 ( 1 ) C9 C17 C18 1 1 9 . 7 ( 2 ) C12 C9 C17 1 2 7 . 2 ( 1 ) C9 C17 C22 1 2 1 . 4 ( 2 ) C4A C IO C 1 0 A 1 0 3 . 6 ( 1 ) C18 C17 C22 1 1 8 . 5 ( 2 ) A n g l e s a r e i n d e g r e e s E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -156-Table 28 (contd.) a t o m a t o m a t o m a n g l e C17 C18 C19 1 2 0 . 6 ( 2 ) C18 C19 C20 1 2 0 . 4 ( 2 ) C19 C20 C21 1 1 9 . 6 ( 2 ) C20 C21 C22 1 2 0 . 6 ( 2 ) C17 C22 C21 1 2 0 . 3 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -157-Compound 33 A crystal having approximate dimensions of 0.25 x 0.2 x 0.4 mm3 was used for data collection. Preliminary reflections indicated an ortho-rhombic c e l l with Z =4 (with an estimated density of 1.45 g cm - 3). A total of 2199 reflections (h,k,l limits: 0 to 13, 0 to 22, 0 to 12) was collected of which 1824 were observed. Final c e l l parameters were deter-mined using 6 carefully centered reflections (89.65 < 26 < 103.55°). The intensities of three standard reflections (1,-4,-1; -1,-4,-1; 0,-6,0) did not vary significantly during data collection (no decay correction was applied). Lp corrections were made, and an empirical absorption correc-tion was applied (transmission factors: 0.85 to 1.00). Based on systematic absences (hOO: h ^ 2n; OkO: k * 2n; 001: 1 * 2n), and successful structure solution and refinement, the space group was determined to be P2^2]^2^. The structure was solved using direct methods. The molecular fragment obtained from the best E-map was used in DIRDIF which gave the positions of a l l non-hydrogen atoms. The t r i a l structure was then refined isotro-pically for two cycles and then anisotropically. A l l aromatic hydrogens and two ester methyl hydrogens (remaining were calculated) were found in AF-maps, and were refined isotropically. A secondary extinction correc-tion was applied (final coefficient = 0.429xl0 - 5). The model was then refined in the second enantiomorph possible which gave a lower R-value (0.039 versus 0.055). The enantiomorph with lower R-value was chosen as the correct one. The refinement converged at R = 0.039, Rw = 0.061 (S = 2.04; including zeros: R = 0.059, Rw = 0.063) for 292 variables. The last cycle had a largest parameter shift of 0.01a, and -158-the maximum and minimum residual peaks in the AF-map were 0.20 and -0.26 eA~3. The f i n a l atomic positions and isotropic or equivalent isotropic thermal parameters are given in Table 29. The bond lengths, bond angles are given in Tables 30 and 31, respectively. -159-Table 29. Atomic p o s i t i o n s and B e q values of compound 33. atom X y z B(eq) C L l 0 .9407(1) 0 .91072(7) 0 .9148(1) 4.28(4) CL2 1 .2136(1) 1 .02687(7) 1 .3421(1) 5.19(5) 01 0 .7446(3) 0 .9769(2) 1 .1353(4) 4.5(1) 02 0 .7082(3) 0 .8555(2) 1 .1848(5) 5.3(2) 03 0 .9250(3) 1 .0800(2) 1 .2571(3) 4.3(1) 04 1 .0080(5) 1 .0793(2) 1 .0448(4) 6.1(2) CI 0 .8975(5) 0 .8094(3) 1 .4114(5) 4.4(2) C2 0 .9519(7) 0 .7862(4) 1 .5351(6) 6.0(3) C3 1 .0671(7) 0 .8158(4) 1 .5809(5) 6.2(3) C4A 1 .0738(4) 0 .8957(3) 1 .3832(4) 3.5(2) C4 1 .1308(5) 0 .8713(3) 1 .5052(5) 4.7(2) C5 1 .3379(4) 0 .8738(3) 1 .2093(5) 3.8(2) C6 1 .3892(4) 0 .8195(3) 1 .1208(5) 4.3(2) C7 1 .3163(4) 0 .7884(3) 1 .0152(5) 4.0(2) C8 1 .1894(4) 0 .8107(3) 0 .9953(4) 3.6(2) C8A 1 .1391(3) 0 .8660(2) 1 .0819(4) 2.9(1) C9A 0 .9596(4) 0 .8650(2) 1 .3372(4) 3.2(1) C9 1 .0129(3) 0 .9035(2) 1 .0773(4) 3.0(1) C10A 1 .2136(4 ) 0 .8961(2) 1 .1872(4 ) 3.1(1) CIO 1 .1305(4) 0 .9477(2) 1 .2752(4 ) 3.3(1) C l l 0 .9196(4) 0 .9037(2) 1 .2064(4) 3.1(1) C12 1 .0135(3) 0 .9669(2) 1 .1800( 4 ) 2.9(1) C13 0 .7787(4) 0 .9090(2) 1 •1754(4) 3.3(1) C14 0 .6125(5) 0 .9878(4) 1 .0935(8) 5.6(3) C15 0 .9814(4) 1 .0478(2) 1 .1489(5) 3.7(2) C16 * 0 .893(1) 1 .1582(4) 1 .246(1) 6.6(4) HI 0 .820(6) 0 .789(3) 1 .361(6) 5(1) H2 0 .921(7) 0 .759(4) 1 .586(8) 7(2) H3 1 .12(1) 0 .789(6) 1 .65(1) 15(4) H4 1 .211(6) 0 .894(3) 1 .518(6) 5(1) H5 1 .388(7) 0 .910(4) 1 .283(7) 7(2) H6 1 .487(5) 0 .811(3) 1 .132(6) 5(1) H7 1 .353(5) 0 .757(3) 0 .949(6) 5(1) H8 1 .123(5) 0 .794(3) 0 .918(6) 4(1) H14A 0 .57(1) 0 .972(5) 1 .17(1) 10(3) H14B 0 .614(5) 1 .046(3) 1 .084(6) 5(1) H14C 0 .622(8) 0 .972(5) 0 .98(1) 11(3) H16B 0 .887(8) 1 .183(5) 1 .36(1) 10(2) H16A 0 .96(1) 1 .181(7) 1 .18(1) 13(3) H16C 0 .840(7) 1 .164(4) 1 .203(7) 5(2) -160-Table 3 0 . Bond lengths involving non-hydrogen atoms of compound 3 3 . a t o m a t o m d i s t a n c e a t o m a t o m d i s t a n c e C L l C 9 1 . 7 5 1 ( 4 ) C 5 C 1 0 A 1 . 3 7 0 ( 5 ) C L 2 C I O 1 . 7 6 7 ( 4 ) C 5 C6 1 . 3 9 4 ( 7 ) 0 1 C 1 3 1 . 3 0 8 ( 5 ) C6 C7 1 . 3 8 9 ( 7 ) 0 1 C 1 4 1 . 4 4 8 ( 6 ) C7 C8 1 . 3 9 2 ( 6 ) 0 2 C 1 3 1 . 2 0 1 ( 5 ) C8 C 8 A 1 . 3 9 1 ( 6 ) 0 3 C 1 5 1 . 3 3 0 ( 5 ) C 8 A C 1 0 A 1 . 3 8 8 ( 5 ) 0 3 C 1 6 1 . 4 2 4 ( 7 ) C 8 A C 9 1 . 4 7 3 ( 5 ) 0 4 C 1 5 1 . 1 8 5 ( 6 ) C 9 A C l l 1 . 5 0 0 ( 5 ) C I C 9 A 1 . 3 7 8 ( 6 ) C 9 C 1 2 1 . 4 9 7 ( 5 ) C I C2 1 . 3 8 9 ( 8 ) C 9 C l l 1 . 5 8 5 ( 5 ) C2 C3 1 . 3 8 ( 1 ) C 1 0 A C I O 1 . 5 2 0 ( 5 ) C 3 C4 1 . 3 9 ( 1 ) C I O C 1 2 1 . 5 6 6 ( 5 ) C 4 A C 9 A 1 . 3 8 1 ( 6 ) C l l C 1 3 1 . 5 0 1 ( 5 ) C 4 A C4 1 . 3 9 2 ( 6 ) C l l C 1 2 1 . 5 0 6 ( 5 ) C 4 A C I O 1 . 5 1 3 ( 6 ) C 1 2 C 1 5 1 . 4 9 8 ( 6 ) D i s t a n c e s a r e i n a n g s t r o m s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -161-T a b l e 31 . Bond a n g l e s i n v o l v i n g non-hydrogen atoms o f compound 33 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 6 ( 4 ) C5 C 1 0 A CIO 1 2 8 . 5 ( 4 ) C15 03 C16 1 1 7 . 3 ( 5 ) C8A C 1 0 A CIO 1 0 8 . 9 ( 3 ) C9A CI C2 1 1 7 . 9 ( 5 ) C4A CIO C 1 0 A 1 0 4 . 3 ( 3 ) C3 C2 C I 1 2 1 . 4 ( 6 ) C4A CIO C12 1 0 3 . 6 ( 3 ) C2 C3 C4 1 2 0 . 7 ( 5 ) C4A CIO CL2 1 1 4 . 7 ( 3 ) C9A C4A C4 1 2 1 . 4 ( 5 ) C 1 0 A CIO C12 1 0 4 . 0 ( 3 ) C9A C4A C IO 1 1 0 . 6 ( 3 ) C 1 0 A CIO CL2 1 1 3 . 7 ( 3 ) C4 C4A CIO 1 2 7 . 5 ( 4 ) C12 CIO CL2 1 1 5 . 3 ( 3 ) C4A C4 C3 1 1 7 . 5 ( 5 ) C9A C l l C13 1 1 8 . 0 ( 3 ) C10A C5 C6 1 1 7 . 6 ( 4 ) C9A C l l C12 1 0 7 . 5 ( 3 ) C7 C6 C5 1 2 1 . 1 ( 4 ) C9A C l l C9 1 1 9 . 8 ( 3 ) C6 C7 C8 1 2 0 . 6 ( 4 ) C13 C l l C12 1 2 3.7 ( 3 ) C8A C8 C7 1 1 8 . 2 ( 4 ) C13 C l l C9 1 1 6 . 2 ( 3 ) C10A C8A C8 1 2 0 . 1 ( 4 ) C12 C l l C9 5 7 . 9 ( 2 ) C10A C8A C9 1 1 0 . 4 ( 3 ) C9 C12 C15 1 2 5 . 2 ( 3 ) C8 C8A C9 1 2 9 . 4 ( 4 ) C9 C12 C l l 6 3 . 7(2) CI C9A C4A 1 2 1 . 0 ( 4 ) C9 C12 CIO 1 0 3 . 6 ( 3 ) CI C9A C l l 1 2 9 . 4 ( 4 ) C15 C12 C l l 1 2 6 . 5 ( 3 ) C4A C9A C l l 1 0 9 . 5 ( 3 ) C15 C12 CIO 1 1 9 . 9 ( 3 ) C8A C9 C12 1 0 8 . 2 ( 3 ) C l l C12 CIO 1 0 4 . 2 ( 3 ) C8A C9 C l l 1 2 1 . 6 ( 3 ) 02 C13 01 1 2 5 . 2 ( 4 ) C8A C9 CL1 1 1 6 . 3 ( 3 ) 02 C13 C l l 1 2 2 . 2 ( 4 ) C12 C9 C l l 5 8 . 4 ( 2 ) 01 C13 C l l 1 1 2 . 5 ( 3 ) C12 C9 CL1 1 2 3 . 1 ( 3 ) 04 C15 03 1 2 5 . 1 ( 4 ) C l l C9 CL1 1 1 6 . 6 ( 2 ) 04 C15 C12 1 2 4 . 5 ( 4 ) C5 C 1 0 A C8A 1 2 2 . 3 ( 4 ) 03 C15 C12 1 1 0 . 3 ( 4 ) A n g l e s a r e i n d e g r e e s E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -162-Compound 38 A crystal of approximate dimensions of 0.2 x 0.2 x 0.3 mm3 was chosen for data collection. A C-centered monoclinic c e l l with Z = 8 (assuming density of 1.30 g cm - 3) was indicated by preliminary reflections. In the h,k,l range of -37 to 37, 0 to 17, 0 to 17, a total of 5409 reflections was collected of which 5175 were unique and 2261 were observed. Least squares refinement of 21 reflections (50.32 < 28 < 79.80°) gave the fin a l c e l l parameters. During the data collection, the standard reflections (-6,-2,0; -1,-3,2; -7,-1,0) showed no significant change in their intensities (no decay correction was applied). Lp corrections were made, and an empirical absorption correction using the program DIFABS^ was applied (transmission factors: 0.87 to 1.16). Equivalent reflections were merged. Based on systematic absences (hkl: h+k 2n; hOl: 1 * 2n), E-statis-tics, and successful structure solution and refinement, the space group was found to be C2/c. The structure was solved by direct methods. The molecular fragment obtained from the best E-map was used in DIRDIF which gave a l l the non-hydrogen atoms (except the two vinylic carbons). The model was refined isotropically, and the difference Fourier synthesis at this stage gave the remaining two carbon atoms. The model structure was then refined aniso-tropically. A l l hydrogen atoms were found in subsequent AF-maps and were refined isotropically; however, in later cycles, the ester methyl hydrog-ens and an aromatic hydrogen were excluded from refinement as they were found to move to geometrically unacceptable positions. A minor disorder was noticed at this stage in one of the ester groups. The two highest -163-residual peaks (0.37 and 0.31 eA-3) in the difference map were included in the model as a disordered oxygen and a methyl carbon (01', C14') with an occupancy factor.of 0.1 each and were refined isotropically. Two reflec-tions, -1, 1, 0 and 2,0,0 with AF/oF values of 21.83 and 33.93 were removed from refinement in later cycles. The refinement converged at R = 0.068, R^ . = 0.088 and S = 2.32 for 401 variables (including zeros: R = 0.175, R„ = 0.102). In the last cycle, largest parameter shift was O.Olcr, and the difference map contained peaks between 0.25 and -0.27 eA-3. The f i n a l atomic coordinates and their isotropic or equivalent iso-tropic thermal parameters are given in Table 32. The bond lengths and bond angles involving non-hydrogen atoms are presented in Tables 33 and 34, respectively. Table 32. Atomic positions and B e q values of compound 38. atom X y z B(eq) 01 0 .2779(2) 0 .1760(4) 0 .8832(4) 7.9(2) 02 0 .3150(2) 0 .2110(4) 0 .7651(5) 8.0(3) 03 0 .2523(2) 0 .3820(3) 0 .9026(3) 9.9(3) 04 0 .2346(3) 0 .4996(3) 0 .7884(4) 12.5(3) 01' 0 .307(1) 0 .242(2) 0 •826(3) 3.2(6) CI 0 .1839(2) 0 .2452(4) 0 .7414(4 ) 3.5(2) C2 0 .2242(2) 0 .2347(6) 0 .5964(5) 5.7(3) C3 0 .1980(2) 0 .3104(5) 0 .5384(5) 5.3(3) C4A 0 .1271(2) 0 .3242(3) 0 .5835(3) 3.3(2) C4 0 .1771(2) 0 .3731(4) 0 .6068(4) 4.0(2) C5 -0 .0022(2) 0 .2942(5) 0 .4077(5) 5.2(3) C6 -0 .0410(2) 0 .2316(5) 0 .3921(5) 6.7(3) C7 -0 .0346(2) 0 .1489(5) 0 .4611(5) 6.1(3) C8 0 .0089(2) 0 .1308(4) 0 .5407( 4 ) 4.6(2) C8A 0 .0493(2) 0 .1940(3) 0 .5609(4) 3.4(2) C9 0 .0954(2) 0 .1773(3) 0 .6457( 3 ) 3.0(2) C9A 0 .1337(2) 0 .2409(3) 0 .6570(3) 3.2(2) C10A 0 .0426(2) 0 .2802(3) 0 .4893(4) 3.7(2) -164-Table 32 (contd.) atom X y z B(eq) CIO 0 . 0 8 3 8 ( 2 ) 0 . 3 4 3 9 ( 3 ) 0 .5031(3) 3 • 4( 2) C l l 0 . 2 2 9 3 ( 2 ) 0 .2396(4) 0 .7114(4) 4 .6( 2) C12 0 .2069(2) 0 .3408(4) 0 .7238(4) 3 • 8( 2) C13 0 .2784(3) 0 .2095(4) 0 .7902(7) 6 . 3( 3) C14 0 .3276(3) 0 .1643(7) 0 .9645(7) 9 • 7( 4) C15 0 .2318(2) 0 .4165(4) 0 .8071(4) 4 • 6( 2) C16 0 .2809(3) 0 .4499(5) 0 .9889(5) 9 • 3( 4) C17 0 .1028(2) 0 .0894(3) 0 .7204(4) 3 -2( 2) C18 0 .1380(2) 0 .0177(4) 0 .7261(4) 4 .2( 2) C19 0 .1440(2) -0 .0657(4) 0 .7913(5) 5 .0( 2) C20 0 . 1 1 5 6 ( 3 ) -0 .0785(4) 0 .8520(5) 5 5( 3) C21 0 .0818(3) -0 .0080(5) 0 .8509(5) 5 -7( 3) C22 0 .0765(2) 0 .0760(4) 0 .7866(5) 4 .6( 2) C23 0 .0787(2) 0 .4323(4) 0 .4292(4) 4 • K 2) C24 0 .0576(2) 0 .5197(4) 0 .4449(5) 5 0( 2) C25 0 .0547(3) 0 .6004(5) 0 .3775(6) 6 3( 3) C26 0 .0712(3) 0 .5959(7) 0 .2957(6) 7 6( 4) C27 0 .0935(3) 0 .5094(7) 0 .2795(5) 7 5( 4) C28 0 .0967(2) 0 .4267(5) 0 .3452(4) 5 6( 3) C14' 0 .360(2) 0 .218(4) 0 .905(5) 6< 1) HI 0 .184(2) 0 .227(4) 0 .806(4) 5 1) H2 0 .243(2) 0 .180(4) 0 . 574( 4 ) 6< 1) H3 0 .187(2) 0 .316(4) 0 .455(4) 5 1) H4 0 .174(2) 0 .445(4) 0 .595(4) 5( 1) H5 -0 .003(2) 0 .342(5) 0 .364(5) 81 2) H6 -0 .072(2) 0 .245(3) 0 .342(3) 2 7( 8) H7 -0 .060(2) 0 .111(4) 0 .439(4) 4( 1) H8 0 .011(2) 0 .066(4) 0 .580(4) 5( 1) H14C 0 .3395 0 .2275 0 .9961 11. 6 H 1 4 B 0 .3485 0 .1386 0 .9301 11 6 H 1 4 A 0 .3270 0 .1194 1 .0197 11. 6 H16C 0 .2610 0 .5045 0 .9931 11 .1 H 1 6 B 0 .3081 0 .4742 0 .9734 11 . 1 H 1 6 A 0 .2924 0 .4153 1 .0565 11 .1 H18 0 .160(2) 0 .022(3) 0 .691(3) 4 1) H 1 9 0 .170(2) -0 .111(4) 0 .788(4) 6 1) H20 0 .114(3) -0 .136(6) 0 .887(6) 10 2) H21 0 .061(2) -0 .013(4) 0 .899(4) 5 1) H22 0 .054(2) 0 .121(4) 0 .780(4 ) 4 1) H24 0 .041(2) 0 .525(4) 0 .494(4) 6< 1) H25 0 .045(2) 0 .656(4 ) 0 .400(4) 5< 1) H 2 6 0 .0676 0 .6517 0 .2489 9 2 H27 0 .111(3) 0 .513(6) 0 .232(6) 111 3) H28 0 .117(2) 0 .368(4) 0 .333(4) 5( 1) -165-Table 33. Bond lengths involving non-hydrogen atoms of compound 38. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.312(8) C8 C8A 1.398(6) 01 C14 1.469(8) C8A C9 1.423(6) 02 C13 1.234(8) C8A C10A 1.458(6) 03 C15 1.267(6) C9 C9A 1.375(6) 03 C16 1.457(7) C9 C17 1.498(6) 04 C15 1.149(6) C10A CIO 1.436(6) 01' C13 0.91(4) CIO C23 1.505(6) 01' C14' 1.55(7) C l l C12 1.540(7) CI C9A 1.487(6) C l l C13 1.491(8) CI C l l 1.526(7) C12 C15 1.475(7) CI C12 1.504(6) C17 C18 1.392(7) C2 C3 1.330(9) C17 C22 1.373(7) C2 C l l 1.469(8) C18 C19 1.379(7) C3 C4 1.516(7) C19 C20 1.363(9) C4A C4 1.533(6) C20 C21 1.365(9) C4A C9A 1.443(6) C21 C22 1.381(7) C4A CIO 1.350(6) C23 C24 1.374(8) C4 C12 1.530(6) C23 C28 1.392(8) C5 C6 1.368(8) C24 C25 1.382(8) C5 C10A 1.373(7) C25 C26 1.34(1) C6 C7 1.401(8) C26 C27 1.38(1) C7 C8 1.346(8) C27 C28 1.387(9) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -166-Table 34. Bond angles involving non-hydrogen atoms of compound 38 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 1 . 6 ( 6 ) C4A C9A C9 1 2 0 . 1 ( 4 ) C15 03 C16 1 1 8 . 5 ( 5 ) C5 C 1 0 A C8A 1 1 8 . 5 ( 5 ) C13 0 1 ' C 1 4 ' 1 3 9 ( 4 ) C5 C 1 0 A C IO 1 2 2 . 6 ( 5 ) C9A C I C l l 1 2 1 . 6 ( 4 ) C8A CI OA CIO 1 1 8 . 8 ( 4 ) C9A C I C12 1 0 7 . 2 ( 4 ) C4A C IO C 1 0 A 1 1 9 . 4 ( 4 ) C l l C I C12 6 1 . 1 ( 3 ) C4A C IO C23 1 2 0 . 2 ( 4 ) C3 C2 C l l 1 1 2 . 3 ( 6 ) C 1 0 A C IO C23 1 2 0 . 4 ( 4 ) C2 C3 C4 1 1 0 . 7 ( 5 ) C I C l l C2 1 2 0 . 1 ( 5 ) C4 C4A C9A 1 0 8 . 2 ( 4 ) C I C l l C12 5 8 . 7 ( 3 ) C4 C4A C IO 1 2 9 . 2 ( 4 ) C I C l l C13 1 2 3 . 2 ( 5 ) C9A C4A C IO 1 2 2 . 3 ( 4 ) C2 C l l C12 1 0 5 . 2 ( 5 ) C3 C4 C4A 1 0 2 . 2 ( 4 ) C2 C l l C13 1 1 4 . 5 ( 5 ) C3 C4 C12 1 0 3 . 7 ( 5 ) C12 C l l C13 1 2 0 . 3 ( 5 ) C4A C4 C12 1 0 3 . 5 ( 4 ) C I C12 C4 1 0 5 . 8 ( 4 ) C6 C5 CI OA 1 2 2 . 7 ( 6 ) C I C12 C l l 6 0 . 2 ( 3 ) C5 C6 C7 1 1 8 . 7 ( 6 ) C I C12 C15 1 2 6 . 6 ( 4 ) C6 C7 C8 1 2 0 . 7 ( 6 ) C4 C12 C l l 1 0 4 . 4 ( 4 ) C7 C8 C8A 1 2 2 . 4 ( 5 ) C4 C12 C15 1 2 0 . 0 ( 4 ) C8 C8A C9 1 2 3 . 4 ( 4 ) C l l C12 C15 1 2 4 . 6 ( 4 ) C8 C8A C 1 0 A 1 1 6 . 9 ( 4 ) 01 C13 02 1 2 4 . 5 ( 6 ) C9 C8A C 1 0 A 1 1 9 . 7 ( 4 ) 01 C13 0 1 ' 9 0 ( 2 ) C8A C9 C9A 1 1 9 . 6 ( 4 ) 01 C13 C l l 1 1 3 . 8 ( 6 ) C8A C9 C17 1 2 0 . 5 ( 4 ) 02 C13 C l l 1 2 1 . 6 ( 7 ) C9A C9 C17 1 1 9 . 9 ( 4 ) 0 1 ' C13 C l l 1 3 5 ( 2 ) C I C9A C4A 1 0 9 . 0 ( 4 ) 03 C15 04 1 2 1 . 3 ( 5 ) C I C9A C9 1 3 0 . 7 ( 4 ) 03 C15 C12 1 1 4 . 6 ( 5 ) Angles are i n degrees. Estimated standard deviations i n the least s i g n i f i c a n t figure are given i n parentheses. -167-Table 34 (contd.) a t o m a t o m a t o m a n g l e 04 C15 C12 1 2 4 . 0 ( 5 ) C9 C17 C18 1 2 0 . 2 ( 4 ) C9 C17 C22 1 2 2 . 7 ( 4 ) C18 C17 C22 1 1 7 . 0 ( 5 ) C17 C18 C19 1 2 1 . 0 ( 6 ) C18 C19 C20 1 2 0 . 1 ( 6 ) C19 C20 C21 1 2 0 . 4 ( 6 ) C20 C21 C22 1 1 9 . 2 ( 6 ) C17 C22 C21 1 2 2 . 2 ( 6 ) C IO C23 C24 1 2 0 . 9 ( 5 ) C IO C23 C28 1 1 9 . 8 ( 5 ) C24 C23 C28 1 1 9 . 3 ( 5 ) C23 C24 C25 1 1 9 . 5 ( 7 ) C24 C25 C26 1 2 1 . 9 ( 8 ) C25 C26 C27 1 1 9 . 6 ( 6 ) C26 C27 C28 1 1 9 . 9 ( 7 ) C23 C28 C27 1 1 9 . 7 ( 7 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -168-CYCLOOCTATETRAENE (COT) DERIVATIVES The data collection parameters and crystal data for the compounds discussed in chapter 11 are presented in Table 35, followed by a brief description of the structure determination for each compound. -169-Table 35. Data collection parameters and crystal data for compounds of chapter 11. Compound 15 Compound 20 Compound 23 Formula F.W. F(000) Dc (g cm"3) Radiation At (cm - 1) 2^max (°) to-scan width (°) Scan speed (° min - 1)t Orientation check Space group a (A) b (A) c (A) a (°) ft (°) 7 <°) v (A3) C22 H20°4 348.40 736 1.233 CuKa 6.47 155.1 0.94+0.30tantf 8 150 P2x/n 9.124(2) 14.392(2) 14.328(1) 90 94.30(1) 90 1876.1(5) 4 C26 H20°4 396.44 832 I. 261 CuK a 6.46 155.3 1.05+0.3Otan0 16 150 PI II. 074(2) 25.298(6) 7.668(2) 94.22(2) 94.53(2) 101.77(2) 2087.5(8) 4 C21 H18°4 334.37 704 1.277 CuKQ 6.79 155.4 O.94+O.3Otan0 16 150 Pna2;L 18.364(4) 10.485(3) 9.031(4) 90 90 90 1739(2) 4 f A maximum of 8 rescans i f I < 40.0a(I). -170-Table 35 (continued). Compound 25 Formula C22 H20°4 F.W. 348.40. F(000) 736 Dc (g cm-3) 1.26 Radiation CuKQ JJ. (cm - 1) 6.60 2^max (°) 155.3 w-scan width (°) 1.155+0. 30tant9 Scan speed (° min - 1)t 32 Orientation check 150 Space group P21/n a (A) 9.1209(9) b (A) 20.4863(9) c (A) 10.028 (1) a (") 90 P (°) 100.914(8) 7 (°) 90 V (A 3) 1839.8(3) Z 4 | A maximum of 8 rescans i f I < 40.0a(I). -171-Compound 15 A crystal having approximate dimensions of 0.25 x 0.1 x 0.3 mmJ (grown from diethyl ether) was used for data collection. Preliminary reflections indicated a primitive, monoclinic c e l l with Z = 4 (based on an estimated density of 1.233 g cm - 3). A total of 4045 reflections (in the range of h,k,l: -12 to 12, 0 to 18, 0 to 18) was collected of which 3900 were unique and 2289 considered observed. Final c e l l parameters were deter-mined from a least-squares refinement of 10 well-centered reflections (85.69 < 28 < 93.66°). The intensities of three standard reflections (1,0,5; —1,3,2; 2,2,2) did not show any significant change during the data collection (decay correction was not applied). Lp corrections were made, and an empirical absorption correction was applied (transmission factors: 0.87 to 1.00); equivalent reflections were merged. Based on systematic absences (hOl: h+1 ^ 2n; OkO: k * 2n), E-stat i s t i c s , and successful solution and refinement of the structure, the space group was determined to be P2]^/n. The structure was solved using direct methods. The best E-map gave the positions of a l l non-hydrogen atoms (except one ester methyl carbon which was subsequently located on the difference Fourier map), which were refined i n i t i a l l y with isotropic thermal parameters and later with anisotropic thermal parameters. A l l hydrogen atoms were located in subsequent AF-maps and were refined isotropically. A secondary extinction correction was applied at this stage (final coefficient = 0.978 x 10 -^). The refinement converged at R = 0.063, R^, = 0.087. The residual electron density peaks in the difference map (as high as 0.826 eA - 3) indicated the presence of a minor disorder in the region of one of the ester groups. -172-The two highest peaks were included in the model as disordered oxygen atoms (03', 04') with the occupancy factors of 0.15 each, while that of the original oxygen atoms (03, 04) of the ester group were adjusted to 0.85 each. Further refinement (the disordered atoms with lower occupancy were refined isotropically) did not produce a completely meaningful geometry of the disordered atoms, but reduced the R-value to 0.048 (R w = 0.065; including unobserved reflections: R = 0.101, R„ = 0.069; S =1.89 for 276 variables). In the f i n a l cycles, as refinement of methyl hydrogens was found to move them to geometrically unacceptable positions, they were included in idealized positions with 20% greater isotropic thermal parameters than the B eq value of the atom to which they are bound, and were excluded from refinement. In the last cyle of refinement, largest parameter shift was 0.01a, and the maximum and minimum peaks on the AF-map were 0.28 and -0.22 eA - 3, respectively. The f i n a l atomic positions and isotropic or equivalent isotropic thermal parameters are given in Table 36, while the bond lengths and bond angles involving non-hydrogen atoms are presented in Tables 37 and 38, respectively. -173-Table 36. Atomic coordinates and B e q values of compound 1 5 . a t o m X y z B ( e q ) 01 0 .4596(3) 0 .3172(2) 0 .8591(2) 6.0 1 02 0 .3366(4) 0 .2099(2) 0 .9283(2) 8.5( 2 03 0 .8945(3) 0 .0571(2) 0 .7936(2) 5.8< 1 04 0 .9908(3) 0 .1179(3) 0 .6740(3) 10.5 2 03' 0 .907(2) 0 .033(1) 0 .749(1) 4.2( 3 04' 0 .977(2) 0 .175(1) 0 .755(1) 6 . 3 1 3 C I 0 .2778(3) 0 .2523(2) 0 . 6 5 4 6 ( 2 ) 4.3 1 C2 0 .2563(4) 0 .2992(2) 0 .5705(2) 5 . 1 1 1 C3 0 .3752(4) 0 .3201(2) 0 .5200(2) 5 . 1 1 1 C4A 0 .5380(3) 0 .2460(2) 0 .6379(2) 3.3 1 C4 0 .5147(4) 0 .2950(2) 0 .5537(2) 4.2 1 C5 0 .6734(3) -0 . 0 0 8 5 ( 2 ) 0 .5910(2) 3 . 9 1 1 C6 0 .5924(3) -0 . 0 8 6 6 ( 2 ) 0 .5666(2) 4.4 1 C7 0 .4689(3) -0 .1062(2) 0 .6137(2) 4.4 1 C8A 0 .5121(3) 0 .0306(2) 0 .7095(2) 3.2( 1 C8 0 .4295(3) -0 .0492(2) 0 .6844(2) 4.0< 1 C9A 0 .4182(3) 0 .2248(2) 0 .6892(2) 3.3 1 C9 0 .4737(3) 0 . 0 8 6 6 ( 2 ) 0 .7912(2) 3.5 1 C10A 0 .6351(3) 0 .0513(2) 0 .6615(2) 3.3( 1 CIO 0 .6908(3) 0 .2212(2) 0 .6730(2) 3.6< 1 C l l 0 •4346(3) 0 .1763(2) 0 .7816(2) 3.5 1 C12 0 .7315(3) 0 .1328(2) 0 .6854(2) 3.5( 1 C13 0 .4036(3) 0 .2337(2) 0 .8641(2) 4 .2! 1 C14 0 .4459(6) 0 .3794(4) 0 .9374(3) 6.91 2 C15 0 .8848(3) 0 .1068(2) 0 .7176(2) 4.7 1 C16 1 .0375(5) 0 .0196(5) 0 .8231(5) 8.2< 3 C17 0 .4884(5) 0 .0357(3) 0 .8835(2) 5.3 2 C18 0 .7927(4 ) 0 .3029(3) 0 .6904(3) 6.1 2 H i 0 .195(3) 0 .232(2) 0 .693(2) 4 . 5 ( 6 H2 0 .146(4) 0 .313(2) 0 .544(2) 6.8! 8 H3 0 .349(4) 0 .358(2) 0 .461(3) 7.3 9 H4 0 .610(3) 0 .309(2) 0 .517(2) 4.8 6 H5 0 .757(3) 0 .003(2) 0 .557(2) 5.3< 7 H6 0 .616(3) -0 .135(2) 0 .515(2) 5.7 7 H7 0 .422(3) -0 .160(2) 0 .599(2) 5.0 7 H8 0 .341(3) -0 .063(2) 0 .719(2) 5.11 7 H14B 0 .347(6) 0 .355(3) 0 .960(4) 12(1 H 1 4 A 0 .544(8) 0 .428(5) 0 .947(5) 16( 2 H 1 4 C 0 .482(6) 0 .351(4) 0 .982(4) 9(2 H16B 1 .029(7) 0 .012(5) 0 .894(5) 14(2 H 1 6 A 1 .094(5) 0 .069(4) 0 .833(3) 9(1 H16C 1 .096(9) -0 .017(6) 0 .779(5) 18( 3 H17B 0 .595(6) 0 .006(3) 0 .892(3) 10(1 H17A 0 .468(4) 0 .074(3) 0 .940(3) 7(1 H17C 0 .425(7) -0 .002(5) 0 .883(4 ) 13(2 H 1 8 B 0 .890(5) 0 .283(3) 0 .732(3) 10(1 H 1 8 A 0 .82(1) 0 .349(7) 0 .637(7) 23(3 H18C 0 .752(5) 0 .361(4) 0 .728(4 ) 11(1 -174-Table 37. Bond lengths involving non-hydrogen atoms of compound 15. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.317(3) C7 C8 1.373(4) 01 C14 1.443(3) C8 C8A 1.400(3) 02 C13 1 . 1 9 K 3) C8A C9 1.487(3) 03 C15 1.299(4) C8A C10A 1.394(3) 03 C16 1.445(4) C9 C l l 1.339(3) 04 C15 1.200(4) C9 C17 1.508(3) CI C2 1.379(4) C9A C l l 1.498(3) CI C9A 1.397(3) CIO C12 1.341(3) C2 C3 1.371(4) CIO C18 1.504(4) C3 C4 1.374(4) C10A C12 1.485(3) C4 C4A 1.399(3) C l l C13 1.486(3) C4A C9A 1.391(3) C12 C15 1.484(3) C4A CIO 1.486(3) C15 03' 1.17(2) C5 C6 1.372(4) C15 04 ' 1.40(2) C5 C10A 1.396(3) C16 03' 1.56(2) C6 C7 1.381(4) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are g i v e n i n p a r e n t h e s e s . -175-Table 38. Bond angles involving non-hydrogen atoms of compound 15. a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 2 ( 2 ) C4A C IO C18 1 1 5 . 1 ( 2 ) C15 03 C16 1 1 7 . 0 ( 3 ) C12 C IO C18 1 2 3 . 9 ( 2 ) C2 C I C9A 1 2 0 . 9 ( 3 ) C5 C 1 0 A C8A 1 1 8 . 5 ( 2 ) C I C2 C3 1 2 0 . 1 ( 3 ) C5 C 1 0 A C12 1 1 8 . 6 ( 2 ) C2 C3 C4 1 2 0 . 0 ( 3 ) C8A C I OA C12 1 2 2 . 8 ( 2 ) C3 C4 C4A 1 2 0 . 9 ( 3 ) C9 C l l C9A 1 2 3 . 0 ( 2 ) C4 C4A C9A 1 1 9 . 1 ( 2 ) C9 C l l C13 1 2 1 . 1 ( 2 ) C4 C4A C IO 1 1 9 . 4 ( 2 ) C9A C l l C13 1 1 5 . 8 ( 2 ) C9A C4A C IO 1 2 1 . 5 ( 2 ) C10 C12 C 1 0 A 1 2 4 . 4 ( 2 ) C6 C5 C 1 0 A 1 2 1 . 9 ( 3 ) C10 C12 C15 1 2 1 . 8 ( 2 ) C5 C6 C7 1 1 9 . 3 ( 3 ) C 1 0 A C12 C15 1 1 3 . 6 ( 2 ) C6 C7 C8 1 2 0 . 2 ( 3 ) 01 C13 02 1 2 2 . 0 ( 2 ) C7 C8 C8A 1 2 1 . 0 ( 3 ) 01 C13 C l l 1 1 1.4 ( 2 ) C8 C8A C9 1 1 9 . 6 ( 2 ) 02 C13 C l l 1 2 6 . 6 ( 3 ) C8 C8A C 1 0 A 1 1 9 . 1 ( 2 ) 03 C15 04 1 2 0 . 4 ( 3 ) C9 C8A C10A 1 2 1 . 1 ( 2 ) 03 C15 C12 1 1 3 . 7 ( 2 ) C8A C9 C l l 1 2 1 . 3 ( 2 ) 03 C15 04 ' 9 3 . 8 ( 7 ) C8A C9 C17 1 1 4 . 2 ( 2 ) 04 C15 C12 1 2 5.4 ( 3 ) C l l C9 C17 1 2 4 . 4 ( 2 ) 04 C15 0 3 ' 1 0 2 . 3 ( 8 ) C I C9A C4A 1 1 9 . 0 ( 2 ) C12 C15 0 3 ' 1 1 8 . 4 ( 8 ) C I C9A C l l 1 1 8 . 4 ( 2 ) C12 C15 04 ' 1 1 7 . 6 ( 7 ) C4A C9A C l l 1 2 2 . 6 ( 2 ) 0 3 ' C15 04 ' 1 1 6 ( 1 ) C4A C IO C12 1 2 1 . 0 ( 2 ) C15 0 3 ' C16 1 1 7 ( 1 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -176-Compound 2 0 A crystal of approximate 0.3 x 0.1 x 0.4 mm3 size was used for data collection. Using preliminary reflections and an estimated density of 1.261 g cm-3, a t r i c l i n i c c e l l with Z = 4 was obtained. Of 7776 reflect-ions collected (in the limits of h,k,l: 0 to 14, -32 to 32, -10 to 10), 7301 were unique and 4668 were considered observed. The fi n a l c e l l par-ameters were obtained using 23 carefully centered reflections (84.21 < 26 < 93.76°). The standard reflections (3,-3,-1; 3,-2,1; 3,-2,0) monitored during the data collection did not show any significant change in their intensities (no decay correction was applied). Lp corrections, and an empirical absorption correction were applied (transmission factors: 0.92 to 1.00). Equivalent reflections were merged. Based on E-statistics, and successful solution and refinement of the structure, the space group was determined as PI (with two molecules per asymmetric unit). The structure was solved using direct methods. MITHRIL with standard default options failed to produce a meaningful solution; however, when the number of E's to be used in the t r i p l e t calculation was specified as 300 (while other parameters were given standard default values), the correct solution was obtained. The positions of 58 non-hydrogen atoms obtained from the best E-map were refined with isotropic thermal parameters, following which the remaining ester methyl carbon for each of the two molecules in the asymmetric unit was located in the AF-map. A l l non-hydrogen atoms were then refined anisotropically. A l l hydrogen atoms (except ester methyl hydrogens) were found in AF-maps in subsequent cycles and were refined isotropically, while the ester methyl hydrogens were -177-placed in idealized positions and were excluded from refinement. A secondary extinction correction was applied (final coefficient = 0.552xl0~5). The refinement converged at R = 0.039, R w - 0.053 (S = 1.55; including zeros: R = 0.087, Rw = 0.057) for 654 variables. The largest parameter shift in the last cycle was 0.08CT, while the residual electron density peaks in the difference Fourier map were between 0.17 and -0.17 eA - 3. The f i n a l atomic positions along with their isotropic or equivalent isotropic thermal parameters are given in Table 39. The bond lengths and bond angles involving non-hydrogen atoms are given in Tables 40 and 41. -178-Table 39. Atomic positions and B e a values of compound 20. atom X y z B(eq) 0( 1) 0 .6337(1) 0 .12216(6) 0 .1587(2) 4.27(6) 0( 2) 0 .7117(2) 0 .1457(1) 0 .4360(3) 6.60(9) 0( 3) 0 .1304(2) 0 .08046(6) -0 .0750(2) 4.73(7) 0( 4) 0 .1397(1) -0 .00642(6) -0 .0545(2) 4.59(6) C( 1) 0 .5051(2) 0 .0963(1) 0 .6649(3) 4.3(1) C( 2) 0 .4717(2) 0 .0587(1) 0 .7833(3) 4.7(1) C( 3) 0 .3867(2) 0 .0116(1) 0 .7302(3) 4.7(1) C( 4) 0 .3322(2) 0 .0027(1) 0 .5599(3) 4.2(1) C( 4A) 0 .3599(2) 0 .04105(8) 0 .4403(3) 3.29(7) C( 5) 0 .0755(2) 0 .1114(1) 0 .3096(3) 3.70(8) C( 6) 0 .0479(2) 0 .1564(1) 0 .3978(3) 4 . 0(1) C( 7) 0 .1403(2) 0 .2008(1) 0 .4506(3) 4.08(9) C( 8) 0 .2603(2) 0 .20110(9) 0 .4138(3) 3.80(8) C( 8A) 0 .2902(2) 0 .15570(8) 0 .3278(3) 3.11(7) C( 9) 0 .4211(2) 0 .15850(8) 0 .2880(3) 3.23(7) C( 9A) 0 .4494(2) 0 .08857(8) 0 .4930(3) 3.32(8) C( 10) 0 .2940(2) 0 .02942(8) 0 .2632(3) 3.49(8) C( 10A) 0 .1969(2) 0 .11006(8) 0 .2764(3) 3.12(7) C( 11) 0 .4918(2) 0 .12803(8) 0 .3650(3) 3.42(8) C( 12) 0 .2223(2) 0 .05966(8) 0 .1875(3) 3.15(7) C( 13) 0 .6247(2) 0 .13396(9) 0 •3286(3) 3.85(8) C( 14) 0 .7561(2) 0 .1304(1) 0 .1008(4) 6.4(1) C( 15) 0 .1598(2) 0 .03997(9) 0 .0092(3) 3.48(8) c< 16) 0 ,0715(3) 0 .0669(1) -0 .2513(4) 6.6(1) C! 17) 0 .4690(2) 0 .19847(8) 0 •1636(3) 3.50(8) c< 18) 0 .4227(2) 0 .1899(1) -0 .0106(3) 4.7(1) C( 19) 0 .4708(3) 0 .2254(1) -0 .1292(4 ) 6.1(1) c< 20) 0 .5629(3) 0 .2699(1) -0 .0749(5) 6.6(2) c< 21) 0 .6060(3) 0 .2794(1) 0 .0996(5) 6.5(1) c< 22) 0 .5610(2) 0 .2439(1) 0 .2188(4) 4.9(1) H 1) 0 .569(2) 0 .132(1) 0 •698(3) 6.0(6) H 2) 0 .510(2) 0 .068(1) 0 .905(3) 5.2(6) H 3) 0 .367(2) -0 .014(1) 0 .812(3) 5.7(6) H 4) 0 .272(2) -0 .031(1) 0 .523(3) 4.6(5) H 5) 0 .013(2) 0 .081(1) 0 ,273(3) 5.7(6) H 6) -0 .035(2) 0 .158(1) 0 .425(3) 5 . 0(6) H 7) 0 .124(2) 0 .232(1) 0 •513(3) 5 . 0(5) H 8) 0 .331(2) 0 .231(1) 0 .454(3) 5.4(6) H 10) 0 .299(2) -0 .005(1) 0 .200(3) 4.9(5) H 1 4 A ) 0 .7967 0 .1673 0 .1277 7.6 H 14B) 0 .7501 0 .1214 -0 .0225 7.6 H 14C) 0 .8021 0 .1079 0 .1589 7.6 H 16A) 0 .0624 0 .0991 -0 .3022 8.0 H 16B) 0 .1210 0 .0485 -0 .3193 8.0 H 16C) -0 .0078 0 .0441 -0 .2487 8.0 H 18) 0 .357(2) 0 .157(1) -0 .056(3) 5.1(6) H 19) 0 .438(3) 0 .218(1) -0 .249(4) 7.9(9) H 20) 0 •603(3) 0 .294(1) -0 .160(4) 9(1) H [21) 0 .675(3) 0 .314(1) 0 .143(4) 9(1) -179-Table 39 (contd.) atom X y z B(eq) H( 22) 0 .591(3) 0 .249(1) 0 .351(4) 6.7(7) 0( 1' ) 0 .2992(2) 0 .47959(7) -0 .2740(3) 6.01 (9) 0( 2' ) 0 .3427(2) 0 .50518 (8) 0 .0119(3) 7.4(1) 0( 3' ) -0 .0300(2) 0 .30617 (7) -0 .5506(2) 4 . 8 7(7) 0( 4' ) -0 .1907(2) 0 .34637(9) -0 .5290(2) 6.34 (9) C( 1' ) 0 .1519(3) 0 .4402(1) 0 . 2 2 1 1 ( 4 ) 5.4(1) C( 2' ) 0 .0669(4) 0 .4500(1) 0 .3350(4) 6 . 5(1) C( 3' ) -0 .0551(4) 0 .4451(1) 0 .2741(4) 6.3(1) C( 4' ) -0 .0943(3) 0 .4287(1) 0 .1008(4) 5 .1(1) C( 4 A ' ) -0 .0110(2) 0 .41626 (9) -0 .0161(3) 4.05(9) C( 5' ) -0 .0525(2) 0 .2564(1) -0 .1867(3) 4 . 3(1) C( 6' ) 0 .0009(3) 0 .2170(1) -0 .1166(3) 4.7(1) C( 7' ) 0 .1238(3) 0 .2284(1) -0 .0564(3) 4 . 6(1) C( 8' ) 0 .1949(2) 0 .2790(1) -0 . 0 6 9 K 3) 4.1(1) C( 8A' ) 0 .1429(2) 0 .31978(8) -0 .1391(3) 3.36(8) C( 9' ) 0 . 2 2 4 7 ( 2 ) 0 .37273(8) -0 .1605(3) 3.61(8) C( 9A' ) 0 .1145(2) 0 .42373(9) 0 . 0 4 4 0 ( 3 ) 4.15(9) C( 10' ) -0 .0587(2) 0 .3956(1) -0 .1977(3) 4.03(9) C( 1 0 A ' ) 0 .0173(2) 0 .30869(8) -0 .1962(3) 3.46(8) C( 11' ) 0 .2095(2) 0 .41928(9) -0 .0806(3) 4.02(9) C( 12' ) -0 .0451(2) 0 .34884(9) -0 .2782(3) 3.67(8) C( 13' ) 0 .2917(2) 0 .4721(1) -0 .1052(4 ) 4.8(1) C( 14' ) 0 .3878(4) 0 .5265(1) -0 .3116(6) 9.1(2) C( 15' ) -0 . 0 9 9 3 ( 2 ) 0 . 3 3 4 3 ( 1 ) -0 .4625(3) 4.2(1) C( 16' ) -0 .0659(3) 0 .2913(1) -0 .7350(4) 6.3(1) c( 17' ) 0 .3270(2) 0 .36986(8) -0 .2741(3) 3.94(9) C( 18' ) 0 .3006(3) 0 .3474(1) -0 .4449(4) 5.1(1) C( 19' ) 0 .3960(3) 0 .3446(1) -0 .5513(5) 6.3(1) C( 20' ) 0 .5172(3) 0 . 3 6 3 3 ( 1 ) -0 .4820(6) 6.7(2) C( 21' ) 0 .5439(3) 0 .3858(1) -0 .3147(6) 6.2(1) C( 22' ) 0 .4505(2) 0 .3895(1) -0 .2084(4) 5.3(1) H' 1' ) 0 .241(3) 0 .444(1) 0 .260(3) 6.1(7) HI 2') 0 .097(3) 0 .460(1) 0 .452(4) 6 . 9(7) Hi 3' ) -0 .121(3) 0 .451(1) 0 .352(5) 9(1) Hi 4' ) -0 .189(3) 0 .423(1) 0 .052(3) 6 . 3(7) Hi 5' ) -0 .142(2) 0 .248(1) -0 .236(3) 5.3(6) H( 6' ) -0 .051(2) 0 .181(1) -0 .117(3) 5.8(6) H( 7' ) 0 .162(2) 0 .201(1) -0 .005(3) 5.9(6) H( 8' ) 0 .282(2) 0 .288(1) -0 .031(3) 5 .6 (6 ) H 10' ) -0 .110(2) 0 •417(1) -0 .270(3) 4.8(5) HI 14A' ) 0 .4680 0 .5246 -0 .2621 11.0 H 14B' ) 0 .3880 0 .5275 -0 . 4352 11 .0 H 1 4 C ) 0 .3658 0 .5584 -0 . 2 6 2 2 11.0 HI 16A' ) -0 .0719 0 .3228 -0 .7922 7 .5 H 16B' ) -0 .0055 0 .2746 -0 .7845 7.5 H 1 6 C ) -0 .1440 0 .2667 -0 .7501 7 .5 H 18' ) 0 .212(2) 0 .337(1) -0 .496(3) 5.7(6) H 19' ) 0 .372(3) 0 .336(1) -0 .678(5) 10(1) H 20' ) 0 .577(3) 0 .358(1) -0 .565(4) 8.3(8) H 21' ) 0 .634(3) 0 .402(1) -0 .268(4) 9(1) H( 22' ) 0 .468(3) 0 .405(1) -0 .074(4) 7 . 8(8) -180-Table 40. Bond lengths involving non-hydrogen atoms of compound 2 0 . a t o m a t o m d i s t a n c e a t o m a t o m d i s t a n c e 0 1 C I 3 1 . 3 3 2 ( 3 ) C 1 2 C 1 5 1 . 4 8 5 ( 3 ) 0 1 C 1 4 1 . 4 3 8 ( 3 ) C 1 7 C 1 8 1 . 3 7 8 ( 3 ) 0 2 C 1 3 1 . 1 9 1 ( 3 ) C 1 7 C 2 2 1 . 3 8 6 ( 3 ) 0 3 C 1 5 1 . 3 3 1 ( 3 ) C 1 8 C 1 9 1 . 3 8 5 ( 4 ) 0 3 C 1 6 1 . 4 3 9 ( 3 ) C 1 9 C 2 0 1 . 3 7 0 ( 5 ) 0 4 C 1 5 1 . 2 0 7 ( 2 ) C 2 0 C 2 1 1 . 3 7 1 ( 5 ) C I C2 1 . 3 7 9 ( 4 ) C 2 1 C 2 2 1 . 3 7 9 ( 4 ) C I C 9 A 1 . 3 9 3 ( 3 ) 0 1 ' C 1 3 ' 1 . 3 2 8 ( 3 ) C 2 C 3 1 . 3 7 1 ( 4 ) 0 1 ' C 1 4 ' 1 . 4 4 0 ( 4 ) C 3 C4 1 . 3 7 8 ( 3 ) 0 2 ' C 1 3 ' 1 . 2 0 1 ( 3 ) C4 C 4 A 1 . 3 9 0 ( 3 ) 0 3 ' C 1 5 ' 1 . 3 3 6 ( 3 ) C 4 A C 9 A 1 . 4 0 4 ( 3 ) 0 3 ' C 1 6 ' 1 . 4 3 9 ( 3 ) C 4 A C I O 1 . 4 7 0 ( 3 ) 0 4 ' C 1 5 ' 1 . 2 0 3 ( 3 ) C 5 C6 1 . 3 8 K 3 ) C I ' C 2 ' 1 . 3 8 0 ( 4 ) C 5 C 1 0 A 1 . 3 9 5 ( 3 ) C I ' C 9 A ' 1 . 3 9 5 ( 3 ) C6 C7 1 . 3 6 8 ( 3 ) C 2 ' C 3 ' 1 . 3 7 2 ( 5 ) C7 C8 1 . 3 7 8 ( 3 ) C 3 ' C4 ' 1 . 3 7 1 ( 4 ) C8 C 8 A 1 . 3 9 4 ( 3 ) C 4 ' C 4 A ' 1 . 4 0 1 ( 3 ) C 8 A C 9 1 . 4 9 3 ( 3 ) C 4 A ' C 9 A ' 1 . 4 0 0 ( 3 ) C 8 A C 1 0 A 1 . 3 9 3 ( 3 ) C 4 A ' C I O ' 1 . 4 6 8 ( 3 ) C 9 C l l 1 . 3 4 0 ( 3 ) C 5 ' C 6 ' 1 . 3 7 9 ( 4 ) C 9 C 1 7 1 . 4 8 9 ( 3 ) C 5 ' C 1 0 A ' 1 . 3 9 9 ( 3 ) C 9 A C l l 1 . 4 8 6 ( 3 ) C 6 ' C 7 ' 1 . 3 6 7 ( 4 ) C I O C 1 2 1 . 3 3 8 ( 3 ) C 7 ' C 8 ' 1 . 3 7 3 ( 3 ) C 1 0 A C 1 2 1 . 4 9 0 ( 3 ) C 8 ' C 8 A ' 1 . 4 0 0 ( 3 ) C l l C 1 3 1 . 4 9 9 ( 3 ) C 8 A ' C 9 ' 1 . 4 8 4 ( 3 ) -181-Table 40 (contd.) atom atom d i s t a n c e C8A' C10A' 1 .390(3) C9' C l l ' 1 .334(3) C9' C17' 1 .493(3) C9A' C l l ' 1 .492(3) CIO' C12' 1 .336(3) C10A' C12' 1 .488(3) C l l ' C13' 1 .489(3) C12' C15' 1 .481(3) C17' C18' 1 .374(4) C17' C22' 1 .395(3) C18' C19' 1 .395(4) C19' C20' 1 .378(5) C20' C21' 1 .350(5) C21' C22' 1 .381(4) D i s t a n c e s are i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s the l e a s t s i g n i f i c a n t f i g u r e are g i v e n i n p a r e n t h e s e s . -182-Table 4 1 . Bond angles involving non-hydrogen atoms of compound 2 0 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 5 ( 2 ) C9 C l l C9A 1 2 4 . 5 ( 2 ) C 1 5 0 3 C16 1 1 6 . 8 ( 2 ) C9 C l l C13 1 2 0 . 0 ( 2 ) C2 C I C 9 A 1 2 1 . 0 ( 2 ) C9A C l l C13 1 1 5 . 4 ( 2 ) C I C2 C3 1 2 0 . 0 ( 2 ) C IO C 1 2 C I OA 1 2 3 . 5 ( 2 ) C2 C3 C4 1 1 9 . 9 ( 2 ) C IO C12 C 1 5 1 1 7 . 8 ( 2 ) C3 C4 C4A 1 2 1 . 2 ( 2 ) C 1 0 A C12 C 1 5 1 1 8 . 6 ( 2 ) C4 C4A C 9 A 1 1 8 . 9 ( 2 ) 01 C13 02 1 2 3 . 4 ( 2 ) C4 C4A C IO 1 1 7 . 9 ( 2 ) 01 C13 C l l 1 1 1 . 0 ( 2 ) C9A C4A C IO 1 2 3 . 2 ( 2 ) 02 C13 C l l 1 2 5 . 6 ( 2 ) C6 C5 C 1 0 A 1 2 0 . 9 ( 2 ) 0 3 C15 04 1 2 3 . 6 ( 2 ) C5 C6 C7 1 1 9 . 8 ( 2 ) 03 C15 C12 1 1 1 . 3 ( 2 ) C6 C7 C8 1 2 0 . 3 ( 2 ) 04 C 1 5 C12 1 2 5 . 1 ( 2 ) C7 C8 C8A 1 2 0 . 7 ( 2 ) C9 C17 C18 1 1 9 . 6 ( 2 ) C8 C8A C9 1 1 8 . 6 ( 2 ) C9 C17 C22 1 2 1 . 3 ( 2 ) C8 C8A C 1 0 A 1 1 9 . 2 ( 2 ) C18 C17 C22 1 1 9 . 0 ( 2 ) C9 C8A C 1 0 A 1 2 2 . 2 ( 2 ) C17 C18 C19 1 2 0 . 1 ( 3 ) C8A C9 C l l 1 2 1 . 5 ( 2 ) C18 C19 C20 1 2 0 . 7 ( 3 ) C8A C9 C17 1 1 6 . 0 ( 2 ) C19 C20 C21 1 1 9 . 1 ( 3 ) C l l C9 C17 1 2 2 . 4 ( 2 ) C20 C21 C22 1 2 0 . 9 ( 3 ) C I C9A C4A 1 1 8 . 9 ( 2 ) C17 C22 C21 1 2 0 . 0 ( 3 ) C I C9A C l l 1 2 0 . 1 ( 2 ) C 1 3 ' 0 1 ' C 1 4 ' 1 1 6 . 1 ( 3 ) C4A C9A C l l 1 2 0 . 9 ( 2 ) C 1 5 ' 0 3 ' C 1 6 ' 1 1 7 . 6 ( 2 ) C4A C IO C12 1 2 5 . 9 ( 2 ) C 2 ' C I ' C 9 A ' 1 2 0 . 5 ( 3 ) C5 C I OA C8A 1 1 9 . 1 ( 2 ) C I ' C 2 ' C 3 ' 1 2 0 . 2 ( 3 ) C5 C 1 0 A C12 1 1 8 . 8 ( 2 ) C 2 ' C 3 ' C4 ' 1 2 0 . 3 ( 3 ) C8A C 1 0 A C12 1 2 2 . 2 ( 2 ) C 3 ' C 4 ' C 4 A ' 1 2 0 . 7 ( 3 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -183-Table 41 (contd.) a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C 4 ' C 4 A ' C 9 A ' 1 1 9 . 0 ( 2 ) 0 1 ' C 1 3 ' 0 2 ' 1 2 3 . 2 ( 3 ) C 4 ' C 4 A ' C I O ' 1 1 8 . 7 ( 2 ) 0 1 ' C 1 3 ' C l l ' 1 1 1 . 9 ( 2 ) C 9 A ' C 4 A ' C I O ' 1 2 2 . 3 ( 2 ) 0 2 ' C 1 3 ' C l l ' 1 2 4 . 8 ( 3 ) C 6 ' C 5 ' C 1 0 A ' 1 2 0 . 8 ( 2 ) 0 3 ' C 1 5 ' 0 4 ' 1 2 3 . 2 ( 2 ) C 5 ' C 6 ' C 7 ' 1 2 0 . 3 ( 2 ) 0 3 ' C 1 5 ' C 1 2 ' 1 1 0 . 3 ( 2 ) C 6 ' C 7 ' C 8 ' 1 1 9 . 9 ( 2 ) 0 4 ' C 1 5 ' C 1 2 ' 1 2 6 . 5 ( 2 ) C 7 ' C 8 ' C 8 A ' 1 2 1 . 0 ( 2 ) C 9 ' C 1 7 ' C 1 8 ' 1 2 0 . 2 ( 2 ) C 8 ' C 8 A ' C 9 ' 1 1 9 . 1 ( 2 ) C 9 ' C 1 7 ' C 2 2 ' 1 2 0 . 7 ( 2 ) C8 ' C 8 A ' C 1 0 A ' 1 1 9 . 2 ( 2 ) C 1 8 ' C 1 7 ' C 2 2 ' 1 1 9 . 1 ( 2 ) C9 ' C 8 A ' C 1 0 A ' 1 2 1 . 5 ( 2 ) C 1 7 ' C 1 8 ' C 1 9 ' 1 2 0 . 3 ( 3 ) C 8 A ' C 9 ' C l l ' 1 2 2 . 4 ( 2 ) C 1 8 ' C 1 9 ' C 2 0 ' 1 1 9 . 4 ( 3 ) C8A' C9 ' C 1 7 ' 1 1 5 . 0 ( 2 ) C 1 9 ' C 2 0 ' C 2 1 ' 1 2 0 . 6 ( 3 ) C l l ' C9 ' C 1 7 ' 1 2 2 . 5 ( 2 ) C 2 0 ' C 2 1 ' C 2 2 ' 1 2 0 . 7 ( 3 ) CI' C 9 A ' C 4 A ' 1 1 9 . 1 ( 2 ) C 1 7 ' C 2 2 ' C 2 1 ' 1 1 9 . 9 ( 3 ) CI' C 9 A ' C l l ' 1 1 9 . 6 ( 2 ) C4A' C 9 A ' C l l ' 1 2 1 . 0 ( 2 ) C4A' C I O ' C 1 2 ' 1 2 5 . 2 ( 2 ) C5' C10A' C 8 A ' 1 1 8 . 7 ( 2 ) C5' C 1 0 A ' C 1 2 ' 1 1 8 . 1 ( 2 ) C8A' C 1 0 A ' C 1 2 ' 1 2 3 . 0 ( 2 ) C 9 ' C l l ' C 9 A ' 1 2 4 . 5 ( 2 ) C9 ' C l l ' C 1 3 ' 1 2 1 . 7 ( 2 ) C 9 A ' C l l ' C 1 3 ' 1 1 3 . 8 ( 2 ) C I O ' C 1 2 ' C I OA ' 1 2 5 . 4 ( 2 ) C I O ' C 1 2 ' C 1 5 ' 1 1 8 . 1 ( 2 ) C 1 0 A ' C 1 2 ' C 1 5 ' 1 1 6 . 5 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -184-Compound 23 A crystal with approximate dimensions of 0.3 x 0.2 x 0.4 mm3 was used for data collection. An orthorhombic c e l l with Z = 4 was obtained based on preliminary reflections and assuming a density of 1.277 g cm - 3. In the h,k,l range of 0 to 13, 0 to 23, 0 to 11, 2132 reflections were collected of which 1303 were observed. A least squares refinement of 23 well-centered reflections (50.04 < 20 < 69.83°) gave the f i n a l c e l l parameters. The intensities of the standard reflections (-1,-2,-2; 2,-3,-1; 1,-4,-1) did not show any significant change (decay correction was not applied). Lp corrections, and an emipirical absorption correction were applied (transmission factors: 0.57 to 1.00). Based on systematic absences (Okl: k+1 * 2n; hOl: h ^ 2n), E-statis-tics, and successful structure solution and refinement, the space group was determined to be Pna2^. The structure was solved using direct methods. The best E-map from MITHRIL did not produce a meaningful solution; however, the molecular fragment found was used in DIRDIF which gave a l l (except two) non-hydrogen atoms. Full-matrix least squares refinement of these atoms with isotropic thermal parameters followed by difference Fourier synthesis gave the positions of the remaining two non-hydrogen atoms. The z-coordinate of 01 was fixed to define the origin. The model was then refined with aniso-tropic thermal parameters. In subsequent AF maps, the aromatic and vinylic hydrogens were located, and refined isotropically. A l l methyl and ester methyl hydrogens were calculated and were not refined. At this stage, the model was refined in the second polarity possible. The R-values were identical (0.053033), however, R^^ was slightly lower for one -185-of the polarities (0.066040 versus 0.066077) which was taken as the correct one. Refinement of the aromatic hydrogens on one of the benzene rings was found to move them to unacceptable positions and hence they were placed in calculated postitions and excluded from refinement in further cylces. The refinement converged at R = 0.054, R w = 0.068 for 246 variables (S = 1.99; including zeros: R = 0.100, R^  = 0.072). In the last cycle, the largest parameter shift was 0.003CT, and the highest and lowest peaks in AF-map were 0.20 and -0.19 eA - 3, respectively. The f i n a l atomic positions and their isotropic or equivalent isotropic thermal parameters are given in Table 42. The bond lengths and bond angles involving non-hydrogen atoms are given in Tables 43 and 44, respectively. -186-Table 42. Atomic positions and B e Q values of compound 23. atom X y z B ( e q ) 01 0.5342(2) 1.1651(3) 0.2595 5.5(2 02 0.4501(2) 1.0374(4) 0.1635(8) 7.1(2 03 0.7983(2) 0.9718(4) 0.5092(7) 5.8(2 04 0.8428(2) 1.0275(4) 0.2890(7) 5.6(2 CI 0.5050(3) 0.7682(6) 0.1972(9) 4.9(3 C2 0.4934(3) 0.6527(6) 0.270(1) 6.0(3 C3 0.5393(4) 0.6160(6) 0.380(1) 5.8(3 C4 0.5976(3) 0.6885(5) 0.4179(8) 5.2(3 C4A 0.6135(2) 0.8033(5) 0.3435(7) 3.7(2 C5 0.7960(3) 0.7921(6) 0.0993(9) 4.7(3 C6 0.8051(3) 0.7568(6) -0.047(1) 5.4(3 C7 0.7588(3) 0.8024(7) -0.153(1) 5.9(3 C8 0.7017(3) 0.8839(7) -0.1113(8) 5.2(3 C8A 0.6901(2) 0.9154(5) 0.0350(7) 3.9(2 C9 0.6297(2) 1.0046(5) 0.0708(8) 4.1(2 C9A 0.5661(2) 0.8425(4) 0.2321(7) 3.9(2 C10A 0.7386(3) 0.8705(5) 0.1429(7) 3.6(2 CIO 0.6770(3) 0.8755(5) 0.3892(9) 4.0(2 C l l 0.5749(2) 0.9714(5) 0.1614(7) 3.8(2 C12 0.7331(2) 0.9066(4) 0.3018(8) 3.5(2 C13 0.5129(3) 1.0597(5) 0.1911(8) 4.7(3 C14 0.4801(3) 1.2586(6) 0.292(1) 6.2(3 C15 0.7970(3) 0.9755(5) 0.3632(8) 4.2(2 C16 0.8565(4) 1.0377(8) 0.580(1) 7.8(4 C17 0.6349(3) 1.1317(6) -0.005(1) 5.6(3 H i 0.4715 0.7966 0.1241 5.9 H2 0.4537 0.5997 0.2420 7.3 H3 0.5304 0.5384 0.4314 7.0 H4 0.6283 0.6613 0.4964 6.3 H5 0.828(3) 0 . 7 5 K 5) 0.173(6) 5(1) H6 0.855(3) 0.685(5) -0.081(7) 5(1) H7 0.769(3) 0.783(7) -0.266(9) 7(2) H8 0.673(3) 0.914(5) -0.192(8) 6(1) H10 0.679(3) 0.892(5) 0.502(7) 5(1) H 1 4 A 0.4581 1.2862 0.2021 7.4 H14C 0.4441 1.2225 0.3545 7.4 H 1 4 B 0.5022 1.3293 0.3398 7.4 H16A 0.9016 1.0025 0.5484 9.4 H16C 0.8521 1.0291 0.6840 9.4 H16B 0.8547 1.1254 0.5537 9.4 H17C 0.6777 1.1344 -0.0636 6.7 H 1 7 A 0.5934 1.1437 -0.0663 6;7 H17B 0 . 6 3 6 7 1.1974 0.0674 6.7 -187-Table 43. Bond lengths involving non-hydrogen atoms of compound 23. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.325(6) C5 CI OA 1.395(7) 01 C14 1.426(7) C6 C7 1.37(1) 02 C13 1.203(6) C7 C8 1.405(9) 03 C15 1.320(7) C8 C8A 1.378(8) 03 C16 1.423(7) C8A C9 1.487(7) 04 C15 1.205(6) C8A C10A 1.401(7) CI C2 1.393(9) C9 C l l 1.343(7) CI C9A 1.401(7) C9 C17 1.500(8) C2 C3 1.36(1) C9A C l l 1.504(7) C3 C4 1.356(8) C10A C12 1.488(7) C4 C4A 1.409(7) CIO C12 1.339(7) C4A C9A 1.393(7) C l l C13 1.492(7) C4A CIO 1.450(7) C12 C15 1.485(7) C5 C6 1.385(9) D i s t a n c e s are i n angstroms. Estimated standard d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are given i n parentheses. -188-T a b l e 44. Bond a n g l e s i n v o l v i n g non-hydrogen atoms o f compound 23 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 5 ( 4 ) C I C9A C 4 A 1 2 0 . 0 ( 5 ) C15 03 C16 1 1 6 . 5 ( 6 ) C I C9A C l l 1 1 9 . 4 ( 5 ) C2 C I C9A 1 2 0 . 0 ( 6 ) C4A C9A C l l 1 2 0 . 3 ( 4 ) C I C2 C3 1 1 9 . 7 ( 5 ) C5 CI OA C8A 1 1 8 . 8 ( 5 ) C2 C3 C4 1 2 0 . 9 ( 6 ) C5 CI OA C12 1 1 8 . 2 ( 5 ) C3 C4 C4A 1 2 1 . 5 ( 6 ) C8A CI OA C12 1 2 2 . 9 ( 4 ) C4 C4A C9A 1 1 7 . 8 ( 5 ) C4A C IO C12 1 2 5 . 3 ( 5 ) C4 C4A C IO 1 1 8 . 5 ( 5 ) C9 C l l C9A 1 2 4 . 9 ( 4 ) C9A C4A CIO 1 2 3 . 7 ( 5 ) C9 C l l C13 1 2 1 . 4 ( 5 ) C6 C5 C10A 1 2 1 . 2 ( 6 ) C9A C l l C13 1 1 3 . 5 ( 4 ) C5 C6 C7 1 2 0 . 1 ( 6 ) C I OA C12 CIO 1 2 4 . 0 ( 5 ) C6 C7 C8 1 1 9 . 2 ( 6 ) C I OA C12 C15 1 1 5 . 5 ( 4 ) C7 C8 C8A 1 2 1 . 3 ( 6 ) CIO C12 C15 1 2 0 . 5 ( 5 ) C8 C8A C9 1 1 8 . 3 ( 5 ) 01 C13 02 1 2 2 . 8 ( 5 ) C8 C8A C 1 0 A 1 1 9 . 3 ( 5 ) 01 C13 C l l 1 1 2 . 1 ( 4 ) C9 C8A C 1 0 A 1 2 2 . 3 ( 5 ) 02 C13 C l l 1 2 5 . 0 ( 5 ) C8A C9 C l l 1 2 1 . 9 ( 4 ) 03 C15 04 1 2 3 . 8 ( 5 ) C8A C9 C17 1 1 4 . 3 ( 4 ) 03 C15 C12 1 1 1 . 9 ( 5 ) C l l C9 C17 1 2 3 . 7 ( 5 ) 04 C15 C12 1 2 4 . 3 ( 5 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -189-Compound 25 A crystal of 0.3 X 0.3 x 0.4 mm3 approximate size was used for data collection. A monoclinic c e l l with Z = 4 was indicated by the preliminary reflections (with Dc = 1.26 g cm - 3). A total of 4212 reflections was collected in the h,k,l range of -12 to 12, 0 to 26, 0 to 13, of which 3821 were unique, and 2688 were observed. The standard reflections (-1,1,-4; 0,1,-3; 0,-4,-4) did not indicate any crystal decay (decay correction was not applied). Lp corrections were made. Absorption correction was not applied (transmission factors: 0.98 to 1.00). Based on systematic absences (hOl: h+1 ^ 2n; OkO: k * 2n), E-statis-ti c s , and successful solution and refinement of the structure, the space group was determined as P2^/n. The structure was solved by direct methods. The best E-map gave 23 non-hydrogen atoms which were refined isotropically for 2 cycles. The AF-map gave the positions of the remaining three non-hydrogen atoms. The model was then refined with anisotropic thermal parameters. A l l hydrogens (except one hydrogen on the isopropyl methyl group, which was calculated) were found in subsequent difference maps and were refined isotropically. The refinement converged at R — 0.043, = 0.063 for 316 variables (S = 1.85; including zeros: R = 0.094, R w = 0.066). The largest parameter shift in the last cycle was 0.008a, and the residual electron density peaks in the difference map were between 0.21 and -0.22 eA-3. Table 45 contains the fi n a l atomic positions and their isotropic or equivalent isotropic thermal parameters. The bond lengths and bond angles of non-hydrogen atoms are given in Tables 46 and 47, respectively. -190-Table 45. Atomic coordinates and B e a values of compound 25. atom X y z B(eq) 01 0 .0106(2) 0 .31638(7) 0 .4617(2) 5.32(7) 02 0 .2269(2) 0 .36977(8) 0 .4795(2) 6.22(8) 03 0 .2693(2) 0 .04000(6) 0 .5736(1) 4.49(6) 04 0 .4763(2) 0 .08467(9) 0 .6917(2) 6.90(8) CI 0 .2936(2) 0 .05291(9) 0 .2833(2) 4.03(7) C2 0 .2088(3) 0 .0349(1) 0 .1600(2) 4.92(9) C3 0 .0962(3) 0 .0756(1) 0 .0966(2) 4.81(9) C4 0 .0680(2) 0 .1334(1) 0 .1570(2) 4.12(7) C4A 0 .1551(2) 0 .15296(8) 0 .2801(2) 3.32(6) C5 0 .3761(3) 0 .3199(1) 0 .2415(2) 4.71(8) C6 0 •5146(3) 0 . 3274(1) 0 .2069(3) 5.6(1) C7 0 .6331(3) 0 .2899(1) 0 • 2704( 3 ) 5.6(1) C8A 0 .4719(2) 0 .23318(8) 0 .3958(2) 3.59(6) C8 0 .6128(2) 0 .2443(1) 0 .3652(2) 4.73(9) C9A 0 .2712(2) 0 .11245(8) 0 .3446(2) 3.28(6) C9 0 .3680(2) 0 .12981(8) 0 .4762(2) 3.41(6) CIO 0 .1154(2) 0 .21358(8) 0 .3440(2) 3.56(6) C10A 0 .3521(2) 0 .27214(8) 0 .3349(2) 3.53(6) C l l 0 .4564(2) 0 .18246(8) 0 .4966(2) 3.67(6) C12 0 .2020(2) 0 .26607(8) 0 .3711(2) 3.49(6) C13 0 .1500(2) 0 .32321(9) 0 ;4422(2) 4.16(7) C14 -0 .0445(4) 0 .3662(2) 0 .5407(4) 6.9(1) C15 0 .3793(2) 0 .08339(9) 0 .5927(2) 3.99(7) C16 0 .2714(3) -0 .0116(1) 0 .6748(2) 4.85(9) C17 0 .1906(5) 0 .0106(2) 0 .7820(3) 7.1(2) C18 0 .1968(7) -0 .0694(2) 0 .5994(5) 9.4(2) HI 0 . 370( 3) 0 .024(1) 0 .325(2) 4.6(5) H2 0 .226(3) -0 .007(1) 0 .119(2) 4.8(5) H3 0 .032(3) 0 .067(1) 0 .011(3) 5.4(5) H4 -0 .016(3) 0 .161(1) 0 .119(2) 5.4(5) H5 0 .292(3) 0 .350(1) 0 .206(2) 4.9(5) H6 0 .523( 3 ) 0 .361(1) 0 .140(3) 6.4(6) H7 0 .733( 3 ) 0 .292(1) 0 .253(3) 6.5(6) H8 0 .699( 3 ) 0 .218(1) 0 .413(2) 5.3(5) H10 0 .017(3) 0 .214(1) 0 .365(2) 4.5(4) H l l 0 .524(3) 0 .187(1) 0 .591(2) 4.6(5) H14A 0 .021(5) 0 .374(2) 0 .625(4) 11(1) H14C -0 .156(5) 0 .357(2) 0 .522(4) 10(1) H14B -0 .035(4) 0 .408(2) 0 .490(3) 8.8(9) H16 0 .380(4) -0 .016(1) 0 .721(3) 7.4(7) H17A 0 .079(5) 0 .013(2) 0 .739(4) 10(1) H17B 0 .230(4) 0 .055(2) 0 .820(4) 10(1) H17C 0 .210(4) -0 .025(2) 0 .858(3) 9.3(9) H18A 0 •205(5) -0 .104(2) 0 .666( 4 ) 11(1) H18B 0 .084(8) -0 .053(3) 0 .572(7) 20(3) H18C 0 .249(5) -0 .075(2) 0 .535(5) 12(1) -191-Table 46. Bond lengths inolving non-hydrogen atoms of compound 25. atom atom d i s t a n c e atom atom d i s t a n c e 01 C13 1.330(3) C5 C10A 1.400(3) 01 C14 1.440(3) C6 C7 1.379(4) 02 C13 1.201(2) C7 C8 1.370(3) 03 C15 1.327(2) C8A C8 1.396(3) 03 C16 1.463(2) C8A C10A 1.396(2) 04 C15 1.198(2) C8A C l l 1.475(3) CI C2 1.379(3) C9A C9 1.486(2) CI C9A 1.398(2) C9 C l l 1.339(2) C2 C3 1.381(4) C9 C15 1.494(2) C3 C4 1.375(3) CIO C12 1.331(2) C4 C4A 1.395(3) C10A C12 1.487(2) C4A C9A 1.403(2) C12 C13 1.494(2) C4A CIO 1.474(2) C16 C17 1.485(4) C5 C6 1.381(3) C16 C18 1.498(4) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -192-r a b l e 4 7 . Bond a n g l e s i n v o l v i n g non--hydrogen atoms o f compound 2 5 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 7 ( 2 ) C l l C9 C15 1 1 6 . 3 ( 2 ) C15 03 C16 1 1 8 . 2 ( 2 ) C9A C9 C15 1 1 8 . 9 ( 1 ) C2 CI C9A 1 2 1 . 6 ( 2 ) C12 CIO C4A 1 2 5 . 8 ( 2 ) C I C2 C3 1 1 9 . 6 ( 2 ) C8A C 1 0 A C5 1 1 8 . 9 ( 2 ) C4 C3 C2 1 2 0 . 1 ( 2 ) C8A C 1 0 A C12 1 2 1 . 7 ( 2 ) C3 C4 C4A 1 2 1 . 0 ( 2 ) C5 C 1 0 A C12 1 1 9 . 3 ( 2 ) C4 C4A C9A 1 1 9 . 4 ( 2 ) C9 C l l C8A 1 2 6 . 6 ( 2 ) C4 C4A CIO 1 1 8 . 8 ( 2 ) CIO C12 CI OA 1 2 3 . 8 ( 2 ) C9A C4A C IO 1 2 1 . 6 ( 2 ) C10 C12 C13 1 2 0 . 1 ( 2 ) C6 C5 C 1 0 A 1 2 0 . 8 ( 2 ) C10A C12 C13 1 1 6 . 2 ( 2 ) C7 C6 C5 1 1 9 . 8 ( 2 ) 02 C13 01 1 2 3.8 ( 2 ) C8 C7 C6 1 2 0 . 2 ( 2 ) 02 C13 C12 1 2 3 . 5 ( 2 ) C8 C8A CI OA 1 1 9 . 2 ( 2 ) 01 C13 C12 1 1 2 . 7 ( 2 ) C8 C8A C l l 1 1 8 . 5 ( 2 ) 04 C15 03 1 2 3 . 6 ( 2 ) C10A C8A C l l 1 2 2 . 2 ( 2 ) 04 C15 C9 1 2 4.4 ( 2 ) C7 C8 C8A 1 2 1 . 0 ( 2 ) 03 C15 C9 1 1 2 . 0 ( 2 ) C I C9A C4A 1 1 8 . 3 ( 2 ) 03 C16 C17 1 0 9 . 7 ( 2 ) C I C9A C9 1 1 9 . 2 ( 2 ) 03 C16 C18 1 0 6 . 0 ( 2 ) C4A C9A C9 1 2 2 . 5 ( 1 ) C17 C16 C18 1 1 1 . 6 ( 3 ) C l l C9 C9A 1 2 4 . 6 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -193-UNUSUAL PRODUCTS The data collection parameters and crystal data for compounds discussed in chapter 12 are summarized in Table 48, followed by a brief description of the structure determination for each compound. -194-Table 48. Data collection parameters and crystal data for compounds of chapter 12. Compound 16 Compound 29 Compound 30 Formula F.W. F(000) Dc (g cm"3) Radiation \i (cm - 1) 26 max (°) w-scan width (°) Scan speed (° min — 1)t Orientation check Space group a (A) b (A) c (A) a <•) P (°) 7 (°) V (A3) Z C22 H20°4 348.40 1472 1.233 CuKQ 6.47 155.2 1.05+0.3Otan0 16 150 C2/c 21.994(4) 11.963(1) 19.020(6) 90 131.434(9) 90 3752(2) 8 C 2 1H 1 7C10 4 368.82 768 1.383 CuKQ 21.18 155.1 1.35+O.2Otan0 32 200 PI 13.8925(9) 15.968 (2) 8.191 (2) 98.13(2) 91.78(2) 99.54(1) 1771.2(4) 4 C21 H17 C 1 04 368.82 768 1.372 CuKa 21.02 155.2 1.21+O.25tan0 32 150 P2x/c 14.777(1) 8.581(1) 15.192(1) 90 112.104(6) 90 1784.8(3) 4 f A maximum of 8 rescans i f I < 40.0CT(I). -195-Table 48 (continued). Compound 3 4 Formula C20 H14 C 12°6 F.W. 421.24 F(000) 432 Dc (g cm"3) 1.390 Radiation CuKQ fx (cm - 1) 33.81 2^max (°) 155.3 w-scan width (°) l.lO+O.3Otan0 Scan speed (° min - 1)t 16 Orientation check 150 Space group Pi a (A) 9.012(4) b (A) 13.272(8) c (A) 7.869(6) c* (°) 94.07(6) £ (°) 97.79(5) 7 (°) 88.34(4) v (A3) 930(1) z 2 f A maximum of 8 rescans i f I < 40.0a(I). -196-Compound 16 A crystal with approximate dimensions of 0.30 x 0.20 x 0.20 mmJ was chosen for data collection. I n i t i a l reflections collected indicated a C-centered monoclinic c e l l with Z = 8 (D c = 1.233 g cm - 3). A total of 4282 reflections was collected in the h,k,l limits of -28 to 28, 0 to 15, 0 to 24, of which 4077 were unique and 1574 were considered observed. The fi n a l c e l l parameters were determined using 20 well centered reflections (50.03 < 26 < 80.75°). The intensities of three standard reflections (0, -4, 0; 7, —1, —3; 0, —4, -1) did not vary significantly and hence there was no need for decay correction. Lp corrections were made. An empirical absorption correction was applied (transmission factors: 0.95 to 1.00), following which the equivalent reflections were merged. Based on systematic absences (hkl: h+k * 2n; hOl: 1 * 2n) and E-sta t i s t i c s , the space group selected was C2/c. However, several attempts to solve the structure by direct methods in this space group were not succ-essful. The structure solution was then attempted in Cc. MITHRIL when used with HARD option gave 51 non-hydrogen atoms as two independent mole-cules, which were refined isotropically. In the subsequent AF-map the remaining one carbon atom was found. The model was later refined with anisotropic thermal motion, and the two molecules were found to be highly correlated. A careful analysis of the coordinates of each molecule revealed the presence of a C 2 axis perpendicular to the plane of the molecular frame. The model was then refined in space group C2/c with two independent half-molecules each containing a crystallographic 2-fold axis at positions (0, y, 1/4) and (0, y, 3/4). The origin was shifted such that the mid-point of the isolated C = C double bond of the dibenzopental--197-ene is situated at the aforementioned special positions of the crystal. A l l hydrogens were placed in calculated positions and were not refined. The refinement converged with the largest parameter shift of O.Olcr at R = 0.072, R w = 0.100 and S = 2.64 for 235 variables (including zeros: R = 0.184, R w = 0.115). The carbonyl oxygens were found to have relatively large thermal parameters which may be result of a minor disorder. The f i n a l difference map contained peaks between 0.32 and -0.30 eA-3. The f i n a l atomic coordinates and the isotropic or equivalent isotropic thermal parameters are given in Table 49. The bond lengths and angles between non-hydrogen atoms are given in Tables 50 and 51. -198-Table 49. Atomic positions and B e q values of compound 16. atom X y z B(eq) 0( 1) -0 .1114(3) 0 .4835(4) 0 .2485(3) 9 .3(2) 0( 2) -0 .2124(3) 0 .5804(5) 0 .1371(5) 13 .2(3) C( 1) -0 .1303(3) 0 .6685(5) 0 .0329(4) 5 .6(2) CI 2) -0 .1263(4) 0 .6651(5) -0 .0364(4) 7 .0(3) CI 3) -0 .0530(4) 0 .6647(6) -0 .0148(5) 7 .8(3) C( 4) 0 .0189(4) 0 .6685(5) 0 .0775(4) 6 .8(3) C( 4A) 0 .0161(3) 0 .6691(4) 0 .1471(4) 5 .1(2) C( 9) -0 .0865(3) 0 .6743(4) 0 .2476(4) 4 .9(2) CI 9A) -0 .0574(3) 0 .6698(4 ) 0 .1247(4) 4 .7(2) CI 11) -0 .0398(3) 0 .6712(4) 0 .2142(4 ) 4 .7(2) C( 13) -0 .1429(3) 0 .5760(6) 0 .2073(4) 5 .7(3) C( 14) -0 .1608(4) 0 .3844(5) 0 .2137(5) 9 .0(3) C( 17) -0 .1350(4) 0 .7833(5) 0 .2173(5) 7 .3(3) Hi 1) -0 .1808 0 .6698 0 .0183 6 .8 H( 2) -0 .1750 0 .6630 -0 .1003 8 .4 H( 3) -0 .0517 0 .6619 -0 .0637 9 .4 H( 4) 0 .0695 0 .6707 0 .0923 8 .1 H 14A) -0 .1910 0 .3776 0 .1482 10 .8 Hi 14B) -0 .1970 0 .3896 0 .2247 10 .8 Hi 14C) -0 .1271 0 . 3207 0 .2451 10 .8 H( 17A) -0 .1767 0 .7847 0 .1510 8 .8 H 17B) -0 .0999 0 .8453 0 .2375 8 .8 H( 17C) -0 .1586 0 .7872 0 .2448 8 .8 0( 1' ) -0 .0551(3) 0 .7204(4) 0 •6203(3) 8 .1(2) 0( 2' ) -0 .1421(4) 0 .8010(5) 0 .4910(4) 17 .3(3) C( 1' ) -0 • 177K 3) 0 .9148(5) 0 .6691(4) 6 .2(3) C( 2' ) -0 .2110(4) 0 .9145(6) 0 .7112(5) 7 .3(3) c< 3' ) -0 .1613(4) 0 .9159(6) 0 .8077(5) 7 .1(3) C( 4' ) -0 .0776(4) 0 .9158(5) 0 .8658(4) 6 .3(3) C( 4A' ) -0 .0449(3) 0 .9148(4 ) 0 .8250(4) 5 .2(2) C( 9' ) -0 .0468(3) 0 .9152(4) 0 .6256(4) 5 .5(2) c< 9A' ) -0 .0925(3) 0 .9149(4) 0 .7291(4) 4 .9(2) C( 11' ) -0 .0378(3) 0 .9159(4 ) 0 .7094(3) 4 .9(2) c< 13' ) -0 .0874(4) 0 •8079(5) 0 .5704(4) 6 .2(3) C( 14' ) -0 .0866( 4 ) 0 .6116(5) 0 .5775(5) 8 .2(3) C( 17' ) -0 .0933(4) 1 .0167(5) 0 .5618(4) 7 .1(3) Hi 1' ) -0 .2102 0 .9149 0 .6029 7 .4 H I 2' ) -0 .2683 0 .9134 0 .6730 8 .7 H I 3' ) -0 .1852 0 .9168 0 .8349 8 . 5 H( 4' ) -0 .0439 0 .9165 0 .9321 7 .6 H( 14A' ) -0 .1419 0 .6067 0 .5489 9 .9 H< 14B' ) -0 .0825 0 .6014 0 .5313 9 .9 H 1 4 C ) -0 .0563 0 .5553 0 .6241 9 .9 Hi 17A' ) -0 .0887 1 .0191 0 . 5154 8 .5 Hi 17B' ) -0 .0711 1 .0832 0 .5982 8 .5 H( 1 7 C ) -0 .1488 1 .0109 0 .5321 8 .5 -199-T a b l e 50. Bond l e n g t h s i n v o l v i n g non-hydrogen atoms o f compound 16 . a t o m a t o m d i s t a n c e A D C ( * ) a t o m a t o m d i s t a n c e ADC( * 01 C13 1 . 2 6 4 ( 7 ) 1 0 1 ' C 1 3 ' 1 . 2 6 8 ( 6 ) 1 01 C14 1 . 4 4 0 ( 7 ) 1 0 1 ' C 1 4 ' 1 . 4 4 6 ( 6 ) 1 02 C13 1 . 1 9 1 ( 7 ) 1 0 2 ' C 1 3 ' 1 . 1 5 4 ( 7 ) 1 C I C2 1 . 3 8 0 ( 8 ) 1 C I ' C 2 ' 1 . 4 1 0 ( 8 ) 1 C I C9A 1 . 3 8 3 ( 7 ) 1 C I ' C 9 A ' 1 . 3 9 7 ( 7 ) 1 C2 C3 1 . 3 7 4 ( 8 ) 1 C 2 ' C 3 ' 1 . 3 8 2 ( 9 ) 1 C3 C4 1 . 3 8 2 ( 8 ) 1 C 3 ' C 4 ' 1 . 3 8 6 ( 8 ) 1 C4 C4A 1 . 3 6 7 ( 7 ) 1 C4 ' C 4 A ' 1 . 3 6 1 ( 7 ) 1 C4A C9 1 . 5 1 9 ( 7 ) 2 C 4 A ' C 9 ' 1 . 5 6 3 ( 7 ) 55602 C4A C9A 1 . 3 7 1 ( 6 ) 1 C 4 A ' C 9 A ' 1 . 3 7 8 ( 7 ) 1 C9 C l l 1 . 5 2 3 ( 7 ) 1 C 9 ' C l l ' 1 . 4 7 2 ( 7 ) 1 C9 C13 1 . 5 0 1 ( 8 ) 1 C9 ' C 1 3 ' 1 . 5 1 9 ( 8 ) 1 C9 C17 1 . 5 3 6 ( 7 ) 1 C 9 ' C 1 7 ' 1 . 5 3 4 ( 7 ) 1 C9A C l l 1 . 4 7 6 ( 7 ) 1 C 9 A ' C l l ' 1 . 4 7 8 ( 7 ) 1 C l l C l l 1 . 3 2 8 ( 9 ) 2 C l l ' C l l ' 1 . 3 2 4 ( 9 ) 55602 D i s t a n c e s a r e i n a n g s t r o m s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -200-T a b l e 5 1 . Bond a n g l e s i n v o l v i n g n o n - h y d r o g e n atoms o f compound 1 6 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C I 4 1 1 9 . 9 ( 5 ) C 1 3 ' 0 1 ' C 1 4 ' 1 1 9 . 9 ( 5 ) C2 C I C 9 A 1 1 6 . 9 ( 5 ) C 2 ' C I ' C 9 A ' 1 1 7 . 1 ( 6 ) C I C2 C3 1 2 1 . 2 ( 5 ) C I ' C 2 ' C 3 ' 1 2 0 . 2 ( 5 ) C2 C3 C4 1 2 0 . 7 ( 6 ) C 2 ' C 3 ' C 4 ' 1 2 1 . 7 ( 6 ) C3 C4 C 4 A 1 1 8 . 9 ( 6 ) C 3 ' C 4 ' C 4 A ' 1 1 8 . 0 ( 6 ) C4 C4A C9 1 2 8 . 1 ( 5 ) C 4 ' C 4 A ' C 9 ' 1 2 7 . 9 ( 5 ) C4 C 4 A C9A 1 1 9 . 9 ( 5 ) C 4 ' C 4 A ' C 9 A ' 1 2 2 . 0 ( 5 ) C9 C4A C9A 1 1 1 . 9 ( 5 ) C 9 ' C 4 A ' C 9 A ' 1 1 0 . 1 ( 5 ) C4A C9 C l l 9 9 . 7 ( 4 ) C 4 A ' C 9 ' C l l ' 9 8 . 9 ( 4 ) C4A C9 C13 1 1 4 . 7 ( 5 ) C 4 A ' C9 ' C 1 3 ' 1 1 0 . 4 ( 4 ) C4A C9 C17 1 1 2 . 2 ( 4 ) C 4 A ' C9 ' C 1 7 ' 1 1 3 . 4 ( 4 ) C l l C9 C13 1 0 9 . 1 ( 4 ) C l l ' C 9 ' C 1 3 ' 1 1 0 . 4 ( 5 ) C l l C9 C 1 7 1 1 1 . 0 ( 5 ) C l l ' C9 ' C 1 7 ' 1 1 3 . 2 ( 5 ) C13 C9 C17 1 0 9 . 8 ( 4 ) C 1 3 ' C 9 ' C 1 7 ' 1 1 0 . 1 ( 5 ) C I C9A C4A 1 2 2 . 4 ( 5 ) C I ' C 9 A ' C 4 A ' 1 2 1 . 1 ( 5 ) C I C9A C l l 1 3 1 . 0 ( 5 ) C I ' C 9 A ' C l l ' 1 3 1 . 3 ( 5 ) C4A C9A C l l 1 0 6 . 6 ( 4 ) C 4 A ' C 9 A ' C l l ' 1 0 7 . 6 ( 5 ) C9 C l l C9A 1 3 8 . 3 ( 4 ) C 9 ' C l l ' C 9 A ' 1 3 6 . 6 ( 5 ) C9 C l l C l l 1 1 1 . 6 ( 6 ) C 9 ' C l l ' C l l ' 1 1 5 . 3 ( 6 ) C9A C l l C l l 1 1 0 . 1 ( 6 ) C 9 A ' C l l ' C l l ' 1 0 8 . 1 ( 6 ) 01 C13 02 1 2 0 . 3 ( 6 ) 0 1 ' C 1 3 ' 0 2 ' 1 2 0 . 2 ( 6 ) 01 C13 C9 1 1 6 . 1 ( 5 ) 0 1 ' C 1 3 ' C 9 ' 1 1 3 . 5 ( 5 ) 02 C13 C9 1 2 3 . 5 ( 7 ) 0 2 ' C 1 3 ' C 9 ' 1 2 6 . 3 ( 6 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -201-Compound 29 A crystal having approximate dimensions of 0.4 x 0.15 x 0.5 mm3 was used for data collection. A t r i c l i n i c c e l l with Z = 4 was indicated by o preliminary reflections (assuming a density of 1.383 g cm J ) . In the h,k,l limits of -18 to 18, -20 to 20, -10 to 0, 7743 reflections were measured of which 7198 were unique and 5645 observed. Final c e l l parame-ters were obtained using 24 well-centered reflections (92.35 < 28 < 95.81°). The intensities of standard reflections (0,2,-2; -1,4,-1; -3,3,0) remained roughly constant during data collection (no decay correc-tion was applied). Lp corrections were made, and an empirical absorption correction was applied (transmission factors: 0.61 to 1.00). Equivalent reflections were merged. Based on E-statistics, and successful solution and refinement of the structure, the space group was determined as PI with two independent mole-cules per asymmetric unit. The structure was solved using direct methods. The best E-map gave the positions of 45 (of 52) non-hydrogen atoms which were used in iso-tropic refinement of the t r i a l structure. The remaining 7 non-hydrogen atoms were found in subsequent difference maps, and the model was refined anisotropically. Two reflections (3,5,-1; 3,5,0) were excluded from ref-inement in later cycles due to suspected error in the measurement of their intensities. A l l hydrogen atoms were found in difference maps and were refined isotropically. At this stage, disorder was noticed in one of the ester groups of one of the two independent molecules. The highest residual peak (0.50 eA - 3) was included in the model as a disordered ester methyl carbon (C16''). -202-The occupancy factors of the two disordered carbons (C16', C16'') were refined while keeping their Beq's fixed at the same value of 5.0. The refinement converged at approximately 0.5 occupancy for both carbons. Then the model was further refined (disordered carbons were given 0.5 occupancy each and were refined isotropically). Hydrogens on the disordered carbons were placed in caclulated positions and were not refined. The refinement converged at R = 0.045, R w - 0.063 (S = 2.52; including zeros: R = 0.062, = 0.065) for 593 variables. In the last cycle, the largest parameter shift was 0.02a, and residual peaks in the AF-map were between 0.35 and -0.33 eA - 3. The f i n a l atomic coordinates and their isotropic or equivalent iso-tropic thermal parameters are given in Table 52. The bond lengths, bond angles involving non-hydrogen atoms are given in Tables 53 and 54, respectively. -203-Table 52. Atomic positions and B e g values of compound 29. a t o m X y z B ( e q ) C I 0.24007(4) 0.15552(4) 0.48086(8) 5.11(2) 0 ( 1 ) 0.3990(1) 0.2964(1) 1.01071 2) 4.47(6) 0 ( 2 ) 0.5515(1) 0.3683(1) 1.0232 2) 6.41(8) 0 ( 3 ) 0.3341(1) 0.1021(1) 0.83121 2) 4.73 ( 7 ) 0 ( 4 ) 0.4938(1) 0.1470(1) 0.8892< 2) 5.07(7) C ( l ) 0.4312(2) 0.4516(1) 0.68831 3) 4.6(1) C ( 2 ) 0.3641(2) 0.4924(2) 0.6157< 4) 5.2(1) C( 3) 0.2764(2) 0.4468(2) 0.54471 3) 4.9(1) C( 4 A ) 0.3181(1) 0.3184(1) 0.62171 2) 3 . 1 9 ( 6 ) C ( 4 ) 0.2519(2) 0.3596(2) 0.54771 3) 4.04(8) C(5) 0.4518(2) 0.1051(2) 0.4405 3) 4.6(1) C ( 6 ) 0.5173(2) 0.0888(2) 0.3209( 4) 6.2(1) C ( 7 ) 0.6006(2) 0.1480(2) 0.30841 4) 6.5(1) C( 8 A ) 0.5571(1) 0.2400(1) 0.53871 3) 3.69 ( 7 ) C ( 8 ) 0.6224(2) 0.2223(2) 0.41731 4) 5.3(1) C( 9 A ) 0.4076(1) 0.3638(1) 0.68891 3) 3.30(7) C ( 9 ) 0.5681(1) 0.3126(1) 0.6724) 3) 3.60(7) C ( 1 0 A ) 0.4712(1) 0.1831(1) 0.5463< 3 ) 3 . 3 7 ( 7 ) C(10) 0.3072(1) 0.2271(1) 0.6503< 3) 3.27(7) C( 1 1 ) 0.4716(1) 0.3061(1) 0.75661 2 ) 3.10(6) C ( 1 2 ) 0.4126 ( 1 ) 0 . 2 1 2 4 ( 1 ) 0.6912( 2) 2.93(6) C ( 1 3 ) 0.4816(2) 0.3275 ( 1 ) 0 . 9 4 4 5 < 3) 3 . 8 9 ( 8 ) C ( 1 4 ) 0 . 4 0 1 9 ( 3 ) 0 . 3 0 4 7 ( 3 ) 1 . 1 8 9 K 4 ) 6.3 ( 1 ) C(15) 0.4193 ( 1 ) 0.1513(1) 0.8167( 3) 3.51 ( 7 ) C(16) 0.3320(3) 0.0466(2) 0.957K 5) 6.3(1) C ( 1 7 ) 0.6470(2) 0.3729 ( 2 ) 0.70921 4 ) 5.1(1) C l ( ' ) 0.11426(5) 0.14935(5) 0.97091 1) 6.53(3) 0 ( 1 ' ) 0.0026(1) 0.2774(1) 1.49101 2 ) 5.32(7) 0 ( 2 ' ) -0.1206(2) 0.3506(2) 1.4926< 3) 7.2(1) 0 ( 3 ' ) -0.1468(1) 0.1293(1) 1.3354( 3) 7 . 2 ( 1 ) 0 ( 4 ' ) - 0 . 0 0 7 1 ( 1 ) 0 . 0 8 1 5 ( 1 ) 1.2928( 2 ) 5 . 7 0 ( 8 ) C ( l ' ) 0.0306(2) 0 . 4 4 0 6 ( 2 ) 1.184K 4 ) 5.0 ( 1 ) C( 2 ' ) 0.1123(2) 0.4848(2) 1.12051 4 ) 5.8(1) C ( 3 ' ) 0.1820(2) 0 . 4 4 2 1 ( 2 ) 1.05071 4 ) 5 . 4 ( 1 ) C ( 4 ' ) 0 . 1 7 4 3 ( 2 ) 0.3543(2) 1.04701 3) 4.6(1) C ( 4 A ' ) 0.0940(1) 0.3103(1) 1.1129< 3) 3.53(7) C ( 5 ' ) -0.1177(2) 0.0932 ( 2 ) 0.9067( 4 ) 5.0 ( 1 ) C ( 6 ' ) -0.1955 ( 3 ) 0.0729(2) 0.7892( 4 ) 6.6 ( 1 ) C ( 7 ' ) -0.2625(2) 0.1267 ( 2 ) 0.78021 5 ) 6.9 ( 1 ) C ( 8 ' ) -0.2553(2) 0.2013(2) 0.88741 4 ) 5.5 ( 1 ) C( 8 A ' ) -0.1774(1) 0.2234 ( 1 ) 1.0060< 3) 3.95(8) C ( 9 ' ) -0.1592(1) 0.2962(1) 1.13801 3) 3.75(8) C( 9 A ' ) 0.0215(1) 0.3529(1) 1.1764( 3) 3.49(7) C(10') 0.0729(2) 0.2180(1) 1.13521 3) 3.98(8) C ( 1 0 A ' ) -0.1081(1) 0.1701(1) 1.01331 3) 3.64(7) C ( l l ' ) -0.0638(1) 0.2915 ( 1 ) 1.2316( 3 ) 3.39 ( 7 ) C(12') -0.0377(1) 0.2001(1) 1.1637( 3) 3 . 4 1 ( 7 ) C(13') -0.0667(2) 0.3097(2) 1.4176( 3) 4.40(9) C(14') 0.0046(4) 0.2859(4) 1.6706( 4 ) 7.8(2) -204-Table 52 (contd.) a tom X y z B ( e q ) C( 1 5 ' ) - 0 . 0 6 4 9 ( 2 ) 0 . 1 3 3 1 ( 2 ) 1 . 2 7 7 4 ( 4 ) 5.3 1) C( 1 6 ' ) - 0 . 1 7 7 2 ( 5 ) 0 . 0 5 1 7 ( 4 ) 1 . 3 9 5 6 ( 8 ) 6 .2 1) C( 1 7 ' ) - 0 . 2 1 3 5 ( 2 ) 0 . 3 5 7 4 ( 2 ) 1 . 1 6 9 2 ( 4 ) 5.3 1) C( 1 6 " ) - 0 . 0 4 4 5 ( 5 ) 0 . 0 1 5 3 ( 5 ) 1 . 3 9 8 ( 1 ) 7 .0 1) H( 1) 0 . 4 9 6 ( 2 ) 0 . 4 8 3 ( 2 ) 0 . 7 3 7 ( 3 ) 4 . 7 5) H( 2) 0 . 3 8 1 ( 2 ) 0 . 5 5 4 ( 2 ) 0 . 6 1 0 ( 4 ) 6 .5 7) Hi 3) 0 . 2 3 2 ( 2 ) 0 . 4 7 5 ( 2 ) 0 . 4 9 2 ( 4 ) 6 .4 7) H( 4) 0 . 1 9 3 ( 2 ) 0 . 3 3 1 ( 2 ) 0 . 4 9 9 ( 3 ) 4 .2 5) H( 5) 0 . 3 9 0 ( 2 ) 0 . 0 6 2 ( 2 ) 0 . 4 5 0 ( 3 ) 5.31 6) Hi 6) 0 . 4 9 8 ( 2 ) 0 . 0 3 4 ( 2 ) 0 . 2 3 5 ( 4 ) 7 .8 8) Hi 7) 0 . 6 4 4 ( 3 ) 0 . 1 3 7 ( 3 ) 0 . 2 3 6 ( 5 ) 10 (1 H( 8) 0 . 6 7 5 ( 2 ) 0 . 2 5 7 ( 2 ) 0 . 4 1 9 ( 4 ) 6 . 0 7) H( 10) 0 . 2 6 3 ( 2 ) 0 . 2 1 8 ( 1 ) 0 . 7 4 6 ( 3 ) 3.5 4) H< 14B) 0 . 4 0 8 ( 3 ) 0 . 3 6 2 ( 3 ) 1 . 2 4 4 ( 6 ) 10 (1 H( 14C) 0 . 4 5 8 ( 3 ) 0 . 2 8 1 ( 3 ) 1 . 2 3 3 ( 5 ) 10(1 H( 14A) 0 . 3 4 0 ( 3 ) 0 . 2 6 8 ( 2 ) 1 . 2 1 2 ( 5 ) 9(1 H( 16A) 0 . 3 3 1 ( 3 ) 0 . 0 8 0 ( 3 ) 1 . 0 5 7 ( 5 ) 9 (1 H( 16B) 0 . 2 7 6 ( 3 ) 0 . 0 0 8 ( 3 ) 0 . 9 4 2 ( 5 ) 10 (1 H 16C) 0 . 3 9 2 ( 3 ) 0 . 0 1 4 ( 2 ) 0 . 9 5 0 ( 5 ) 8 (1 H( 17A) 0 . 6 4 5 ( 2 ) 0 . 4 1 7 ( 2 ) 0 . 7 9 7 ( 4 ) 7.11 8) H( 17B) 0 . 7 0 8 ( 2 ) 0 . 3 7 1 ( 2 ) 0 . 6 4 4 ( 3 ) 5.2 6) H 1' ) - 0 . 0 1 8 ( 2 ) 0 . 4 7 1 ( 2 ) 1 . 2 2 9 ( 4 ) 7 .0 8) H 2 ' ) 0 . 1 2 2 ( 2 ) 0 . 5 5 1 ( 2 ) 1 . 1 1 9 ( 4 ) 7 .8 8) H( 3' ) 0 . 2 4 2 ( 2 ) 0 . 4 7 3 ( 2 ) 1 . 0 0 6 ( 4 ) 7.2 8) H| 4 ' ) 0 . 2 1 9 ( 2 ) 0 . 3 2 6 ( 2 ) 1 . 0 0 8 ( 4 ) 5.3 6) H( 5' ) - 0 . 0 6 5 ( 2 ) 0 . 0 5 3 ( 2 ) 0 . 9 2 6 ( 4 ) 6 .5 7) H( 6 ' ) - 0 . 2 0 0 ( 2 ) 0 . 0 1 9 ( 2 ) 0 . 7 1 6 ( 4 ) 7 .5 8) H( 7 ' ) - 0 . 3 2 0 ( 2 ) 0 . 1 0 8 ( 2 ) 0 . 7 0 6 ( 4 ) 7 .5 8) H 8 ' ) - 0 . 3 0 2 ( 2 ) 0 . 2 4 0 ( 2 ) 0 . 8 8 6 ( 4 ) 6.1 7) H 1 0 ' ) 0 . 1 1 1 ( 2 ) 0 . 2 0 8 ( 2 ) 1 . 2 3 0 ( 3 ) 4 .6 5) H< 1 4 B ' ) 0 . 0 4 9 ( 4 ) 0 . 2 4 0 ( 3 ) 1 . 6 9 6 ( 6 ) 13 (2 H 1 4 C ) - 0 . 0 5 1 ( 3 ) 0 . 2 7 2 ( 3 ) 1 . 7 0 7 ( 5 ) 9 (1 H 1 4 A ' ) 0 . 0 4 6 ( 5 ) 0 . 3 3 6 ( 4 ) 1 . 6 9 7 ( 8 ) 17 (2 H 1 7 B ' ) - 0 . 1 9 4 ( 2 ) 0 . 4 0 5 ( 2 ) 1 . 2 6 0 ( 4 ) 6.1 7) HI 1 7 A ' ) - 0 . 2 7 0 ( 2 ) 0 . 3 5 3 ( 2 ) 1 . 1 0 2 ( 4 ) 6 .5 7) H 1 6 A ' ) - 0 . 2 3 9 8 0 . 0 5 1 7 1 .4391 7.4 H 1 6 B ' ) - 0 . 1 8 0 7 0 . 0 0 5 2 1 .3082 7.4 H 1 6 C ) - 0 . 1 3 1 7 0 . 0 4 5 7 1 .4803 7.4 H 1 6 A ' ' ) - 0 . 0 5 4 4 0 . 0 4 2 8 1 .5051 8 .4 H 1 6 B ' ' ) - 0 . 1 0 4 7 - 0 . 0 1 7 2 1 .3496 8 .4 H 1 6 C ' ) 0 . 0 0 1 8 - 0 . 0 2 1 7 1 .4055 8 .4 -205-Table 53. Bond lengths involving non-hydrogen atoms of compound 29. atom atom d i s t a n c e atom atom d i s t a n c e CL CIO 1.795(2) C l l C12 1.593(3) 01 C13 1.335(3) C l l C13 1.526(3) 01 C14 1.447(3) C12 C15 1.526(3) 02 C13 1.190(3) CL' CIO' 1.784(2) 03 C15 1.327(2) 01' C13' 1.330(3) 03 C16 1.450(3) 01' C14' 1.457(4) 04 C15 1.193(3) 02' C13' 1.201(3) CI C2 1.386(3) 03' C15' 1.242(3) CI C9A 1.387(3) 03' C16' 1.403(7) C2 C3 1.377(4) 04' C15' 1.258(3) C3 C4 1.382(3) 04 ' C16' ' 1.492(7) C4A C4 1.387(3) C I ' C2' 1.389(4) C4A C9A 1.385(3) C I ' C9A' 1.379(3) C4A CIO 1.493(3) C2' C3' 1.368(4) C5 C6 1.384(4) C3' C4' 1.385(4) C5 C 1 0 A 1.394(3) C4' C4A' 1.383(3) C6 C7 1.384(5) C4A' C9A' 1.381(3) C7 C8 1.364(5) C4A' CIO' 1.493(3) C8A C8 1.398(3) C5' C6' 1.390(4) C8A C9 1.462(3) C5' C 1 0 A ' 1.387(3) C 8 A C 1 0 A 1.384(3) C6' C7' 1.375(5) C9A C l l 1.526(3) C7' C8' 1.363(5) C9 C l l 1.522(3) C8' C8A' 1.396(3) C9 C17 1.330(3) C8A' C9' 1.454(3) C 1 0 A C12 1.523(3) C8A' C 1 0 A ' 1.392(3) CIO C12 1.554(3) C9' C l l ' 1.529(3) -206-Table 53 (contd.) atom atom d i s t a n c e C9' C17' 1.333(3) C9A' C l l ' 1.530(3) CIO' C12' 1.546(3) C10A' C12' 1.519(3) C l l ' C12' 1.590(3) C l l ' C13' 1.514(3) C12' C15' 1.525(3) D i s t a n c e s are i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a re g i v e n i n p a r e n t h e s e s . -207-Table 5 4 . Bond angles involving non-hydrogen atoms of compound 2 9 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 2 ( 2 ) CL C IO C12 1 1 6 . 4 ( 1 ) C 1 5 0 3 C16 1 1 6 . 1 ( 2 ) C4A C IO C12 1 0 5 . 3 ( 1 ) C2 C I C9A 1 1 8 . 5 ( 2 ) C 9 A C l l C9 1 1 0 . 2 ( 2 ) C I C2 C3 1 2 0 . 9 ( 2 ) C9A C l l C12 1 0 2 . 4 ( 1 ) C2 C3 C4 1 2 0 . 8 ( 2 ) C9A C l l C13 1 0 9 . 1 ( 2 ) C4 C4A C9A 1 2 0 . 5 ( 2 ) C9 C l l C12 1 0 6 . 1 ( 2 ) C4 C4A C IO 1 2 9 . 2 ( 2 ) C9 C l l C13 1 1 4 . 7 ( 2 ) C9A C4A C IO 1 1 0 . 2 ( 2 ) C12 C l l C13 1 1 3 . 6 ( 2 ) C3 C4 C4A 1 1 8 . 7 ( 2 ) C I OA C12 .C IO 1 1 7 . 1 ( 2 ) C6 C5 C 1 0 A 1 1 8 . 3 ( 2 ) C 1 0 A C12 C l l 1 0 2 . 0 ( 1 ) C5 C6 C7 1 2 0 . 8 ( 3 ) C 1 0 A C12 C 1 5 1 0 6 . 7 ( 2 ) C6 C7 C8 1 2 1 . 0 ( 3 ) C IO C12 C l l 1 0 4 . 3 ( 1 ) C8 C8A C9 1 2 8 . 2 ( 2 ) C IO C12 C 1 5 1 1 4 . 5 ( 2 ) C8 C8A C 1 0 A 1 2 0 . 1 ( 2 ) C l l C 1 2 C15 1 1 1 . 6 ( 2 ) C9 C8A C 1 0 A 1 1 1 . 6 ( 2 ) 01 C13 02 1 2 3 . 8 ( 2 ) C7 C8 C8A 1 1 9 . 0 ( 3 ) 01 C13 C l l 1 1 0 . 6 ( 2 ) C I C9A C4A 1 2 0 . 6 ( 2 ) 02 C13 C l l 1 2 5 . 6 ( 2 ) C I C9A C l l 1 2 7 . 0 ( 2 ) 03 C15 04 1 2 4 . 4 ( 2 ) C4A C9A C l l 1 1 2 . 4 ( 2 ) 03 C15 C12 1 1 2 . 3 ( 2 ) C8A C9 C l l 1 0 6 . 6 ( 2 ) 04 C15 C12 1 2 3 . 3 ( 2 ) C8A C9 C17 1 2 5 . 9 ( 2 ) C 1 3 ' 0 1 ' C 1 4 ' 1 1 6 . 8 ( 3 ) C l l C9 C17 1 2 7 . 4 ( 2 ) C 1 5 ' 0 3 ' C 1 6 ' 1 1 2 . 3 ( 3 ) C5 C 1 0 A C 8 A 1 2 0 . 5 ( 2 ) C 1 5 ' 0 4 ' C 1 6 ' ' 1 1 3 . 0 ( 3 ) C5 C 1 0 A C12 1 2 7 . 2 ( 2 ) C 2 ' C I ' C 9 A ' 1 1 8 . 6 ( 3 ) C8A C 1 0 A C12 1 1 1 . 8 ( 2 ) C I ' C 2 ' C 3 ' 1 2 0 . 8 ( 3 ) CL C IO C4A 1 1 1 . 5 ( 1 ) C 2 ' C 3 ' C4 ' 1 2 0 . 6 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -208-Table 54 (contd.) a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C 3 ' C 4 ' C 4 A ' 1 1 8 . 7 ( 2 ) C 9 A ' C l l ' C 1 2 ' 1 0 2 . 1 ( 2 ) C 4 ' C 4 A ' C 9 A ' 1 2 0 . 5 ( 2 ) C 9 A ' C l l ' C 1 3 ' 1 0 9 . 0 ( 2 ) C 4 ' C 4 A ' C I O ' 1 2 8 . 9 ( 2 ) C 1 2 ' C l l ' C 1 3 ' 1 1 4 . 4 ( 2 ) C 9 A ' C 4 A ' C I O ' 1 1 0 . 5 ( 2 ) C I O ' C 1 2 ' C 1 0 A ' 1 1 7 . 9 ( 2 ) C 6 ' C 5 ' C 1 0 A ' 1 1 8 . 4 ( 3 ) C I O ' C 1 2 ' C l l ' 1 0 4 . 8 ( 2 ) C 5 ' C 6 ' C 7 ' 1 2 1 . 1 ( 3 ) C I O ' C 1 2 ' C 1 5 ' 1 1 3 . 3 ( 2 ) C 6 ' C 7 ' C 8 ' 1 2 1 . 0 ( 3 ) C 1 0 A ' C 1 2 ' C l l ' 1 0 2 . 6 ( 2 ) C 7 ' C 8 ' C 8 A ' 1 1 9 . 0 ( 3 ) C 1 0 A ' C 1 2 ' C 1 5 ' 1 0 4 . 4 ( 2 ) C 8 ' C 8 A ' C 9 ' 1 2 8 . 1 ( 2 ) C l l ' C 1 2 ' C 1 5 ' 1 1 3 . 6 ( 2 ) C 8 ' C 8 A ' C 1 0 A ' 1 2 0 . 3 ( 2 ) 0 1 ' C 1 3 ' 0 2 ' 1 2 3 . 1 ( 2 ) C9 ' C 8 A ' C 1 0 A ' 1 1 1 . 5 ( 2 ) 0 1 ' C 1 3 ' C l l ' 1 1 0 . 9 ( 2 ) C 8 A ' C 9 ' C l l ' 1 0 7 . 2 ( 2 ) 0 2 ' C 1 3 ' C l l ' 1 2 5 . 9 ( 2 ) C 8 A ' C 9 ' C 1 7 ' 1 2 6 . 7 ( 2 ) 0 3 ' C 1 5 ' 04 ' 1 2 5 . 2 ( 2 ) C l l ' C 9 ' C 1 7 ' 1 2 6 . 0 ( 2 ) 0 3 ' C 1 5 ' C 1 2 ' 1 1 6 . 7 ( 2 ) C I ' C 9 A ' C 4 A ' 1 2 0 . 5 ( 2 ) 04 ' C 1 5 ' C 1 2 ' 1 1 7 . 8 ( 3 ) C I ' C 9 A ' C l l ' 1 2 7 . 3 ( 2 ) C 4 A ' C 9 A ' C l l ' 1 1 2 . 1 ( 2 ) C L ' C I O ' C 4 A ' 1 1 2 . 5 ( 2 ) C L ' C I O ' C 1 2 ' 1 1 6 . 3 ( 2 ) C 4 A ' C I O ' C 1 2 ' 1 0 4 . 9 ( 2 ) C 5 ' C 1 0 A ' C 8 A ' 1 2 0 . 2 ( 2 ) C 5 ' C 1 0 A ' C 1 2 ' 1 2 7 . 5 ( 2 ) C 8 A ' C 1 0 A ' C 1 2 ' 1 1 1 . 5 ( 2 ) C 9 ' C l l ' C 9 A ' 1 1 0 . 8 ( 2 ) C9 ' C l l ' C 1 2 ' 1 0 5 . 6 ( 2 ) C 9 ' C l l ' C 1 3 ' 1 1 4 . 3 ( 2 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -209-Compound 30 A crystal of approximate size of 0.25 x 0.20 X 0.50 mm3 was used for data collection. A monoclinic c e l l with Z = 4 was indicated by the pre-liminary reflections collected (assuming a density of 1.372 g cm - 3). In total, 3951 reflections were measured (h,k,l limits: 0 to 19, 0 to 11, -19 to 19) of which 3801 were unique and 2874 were observed. The fi n a l c e l l parameters were determined by the least squares f i t of 25 well-centered reflections (79.22 < 28 < 87.66°). The three standard reflections (-4, 0, 2; 0, 2, 2; 2, -1, 2) monitored did not indicate any need for decay cor-rection. Lp corrections were applied to the data. An empirical absorp-tion correction using the program DIFABS^ was applied (transmission fac-tors: 0.86 to 1.13) and the equivalent reflections were averaged. Based on systematic absences (hOl: 1 ^  2n; 001: 1 ^  2n) and E-statis-tics, the space group selected was P2/c. However, attempts to solve the structure by MITHRIL were not successful. The structure solution was then attempted in space group Pc which led to a meaningful solution. A l l non-hydrogen atoms were found in the best E-map as two independent molecules in the asymmetric unit which were taken as the model and refined isotro-pically. Anisotropic refinement in Pc resulted in a large number of cor-relation coeffecients. A careful examination of the coordinates indicated that the two molecules are related by a 2^  axis parallel to b. Four OkO reflections with k ^ 2n were observed out of five that were measured; how-ever, these reflections were relatively weak and were deleted. The origin was shifted appropriately and the coordinates of one of the molecules were tranformed, and the model was refined in P2^/c with one molecule per asym-metric unit. A l l hydrogens were calculated and excluded from the refine--210-ment. Further refinement did not improve the R-values as there were a large number of reflections with AF/aF >10. Thirteen reflections with unreaso-nably high AF/aF values were removed from refinement. The presence of a disorder in the structure was evident in the difference map (highest peak of 1.0 eA~~3), but the residual peaks did not connect in a meaningful geometry with the rest of the structure. As pointed out in chapter 12, the crystal used for data collection was only 85% pure, and this is a probable reason for the high discrepancy factors observed. The refinement converged at R = 0.103, R w = 0.152 and S = 5.69 for 255 variables (including zeros: R = 0.121, Rw = 0.154). The largest parameter shift in the f i n a l cycle was 0.02a, and the maximum and minimum residual peaks in the AF-map were 0.96 and —0.93 eA-3, respectively. The f i n a l atomic positions and their B eq values are presented in Table 55; the bond lengths and bond angles of the non-hydrogen atoms are given in Tables 56 and 57, respectively. - 2 1 1 -Table 55. Atomic positions and B e q values of compound 30. a t o m X y z B ( e q ) C I 0 . 3 5 0 3 ( 2 ) - 0 . 1 1 0 6 ( 2 ) 0 . 0 5 5 5 ( 2 ) 6 . 8 ( 1 ) 0 ( 1 ) 0 . 0 9 8 8 ( 2 ) 0 . 2 7 5 4 ( 5 ) 0 . 1 3 9 3 ( 3 ) 4 . 3 ( 2 ) 0 ( 2 ) 0 . 1 6 9 6 ( 3 ) 0 . 4 8 1 0 ( 5 ) 0 . 1 0 0 2 ( 3 ) 4 . 9 ( 2 ) 0 ( 3 ) 0 . 1 6 2 7 ( 3 ) 0 . 1 5 8 8 ( 4 ) - 0 . 0 1 3 8 ( 3 ) 4 . 1 ( 1 ) 0 ( 4 ) 0 . 1 1 8 9 ( 4 ) - 0 . 0 6 7 4 ( 5 ) 0 . 0 3 1 5 ( 3 ) 5 . 9 ( 2 ) C ( 1 ) 0 . 3 8 3 9 ( 4 ) 0 . 4 6 1 0 ( 6 ) 0 . 1 4 5 5 ( 4 ) 3 . 9 ( 2 ) C ( 2 ) 0 . 4 6 5 8 ( 4 ) 0 . 4 8 2 4 ( 8 ) 0 . 1 2 2 3 ( 5 ) 4 . 8 ( 2 ) C ( 3 ) 0 . 5 1 0 9 ( 4 ) 0 . 3 6 0 4 ( 9 ) 0 . 1 0 0 1 ( 5 ) 5 . 1 ( 3 ) C ( 4 ) 0 . 4 7 8 7 ( 4 ) 0 . 2 0 7 6 ( 8 ) 0 . 1 0 0 6 ( 4 ) 4 . 4 ( 2 ) C ( 4 A ) 0 . 3 9 6 5 ( 3 ) 0 . 1 8 5 9 ( 6 ) 0 . 1 2 4 7 ( 4 ) 3 . 3 ( 2 ) C ( 5 ) 0 . 2 1 3 9 ( 4 ) - 0 . 1 5 7 8 ( 7 ) 0 . 2 3 2 8 ( 4 ) 4 . 2 ( 2 ) C ( 6 ) 0 . 2 0 9 9 ( 5 ) - 0 . 2 0 4 5 ( 9 ) 0 . 3 2 0 7 ( 6 ) 5 . 0 ( 3 ) C ( 7 ) 0 . 2 2 9 8 ( 4 ) - 0 . 1 0 3 6 ( 8 ) 0 . 3 9 4 9 ( 5 ) 4 . 7 ( 3 ) C ( 8 ) 0 . 2 5 6 6 ( 4 ) 0 . 0 4 6 2 ( 7 ) 0 . 3 8 8 2 ( 4 ) 4 . 0 ( 2 ) C ( 8 A ) 0 . 2 6 2 1 ( 3 ) 0 . 0 9 6 5 ( 6 ) 0 . 3 0 4 0 ( 3 ) 3 . 1 ( 2 ) C ( 9 ) 0 . 2 9 1 6 ( 4 ) 0 . 2 4 9 6 ( 6 ) 0 . 2 8 1 4 ( 3 ) 3 . 6 ( 2 ) C ( 9 A ) 0 . 3 5 0 2 ( 3 ) 0 . 3 0 9 5 ( 6 ) 0 . 1 4 7 5 ( 3 ) 3 . 0 ( 2 ) C ( 1 0 ) 0 . 3 5 1 8 ( 4 ) 0 . 0 3 6 4 ( 6 ) 0 . 1 3 6 0 ( 4 ) 3 . 7 ( 2 ) C ( 1 0 A ) 0 . 2 3 8 6 ( 3 ) - 0 . 0 0 4 1 ( 6 ) 0 . 2 2 5 5 ( 4 ) 3 . 1 ( 2 ) C ( I D 0 . 2 6 6 9 ( 3 ) 0 . 2 5 4 7 ( 5 ) 0 . 1 7 3 5 ( 3 ) 2 . 7 ( 2 ) C ( 1 2 ) 0 . 2 5 1 7 ( 3 ) 0 . 0 7 7 1 ( 5 ) 0 . 1 4 3 5 ( 3 ) 2 . 9 ( 2 ) C ( 1 3 ) 0 . 1 7 4 7 ( 4 ) 0 . 3 5 3 3 ( 6 ) 0 . 1 3 1 7 ( 4 ) 3 . 2 ( 2 ) C ( 1 4 ) 0 . 0 0 5 8 ( 4 ) 0 . 3 5 7 ( 1 ) 0 . 1 1 2 1 ( 6 ) 6 . 1 ( 3 ) C ( 1 5 ) 0 . 1 6 9 5 ( 4 ) 0 . 0 4 6 3 ( 6 ) 0 . 0 4 8 5 ( 4 ) 3 . 5 ( 2 ) C ( 1 6 ) 0 . 0 8 4 9 ( 5 ) 0 . 1 4 3 ( 1 ) - 0 . 1 0 5 7 ( 4 ) 5 . 7 ( 3 ) C ( 1 7 ) 0 . 3 0 5 0 ( 6 ) 0 . 3 9 2 6 ( 8 ) 0 . 3 3 8 5 ( 4 ) 6 . 1 ( 3 ) H( 1 ) 0 . 3 5 1 7 0 . 5 4 7 7 0 . 1 5 9 7 4 . 7 H( 2 ) 0 . 4 8 3 ( 5 ) 0 . 5 8 7 ( 8 ) 0 . 0 9 7 ( 5 ) 6 ( 2 ) H( 3 ) 0 . 5 6 5 9 0 . 3 7 9 1 0 . 0 8 3 6 6 . 2 H( 4 ) 0 . 5 1 0 9 0 . 1 2 2 0 0 . 0 8 5 4 5 . 3 H( 5 ) 0 . 2 1 1 ( 3 ) - 0 . 2 3 8 ( 5 ) 0 . 1 7 9 ( 3 ) 2 . 3 ( 9 ) H( 6 ) 0 . 1 9 6 ( 4 ) - 0 . 2 7 9 ( 7 ) 0 . 3 2 7 ( 4 ) 4 ( 1 ) H( 7 ) 0 . 2 4 4 ( 6 ) - 0 . 1 3 4 ( 8 ) 0 . 4 7 8 ( 5 ) 7 ( 2 ) H( 8 ) 0 . 2 7 7 ( 5 ) 0 . 1 1 4 ( 8 ) 0 . 4 4 4 ( 5 ) 6 ( 2 ) H( 1 0 ) 0 . 3 9 2 1 - 0 . 0 0 1 9 0 . 1 9 6 8 4 . 5 H( 1 4 A ) - 0 . 0 1 6 3 0 . 3 8 4 5 0 . 0 4 6 8 7 . 3 H( 1 4 B ) 0 . 0 1 3 9 0 . 4 4 8 4 0 . 1 4 9 4 7 . 3 HI 1 4 C ) - 0 . 0 4 1 0 0 . 2 9 0 8 0 . 1 2 2 2 7 . 3 H( 1 6 A ) 0 . 0 8 8 7 0 . 2 2 5 6 - 0 . 1 4 5 9 6 . 9 H( 1 6 B ) 0 . 0 2 3 7 0 . 1 4 7 1 - 0 . 0 9 8 7 6 . 9 H( 1 6 C ) 0 . 0 9 1 0 0 . 0 4 6 0 - 0 . 1 3 3 1 6 . 9 HI 1 7 A ) 0 . 3 2 4 4 0 . 4 8 6 5 0 . 3 1 7 5 7 . 4 H( 1 7 B ) 0 . 2 9 4 2 0 . 3 9 0 9 0 . 3 9 6 3 7 . 4 -212-Table 56. Bond lengths involving non-hydrogen atoms of compound 30. atom atom d i s t a n c e atom atom d i s t a n c e CL CIO 1.752(5) C5 C10A 1.384(7) 01 C13 1.347(6) C6 C7 1.36(1) 01 C14 1.456(7) C7 C8 1.360(9) 02 C13 1.187(6) C8 C8A 1.381(7) 03 C15 1.329(6) C8A C9 1.465(7) 03 C16 1.443(7) C8A C10A 1.406(7) 04 C15 1.197(6) C9 C l l 1.540(6) CI C2 1.394(8) C9 C17- 1.473(8) CI C9A 1.397(7) C9A C l l 1.503(6) C2 C3 1.35(1) CIO C12 1.565(7) C3 C4 1.396(9) C10A C12 1.502(6) C4 C4A 1.407(7) C l l C12 1.583(6) C4A C9A 1.375(7) C l l C13 1.525(6) C4A CIO 1.482(7) C12 C15 1.520(7) C5 C6 1.416(9) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e are g i v e n i n p a r e n t h e s e s . -213-T a b l e 57. Bond a n g l e s i n v o l v i n g n o n - h y d r o g e n atoms o f compound 3 0 . a t o m a t o m a t o m a n g l e a t o m a t o m a t o m a n g l e C13 01 C14 1 1 7 . 7 ( 5 ) CL C IO C12 1 1 6 . 6 ( 4 ) C15 03 C16 1 1 6 . 1 ( 4 ) C4A C IO C 1 2 1 0 6 . 9 ( 4 ) C2 C I C9A 1 1 8 . 6 ( 5 ) C5 C 1 0 A C8A 1 2 0 . 3 ( 5 ) C I C2 C3 1 2 1 . 2 ( 6 ) C5 C I OA C12 1 2 9 . 0 ( 5 ) C2 C3 C4 1 2 1 . 7 ( 5 ) C8A C 1 0 A C12 1 1 0 . 6 ( 4 ) C3 C4 C4A 1 1 7 . 1 ( 5 ) C9 C l l C9A 1 1 3 . 5 ( 4 ) C4 C4A C9A 1 2 1 . 6 ( 5 ) C9 C l l C12 1 0 3 . 3 ( 4 ) C4 C4A C IO 1 2 7 . 6 ( 5 ) C9 C l l C13 1 0 6 . 0 ( 4 ) C9A C4A C IO 1 1 0 . 7 ( 4 ) C9A C l l C12 1 0 5 . 5 ( 4 ) C6 C5 C 1 0 A 1 1 6 . 8 ( 6 ) C9A C l l C13 1 1 4 . 1 ( 4 ) C5 C6 C7 1 2 1 . 8 ( 6 ) C12 C l l C13 1 1 4 . 0 ( 4 ) C6 C7 C8 1 2 1 . 1 ( 6 ) C10 C12 C 1 0 A 1 1 2 . 2 ( 4 ) C7 C8 C8A 1 1 9 . 0 ( 6 ) C IO C12 C l l 1 0 1 . 5 ( 4 ) C8 C8A C9 1 2 8 . 6 ( 5 ) C IO C12 C15 1 0 9 . 4 ( 4 ) C8 C8A C 1 0 A 1 2 0 . 8 ( 5 ) C 1 0 A C12 C l l 1 0 4 . 8 ( 4 ) C9 C 8 A C 1 0 A 1 1 0 . 6 ( 4 ) C 1 0 A C12 C15 1 1 3 . 6 ( 4 ) C8A C9 C l l 1 0 7 . 6 ( 4 ) C l l C12 C15 1 1 4 . 7 ( 4 ) C8A C9 C17 1 2 6 . 5 ( 4 ) 01 C13 02 1 2 4 . 3 ( 5 ) C l l C9 C17 1 2 1 . 9 ( 4 ) 01 C13 C l l 1 0 9 . 4 ( 4 ) C I C9A C4A 1 1 9 . 8 ( 4 ) 02 C13 C l l 1 2 6 . 2 ( 4 ) C I C9A C l l 1 2 9 . 1 ( 4 ) 0 3 C15 04 1 2 4 . 4 ( 5 ) C4A C9A C l l 1 1 1 . 0 ( 4 ) 03 C15 C12 1 1 1 . 6 ( 4 ) CL C IO C4A 1 1 5 . 6 ( 4 ) 04 C 1 5 C12 1 2 3 . 9 ( 5 ) A n g l e s a r e i n d e g r e e s . E s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . -214-Compound 3 4 A crystal of approximate dimensions of 0.35 x 0.10 x 0.40 mm3 was chosen for data collection. A t r i c l i n i c c e l l with Z = 2 was suggested by the i n i t i a l reflections collected (D c = 1.390 g cm - 3). Between the h,k,l limits of 0 to 11, -17 to 17, -10 to 10, 4021 reflections were collected out of which 3773 were unique and 3080 were observed. Using the positions of 24 carefully centered reflections in the range of 64.93 < 28 < 86.66°, the f i n a l c e l l parameters were determined. The intensities of standard reflections (3, 2, 1; 3, -1, 0; 2, -2, 0) monitored during data collec-tion did not vary significantly (no decay correction applied). Lp correc-tions were made. An empirical absorption correction was applied (trans-mission factors: 0.66 to 1.00), and the equivalent reflections merged. Based on E-statistics and successful structure solution and refine-ment, the space group was determined as PI. The structure was solved by direct methods. The positions of 27 non-hydrogen atoms found in the best E-map were refined isotropically. One of these atoms was found to have a very small B value and hence was deleted. The difference map at this stage gave the positions of the remaining two ester methyl carbon atoms. A l l 28 non-hydrogen atoms were then refined isotropically for 2 cycles and anisotropically for 2 cycles. Two atoms that were refined as carbons were found to have very small B eq values and in the difference map there were residual peaks of about 1.0 eA J very close to these atoms. These atoms were refined as oxygens in later cylces (the molecular formula of this compound was not known at the time of the X-ray analysis) which was found to be their correct atom type. Some of the aromatic hydrogens were found on the difference map and were -215-refined isotropically, whereas a l l other hydrogens were calculated and not refined. At this stage a minor disorder in the structure was observed (highest peak = 0.50 eA - 3). Attempts to resolve the disorder were not successful as the residual peaks did not make any meaningful geometry among themselves or with the rest of the structure. A seconday extinction correction was applied (final coefficient = 0.469 x 10 -^). The reflec-tions 0, 1, 1; 1, -1, -2; 1, -5, -9 with AF/aF 15.59, -10.44 and 21.16, respectively, were removed from refinement. The refinement converged at R = 0.087, R^, = 0.121 and S =3.74 for 254 variables (including zeros: R = 0.113, Rw = 0.128), the largest parameter shift being 0.01a, and the highest and lowest residual peaks in the AF-map were 0.53 and -0.70 eA—3, respectively. The f i n a l atomic coordinates along with the B gq values are given in Table 58. The bond lengths and angles for non-hydrogen atoms are given in Tables 59 and 60. -216-Table 58. Atomic coordinates and B e_ values of compound 3 4 . atom X y . z B ( e q ) C l ( l ) 0.6155( 1) 0.39931 1) 0.4796! 2) 5.75(6) C l ( 2 ) 0.97431 1) 0.2680! 1) 1.0073! 1) 5.46(5) 0(1) 0.591K 3) 0.1385! 3) 0.9550! 4) 5.5(1) 0(2) 0.40571 4) 0.13321 3) 0.73291 5) 6.1(2) 0(3) 0.76121 4) 0.4260! 2) 0.86471 4) 5.3(1) 0(4) 0.5518( 4) 0.3424! 3) 0.8774! 5) 6.5(2) 0(5) 0.70401 3) 0.2118! 2) 0.4317! 4) 4.8(1) 0(6) 0.58431 3) 0.1701! 2) 0.5124! 4) 4.9(1) C ( l ) 0.7610( 5) -0.0188! 3) 0.65671 7) 5.1(2) C(2) 0.8861! 6) -0.08151 4) 0.6730! 7) 5.8(2) C( 3) 1.02541 6) -0.0417! 4) 0.7316! 8) 5.9(2) C(4) 1.04221 5) 0.0602 4) 0.7708 7) 5.2(2) C( 4A) 0.91661 5) 0.1226! 3) 0.75381 5) 4.2(2) C(5) 1.15021 5) 0.3032! 4) 0.68331 6) 4.9(2) C(6) 1.2064 5) 0.3512 4) 0.5579! 8) 5.8(2) C(7) 1.11231 6) 0.38511 4) 0.4200! 7) 5.7(2) C(8) 0.9604 6) 0.3723 4) 0.4033! 6) 5.1(2) C( 8 A ) 0.9043 5) 0.3238 3) 0.5296 5) 4.3(2) C(9) 0.74561 5) 0.2986 3) 0.5403! 5) 4.2(2) C( 9A) 0.7778 5) 0.0831 3) 0.6983! 5) 4.2(2) C(10) 0.9111 4) 0.2354 3) 0.7848 5) 4.2(2) C(10A) 0.9970< 4) 0.2902 3) 0.6690! 5) 4.1(2) C( 11) 0.6566 4) 0.1643 3) 0.6860 5) 4.1(2) C(12) 0.7428 4) 0.2646 3) 0.7255 5) 3.9(1) C(13) 0.5329< 5) 0.1454 3) 0.7908! 6) 4.6(2) C(14) 0.4848 7) 0.1307 5) 1.0759! 8) 7.3(3) C(15) 0.6734 5) 0.3472 3) 0.8346 6) 4.7(2) C(16) 0.7076! 8) 0.5110 4 ) 0.9636 8) 7.3(3) H ( l ) 0.6648 -0.0454 0.6173 6.2 H(2) 0.8766 -0.1520 0.6441 7.0 H(3) 1.1108 -0.0855 0.7448 7.1 H( 4) 1.1384 0.0872 0.8090 6.2 H( 5) 1.2151 0.2793 0.7781 5.9 H(6) 1.3111 0.3612 0.5661 6.9 H(7) 1.1535 0.4182 0.3345 6.8 H(8) 0.8960 0.3959 0.3080 6.1 H(14A) 0.4077 0.0859 1.0272 8.7 H(14B) 0.4423 0.1955 1.1007 8.7 H(14C) 0.5347 0.1055 1.1790 8.7 H(16A) 0.6774 0.4889 1.0657 8.7 H(16B) 0.6245 0.5417 0.8978 8.7 H(16C) 0.7852 0.5585 0.9927 8.7 -217-Table 59. Bond lengths involving non-hydrogen atoms of compound 34. atom atom d i s t a n c e atom atom d i s t a n c e C L l C9 1.800(5) C4A C9A 1.374(6) CL2 CIO 1.793(4) C4A CIO 1.500(6) 01 C13 1.336(6) C5 C6 1.371(7) 01 C14 1.450(6) C5 C10A 1.385(6) 02 C13 1.186(5) C6 C7 1.377(8) 03 C15 1.319(5) C7 C8 1.372(7) 03 C16 1.434(6) C8 C8A 1.379(7) 04 C15 1.194(5) C8A C9 1.493(6) 05 06 1.464(4) C8A C10A 1.379(6) 05 C9 1.413(5) C9 C12 1.560(6) 06 C l l 1.438(5) C9A C l l 1.510(6) CI C2 1.379(7) CIO CI OA 1.509(6) CI C9A 1.376(6) CIO C12 1.570(6) C2 C3 1.384(8) C l l C12 1.552(6) C3 C4 1.374(7) C l l C13 1.510(6) C4 C4A 1.381(6) C12 C15 1.517(6) D i s t a n c e s a re i n angstroms. E s t i m a t e d s t a n d a r d d e v i a t i o n s i n the l e a s t s i g n i f i c a n t f i g u r e a r e g i v e n i n p a r e n t h e s e s . Table 60. Bond angles involving non a t o m a t o m a t o m a n g l e C13 01 C14 1 1 6 . 1 ( 4 ) C 1 5 0 3 C 1 6 1 1 6 . 7 ( 4 ) 06 0 5 C9 1 0 3 . 0 ( 3 ) 0 5 06 C l l 1 0 1 . 0 ( 3 ) C2 C I C 9 A 1 1 9 . 0 ( 4 ) C I C2 C3 1 1 9 . 9 ( 4 ) C2 C3 C4 1 2 1 . 1 ( 4 ) C3 C4 C4A 1 1 8 . 7 ( 4 ) C4 C4A C9A 1 2 0 . 3 ( 4 ) C4 C4A C IO 1 2 7 . 1 ( 4 ) C9A C4A C IO 1 1 2 . 5 ( 3 ) C6 C5 C 1 0 A 1 1 8 . 6 ( 4 ) C5 C6 C7 1 2 0 . 6 ( 4 ) C6 C7 C8 1 2 1 . 5 ( 5 ) C7 C8 C8A 1 1 7 . 7 ( 5 ) C8 C8A C9 1 2 8 . 4 ( 4 ) C8 C8A C 1 0 A 1 2 1 . 4 ( 4 ) C9 C8A C 1 0 A 1 1 0 . 2 ( 4 ) CL1 C9 0 5 1 0 8 . 0 ( 3 ) CL1 C9 C8A 1 1 2 . 9 ( 3 ) CL1 C9 C12 1 1 4 . 8 ( 3 ) 0 5 C9 C 8 A 1 1 0 . 1 ( 3 ) 0 5 C9 C12 1 0 4 . 4 ( 3 ) C8A C9 C12 1 0 6 . 2 ( 3 ) C I C9A C4A 1 2 1 . 0 ( 4 ) C I C9A C l l 1 2 7 . 2 ( 4 ) hydrogen atoms of compound 34. a t o m a t o m a t o m a n g l e C4A C9A C l l 1 1 1 . 8 ( 3 ) C L 2 C IO C 4 A 1 0 8 . 9 ( 3 ) C L 2 C IO C 1 0 A 1 1 1 . 5 ( 3 ) C L 2 C IO C12 1 1 4 . 4 ( 3 ) C4A C IO C 1 0 A 1 1 3 . 8 ( 3 ) C4A C IO C 1 2 1 0 3 . 9 ( 3 ) C I OA C IO C12 1 0 4 . 2 ( 3 ) C5 C I OA C8A 1 2 0 . 1 ( 4 ) C5 C 1 0 A C IO 1 2 8 . 1 ( 4 ) C8A C 1 0 A C IO 1 1 1 . 6 ( 3 ) 06 C l l C9A 1 1 1 . 6 ( 3 ) 06 C l l C12 1 0 4 . 3 ( 3 ) 06 C l l C13 1 0 5 . 5 ( 3 ) C9A C l l C12 1 0 4 . 3 ( 3 ) C9A C l l C13 1 1 2 . 8 ( 4 ) C12 C l l C13 1 1 8 . 1 ( 4 ) C9 C12 C IO 1 0 3 . 1 ( 3 ) C9 C12 C l l 1 0 0 . 9 ( 3 ) C9 C12 C15 1 1 0 . 3 ( 3 ) C IO C12 C l l 1 0 6 . 9 ( 3 ) C IO C12 C 1 5 1 1 6 . 7 ( 3 ) C l l C12 C15 1 1 7 . 1 ( 3 ) 01 C13 02 1 2 5 . 9 ( 4 ) 01 C13 C l l 1 0 9 . 3 ( 3 ) 02 C13 C l l 1 2 4 . 6 ( 4 ) 03 C15 04 1 2 5 . 4 ( 4 ) 0 3 C 1 5 C12 1 1 0 . 7 ( 4 ) 04 C 1 5 C12 1 2 3 . 8 ( 4 ) -219-REFERENCES 1. V. Ramamurthy, Tetrahedron. 42, 5753 (1986). 2. (a) G. M. J. Schmidt, Pure Appl. Chem.. 27, 647 (1971). (b) G. R. Desiraju, "Crystal Engineering: The Design of Oganic Sol-ids", Elsevier, New York (1989). 3. (a) L. Addadi, M. Cohen, M. Lahav, L. Leiserowitz, J. Chim. Phys.. 83, 831 (1986). (b) F. C. Wireko, L. J. W. Shimon, F. Frolow, Z. Berkovitch-Yellin, M. Lahav, L. Leiserowitz, J. Phvs. Chem.. 91, 472 (1987), and references cited therein. "4. (a) M. C. Etter, G. M. Frankenback, Chem. Mater.. 1, 10 (1989). (b) T. W. Panunto, Z. Urbanczyk-Lipkowska, R. Johnson, M. C. Etter, J. Am. Chem. Soc. . 109, 7786 (1987). 5. J. A. R. P. Sarma, G. R. Desiraju, Acc. Chem. Res.. 19, 222 (1986) and references cited therein. 6. "Non-Linear Optical Properties of Organic Molecules and Crystals", D. S. Chemla, J. Zyss, Eds., Academic Press, New York (1987), vol. 1, 2. 7. (a) V. Ramamurthy, K. Venkatesan, Chem. Rev.. 87, 433 (1987). (b) J. R. Scheffer, M. Garcia-Garibay, 0. Nalamasu in "Organic Photo-chemistry", A. Padwa, Ed., Marcel Dekker, New York (1987), Vol.8, Ch. 4 8. H. W. Kohlschutter, Z. Anorg. Allg. Chem.. 105, 121 (1918). 9. (a) M. D. Cohen, G. M. J. Schmidt, J. Chem. Soc.. 1996 (1964). (b) M. D. Cohen, G. M. J. Schmidt, F. I. Sonntag, J. Chem. Soc.. 2000 (1964) . (c) G. M. J. Schmidt, J. Chem. Soc.. 2014 (1964). 10. M. D. Cohen, Angew. Chem. Int. Ed. Engl.. 14, 386 (1975). 11. S. Ar i e l , S. Askari, J. R. Scheffer, J. Trotter, L. Walsh, J. Am.  Chem. Soc. . 106, 5726 (1984). 12. J. D. Dunitz, "X-Ray Analysis and the Structure of Organic Mole-cules", Cornell University Press, Ithaca, New York (1979), pp 312-318. 13. A. D. Gudmundsdottir, J. R. Scheffer, Tetrahedron Lett.. 30, 423 (1989) . 14. A. Gavezzotti, J. Am. Chem. Soc.. 105, 5220 (1983). 15. J. M. McBride, Acc. Chem. Res.. 16, 304 (1983). -220-16. S. Ar i e l , J. Trotter, Acta Crvst.. B44, 538 (1988). 17. H. E. Zimmerman in "Molecular Rearrangements in Ground and Excited States", P. De Mayo, Ed., Academic Press, New York (1980), Ch. 16. 18. (a) J. R. Scheffer, J. Trotter, M. Garcia-Garibay, F. Wireko, Mol. Crvst. Liq. Crvst. Inc. Nonlin. Opt.. 156, 63 (1988). (b) H. E. Zimmerman, M. J. Zuraw, J. Am. Chem. Soc. . I l l , 7974 (1989) . 19. W. Adam, 0. De Lucchi, M. Dorr, J. Am. Chem. Soc.. I l l , 5209 (1989). 20. (a) L. A. Paquette, E. Bay, J. Org. Chem.. 47, 4597 (1982). (b) L. A. Paquette, E. Bay, J. Am. Chem. Soc.. 106, 6693 (1984). (c) L. A. Paquette, A. Varadarajan, E. Bay, ibid.. 106, 6702 (1984). (b) L. A. Paquette, A. Varadarajan, L. D. Burke, ibid.. 108, 8032 (1986). 21. (a) H. E. Zimmerman, G. L. Grunewald, J. Am. Chem. Soc. . 88 , 183 (1966) . (b) H. E. Zimmerman, R. W. Binkley, R. S. Givens, M. A. Sherwin, J.  Am. Chem. Soc. 89 , 3932 (1967). 22. H. E. Zimmerman, R. S. Givens, R. M. Pagni, J. Am. Chem. Soc.. 90 , 6096 (1968). 23. H. E. Zimmerman, C. 0. Bender, J. Am. Chem. Soc. . 92 , 4366 (1970). 24. E. Ciganek, J. Am. Chem. Soc.. 88 , 2882 (1966). 25. (a) K. E. Richards, R. W. Tillman, G. J. Wright, Aust. J. Chem.. 28 , 1289 (1975). (b) R. G. Paddick, K. E. Richards, G. J. Wright, ibid.. 2 9 , 1005 (1976). (c) M. Iwamura, H. Takuda, H. Iwamura, Tetrahedron Lett.. 21 , 4865 (1980) . 26. P. W. Rabideau, J. B. Hamilton, L. Friedman, J. Am. Chem. Soc. . 90 , 4465 (1968). 27. S. Pratapan, K. Ashok, D. R. Cyr, P. K. Das, M. V. George, J. Org.  Chem.. 52, 5512 (1987). 28. P. R. Pokkuluri, J. R. Scheffer, J. Trotter, Tetrahedron Lett.. 30 , 1601 (1989). 29. M. Garcia-Garibay, J. R. Scheffer, J. Trotter, F. Wireko, J. Am.  Chem. Soc. I l l , 4985 (1989). 30. P. R. Pokkuluri, M. Sc. Thesis, University of British Columbia, 1987. 31. V. C. Yee, J. Trotter, unpublished results. -221-32. G. H. Stout, L. H. Jensen, "X-ray Structure Determination: A Practi-cal Guide". John Wiley & Sons, Inc., New York (1989). 33. M. J. Buerger, "Crystal-Structure Analysis", John Wiley & Sons, Inc., New York (1960). 34. M. F. C. Ladd, R. A. Palmer, "Structure Determination by X-ray Crystallography", Plenum Press, New York (1985). 35. J. P. Glusker, K. N. Trueblood, "Crystal Structure Analysis: A Primer", Oxford University Press, New York (1985). 36. J. D. Dunitz, "X-ray Analysis and the Structure of Organic Molecules", Cornell University Press, Ithaca, New York (1979). 37. TEXRAY - Diffractomer Control Software, Molecular Structure Corporation, College Station, Texas (1987). 38. TEXSAN - Structure Analysis Software, Molecular Structure Corporation, College Station, Texas (1987). 39. A. J. C. Wilson, Nature, 150, 151 (1942). 40. E. R. Howells, D. C. Phillips, D. Rogers, Acta Crvst.. 3, 210 (1950). 41. G. J. Gilmore, J. Appl. Cryst.. 17, 42 (1984). 42. J. Karle, H. Hauptman, Acta Crvst.. 3, 181 (1950). 43. "Crystallographic Computing Techniques", F. R. Ahmed, Ed., Munks-gaard, Copenhagen (1976). 44. D. Sayre, Acta Crvst.. 5, 60 (1952). 45. W. R. Busing, K. 0. Martin, H. A. Levy, Report ORNL-TM-305 (ORFLS), Oak Ridge National Laboratory, Tennessee (1962). 46. D. T. Cromer, J. T. Waber, International Tables for X-ray Crystallo-graphy, Vol. IV, The Kynoch Press, Birmingham, England (1974). Table 2.2A. 47. J. A. Ibers, W. C. Hamilton, Acta Cryst.. 17, 781 (1964). 48. Reference 46, Table 2.3.1. 49. W. R. Busing, K. 0. Martin, H. A. Levy, Report ORNL-TM-306 (0RFFE), Oak Ridge National Laboratory, Tennessee (1964). 50. C. K. Johnson, Report 0RNL-5138 (ORTEP II), Oak Ridge National Laboratory, Tennessee (1976). 51. S. Motherwell, W. Clegg, PLUTO - A Program for Plotting Molecular and Crystal Structures, University of Cambridge, England (1978). -222-52. 0. Diels, K. Alder, Justus Liebigs Ann. Chem.. 486, 191 (1931). 53. J. Rigaudy, J. Guillaume, N. K. Cuong, C. R. Acad. Sc. Paris.. 259 4729 (1964)-. 54. (a) S. Wollowitz, J. Halpern, J. Am. Chem. Soc.. 106, 8319 (1984) and references cited therein, (b) D. A. Lindsay, J. Lusztyk, K. U. Ingold, J. Am. Chem. Soc.. 106 7087 (1984). 55. P. R. Pokkuluri, J. R. Scheffer, J. Trotter, J. Am. Chem. Soc.. 112, 3676 (1990). 56. H. E. Zimmerman, M. J. Zuraw, J. Am. Chem. Soc.. I l l , 7974 (1989). 57. N. L. Allinger, H. L. Flanagan, J. Comput. Chem.. 4, 399 (1983). 58. Parts of this program were taken from the program BMFIT, and were extensively modified by S. Ari e l , University of British Columbia. 59. K. Mirsky, In "Computing in Crystallography, Proceedings of an International Summer School on Crystallographic Computing", Delft University Press: Twente (1978), p 169. 60. Program BMFIT, written by S. C. Nyberg, University of Toronto (1978). 61. C. V. Kumar, B. A. R. C. Murthy, S. Lahiri, E. Chackachery, J. C. Scaiano, M. V. George, J. Org. Chem.. 49, 4923 (1984). 62. M. V. George, personal communication to J. R. Scheffer. 63. (a) H. Gunther, R. Wehner, J. Am. Chem. Soc.. 97, 923 (1975). (b) R. Hoffmann, W-D. Stohrer, ibid.. 93, 6941 (1971). (c) R. Hoffmann, Tetrahedron Lett.. 2907 (1970). (d) H. Gunther, ibid.. 5173 (1970). 64. M. Garcia-Garibay, Ph. D. Thesis, University of British Columbia (1988) . 65. J. Chen, P. R. Pokkuluri, J. R. Scheffer, J. Trotter, J. Photochem.  Photobiol. A. in press. 66. P. J. Wagner, M. J. Lindstrom, J. H. Sedon, D. R. Ward, J. Am. Chem.  Soc.. 103, 3842 (1981). 67. C. Thompson in Electron Spin Resonance: A Specialist Periodical Report, The Chemical Society, London (1973), Vol. 1, Ch. 1. 68. J. Chen, A. Gudmundsdottir, J. R. Scheffer, unpublished results. 69. F. P. A. Zweegers, C. A. G. 0. Varma, J. Phys. Chem.. 83, 1821 (1979) and references cited therein. -223-70. J. R. Scheffer, M. Yap, J. Org. Chem.. 54, 2561 (1989) and references cited therein. 71. F. C. Wireko, Ph. D. Thesis, Univeristy of British Columbia (1988). 72. (a) S. W. Oliver, G. D. Fallon, T. D. Smith, Acta Crvst.. C42, 1047 (1986). (b) K. J. Palmer, D. H. Templeton, Acta Crvst.. B24, 1048 (1968). 73. F. H. Allen, Acta Cryst.. B37, 900 (1981). 74. F. H. Allen, Acta Cryst.. B36, 81 (1980). 75. J. D. Dunitz in Perspectives in Structural Chemistry, J. D. Dunitz, J. A. Ibers, Eds., John Wiley & Sons, New York (1968), Vol. 2, p. 47. 76. W. C. S t i l l , M. Kahn, A. Mitra, J. Org. Chem.. 43, 2923 (1978). 77. N. Walker, D. Stuart, Acta Cryst.. A39, 158 (1983).. i 

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