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X-ray crystallographic studies of five group III compounds 1974

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X-RAY CRYSTALLOGBAPHIC STUDIES 01 F I V E GROUP I I I COMPOUNDS 49. by STEVEN J. E E T T I G B . S . , U n i v e r s i t y o f I l l i n o i s a t C h i c a g o C i r c l e , 1970 A T H E S I S SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n t h e D e p a r t m e n t o f CHEMISTRY We a c c e p t t h i s t h e s i s a s c o n f o r m i n g t c t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRIT ISH COLUMBIA APRIL 1974 In presenting th is thes is in p a r t i a l fu l f i lment of the requirements for an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f ree ly ava i l ab le for reference and study. I fur ther agree that permission for extensive copying of th is thes is for scho la r ly purposes may be granted by the Head of my Department or by h is representat ives . It is understood that copying or pub l i ca t ion of th is thes is fo r f inanc ia l gain sha l l not be allowed without my wri t ten permission. Department of Chemistry The Univers i ty of B r i t i s h Columbia Vancouver 8, Canada Date June 1Q7A i i ABSTRACT Supervisor: Professor James Trotter The structures of f i v e compounds of group III elements have been determined by single c r y s t a l X-ray d i f f r a c t i o n , three boron compounds, one aluminum compound, and one gallium compound: 1» B,B-diphenylboroxazolidine (2-atninoethyl diphenyl- borinate) , C^ H^BNO. 2. B ,B-bis (£-f luorophenyl) boroxazolidine , C-i L^H^BF2 NO. 3. 4 , U-dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2-bor- anatacyclopentane, Cj^H^gBNG^. 4. N-methyldiethanolaminogallane dimer, C ^ Q H ^ G ^ ® 2 ° k ' 5. (£entaha£tocyclopentadienyl) hydridomolybdenum-><-di- me th ylaluminum-/<-[ methylaluminum-di- iju.-£entaha_p_to- (monoha£to)cyclopentadienyl)dimethylaluminum] (£entaha]3- tocyclopentadienyl)hydridomolybdenum, C25 H35 A ̂ 3Mo2* Crystals of B,B-diphenylboroxazolidine are monoclinic, a = 13.840(1), b = 8.9169(5), c = 10.170(1) A, = 98.85 (1)° , Z = 4, space group P2^/n. The structure was determined by direct methods, and refined by electron-density and f u l l - matrix least-squares procedures to R 0.041 for 1458 reflexions. The five-membered boroxazolidine ring i s i n the ha l f - c h a i r conformation. Bond angles i n the ring range from 99.7 f o r OBN to 110.1° for BOC. Bond lengths are as follows: mean B-C, 1.616(2), B - H , 1 .653 (3), B-0, 1.484(3), C - N , 1 .485 (3), C-O, 1.413(3), mean C-C (aromatic) , 1 .392(11 ), and i i i C-C, 1.505(4) A. The s t r u c t u r e c o n s i s t s of d i s c r e t e molecules l i n k e d by 0...H-N hydrogen bonds (2,874(2) A) to form continuous s p i r a l s about the 2^ axes. C r y s t a l s of B,B-bis (£-fluorophenyl)boroxazolidine are orthorhomfcic, a = 13.442 (4), b = 10.214(3), c = 9. 823 (2) ft, Z = 4, space group P2^ 2\ 2\. The s t r u c t u r e was s o l v e d by d i r e c t methods, and r e f i n e d by e l e c t r o n - d e n s i t y and f u l l - m a t r i x l e a s t - s q u a r e s procedures to R 0.047 f o r 1234 r e f l e x i o n s . The five-membered b o r o x a z o l i d i n e r i n g i s i n a d i s t o r t e d h a l f - c h a i r conformation , Bond an g l e s i n the r i n g range from 99.9(2) f o r OBH to 108.2(2)° f o r BOC. Bond lengths are: mean B-C, 1.621:, (3), B-N, 1.652 (4), B-O, 1.471(4), C-N, 1.491(4), C-0, 1.4 18(4), mean C-F, 1.371(1), mean C-C (aromatic) , 1 .390 (13), and C (sp_3) -C ( s £ 3 ) , 1.494 (6) A. The s t r u c t u r e c o n s i s t s of d i s c r e t e molecules each l i n k e d to s i x others by an e x t e n s i v e network of O...H-N (0...N = 2.941(3) A), F...H-N (F...N = 3.171(4) A), ana F...H-C (F...C = 3.318(5) A) hydrogen bonds. C r y s t a l s of 4,4-dimethyl-2,2-diphenyl-1,3-dioxa-4- azonia-2-boranatacyclopentane are orthorhombic, a = 17.043 (3), b = 6.289 (1), c = 13.024 (2) I, Z = 4, space group Pna2i. The s t r u c t u r e was determined by d i r e c t methods, and was r e f i n e d by f u l l - m a t r i x l e a s t - s q u a r e s procedures to R 0,071 f o r 1100 r e f l e x i o n s . Bond angles i n the five-membered r i n g , which has a d i s t o r t e d h a l f - c h a i r conformation, range from 101.5(4) f o r OBO to 107.1(4)° f o r NOB. Bond lengths are: mean B-C, 1.632 (8), B-0, 1.506(7) and 1.556 (8), N-0, i v 1 . 4 0 9 ( 5 ) , C - O , 1. 378 ( 9 ) , C - N , 1 . 4 6 7 - 1 . 5 0 9 ( 7 - 1 0 ) , mean C - C ( a r o m a t i c ) , 1 . 3 9 5 ( 2 5 ) A . T h e s t r u c t u r e c o n s i s t s o f d i s c r e t e m o l e c u l e s s e p a r a t e d by n o r m a l v a n d e r Waals d i s t a n c e s . C r y s t a l s o f t h e N - m e t h y l d i e t h a n o l a m i n o g a l l a n e d i m e r a r e o r t h o r h o m f c i c , a = 1 9 . 1 1 2 ( 4 ) , b = 9 . 9 4 7 ( 2 ) , c = 7 . 7 0 9 ( 2 ) A , Z = 4 , s p a c e g r o u p ^2\2\2i . T h e s t r u c t u r e was d e t e r m i n e d by P a t t e r s o n and F o u r i e r s y n t h e s i s and was r e f i n e d by f u l l - m a t r i x l e a s t - s q u a r e s p r o c e d u r e s t o a f i n a l R o f 0 . 0 5 6 f o r 1477 r e f l e x i o n s . T h e s t r u c t u r e p r o v i d e s t h e f i r s t known c r y s t a l l o g r a p h i c e x a m p l e o f p e n t a c o o r d i n a t e g a l l i u m , t h e d i m e r i z a t i o n o f HeH ( C H 2C H 2 ° ) 2 G a H o c c u r r i n g v i a t h e f o r m a t i o n o f a f o u r - m e m b e r e d Gn2°2 ^ i n 9 « T n e c o o r d i n a t i o n a b o u t t h e g a l l i u m i s d i s t o r t e d t r i g o n a l b i p y r a m i d a l w i t h an a n g l e o f 1 5 1 . 2 ( 4 ) ° b e t w e e n t h e a x i a l s u b s t i t u e n t s . The mean bond d i s t a n c e s a r e : G a - N , 2 . 1 9 2 ( 5 ) , and G a - O , 2 . 0 1 8 ( 2 ) f o r a x i a l l i g a n d s ; G a - O , 1 . 8 4 7 ( 2 ) , 1 .960 ( 8 ) , a n d G a - H , 1 .41 (4 ) f o r e q u a t o r i a l l i g a n d s ; O - C , 1 . 4 1 9 ( 1 4 ) , C - N , 1 . 4 7 0 ( 7 ) , C - C , 1 .520 ( 1 2 ) , and C - H , 1 .00 (13) A . T h e m o l e c u l e h a s C 2 s y m m e t r y t o w i t h i n e x p e r i m e n t a l e r r o r . T h e r e a r e p o s s i b l e C - H . . . 0 h y d r o g e n b o n d s ( C . . . O , 3 . 1 3 ( 1 ) - 3 . 4 4 (1) A) i n t h e s t r u c t u r e . C r y s t a l s o f t h e h y d r i d o m o l y b d e n u m c o m p l e x , C2^H^^A l-^MOg, a r e o r t h o r h o m b i c , a = 1 9 . 3 9 8 (4) , b = 1 4 . 4 3 8 (9) , c = 9 . 0 35 (2) I, Z = 4 , s p a c e g r o u p V.2\2\2\, The s t r u c t u r e was d e t e r m i n e d by P a t t e r s o n a n d F o u r i e r s y n t h e s e s , and r e f i n e d by f u l l - m a t r i x l e a s t - s g u a r e s p r o c e d u r e s t o R 0 . 0 6 6 and Rw 0 . 0 6 3 f o r 1213 r e f l e x i o n s . The m o l e c u l a r s t r u c t u r e e x h i b i t s s e v e r a l u n u s u a l f e a t u r e s : C^E^ g r o u p s w h i c h a r e £ e n t a h a £ t o t o t h e molybdenum atoms and are i n v o l v e d v i a the unique carbon atom i n m u l t i c e n t r e bonding to two aluminum atoms, one of which occurs as an Al (Me)2 u n i t and the other an AlMe u n i t which a l s o bridges the two molybdenum atoms. The t h i r d aluminum atom i s probably i n v o l v e d i n a Mo-H-Al (Me)2-H-Mo l i n k a g e . Mean bond d i s t a n c e s are: Mo-Al, 2.659 and 2.974, A l - C(terminal) , 2.00, ftl-C ( b r i d g e ) , 2.05 and 2.33, Mo- C ( c y c l o p e n t a d i e n y l ) , 2. 285, and C-C (c y c l o p e n t a d i e n y l ) , 1.389 T A B L E OF CONTENTS P a g e T I T L E PAGE i ABSTRACT i i T A B L E OF CONTENTS v i L I S T OF T A B L E S i x L I S T OF F IGURES x i i ACKNOWLEDGEMENTS x i v GENERAL INTRODUCTION 1 PART 1. C R Y S T A L AND MOLECULAR STRUCTURE OF B , B - D I P H E N Y L B O R O X - AZOLID INE (2-A MINOETHYLDIPHENYLBORINATE) 4 I n t r o d u c t i o n 5 E x p e r i m e n t a l 6 S t r u c t u r e a n a l y s i s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 A n a l y s i s o f t h e r m a l m o t i o n 9 R e s u l t s and d i s c u s s i o n . . . . . . . . . . . . . . . . . . . . . . . . . . 12 PART 2 . C R Y S T A L AND MOLECULAR STRUCTURE OF B, B - B I S (J3 - F L U O R O - PHENYLBOROXAZOLIDINE 27 I n t r o d u c t i o n 28 E x p e r i m e n t a l 28 S t r u c t u r e a n a l y s i s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 A n a l y s i s o f t h e r m a l m o t i o n 34 R e s u l t s and d i s c u s s i o n . . . . . . . . . . . . . . . . . . . . . . . . . . 38 v i i PART 3. CRYSTAL AND MOLECULAR STRUCTURE OF 4,4-DIMETHYL-2,2-DIPHENYL-1 ,3-DIOXA- 4 - A ZONIA-2-BOR ANAT ACYCLOPENTAN E . 52 I n t r o d u c t i o n 53 Experimental 55 S t r u c t u r e a n a l y s i s 57 A n a l y s i s of thermal motion 61 R e s u l t s and d i s c u s s i o n 65 PART 4. CRYSTAL AND MOLECULAR STRUCTURE OF THE N-METHYLDIETHANOLAMINOGALLANE DIMER 77 I n t r o d u c t i o n 78 Experimental 79 S t r u c t u r e a n a l y s i s 81 A n a l y s i s of thermal motion ...................... 82 Re s u l t s and d i s c u s s i o n . . 88 PART 5. CRYSTAL AND MOLECULAR STRUCTURE CF (PENTAHAPTOCYCLO- PENTADIENYL)HYDRIDOHOLYBDENUM-^-DIMETHYLALUMINUM^- [ METH YL ALUM IN UM-DI- yu. - £ ENT AH APT 0 (RONOHAPTO) CYCLOP FN- TADIENYL)DIMETHYLALUMINUM] (PENTAHAPTOCYCLOPENT ADIEN- YL) HYDRIDOMOLYBDENUM 103 I n t r o d u c t i o n 104 Experimental 104 S t r u c t u r e a n a l y s i s 106 R e s u l t s and d i s c u s s i o n 108 v i i i PART 6. THE COMPUTER PROGRAM "SIGCOR" 129 Introduction 130 General description 130 Program instructions 139 Source l i s t i n g 143 Example output 149 Discussion 153 SUMMARY . 157 REFERENCES 160 ix LIST OF TABLES Table Page B,B-Diphenylboroxazolidine 1 S t a r t i n g s e t of r e f l e x i o n s 8 2 F i n a l atomic c o o r d i n a t e s 10 3 F i n a l thermal parameters 11 4 Rigid-body thermal parameters ................... 13 5 Bond le n g t h s 17 6 Bond angles 18 7 T o r s i o n angles 20 8 Mean planes 21 9 Non-bonded c o n t a c t s 25 B,B-bis (g-Fluorophenyl) b o r o x a z o l i d i n e 10 S t a r t i n g s e t of r e f l e x i o n s 31 11 R e s u l t s of the phase det e r m i n a t i o n procedure .... 32 12 F i n a l atomic c o o r d i n a t e s 35 13 F i n a l thermal parameters ........................ 36 14 Rigid-body thermal parameters 37 15 Bond l e n g t h s 40 16 Bond angles 41 17 T o r s i o n angles 43 18 Mean planes 47 19 Non-bonded c o n t a c t s 50 X 4,4-Dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2- boranatacyclopentane 20 Starting set of reflexions ...................... 59 21 Results of the phase determination procedure .... 60 22 F i n a l atomic coordinates 62 23 Fi n a l thermal parameters ........................ 63 24 Rigid-body thermal parameters 65 25 Bond lengths 67 26 Bond angles 68 27 Torsion angles 69 28 Mean planes 72 29 Non-bonded contacts 73 N-Methyldiethanolaminogallane Dimer 30 Results of Hamilton's test 83 31 F i n a l atomic coordinates 84 32 F i n a l thermal parameters 85 33 Rigid-body thermal parameters 87 34 Bond lengths ,. 89 35 Bond angles 90 36 Structural data for some gallium complexes 94 37 Mean planes 96 38 Torsion angles 97 39 Non-bonded contacts 101 x i Hydridomolybdenum complex 40 F i n a l atomic c o o r d i n a t e s 109 41 F i n a l thermal parameters 110 42 C a l c u l a t e d hydrogen p o s i t i o n s 111 43 R e s u l t s of Hamilton»s t e s t 113 44 Bond le n g t h s 116 45 Bond angles ... 117 46 Mean planes 121 47 Non-bonded c o n t a c t s 123 48 S t r u c t u r a l data f o r some molybdenum - c y c l o p e n t a d i e n y l complexes ......... 124 Computer program SIGCOR 49 R e s u l t s of sample c a l c u l a t i o n s 154 x i i L I S T OF FIGURES F i g u r e Page B,B-Diphenylboroxazolidine 1 The molecule viewed down b 14 2 View of the molecule showing bond lengths ........ 15 3 The s t r u c t u r e viewed down c 24 B f B - b i s ( j D - F l u o r o p h e n y l ) b o r o x a z o l i d i n e 4 A s t e r e o view of the molecule 39 5 The s t r u c t u r e viewed along b .................... 44 6 The s t r u c t u r e viewed down c 44 4,4-Dimethyl-2,2-diphenyl-1,3-dioxa-4-azonia-2- boranatacyclopentane 7 A s t e r e o view of the molecule 64 8 The s t r u c t u r e viewed along b 74 N-Methyldiethanolaminogallane Dimer 9 A s t e r e o view of the molecule ................... 86 10 C o o r d i n a t i o n about the g a l l i u m atoms ............ 93 11 The s t r u c t u r e viewed along c .................... 99 12 The s t r u c t u r e viewed along b 100 x i i i Hydridomolybdenum complex 13 A s t e r e o view of the molecule 114 14 The s t r u c t u r e viewed down c ..................... 115 15 The s t r u c t u r e viewed along b 115 16 The Al-C-C-Al b r i d g i n g system 120 17 I d e a l i z e d s t r u c t u r e of b i s ( c y c l o p e n t a d i e n y l ) - t r a n s i t i o n metal complexes with canted Cp r i n g s . 127 The computer program SIGCOR 18 Bond c o n t r a c t i o n vs. s c h a r a c t e r ................ 136 19 Bond order vs. bond c o n t r a c t i o n 137 xiv ACKNOWLEDGEMENTS I wish t o thank P r o f e s s o r James T r o t t e r f o r g i v i n g me the o p p o r t u n i t y to j o i n h i s r e s e a r c h group and f o r the help he has g i v e n me during the past f o u r years. I am a l s o indebted to my f e l l o w graduate students and p o s t d o c t o r a l f e l l o w s , i n p a r t i c u l a r Drs. Ian Nowell and B i l l H a r r i s o n , f o r the a s s i s t a n c e they have given me. I would a l s o l i k e to thank Prof. W. K l i e g e l , Technischen U n i v e r s i t a t Braunschwieg, f o r p r o v i d i n g the sample and i n t r o d u c t o r y m a t e r i a l f o r the study of 4,4-Dimethyl-2, 2- diphenyl-1,3-dioxa-4-azonia-2-boranatacyclopentane (Part 3) and Prof. H. Noth, U n i v e r s i t y of Munich, f o r running the 1 1 B NMR spectrum. I thank Dr. Alan S t o r r f o r p r o v i d i n g background m a t e r i a l , d e t a i l s of the p r e p a r a t i o n s , and c r y s t a l s of the N- Methyldiethanolaminogallane dimer (Part 4) and the hydridomolybdenum complex (Part 5) . I am g r a t e f u l to the N a t i o n a l Research C o u n c i l of Canada f o r a postgraduate s c h o l a r s h i p (1972-73 and 1973-74). ENEBAL INTRODUCTION 2 The h i s t o r i c a l background and e s t a b l i s h e d p r i n c i p l e s of X-ray c r y s t a l l o g r a p h y are d e a l t with i n a number of standard t e x t s (1-5) . The c r y s t a l l o g r a p h i c symbols and nomenclature appearing throughout t h i s t h e s i s have t h e i r c o n v e n t i o n a l meanings des c r i b e d i n the " I n t e r n a t i o n a l Tables for X-ray C r y s t a l l o g r a p h y " (6). The main body of the t h e s i s , parts 1-5, c o n s i s t s of the c r y s t a l l o g r a p h i c s t u d i e s of the f i v e compounds c o n t a i n i n g group I I I elements. Each part i n c l u d e s i n t r o d u c t o r y m a t e r i a l r e l e v a n t to that p a r t i c u l a r compound as w e l l as d e t a i l s of the s t r u c t u r e d e t e r m i n a t i o n and a d i s c u s s i o n of the r e s u l t s . The f i n a l p a r t of the t h e s i s d e s c r i b e s a computer program which c a l c u l a t e s approximate valence bond or d e r s from observed molecular geometry. I t i s based on a g e n e r a l r e l a t i o n s h i p which a s s o c i a t e s bond order with the f r a c t i o n a l d i f f e r e n c e between the observed i n t e r a t o m i c d i s t a n c e and the c a l c u l a t e d s i n g l e bond d i s t a n c e . H y b r i d i z a t i o n and e l e c t r o n e g a t i v i t y e f f e c t s are c o n s i d e r e d i n the c a l c u l a t i o n o f the s i n g l e bond d i s t a n c e s . For each of the f i v e c r y s t a l s t r u c t u r e s the l e a s t - squares refinement was based on the minimization of2w(Fo- F c ) 2 where Fo and Fc are the observed and c a l c u l a t e d s t r u c t u r e f a c t o r s and w i s the assigned weighting f a c t o r . The a n i s o t r o p i c thermal f a c t o r s employed i n the refinement are y_i ̂  i n the e x p r e s s i o n : f = f °exp[-2ff2 (y_nh 2a*2 + U 22JS 2b* 2 + ^ j £ 2 £ * z 3 + 2U 1 2hka*b* + 2D 1^h/a*c* + 2U2j^£b*c*) ] where f° i s the t a b u l a t e d s c a t t e r i n g f a c t o r and f i s t h a t c o r r e c t e d f o r thermal motion. The i s o t r o p i c thermal parameters have the form: f = fOexp[-B(sin 9/*) * ] where B i s r e l a t e d to the mean-square displacement, U 2, of the atom from i t s mean p o s i t i o n by the e x p r e s s i o n : B = 8*r202 PART 1 CRYSTAL AND MOLECULAR STRUCTURE OF B,B-DIPHEN YLBOROXAZOLIDINE (2-AMINOETHYL DIPHENYLBORINATE) 5 INTRODUCTION In r e c e n t years the b o r o x a z c l i d i n e s have teen e x t e n s i v e l y s t u d i e d , the primary concern being the unusual s t a b i l i t y of the a m i n o a l c o h c l e s t e r s with r e s p e c t to boron e s t e r s of o r d i n a r y a l c o h o l s . B , B - d i p h e n y l b o r o x a z c l i d i n e Q) was o r i g i n a l l y prepared by L e t s i n g e r and Skoog (7), who c o r r e c t l y proposed the c y c l i c s t r u c t u r e of the e s t e r . The p o s s i b i l i t y of the N—>B d a t i v e bond was f i r s t proposed by Brown and F l e t c h e r (8) f o r t r i e t h a n o l a r a i n e b o r a t e { t r i p t y c h b o r o x a z o l i d i n e ) i n 1951. The f i r s t s u b s t a n t i a l evidence f o r the e x i s t e n c e of the N->B d a t i v e bond i n b o r o x a z o l i d i n e s was the r e s u l t of d e t a i l e d k i n e t i c s t u d i e s of the a c i d h y d r o l y s i s of these compounds by Zimmerman and co-workers, the d e t a i l s of which are the s u b j e c t of a review a r t i c l e by Zimmerman (9). The X-ray c r y s t a l l o g r a p h i c study cf £,B- d i p h e n y l b o r o x a z o l i d i n e was undertaken to provide c o n c l u s i v e proof of the e x i s t e n c e of the b o r o x a z o l i d i n e r i n g . 1 6 EXPERIMENTAL B,B-Diphenylboroxazolidine was prepared as p r e v i o u s l y d e s c r i b e d (7, 10). R e c r y s t a l l i z a t i o n from 1:1 ethanol-carbon t e t r a c h l o r i d e gave c o l o r l e s s n e edles, elongated along b, with (100) , (001) , and (101) v a r i o u s l y developed, The c r y s t a l chosen f o r study was mounted with b p a r a l l e l to the g o n i o s t a t a x i s and was ca. 0.5 mm i n length with a c r o s s s e c t i o n of 0.3 x 0.3 mm. U n i t - c e l l and space group data were ob t a i n e d from f i l m and d i f f T a c t o m e t e r measurements. The u n i t - c e l l parameters were r e f i n e d by a l e a s t - s q u a r e s treatment of sin 2© valu e s f o r 22 r e f l e x i o n s measured on a d i f f T a c t o m e t e r with Cu r a d i a t i o n . C r y s t a l data a r e : c l ^ H l 6 B N 0 f , w * = 2 2 5 * 1 M o n o c l i n i c , a = 13.840(1), b = 8.9169(5), c = 10.170(1) A, j8 = 98.85 (1)° , V = 1240.1(2) A 3. Dm = 1.201(5), Z = 4, D x = 1.2055 (3), F(000) = 480 (20° C, Cu K*, a = 1.5418 A, ^ = 5.9 cm-*). Absent s p e c t r a : OkO, k * 2n and h0^, h + £ # 2n d e f i n e uniquely the space group P2^/n(C"|^, No. 14). I n t e n s i t i e s were measured on a Datex-automated General E l e c t r i c XRD 6 d i f f T a c t o m e t e r , with a s c i n t i l l a t i o n counter, Cu Kc< r a d i a t i o n ( n i c k e l f i l t e r and p u l s e h e i g h t analyser) , and a G-2€ scan at 2° m i n - 1 over a range of (1.80 + 0.86 tan G) degrees i n 29, with 20 s background counts being measured at each end of the scan. Data were measured to 29 = 145° o (minimum i n t e r p l a n a r spacing 0.81 A). A check r e f l e x i o n was monitored every 40 r e f l e x i o n s throughout the data c o l l e c t i o n . 7 The i n t e n s i t y of the check r e f l e x i o n remained w i t h i n ± 2.5% of i t s i n i t i a l value during the data c o l l e c t i o n , the f i n a l value being equal to the i n i t i a l value. L o r e n t z and p o l a r i z a t i o n c o r r e c t i o n s were a p p l i e d , and the s t r u c t u r e amplitudes were d e r i v e d . No a b s o r p t i o n c o r r e c t i o n was made i n view of the low value of //.. Of the 1837 independent r e f l e x i o n s measured, 369 had i n t e n s i t i e s l e s s than 3<r(I) above background where <r2 (I) = S + B + (0.05S) 2 with S = scan count and B = time averaged background count. These r e f l e x i o n s were not i n c l u d e d i n the refinement. S t r u c t u r e A n a l y s i s The s t r u c t u r e was solved by d i r e c t methods. S i x t e e n s e t s of s i g n s f o r 254 r e f l e x i o n s with normalized s t r u c t u r e f a c t o r |E| > 1.50 were determined by a computer program which uses Sayre r e l a t i o n s h i p s i n an i t e r a t i v e procedure (11). The s t a r t i n g s e t of r e f l e x i o n s i s given i n Table 1. One set of si g n s was outsta n d i n g i n t h a t i t converged i n 5 c y c l e s to a se t having the highest c o n s i s t e n c y index (11) (0.85) with 130 p o s i t i v e s i g n s and 124 negative s i g n s . An E-raap was computed using the 254 signed values of E from t h i s s e t . The 17 non- hydrogen atoms accounted f o r the 17 h i g h e s t peaks on the map. A s t r u c t u r e f a c t o r c a l c u l a t i o n based on the p o s i t i o n s from the E-map gave R 0.211. Two c y c l e s of f u l l - m a t r i x l e a s t - squares refinement of the p o s i t i o n s and i s o t r o p i c temperature f a c t o r s of the boron, n i t r o g e n , oxygen, and carbon atoms reduced B to 0.151. A l l 16 hydrogen atoms were then l o c a t e d from a d i f f e r e n c e F o u r i e r . One c y c l e with the non-hydrogen 8 Table 1 Ba s i c s t a r t i n g s e t of r e f l e x i o n s f o r C^H^BNO h IS A HI 6 1 - 8 4 . 00- , I 3 1 - 1 1 2 . 2 5 | - o r i g i n determining 1 2 . 2 0 J 0 2 1 6 3 0 3 . 1 4 1 2 - 4 2 . 4 7 9 3 - 1 3 . 1 9 1 0 3 4 3 . 2 1 9 atoms having a n i s o t r o p i c temperature f a c t o r s and the hydrogen atoms i s o t r o p i c r e s u l t e d i n R = 0.058. Convergence was reached a f t e r two more c y c l e s a t R = 0.041 f o r 1458 r e f l e x i o n s with I > 3<r(I) (10 r e f l e x i o n s were given zero weight i n the f i n a l stages of refinement due to suspected e x t i n c t i o n e r r o r s : 0 0 2, 1 0 -1, 2 0 0, 1 1 1 , 3 1 - 1 , 3 2 0, 0 2 0, 0 2 1 , 2 2 -1, and 1 3 0). The s c a t t e r i n g f a c t o r s of r e f . 12 were used f o r the boron, n i t r o g e n , oxygen, and carbon atoms and those of r e f . 13 f o r the hydrogen atoms. The weighting scheme: w = 1 i f |Fo| < 10; w = ( 1 0 / J F o | ) 2 i f |p 0| > 1 0 , and w = 0,49 f o r the weak r e f l e x i o n s gave constant average values of w (Fo - F c ) 2 over ranges of |Fo|, and was employed i n the f i n a l stages of refinement. On the f i n a l c y c l e of refinement, no parameter s h i f t was g r e a t e r than 0.33 standard d e v i a t i o n s . The f i n a l p o s i t i o n a l and thermal parameters are given i n Tables 2 and 3 r e s p e c t i v e l y . Measured and c a l c u l a t e d s t r u c t u r e amplitudes are a v a i l a b l e on r e q u e s t . THERMAL MOTION AND CORRECTION OF MOLECULAR GEOMETRY The thermal motion has been analysed i n terms of the r i g i d - b o d y modes of t r a n s l a t i o n (T) , l i b r a t i o n (L) , and screw (S) motion using the computer program MGTLS (14), Four a n a l y s e s were c a r r i e d out: the 17 non-hydrogen atoms were con s i d e r e d f i r s t , then each of the three r i n g s i n the molecule was analysed f o r r i g i d - b o d y motion. The a n a l y s i s of the five-membered r i n g and attached atoms C (3) and C (9) Table 2 F i n a l p o s i t i o n a l parameters ( f r a c t i o n a l x 10* ) with estimated standard d e v i a t i o n s i n parentheses Atom X 2 z B 7785 (2) 2708 (2) 3710 (2) 0 7244 (D 4803 (D 3574 (1) N 7069 O) 1504 (2) 2904 (2) C(1) 6243 (2) 3698 (3) 3325 (3) C (2) 6182 (2) 2385 (3) 2386 (3) C(3) 8799 (D 2978 (2) 2988 (2) C (4 ) 8782 (2) 2916 (3) 1616 (2) C(5) 9594 (2) 3304 (3) 1032 (3) C (6) 10440 (2) 3758 (3) 1796 (3) C(7) 10487 (2) 3833 (3) 3157 (3) C (8) 9678 (2) 3449 (2) 3730 (2) C (9) 8111 (D 2110 (2) 5216 (2) C (10) 8600 (2) 759 (3) 5526 (3) • C (11) 8829 (2) 247 (3) 6827 (3) C (12) 859 1 (2) 1086 (3) 7858 (3) C (13) 8111 (2) 2418 (4) 7595 (2) C (14) 7876 (2) 2912 (3) 6289 (2) H(D 6010 (18) 3454 (30) 4199 (27) H (1 ') 5853 (20) 4484 (32) 2942 (25) H (2) 6285 (22) 2691 (34) 1518 (31) H (2 ') 5598 (19) 1826 (28) 2317 (23) H (N ') 7276 (16) 955 (27) 2321 (24 ) H (N) 6900 (20) 776 (34) 3565 (28) H (4) 8142 (19) 2619 (28) 1026 125) H (5) 9514 (19) 3250 (30) 80 (29) H (6) 11013 (19) 3993 (28) 1398 (25) H (7) 11087 (21) 4 149 (30) 3742 (25) H (8) 9720 (15) 3520 (26) 4694 (24) H (10) 8819 (18) 226 (30) 4837 (25) H (1 1) 9176 (23) -700 (38) 6942 (29) H (12) 8777 (21) 744 (32) 8783 (30) H (1 3) 7910 (21) 3063 (35) 8278 (31) H (14) 7529 (17) 3834 (27) 6127 (21) 11 Table 3 F i n a l thermal parameters and t h e i r estimated standard d e v i a t i o n s (a) A n i s o t r o p i c thermal parameters (U^j x 100 A 2) Atom 5 l l «22 u 3 3 "12 Ul3 "23 B 5.2 (1) 4.0 (1) 5.7 (1) -0. 1(1) 1. 1 ( 1) -0.6 ( 1) 0 3.9(1) 3.3 (1) 5.6 (1) 0.1 (1) 0.9 ( 1 ) 0. 1 ( 1) N 4.9 (1) 3.9 (1) 5. 6(1) -0. 4(1) 1. 1 ( 1) -'0. 8 ( 1) C(1) 4.3(1) 4.8 (1) 8.3 (2) 0.2 (1 ) 0.8 ( 1) 0. 1 ( 1) C(2) 4.8 (2) 5. 9 (2) 7.8 (2) -0.8(1) -0.5 ( 1) -0.4 ( 1) C(3) 4.3 (1) 3.1(1) 4.5 (1) 0.3 (1) 0.8 ( 1 ) 0. 0 ( 1) C(4) 5.3 (1) 5. 4 (1) 4.8 (1) -0. 1(1) 1.2( 1) -0. 2 ( 1) C (5) 7.3(2) 6.5 (2) 5.2 (2) 0.1 (1 ) 2.5 ( 1 ) 0. 2 ( 1) C{6) 5.7 (2) 5. 6 (2) 8.0 (2) 0.3(1) 3.2 ( 1) 1.2 ( 1) C{7) 4.4 (1) 5.7 (2) 7.7 (2) -0.4 (1) 1. 1 < 1 ) 0.4 ( 1) C(8) 4.7 (1) 5.0 (1) 5.0 (1) -0.2 (1) 0.9 ( 1) -0. 1 ( 1) C (9) 4.0(1) 3.6 (1) 4.9 (1) -0.5 (1 ) 1.0 \ 1 ) 0. 1 ( 1) C (10) 7.3 (2) 4.0 (1) 6.3 (2) 0.4(1) 0.8 ( 1) 0.3 ( D C(11) 7.9(2) 4.7 (2) 8.1 (2) -0.4 (1) -0.8 i 2) 2. 1 ( 1) C(12) 6.7 (2) 8. 1 (2) 5.5 (2) -2.5 (2) -0. 1 ( 1) 1.8 ( 2) C (13) 6.0(2) 8.7 (2) 4.7 (1) -0.9 (1 ) 1.3 | 1) -0. 1 ( 1) C (14) 4.8 (1) 5.5 (2) 5. 1 (1) 0. 1 (1) 1.2 ( 1) -0. 1 ( 1) (b) I s o t r o p i c thermal parameters Atom B (A z) Atom B (A 2) H(1) 5.9(6) H (6) 5.9 (6) H (1«) 5.7 (6) H(7) 6.0 (6) H (2) 7.1 (8) H (8) 4.6 (5) H (2 •) 5.0 (5) H(10) 5.4 (6) H (W) 6.8 (7) H (11) 7.5 (7) H (N* ) 4. 1 (5) H(12) 6.9(7) H(4) 5.8 (6) H (13) 7.7 (8) H (5) 6. 2 (6) H (14) 4.2 (5) 12 f a i l e d to give a p o s i t i v e - d e f i n i t e L tens o r . The r.m.s. 4 U^ ̂ of 0.0055 A 2 f o r the molecule as a whole i s s i g n i f i c a n t l y l a r g e r than the r.m.s. standard d e v i a t i o n i n the thermal parameters UJJ^ (0.0013 A 2 ) , i n d i c a t i n g that the molecule as a whole i s not a good r i g i d - b o d y . The analyses of the two phenyl groups were s u c c e s s f u l and the r e s u l t s appear i n Table 4. The r.m.s. 4 U ^ values c f 0.0019 and 0.0023 A 2 f o r the phenyl groups i n d i c a t e that the thermal motion of the groups i s adequately d e s c r i b e d by the r i g i d - b o d y parameters i n Table 4, Both groups show n e a r l y i s o t r o p i c t r a n s l a t i o n a l motion and a n i s o t r o p i c l i b r a t i o n a l motion. The o r i e n t a t i o n of the p r i n c i p a l axes of L i s as expected: the l a r g e s t o s c i l l a t i o n s , L^, correspond to r o t a t i o n s about the B-C bonds, the angles between the axes and the bonds being 7.7 (C(3)) and 14.5° ( C ( 9 ) ) . The a p p r o p r i a t e bond d i s t a n c e s and angles i n the phenyl groups have been c o r r e c t e d f o r l i b r a t i o n (15,16) using shape parameters ( j 2 of 0.08 f o r a l l atoms. C o r r e c t e d bond d i s t a n c e s appear i n Tab l e 5 and both c o r r e c t e d and uncorrected bond ang l e s i n Table 6, RESULTS AND DISCUSSION The X-ray a n a l y s i s confirms the c y c l i c s t r u c t u r e f i r s t proposed f o r t h i s compound by L e t s i n g e r and Skoog (7). F i g u r e 1 shows the molecule viewed down the b a x i s . I n d i v i d u a l bond l e n g t h s (not c o r r e c t e d f o r l i b r a t i o n ) with t h e i r standard 1 3 Table 4 algid-body thermal parameters 1 C(3)-C (8) , B C (9) -C (14) , B r 38(6) 6(3) - 12 (3) r 18 (2) 2 (2) 14 (4) n L (deg2) I 20 (2) -3(2) | | 17(3) - 12(4) | L 15(3) J L 47(8) J P r i n c i p a l axes of L r. m. s. Amplitude D i r e c t i o n c o s i n e s ( X 1 0 3 ) 6.7° -882 -273 385 7.5° -321 274 -907 4.2 -269 961 65 4.4 -685 -728 23 3.2 -388 -46 -921 2.7 -654 628 421 P r i n c i p a l axes of reduced T r. m. s. Amplitude D i r e c t i o n c o s i n e s ( X 1 0 3 ) 0.21 6 A 522 12 853 0. 22 A -230 126 -965 0.21 832 215 -511 0.19 -851 445 262 0.18 -189 977 102 0. 18 463 887 5 Displacement of axes from i n t e r s e c t i n g 0 (A) P a r a l l e l to L(1) 0.09 0. 69 P a r a l l e l to L(2) -0.01 0.29 P a r a l l e l t o L(3) 0.11 -0.03 e E f f e c t i v e screw t r a n s l a t i o n s (A) P a r a l l e l to L(1) -0.003 0.014 P a r a l l e l to L(2) -0.017 -0.025 P a r a l l e l to L(3) 0.028 0.003 F r a c t i o n a l c o o r d i n a t e s of unique o r i g i n (x10*) x 8830 8156 % 3087 2595 2 3030 ^ 5136 F r a c t i o n a l c o o r d i n a t e s of c e n t r e of g r a v i t y (x10 4) x 9398 8288 2 3286 1734 z 2559 6181 r.m.s. A j J j ^ 0.0019 0.0023 A 2 lAxes of r e f e r e n c e are orthogonal angstrom axes. E.s.d.'s of components of L are given i n parentheses i n u n i t s of the l a s t p l a c e s shown. F i g u r e 1 The molecule viewed down b, showing c r y s t a l l o g r a p h i c numbering scheme. H(K) H(ll) Figure 2 A general view of the molecule with bond distances (A) and their standard deviations in parentheses. The C(2)-H(2') distance is 0.94(3) A. 1 6 d e v i a t i o n s are shown i n F i g u r e 2 and mean bond l e n g t h s are g i v e n i n Tab le 5. The f ive-membered b o r o x a z o l i d i n e r i n g i s a p p r o x i m a t e l y e i n the h a l f - c h a i r c o n f o r m a t i o n , with C (2) d i s p l a c e d 0,08 A e from the BON p lane and C(1) l y i n g 0.50 A on the o p p o s i t e s i d e of the BON p l a n e . The d i h e d r a l ang les i n the r i n g (see T a b l e 7) are i n good agreement with those ob ta ined from minimum energy c a l c u l a t i o n s f o r UJ^ = 2 5 ° (17) , a l s o shown i n T a b l e 7. The observed magnitudes of the d i h e d r a l a n g l e s are s l i g h t l y s m a l l e r than the c a l c u l a t e d v a l u e s s i n c e the mean v a l e n c e ang le i n the r i n g , 1 0 4 . 8 ° , i s s l i g h t l y g r e a t e r than the c a l c u l a t e d v a l u e of 1 0 4 . 2 ° . A n g l e s i n the f ive-membered r i n g range from 99.7(1) at B to 1 1 0 . 1 ( 2 ) ° at 0. The angu la r s t r a i n i n the r i n g i s p a r t i a l l y r e l i e v e d by a s h o r t e n i n g of the C (1 ) -C (2 ) bond to 1.505 A from the expected v a l u e of 1 .537 A (18) fo r a C (SJ> 3)-C ( s £ 3 ) bond and a l e n g t h e n i n g of the B-N O e bond to 1.653 A from the mean va lue of 1.55 A (18) f o r B ( S £ 3 ) - N ( S £ 3 ) bonds . The i s o e l e c t r o n i c N-C (1.485 A) and 0-B (1.484 A) bonds as w e l l as the C-0 bond (1.413 A) a r e , normal s i n g l e bonds (18). The two phenyl groups are p l a n a r w i t h i n e x p e r i m e n t a l e r r o r (see T a b l e 8 ) . A l l o f the pheny l hydrogen atoms l i e i n the r e s p e c t i v e pheny l p lanes with the e x c e p t i o n of H(10) e which l i e s 0.08 A (3 s t a n d a r d d e v i a t i o n s ) below the C (9)- C(14) p l a n e . The boron atom d e v i a t e s s i g n i f i c a n t l y from both phenyl p l a n e s , be ing d i s p l a c e d 0.15 from the C (3 ) -C (8 ) p lane 0 and - 0 . 0 2 A from the C(9) -C(14) p lane r e p r e s e n t i n g a s l i g h t 17 Table 5 (a) Mean bond l e n g t h s (A) , with r.m. s. d e v i a t i o n s i n parentheses* Atoms number of values uncorrected c o r r e c t e d B-C 2 1.611(2) 1.616(2) B-N 1 1 .653 (3) B-0 1 1.484(3) C-C 1 1.505(4) C-C(ar) 12 1. 383 (1 1) 1.392 (1 1) C-N .1 1 .4 85 (3) C-0 1 1.413(3) C-H 4 0.96 (3) C-H (ar) 10 0.974 (25) N-H 2 0.92 (7) (b) Bond lengths c o r r e c t e d f o r l i b r a t i o n Atoms d i s t a n c e Atoms d i s t a n c e B-C (3) 1. 617 B-C(9) 1.614 C(3)-C(4) 1.404 C (9)-C (10) 1.405 C (4)-C (5) 1.398 C (10) -C ( 11) 1.395 C(5)-C(6) 1.373 C (11)-C (12) 1.381 C(6)-C(7) i 1. 388 C (12) -C (13) 1.377 C(7)-C(8) 1 .386 C (13)-C (14) 1.395 C (8)-C (3) 1. 404 C (14) -C (9) 1.397 •For s i n g l e value parameters, the l e a s t - s q u a r e s standard d e v i a t i o n i s given i n parentheses. T a b l e 6 Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms nncort. c o r r . 0-B-C (3) 108.9 (2) 0-B-C (9) 113.7 (2) 0-B-N 99.7 (1) C (3)-B-C (9) 1 14.0 (2) C (3) -B-H 1 12.9 (2) C (9)-B-N 106. 8 (2) B-0-C(1) 110.1 (2) C (2)-N-B 106. 1 (2) 0-C (1) -C (2) 105.2 (2) H-C (2) -C (1) 102.9 (2) B-C (3) -C (4) 124.1 (2) 124.0 B-C (3) -C (8) 120.0(2) 119.9 C(8)-C(3)-C(4) 1 15.6 (2) 1 15.8 C (3)-C (4)-C(4) 121.8 (2) 121.7 C(4)-C(5)-C(6) 120.6 (2) 120.5 C (5)-C (6)-C (7) 119. 3(2) 119.6 C(6)-C(7)-C(8) 119.7 (2) 1 19.6 C (7)-C (8)-C(3) 122.9 (2) 122.8 B-C (9) -C (10) 122.0 (2) 121.8 B-C (9) -C (14) 122.4(2) 122.3 C (10) -C (9) -C (14) 115.6 (2) 115.9 C (9)-C (10) -C (11) 122. 1 (3) 121.9 C (10) -C (11) -C (12) 120.2 (3) 120. 1 C (1 1)-C (12) -C (13) 1 19. 5(3) 1 19.7 C (12) -C (13) -C (14) 119.8 (3) 119.7 C (13)-C (14)-C (9) 122.8 (2) 122.7 continued... 19 (b) Angles i n v o l v i n g hydrogen atoms Atoms value Atoms value H (N) -N-H (N •) 104 (2) H (5)- C (5)-C (4) 1 16 (2) H (N) -N-B 107 (2) H (5)- C(5) -C(6) 123 (2) H(N) -N-C(2) 109 (2) H (6)- C(6) -C(5) 121 (2) H (N •)-N-C(2) 1 14 (2) H (6)- C (6)-C (7) 120 (2) H (N 1 ) -N-B 1 17 (2) H (7)- C(7)-C(6) 122 (2) H (1) -C (1) -H (1 •) 107 (2) H (7)- C (7)-C (8) 1 19 (2) H(D -C (1)-0 109 (D H (8)- C(8) -C(3) 1 18 (D H (1) -C(1) -C(2) 113 (2) H (8)- C (8)-C (7) 1 19 (D H (1 •)-C (1 )-0 112 (2) H (10) -C (10)-C (9) 1 18 (2) H (1 »)-C(1)-C(2) 110 (2) H (10) -C (10) -C (1 1) 120 (2) H (2) -C(2) -H (2») 109 (2) H (11) -C (1 1 )-C (10) 1 16 (2) H (2] -C (2) -N 104 (2) H (11) -C (1 1)-C (12) 124 (2) H(2) -C(2)-C(1) 111 (2) H (12) -C (12)-C (11 ) 120 (2) H (2' )-C (2)-N 1 14 (2) H (12) -C (1 2) -C (13) 120 (2) H(2< »)-C(2)-C(1) 1 15 (2) H (13) -C (1 3) -C (12) 124 (2) H (4) -C(4) -C(3) 118 (D H (13) -C (13)-C (14) 1 16 (2) H (4] -C (4)-C (5) 120 (D H (14) -C (14)-C (13) 1 18 (D H <1«*) -C (14)-C (9) 1 19 (D T a b l e 7 I n t r a - a n n u l a r t o r s i o n a n g l e s (deg) B o r o x a z o l i d i n e r i n g Bond o b s e r v e d c a l c . B - C - 2 2 . 0 (2) - 2 5 . 0 0 - C ( 1 ) 3 9 . 6 (2) 4 1 . 6 C ( 1 ) - C (2) - 3 9 . 3 (2) - 4 2 . 3 C(2) -H 2 4 . 8 (2) 2 5 . 9 B-B - 3 . 1 (2) - 1 . 3 21 Table 8 Weighted l e a s t - s g u a r e s mean planes (a) Distances (A) of r e l e v a n t atoms from the mean planes Atom d A torn d Plane 1: C(3)-C(8) Plane 2: C (9) -C (14) C(3) 0,000 0.0 C (9) -0,001 0.4 C (4) -0,001 0. 4 C(10) -0.003 1.2 C(5) 0.001 0.5 C (11) 0,007 2.4 C (6) 0.000 0. 1 C(12) -0.004 1.4 C(7) -C.001 0.3 C (13) -0.001 0.5 C{8) 0.00 1 0. 3 C(14) 0.003 1.3 B 0. 150 67.4 B -0.025 10.7 H (4) 0.040 1.6 H (10) -0.080 3.1 H(5) 0.020 0.7 H (11) -0.007 0.2 H (6) -0.032 1.3 H (12) -0.035 1.2 H(7) -0.007 0.3 H (13) 0.006 0.2 H (8) 0.012 0.5 H(14) 0.023 1.0 (b) Equations of planes: £X + wY • nZ = g, where X, Y, and Z are orthogonal angstrom c o o r d i n a t e s d e r i v e d as f o l l o w s : i-X-, r a 0 ccos T r x n III = I 0 b 0 | i n L Z J «- o 0 c s i n J «-ZJ Plane £ m n £ (1) -0.3074 0.9482 -0.0800 -1.3230 (2) -0.8579 -0.4573 -0.0823 -10.4443 The d i h e d r a l angle between plane normals i s 100° 22 f o l d i n g of the two planes away from each other. The angle between phenyl plane normals i s 100°. The two r i n g s are not e q u i v a l e n t as the C(3)-C(8) r i n g i s t w i s t e d 21° with r e s p e c t to the BNC(3) plane while the C(9)-C(14) r i n g l i e s n e a r l y i n the B0C(9) plane, d i h e d r a l angle 7 ° . The C-C (ar) d i s t a n c e s range from 1.373 to 1. 405 A with a mean value of 1.392(1 1 ) A, o i n good agreement with the accepted mean of 1.394 A (18). There a r e , however, s i g n i f i c a n t d i f f e r e n c e s between the i n d i v i d u a l C-C d i s t a n c e s i n the phenyl r i n g s . There i s a n o t i c e a b l e trend toward s h o r t e n i n g of the C-C d i s t a n c e s as they are removed from the boron s u b s t i t u e n t . T h i s i s due to a combination of s t e r i c and e l e c t r o n i c e f f e c t s which are d i s c u s s e d i n more d e t a i l i n P a r t 2. The borcn-carbcn d i s t a n c e s , mean 1.616(2), are s i g n i f i c a n t l y s h o r t e r than the B-C d i s t a n c e s of 1. 63 1 (9) - 1. 646 (8) A found i n the t e t r a p h e n y l borate anion (19), i n accord with e l e c t r o n d e l o c a l i z a t i o n . The mean bond angles at t e t r a h e d r a l l y and t r i g o n a l l y c o o r d i n a t e d atoms are 109.4 and 120.0° r e s p e c t i v e l y . There are a number of s i g n i f i c a n t d e v i a t i o n s from these values, r e s u l t i n g from s t e r i c and charge d e l o c a l i z a t i o n e f f e c t s . I n t r a m o l e c u l a r c o n t a c t s between atom p a i r s N and C(4), N and C(10), and 0 and C(14) are r e s p o n s i b l e f o r angular d i s t o r t i o n s at the boron atom, and a t carbon atoms C(3) and C ( 9 ) . Expansion of the angles NBC (3), 0BC(9), BC(3)C(4), BC(9)C{14), and BC(9)C(10) [ 112.9, 113.7, 124.0, 122. 3, and 121.8° r e s p e c t i v e l y ] allows the d i s t a n c e s C(4)...N (3.143 ), O...C(14) (2.955 ), and N...C(10) (3.210 A) to be equal tc or s l i g h t l y g r e a t e r than the sum of van der Waals r a d i i . The 23 e x p a n s i o n o f 0BC{9) and NBC (3) c a u s e s a c o n t r a c t i o n o f NBC (9) t o 1 0 6 . 8 ° wh ich i s b a l a n c e d by an e x p a n s i o n o f B C ( 9 ) C ( 1 0 ) (as a b o v e ) t o a l l o w t h e N . . . C ( 1 0 ) c o n t a c t t o be n o r m a l . The p h e n y l C - C - C a n g l e s a t C(3) and C(9 ) a r e b o t h c o n t r a c t e d t o a mean v a l u e o f 1 1 5 . 9 ° a s a r e s u l t o f e x p a n s i o n o f t h e B - C - C a n g l e s . T h i s , i n t u r n , makes a n g u l a r a d j u s t m e n t s a t t h e r e m a i n i n g p h e n y l c a r b o n a t o m s n e c e s s a r y t o r e t a i n t h e p l a n a r i t y o f t h e p h e n y l r i n g s . T h e m a g n i t u d e o f t h e s e d i s t o r t i o n s i s a l s o d e p e n d e n t on t h e e l e c t r o n d e l o c a l i z a t i o n i n as much a s t h e C - C d i s t a n c e s a r e n o t a l l e q u a l . The a n g l e o p p o s i t e t h e s m a l l OBN a n g l e ( 9 9 . 7 ° ) i s o p e n e d t o 1 1 4 . 0 ° and i s n o r m a l f o r t h e a n g l e b e t w e e n two b u l k y s u b s t i t u e n t s . T h e i n t e r i o r a n g l e s i n t h e b o r o x a z o l i d i n e r i n g , a s p r e v i o u s l y m e n t i o n e d , a r e a l l c o n t r a c t e d a s a r e t h e H-N-H and H - C - H a n g l e s o p p o s i t e t h e m , a l l o f w h i c h a r e l e s s t h a n , b u t n o t s i g n i f i c a n t l y d i f f e r e n t f r o m t h e t e t r a h e d r a l a n g l e . T h e r e m a i n i n g a n g l e s i n v o l v i n g the r i n g h y d r o g e n a toms a r e g e n e r a l l y g r e a t e r t h a n t h e t e t r a h e d r a l a n g l e . The a n g l e s H ( N » ) - N - C ( 2 ) ( 1 1 3 . 9 ° ) and H ( N » ) - N - B ( 1 1 6 . 9 ° ) r e p r e s e n t b e n d i n g ' o f H (N ' ) t o w a r d t h e o x y g e n a tom t o w h i c h i t i s h y d r o g e n b o n d e d . B o n d a n g l e s i n v o l v i n g p h e n y l h y d r o g e n a toms show a t r e n d t h a t when a d j a c e n t C - C d i s t a n c e s a r e d i f f e r e n t , s o a r e t h e c o r r e s p o n d i n g H - C - C a n g l e s . The H - C - C a n g l e w h i c h i n v o l v e s t h e c a r b o n atom n e a r e r t h e v e r t e x atom i s l a r g e r t h a n t h e o t h e r H - C - C a n g l e . As t h e d i f f e r e n c e b e t w e e n a d j a c e n t C - C d i s t a n c e s i n c r e a s e s , s o d o e s t h a t be tween t h e H- C - C a n g l e s . An e x a m p l e i s C ( 1 1 ) , where C ( 1 0 ) - C ( 1 1) (1. 395) i s 0 f i v e s t a n d a r d d e v i a t i o n s l o n g e r t h a n C ( 1 1 ) - C ( 1 2 ) (1.381 A) O O N O Co B • Ho 5A Figure 3 The structure viewed down c; hydrogen bonds are represented by broken l i n e s . 25 Table 9 (a) S e l e c t e d i n t r a - and i n t e r m o l e c u l a r c o n t a c t s I n t r a m o l e c u l a r I n t e r m o l e c u l a r * Atoms d i s t a n c e Atoms d i s t a n c e 0. . .C (14) 2.955 (3) N...C (3) 1 3.437 (3) 0...C (8) 3. 395 (3) N...C (4) 1 3.470 (3) 0. . .C (4) 3.299 (2) C(4)...H(N) 2 2.72 (3) M. . .C (4) 3.143 (3) C (7)...H (1 1 ) 3 2.84 (3) N...C (10) 3.201 (3) C(11) . . . H (1 *) * 2.87 (3) C (12) . . .H (14) s 2. 83 (2) C (14) . . . H (7) 6 2.99 (3) (b) Hydrogen-bond 0 data ( d i s t a n c e s i n A and angles i n deg) D-H • • • A H. .. A D...A /DHA /XAH N-H (N«) ., .07 2.06 (3) 2. 874 (2) 160 (2) 1 19. 5(6) ,119.6 (6) • S u p e r s c r i p t s r e f e r to atoms at p o s i t i o n s : 1 3/2-x 1-1/2 1/2-2 5 3/2-x 1-1/2 3/2-z 2 3/2-x 1/2+1 1/2-2 6 2-x 1-1 1-z 3 2-x ~I 1-z 7 3/2-x 1-1/2 1/2 + z * 1/2+x 1/2-1 1/2+z 26 and the angles H-C (11) -C (10) (115.9) ana H-C (11)-C (1 2) (123.8°) d i f f e r by more than f o u r standard d e v i a t i o n s . The mean C-H, C-H (a r ) , and N-H bond lengths of 0.96(3), o 0.97(3), and 0.92(7) A are as expected. The d i s t a n c e s are s h o r t e r than those obtained s p e c t r o s c o p i c a l l y i n d i c a t i n g t h at the hydrogen e l e c t r o n has been p u l l e d toward the atom to which i t i s bonded. F i g u r e 3 shows the s t r u c t u r e viewed down c. The c r y s t a l s t r u c t u r e c o n s i s t s of d i s c r e t e molecules cf B,B- d i p h e n y l b o r o x a z o l i d i n e which are l i n k e d by O...H-N hydrogen o bonds (O...N = 2.874 A) to form continuous s p i r a l s about the 2± axes along b. D e t a i l s of the hydrogen bonding scheme are gi v e n i n Table 9 as w e l l as i n t e r - and i n t r a m o l e c u l a r c o n t a c t s l e s s than 3.5 A. There are only two heavy atom i n t e r m o l e c u l a r c o n t a c t s l e s s than 3.5 A: N...C(3), 3.437, and N-C (4), 3.470 A (apart from the hydrogen bond). These, and a l l other i n t e r m o l e c u l a r c o n t a c t s correspond to van der Waals i n t e r a c t i o n s . PART 2 CRYSTAL AND MOLECULAR STRUCTURE OF B-BIS( D -FLUOROPHENYL)BOROXAZOLIDINE 28 I NT RO DU CTION The c y c l i c s t r u c t u r e of B , B - d i p h e n y l b o r o x a z o l i d i n e Q , P a r t 1) has been e s t a b l i s h e d as has t h a t of t r i e t h a n c l a i r i n e borate (TFAB) (20), c o n f i r m i n g the e x i s t e n c e of the N—>B d a t i v e bond i n these e s t e r s . The X-ray a n a l y s i s of B,B-bis(£- f l u o r o p h e n y 1 ) b o r o x a z o l i d i n e (2) was undertaken to study the s t r u c t u r a l e f f e c t s of the f l u o r i n e s u b s t i t u e n t both i n the phenyl r i n g s and i n the five-membered r i n g . The d e n s i t y c f 2 and c r y s t a l l i z a t i o n i n a d i f f e r e n t space group than J suggested the p o s s i b i l i t y of an F...H-N hydrogen bond f o r which t h e r e are only l i m i t e d s t r u c t u r a l d a t a , p a r t i c u l a r l y f o r o r g a n i c s t r u c t u r e s . R e c r y s t a l l i z a t i o n of B,B-bis (n-fluorophenyl) boroxazol- i d i n e from ethanol gave c o l o r l e s s , r e g u l a r c r y s t a l s elongated along b. The specimen used f o r data c o l l e c t i o n was bounded by the (011) and (101) p l a n e s , at d i s t a n c e s of 0.27 and 0.13 mm 1 2 EXPERIMENTAL 29 r e s p e c t i v e l y from an i n t e r n a l o r i g i n and was mounted with b p a r a l l e l to the g o n i o s t a t a x i s . u n i t - c e l l and space group data were obtained from f i l m and diffTactometer measurements. The u n i t - c e l l parameters were r e f i n e d by a l e a s t - s q u a r e s treatment of s i n 2 9 values f o r 30 r e f l e x i o n s measured on a diffTactometer with Cu r a d i a t i o n . C r y s t a l data a r e : C1i4.H1/4.BF2 NO f.w. = 261.1 Orthorhombic, a = 13.442(4), b = 10.214(3), c = 9.283 (2) A, V = 1274.5 (6) A 3 , Dm = 1.37 ( f l o t a t i o n i n aqueous KI) , Z = 4, Dx = 1.361 g cm - 3 , F(000) = 544 (20°C, Cu 1^, A= 1.5418 A,/< = 9.0 cm-*). Absent r e f l e x i o n s : hOO, h # 2n, OkO, k * 2n, and 00j£, J * 2n d e f i n e uniquely the space group B2^2^2^ (C|, No. 19) . I n t e n s i t i e s were measured on a Datex-automated General E l e c t r i c XRD 6 diffTactometer, with a s c i n t i l l a t i o n counter, Cu r a d i a t i o n ( n i c k e l f i l t e r and pulse height a n a l y s e r ) , and a 6-20 scan at 2° m i n - 1 over a range of (1,80 + 0.86 tan 0) degrees i n 29, with 20 s background counts being measured at each end of the scan. Data were measured to 29 = 145° (minimum i n t e r p i a n a r spacing 0.81 A). The r.m.s. d e v i a t i o n of the i n t e n s i t y of the check r e f l e x i o n , measured every 40 r e f l e x i o n s throughout the data c o l l e c t i o n , from i t s i n i t i a l v a l u e was 1.4%. The f i n a l i n t e n s i t y was 99% of the i n i t i a l value. L o r e n t z , p o l a r i z a t i o n , and a b s o r p t i o n c o r r e c t i o n s were a p p l i e d , and the s t r u c t u r e amplitudes were d e r i v e d . Of 1481 independent r e f l e x i o n s measured, 231 had i n t e n s i t i e s l e s s than 3<r(I) above background where <r2 (I) = S + E + (0.03S) 2 30 with S = scan count and B = background count, c o r r e c t e d to time of scan. These r e f l e x i o n s were not i n c l u d e d i n the refinement. S t r u c t u r e A n a l y s i s The s t r u c t u r e was s o l v e d by d i r e c t methods, 200 r e f l e x i o n s with normalized s t r u c t u r e f a c t o r |E| > 1.45 being used i n the symbolic a d d i t i o n procedure f o r non- centrosymmetrie c r y s t a l s (21). The phases of the 11 1 0, 2 0 5, and 6 7 0 r e f l e x i o n s were f i x e d to d e f i n e the o r i g i n and that of 1 0 3 was f i x e d at +250mc to s p e c i f y the enantiomorph. During a manual expansion, c a r r i e d out among the 70 r e f l e x i o n s with l a r g e s t |E| values, symbol phases were assigned t o the 0 5 1, 10 10 1, and 13 3 6 r e f l e x i o n s . The phase of 0 5 1 must be ±250 mc and manual i n d i c a t i o n s gave two p o s s i b l e v a l u e s f o r each of the other symbols, near ±250 mc f o r both 10 10 1 and 13 3 6. These seven r e f l e x i o n s comprise the b a s i c s t a r t i n g group given i n Table 10. Ei g h t s t a r t i n g s e t s were generated by a l l o w i n g each of the three symbol phases to have i n i t i a l v alues of ±250 mc. These s e t s were used as i n p u t to a computer program which determines phases using the tangent formula (22,23). The va l u e s of o v e r a l l t o v e r a l l * , Q, and Rk on the f i n a l c y c l e f o r each of the s e t s are given i n Table 11. Set 1, which had the lowest value of Rk, was expanded to 228 r e f l e x i o n s with |EJ > 1.40 by using as s t a r t i n g values f o r the symbols a, b, and c those c a l c u l a t e d i n set 1, +250, +277, and +135 mc \ Table 1 0 B a s i c s t a r t i n g s e t o f r e f l e x i o n s f o r C j ^ H ^ B F ^ NO h k 111 p h a s e (mc) 11 1 0 4 . 5 8 250T 2 0 5 3 .71 j 250F • o r i g i n d e t e r m i n i n g 6 7 0 3 . 51 I OJ 1 0 3 2 . 4 3 250 e n a n t i o m o r p h 0 5 1 2.21 a 10 10 1 2 . 27 b 13 3 6 2.26 c 32 Table 11 R e s u l t s f o r the e i g h t s t a r t i n g s e t s i n the phase det e r m i n a t i o n procedure Set a (mc) b (mc) c (mc) t 2 JiS 1 1 250 250 250 0. 59 180 0. 39 0.2 0 193 2 250 250 -250 0.54 129 0.44 0.35 178 3 250 -250 250 0. 58 156 0. 40 0. 35 178 4 250 -250 -250 0.55 155 0.43 0.33 177 5 -250 250 250 0. 53 122 0. 46 0.38 172 6 -250 250 -250 0.54 141 0.45 0. 33 173 7 -250 -250 250 0. 55 138 0. 44 0.35 176 8 -250 -250 -250 0.57 155 0.41 0.33 173 33 r e s p e c t i v e l y , A new symbol, 10 6 0, was allowed to take e i t h e r of i t s two p o s s i b l e v a l u e s , 0 or 500 mc. The two r e s u l t i n g v a l u e s of 8k were 0.17 with 10 6 0 having a phase of 500 mc and 0.36 with 10 6 0 at 0 mc. An E -map based on the s e t of 214 determined phases with Bk = 0.17 c l e a r l y gave the s t r u c t u r e , the 19 highest peaks corresponding to the 19 non- hydrogen atoms. Two c y c l e s of f u l l - m a t r i x l e a s t - s q u a r e s refinement of the p o s i t i o n a l and i s o t r o p i c thermal parameters of the non- hydrogen atoms gave B 0.121. T h i s was f o l l o w e d by two c y c l e s of a n i s o t r o p i c refinement which reduced B to 0.093. A d i f f e r e n c e map at t h i s p o i n t r e v e a l e d the p o s i t i o n s of a l l 14 hydrogen atoms which were i n c l u d e d i n a l l subsequent refinement with i s o t r o p i c thermal parameters. Convergence was reached a f t e r two more c y c l e s with R = 0.047 f o r 1234 r e f l e x i o n s with I > 3<r(I) (16 r e f l e x i o n s were given zero weight i n the f i n a l stages of refinement due to suspected e x t i n c t i o n e r r o r s ) . The m i r r o r image (j to - y j was a l s o r e f i n e d to convergence g i v i n g an R value of 0.047. A p p l i c a t i o n of Hamilton's t e s t (24) d i d not show a s i g n i f i c a n t d i f f e r e n c e between the R f a c t o r s f o r the two enantiomorphs, The s c a t t e r i n g f a c t o r s f o r the F, 0, N, C, and E atoms were taken from r e f . 12 and those f o r hydrogen from r e f . 13. The v a l u e s used f o r anomalous d i s p e r s i o n c o r r e c t i o n s 4 f 1 and 4 f " were as f o l l o w s : 0.068 and 0.056 f o r F, 0.050 and 0.032 f o r 0, 0.034 and 0.019 f o r W, and 0.020 and 0.010 f o r C. The 34 v a l u e s f o r C and 0 a r e t h o s e o f H o p e , de l a Camp, and T h i e s s e n ( 2 5 ) . The w e i g h t i n g s c h e m e : w = 1 i f | F o | < 7 ; w = ( 7 / | F o | ) 2 i f | Fo | > 7 ; and w = 0 . 2 0 2 5 f o r t h e weak r e f l e x i o n s g a v e c o n s t a n t a v e r a g e v a l u e s o f w (Fo - F c ) 2 o v e r r a n g e s o f | F o | , and was e m p l o y e d i n t h e f i n a l s t a g e s o f r e f i n e m e n t . On t h e f i n a l c y c l e o f r e f i n e m e n t , no p a r a m e t e r s h i f t was g r e a t e r t h a n 0 . 1 9 s t a n d a r d d e v i a t i o n s . F i n a l p o s i t i o n a l and t h e r m a l p a r a m e t e r s a p p e a r i n t a b l e s 12 and 13 r e s p e c t i v e l y . O b s e r v e d and c a l c u l a t e d s t r u c t u r e a m p l i t u d e s a r e a v a i l a b l e on r e q u e s t . THERMAL MOTION AND CORRECTION OF MOLECULAR GEOMETRY T h e e l l i p s o i d s o f t h e r m a l m o t i o n f o r t h e n o n - h y d r o g e n a t o m s a r e shown i n f i g u r e 4 . The t h e r m a l m o t i o n has b e e n a n a l y s e d i n t e r m s o f t h e r i g i d - b o d y modes a s p r e v i o u s l y d e s c r i b e d . F o u r a n a l y s e s were c a r r i e d o u t : t h e 19 n o n - h y d r o g e n a t o m s were c o n s i d e r e d f i r s t and i n d i c a t i o n s o f s i g n i f i c a n t i n d e p e n d e n t m o t i o n i n t h e p h e n y l r i n g s p r o m p t e d s e p a r a t e a n a l y s e s o f t h e f l u o r o p h e n y l g r o u p s a l o n g w i t h t h e b o r o n a t o m ; f i n a l l y an a n a l y s i s o f the f i v e - m e m b e r e d r i n g and a t o m s C (3) and C(9) f a i l e d t o g i v e a p o s i t i v e - d e f i n i t e L t e n s o r (as f o r t h e p a r e n t m o l e c u l e B , B - d i p h e n y l b o r o x a z o l i d i n e i n P a r t 1 ) . The r e s u l t s o f t h e a n a l y s e s f o r t h e two f l u o r o p h e n y l g r o u p s a r e c o m p i l e d i n t a b l e 14. T h e r . m . s . s t a n d a r d d e v i a t i o n i n t h e t e m p e r a t u r e f a c t o r s o U^^ i s 0 . 0 0 1 6 A 2 w h i c h i n d i c a t e s t h a t t h e e n t i r e m o l e c u l e ( r . m . s . A U * * = 0 . 0 0 6 3 A 2 ) i s n o t a g o o d r i g i d - b o d y ( t h i s was Table 12 F i n a l p o s i t i o n a l parameters ( f r a c t i o n a l x 10* ) with estimated standard d e v i a t i o n s i n parentheses Atom X I z F(1) 11462 (2) 6938 (2) 3863 (3) F(2) 8699 (2) -1240 (2) 7146 <3) 0 7244 (D 4697 (2) 5901 1 (2) N 7190 (2) 3839 (3) 3503 (3) C(1) 6247 (3) 4345 (4) 5584 (4) C(2) 6182 (3) 4267 (5) 3979 (5) C (3) 8903 (2) 4762 (3) 4603 (3) C(4) 9786 (2) 4182 (3) 4154 <4) C (5) 10644 (2) 4892 (4) 3886 (4) C(6) 10613 (2) 6221 (3) 4063 (3) C(7) 9770 (3) 6852 (3) 4498 (5) C(8) 8921 (2) 6120 (3) 4749 (4) C (9) 8102 (2) 2467 (3) 5523 (3) C(10) 8091 (3) 2218 (3) 7007 (4) C(11) 8297 (3) 984 (4) 7550 (4) C(12) 8501 (2) -17 (3) 6622 (4) C (13) 8502 (3) 157 (4) 5167 (4) C(14) 83 01 (3) 1411 (3) 4648 <4) B 7903 (2) 3942 (3) 4949 (3) H(N 1) 7142 (27) 3036 (38) 3166 <4V) H (M2) 7413 (30) 4315 (38) 2642 (50) H(1A) 5361 (34) 5032 (47) 5882 (50) H (1B) 6082 (29) 3462 (44) 5906 (43) H (2A) 5673 (43) 3722 (56) 3625 (65) H (2B) 6132 (30) 5143 (44) 3539 (47) H(4) 9773 (28) 3228 (38) 3943 (41 ) H (5) 11246 (38) 4516 (51) 3733 (55) H(7) 9769 (38) 7868 (51) 4574 (52) H (8) 8361 (27) 6565 (36) 5040 (42) H(10) 7962 (33) 2925 (40) 7618 448) H (11) 8219 (46) 736 (58) 8513 (71) H(13) 8656 (3 8) -615 (52) 4683 (53) H (14) 8267 (30) 1454 (40) 3569 (47) 36 Table 13 F i n a l thermal parameters and t h e i r estimated standard d e v i a t i o n s (a) A n i s o t r o p i c thermal parameters (U.* * x 100 A 2) Atom ^22 o 3 3 2l2 2i3 «23 F(1) 4.8 (1) 7.7 (2) 7.0 (1) -2.0 (1) 0.8(1) -0. 1 ( 1) F (2) 8.7 (2) 4.9 (1) 9.6 (2) 0.3 (1) -1.1 (2) 3.0 ( D 0 4.1 (1) 4.3 (1) 5.0 (1) -0. 1(1) 0.6(1) - 1.0 { 1) N 4.6(1) 3.4 (1) 4.2 (1) -0.0 (1 ) -0.4 (1) 0.4 ( 1) C(1) 4.0 (2) 5.9 (2) 6.8 (2) -0. 2 (2) 0.8(2) - 1. 1 ( 2) C(2) 3,7(2) 7.8 (3) 6.4 (2) 0.1 (2) -0.4 (2) 0. 3 ( 2) C (3) 3,7 (1) 3.8 (1) 3.7 (1) 0.2(1) 0.1 (1) -0.0 ( 1) C(4) 4.2(2) 4.3 (2) 5.9 (2) 0.5 (1 ) 0.1 (1) -0. 6 i 2) C{5) 3.6 (2) 6. 0 (2) 5.8 (2) 0.6 (2) 0.5(2) -0.4 ( 2) C(6) 4.1 (2) 5.<* (2) 4.2 (2) -0.8 (1 ) 0.3 (1 ) 0. 2 ( 2) C (7) 5.6 (2) 3. 6 (2) 7.7 (2) -0.3(1) 0.9 (2) 0.4 ( 2) C{8) 4.3(2) 4.2 (2) 6.1 (2) 0.3 (1 ) 0.7 (2) -0,0 ( 2) C (9) 3.6 (1) 3.8 (1) 4.0 (2) -0.4 (1) 0. 1(1) 0.4 ( D, C(10) 7.8 (2) 4.7 (2) 3.3 (2) -1.3 (2) -0.8 (2 ) 0. 2 ( 1) C (1 1) 8,2 (3) 6. 3 (2) 4.3 (2) -1.4(2) -1.5(2) 1.8 ( 2) C(12) 4.3(2) 4.1 (2) 6.8 (2) -0.3 (1) -1.0 (2) 1.9 ( 2) C (13) 5.9 (2) 4.5 (2) 6.3(2) 1.4(2) 0.4(2) 0.3 ( 2) C(14) 6.6(2) 4.8 (2) 4.4 (2) 1.2 (2) 0.6 (2) 0.4 | D B 3.8 (2) 3. 8 (2) 3.6(1) -0,1 (1) 0.2(1) -0.3 ( 1) (b) I s o t r o p i c thermal parameters Atom B (A 2) Atom B (A z) H (N1) 3.5 (7) H (5) 6, 1 (11 ) H (M2) 4.8(9) H(7) 6.6(12) H(1A) 5.1 (10) H (8) 3,4 (7) H(1B) 4.1(8) H(10) 5.2(9) H(2A) 7.2(13) H(11) 8.6(15) H(2B) 4.7(9) H(13) 5.9(11) H(4) 3.9(7) H(14) 4.9(9) 37 T a b l e 14 R i g i d - b o d y t h e r m a l p a r a m e t e r s 1 F ( 1 ) , C ( 3 ) - C ( 8 ) , B F ( 2 ) , C ( 9 ) - C ( 1 4 ) , B r 53 (6) 22 (3) -11 (3) -, r 14(3) - 1 4 ( 6 ) 4 (3 ) L ( d e g 2 ) | 17(4) - 3 ( 2 ) | | 7 8 ( 1 0 ) - 2 0 (5) | «- ' 13(2) J >• 18(5) J P r i n c i p a l a x e s o f L r . m . s . A m p l i t u d e D i r e c t i o n c o s i n e s ( x 1 0 3 ) 8 . 1 ° 887 413 - 2 0 6 9 . 3 ° 198 - 9 3 9 283 3 . 3 37 377 925 3 .4 543 - 1 3 6 - 8 2 9 2 . 3 460 - 8 2 8 321 3 . 2 816 317 482 P r i n c i p a l a x e s o f r e d u c e d T r . m . s . A m p l i t u d e D i r e c t i o n c o s i n e s ( x 1 0 3 ) 0 . 2 0 A - 7 3 8 -661 132 0 . 2 0 A - 2 6 7 888 - 3 7 3 0 . 1 8 - 1 6 6 372 914 0 . 1 8 - 2 3 2 316 920 0 . 1 8 - 6 5 6 650 - 3 8 3 0 . 1 6 935 332 122 D i s p l a c e m e n t o f a x e s f r o m i n t e r s e c t i n g (A) P a r a l l e l to 0 . 3 7 0 . 89 P a r a l l e l t o L 2 - 0 . 0 8 0 . 6 8 P a r a l l e l t o 0 . 2 6 0 . 0 9 o E f f e c t i v e s c r e w t r a n s l a t i o n s (A) P a r a l l e l t o L 1 0 . 0 1 5 - 0 . 0 3 2 P a r a l l e l t o L 2 - 0 . 0 0 8 0 . 0 6 6 P a r a l l e l t o - 0 . 0 4 1 0 . 0 2 3 F r a c t i o n a l c o o r d i n a t e s o f u n i q u e o r i g i n ( x 1 0 4 ) x 8888 7840 J 4804 2548 z 4668 5470 F r a c t i o n a l c o o r d i n a t e s o f c e n t r e o f g r a v i t y ( x 1 0 4 ) x 9889 8332 2 5606 1038 z 4304 6163 r . m . s . 0 . 0 0 2 3 0 . 0 0 3 6 A 2 lkxes o f r e f e r e n c e a r e o r t h o g o n a l a n g s t r o m a x e s . E . s . d . ' s o f c o m p o n e n t s o f L a r e g i v e n i n p a r e n t h e s e s i n u n i t s o f t h e l a s t p l a c e s s h o w n . 38 a l s o noted i n P a r t 1). Examination of the i n d i v i d u a l A ^ shows s i g n i f i c a n t independent motion of the phenyl groups and a l s o of atoms i n the five-membered r i n g . The r.m.s. A U^^ o values of 0.0023 and 0.0036 A 2 f o r the analyses of the phenyl groups i n d i c a t e t h a t these groups do behave as r i g i d bodies. Both groups show n e a r l y i s o t r o p i c t r a n s l a t i o n a 1 motion and a n i s o t r o p i c l i b r a t i o n a l motion. The p r i n c i p a l axes of L are o r i e n t e d as expected: the l a r g e s t axes, , correspond to r o t a t i o n s about the B-C bonds, the angles between the axes and the bonds being 6.9° (C (3) ) and 2.6° (C (9) ) . The unique o r i g i n s are i n expected l o c a t i o n s , f o r the C(3)-C(8) r i n g approximately at C (3) , and f o r the C(9)-C(14) r i n g near C (9) . The a p p r o p r i a t e bond d i s t a n c e s and angles i n the phenyl groups have been c o r r e c t e d f o r l i b r a t i o n (15,16) using shape parameters cj2 of 0.08 f o r a l l atoms. B i d i n g motion c o r r e c t i o n s based on the < A ^ (26,27) have been a p p l i e d to the C-F bonds. Both c o r r e c t e d and uncorrected bond lengths and angles appear i n Tables 15 and 16. RESULTS AND DISCUSSION F i g u r e 4 shows a g e n e r a l view of the molecule and the c r y s t a l l o g r a p h i c numbering scheme. F i g u r e s 5 and 6 show the packing arrangement viewed along b and c r e s p e c t i v e l y . I n t r a - annular t o r s i o n angles d e f i n i n g the conformation of the b o r o x a z o l i d i n e r i n g are given i n Table 17 and some weighted l e a s t - s q u a r e s mean planes i n Table 18. Non-bonded i n t r a - and i n t e r m o l e c u l a r d i s t a n c e s and d e t a i l s of the hydrogen-bonding 19 n • S) Figure 4 A stereo view of the molecule showing 50'J? p r o b a b i l i t y thermal motion e l l i p s o i d s for the non-hydrogen atoms and the cry s t a l l o g r a p h i c numbering of the atoms. scheme appear i n table 19. The c r y s t a l structure consists of discrete molecules of B,B-bis(£-fluorophenyl)boroxazolidine, each linked to six others by an extensive and i n t e r e s t i n g network of hydrogen bonds. 0...H-N (0... N = 2.941(3) A) and weak F...H-N (F...N = 0 3.171(4) A) hydrogen bonds form continuous s p i r a l s about alternate twofold screw axes along c, thereby forming 'nets' of molecules normal to the a axis. The hydrogen bonding • scheme i s completed by a weak F...H-C (F...C = 3.318(5) A) interaction which forms s p i r a l s about alternate twofcld screw axes along b, l i n k i n g adjacent 'nets' to form a three- dimensional network which employs a l l available acceptors in the molecule. 4 0 Table 15 o Bond l e n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms uncorr. c o r r . Atoms uncorr. c o r r . F ( 1 ) - C ( 6 ) 1 . 3 6 9 ( 4 ) 1. 3 7 2 C ( 3 ) - C ( 8 ) 1. 3 9 4 ( 5 ) 1. 4 0 7 F ( 2 ) - C ( 1 2 ) 1. 3 6 7 ( 4 ) 1. 3 7 0 C ( 4 ) - C ( 5 ) 1. 3 8 4 ( 5 ) 1. 3 8 7 0 - C ( 1 ) 1. 4 1 8 ( 4 ) - — C ( 5 ) - C ( 6 ) 1 . 3 6 9 ( 5 ) 1. 3 8 1 O-B 1. 4 7 1 ( 4 ) -— C ( 6 ) -C ( 7 ) 1 . 3 6 5 ( 5 ) 1. 3 7 4 B - B 1. 6 5 2 ( 4 ) - — C ( 7 ) - C ( 8 ) 1. 3 8 4 ( 5 ) 1. 3 8 7 C ( 3 ) - B 1 . 6 1 6 ( 4 ) 1 . 6 1 9 C ( 9 ) -C ( 1 0 ) 1 . 4 0 1 ( 4 ) 1. 4 1 6 C ( 9 ) - B 1. 6 2 0 ( 5 ) 1. 6 2 3 C ( 9 ) - C ( 1 4 ) 1. 3 7 7 ( 5 ) 1. 3 8 8 N - C ( 2 ) 1 . 4 9 1 ( 4 ) - — C ( 1 0 ) - C ( 1 1 ) 1. 3 8 5 ( 6 ) 1, 3 9 0 C ( 1 ) - C ( 2 ) 1. 4 9 4 ( 6 ) - — C ( 1 1 ) - C ( 1 2 ) 1. 3 6 6 ( 6 ) 1 . 3 7 8 C ( 3 ) - C ( 4 ) 1. 3 9 1 ( 5 ) 1 . 3 9 9 C ( 1 2 ) ~ C ( 1 3 ) 1 . 3 6 2 ( 6 ) 1. 3 7 7 C ( 1 3 ) - C ( 1 4 ) 1. 3 9 5 ( 5 ) 1. 4 0 0 (b) Bonds i n v o l v i n g hydrogen atoms Atoms d i s t a n c e Atoms d i s t a n c e N-H ( N 1 ) 0. 8 8 ( 4 ) C ( 5 ) - H ( 5 ) 0 . 9 1 ( 5 ) N-H ( N 2 ) 0. 9 8 ( 4 ) C ( 7 ) -H ( 7 ) 1 . 0 4 ( 5 ) C ( 1 ) -H ( 1 A ) 0. 9 2 ( 5 ) C ( 8 ) - H ( 8 ) 0 . 9 2 ( 4 ) C ( 1 ) - f l ( 1 B ) 0. 9 8 ( 4 ) C ( 1 0 ) -H ( 1 0 ) 0 . 9 3 (U ) C ( 2 ) -H ( 2 A ) 0. 9 4 ( 6 ) C ( 1 1) - H ( 1 1) - 0 . 9 4 ( 6 ) C ( 2 ) - f l ( 2 B ) 0. 9 9 ( 4 ) C ( 1 3 ) T H ( 1 3 ) 0 . 9 3 ( 5 ) C ( 4 ) - H ( 4 ) 0. 9 9 ( 4 ) C ( 1 4 ) - H ( 1 4 ) 1 . 0 0 ( 4 ) Table 16 Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms uncorr. c o r r . C (1) -0-B 108. 2(2) C (2) -N-B 105.5 (2) 0- B- N 99. 9(2) 0- B-C (3) 110.4 (2) 0-B-C (9) 112.9 (2) N-B-C (3) 110,7 (2) N-B-C (9) 107.7 (2) C(3) -B-C (9) 114.2 (2) 0-C (1) -C (2) 106.0 (3) N-C(2)-C (1) 105.0 (3) B-C (3)-C (4) 123. 3(3) 123. 1 B-C { 3) -C (8) 120.7 (3) 120.6 C (4)-C (3)-C(8) 1 16.0 (3) 116.3 C(3)-C(4)-C(5) 122.8 (3) 122.6 C(4)-C (5)-C{6) 118. 2(3) 118.1 F(1)-C(6)-C(5) 119.3 (3) 119.2 F (1)-C (6)-C(7) 118.7 (3) 118.5 C(5)-C(6)-C(7) 121.9 (3) 122.2 C(6)-C (7)-C(8) 118.7(3) 118.5 C(3)-C(8)-C(7) 122.3 (3) 122.2 B-C (9)-C (10) 119. 4(3) 119.2 B-C (9) -C (14) 124.5 (3) 124.3 C (10)-C (9) -C (14) 116. 1 (3) 116.5 C(9) -C (10)-C (11) 121.4 (3) 121.2 C (10)-C (11)-C(12) 119.5 (3) 1 19.3 F(2)-C(12)-C(11) 120.0 (3) 119.7 F (2) -C (12) -C (13) 118.2(3) 118. 1 C(11)-C(12)-C(13) 121.8 (3) 122. 2 C (12)-C (13) -C (14) 1 17.6 (4) 1 17.4 C(9) -C (14) -C (13) 123.6 (3) 123,4 continued... 42 (b) Angles i n v o l v i n g hydrogen atoms Atoms value Atoms value B-N-H(N1) 113 (2) C (3)- C (4)-H (4) 1 17 (2) B-N-H (N2) 1 17 (2) c (5)- C(4)-H(4) 1 19 (2) C(2)-N-H(N1) 108 (2) c (4)- C(5) -H(5) 123 (3) C (2)-N-H (N2) 112 (2) c (6)- C (5)-H (5) 1 18 (3) H (N1)-N-H (N2) 101 (3) c (6)- C(7)-H(7) 119 (3) 0-C (1) -H (1A) 106 (3) c (8)- C (7)-H (7) 122 (3) 0-C (1)-H (IB) 113 (2) c (3)- C(8) -H(8) 120 (2) C(2)-C(1)-H(1A) 108 (3) c (7)- C (8)-H (8) 1 17 (2) C (2) -C (1) -H (1B) 104 (2) c (9)- C (10)-H (10) 1 17 (3) H (1A)-C (1)-H (1B) 119 <«») c (11) -C (10) -H (10) * 121 (3) N-C (2) -H (2A) 1 13 (3) c (10) -C (1 1 )-H (1 1 ) 125 (4) N-C (2)-H (2B) 102 (2) c (12) -C (11)-H (1 1) 115 (4) C(1)-C(2) -H (2A) 115 <«») c (12) -C (13)-H (13) 1 12 (3) C (1)-C (2)-H (2B) 112 (3) c (14) -C (1 3) -H (1 3) 131 (3) H(2A)-C(2)-H(2B) 110 (4) c (9)- C(14) -H (14) 123 (2) c (13) -C (14) -H (14) 113 (2) Table 17 I n t r a - a n n u l a r t o r s i o n angles (deg) i n the b o r o x a z o l i d i n e r i n g Bond observed a b c a l c , B-0 -22.2(2) 32.9 (3) -37.7 0-C (1) 39.6 (2) 42. 1 (3) 43, 8 C(1)-C{2) -39.3(2) 31.2 (3) -33.3 C (2) -N 24.8 (2) 10. 2(3) 10.0 H-B -3.1 (2) 12.7 (3) 17.2 B , B - d i p h e n y l b o r o x a z c l i d i n e , P a r t 1 T h i s work Figure 5 The structure viewed along b, O...H-N and F...H-N hydrogen bonds are represented by broken l i n e s . Figure 6 The structure viewed into c, broken l i n e s represent hydrogen bonds. 45 The g e o m e t r i c a l data f o r a l l three hydrogen bonds are q u i t e r e a s o n a b l e , the angles a t the hydrogen and at the acceptor atoms are w i t h i n the expected l i m i t s (28). The 0...N d i s t a n c e i s near the accepted mean while the F...N d i s t a n c e of 3.171 i s longer than the mean value of 2.92(11) A (29) and probably r e p r e s e n t s a r e l a t i v e l y weak i n t e r a c t i o n . I t should" be noted, however, t h a t the mean N...F d i s t a n c e i s based on only 10 examples, most ( i f not a l l ) of which occur i n i n o r g a n i c s t r u c t u r e s i n which the i n t e r a c t i o n i s h i g h l y i o n i c i n nature. In the present case the N and F atoms c a r r y only s m a l l p a r t i a l charges and evidence i n d i c a t e s that the n i t r o g e n atom i n t h i s s t r u c t u r e probably c a r r i e s a net negative charge. These f a c t o r s are probably r e s p o n s i b l e f o r the long N...F d i s t a n c e . The F.,.H d i s t a n c e s i n the F...H-N and F...H-C a i n t e r a c t i o n s are 2.35(4) and 2.34(4) A, both of which are s i g n i f i c a n t l y l e s s than the sum of van der Waals r a d i i . The geometry of the F...H-C system i s more n e a r l y i d e a l than t h a t of the F...H-N hydrogen bond and with the F...H d i s t a n c e s equal t h e r e i s l i t t l e doubt t h a t the F...H-C i n t e r a c t i o n i s a weak hydrogen bond. Aside from the hydrogen bonds there i s only one other i n t e r m o l e c u l a r c o n t a c t which i s s i g n i f i c a n t l y l e s s than the sum of van der Waals r a d i i , H (7) ..,H (13) , 2.16(7) A. A l l other i n t e r m o l e c u l a r c o n t a c t s , the s h o r t e s t of which are l i s t e d i n Table 19, correspond to normal van der Waals i n t e r a c t i o n s . 46 The conformation of the five-membered b o r o x a z o l i d i n e r i n g i s d i f f e r e n t from that i n _1 as can be seen by comparison of the corresponding d i h e d r a l angles i n Table 1 7 . The two carbon atoms were on o p p o s i t e s i d e s of the NBO plane i n J while i n the present s t r u c t u r e both C ( 1 ) and C ( 2 ) l i e on the 0 same s i d e of the NBO plane, d i s p l a c e d - 0 . 7 3 and - 0 . 3 2 A from the plane. The observed d i h e d r a l angles i n the r i n g are i n good agreement with those obtained from energy m i n i m i z a t i o n c a l c u l a t i o n s f o r 10\ - 1 0 ° ( 1 7 ) , a l s o shown i n Table 17. The observed magnitudes of the d i h e d r a l angles are s l i g h t l y s m a l l e r than the c a l c u l a t e d values s i n c e the mean valence angle i n the r i n g , 1 0 4 . 9 ° , i s s l i g h t l y g r e a t e r than the c a l c u l a t e d value of 1 0 4 . 2 ° , but i n good agreement with the mean of 1 0 4 . 8 ° i n J_« The i n d i v i d u a l values range from 9 9 . 7 ( 2 ) at B to 1 0 8 . 2 ( 2 ) ° at 0 . There are smal l but s i g n i f i c a n t d i f f e r e n c e s between the angles at 0 , N, an'd C (1 ) i n t h i s s t r u c t u r e and i n 1 which are a r e s u l t of c o n f o r m a t i o n a l and e l e c t r o n i c d i f f e r e n c e s . The angular s t r a i n i n h e r e n t i n the five-membered r i n g i s , as i n \, p a r t i a l l y r e l i e v e d by a s i g n i f i c a n t s h o r t e n i n g of the C ( 1)-C ( 2 ) bond ( 1 . 4 9 4 ( 6 ) A) from the value of 1 .537 A expected f o r a C (sp. 3)-C ( S £ 3 ) s i n g l e e bond. The B-N d i s t a n c e of 1 .652 (4) A agrees well with c h e m i c a l l y s i m i l a r bonds: 1 . 653 i n 1 , 1 .647 i n t r i e t h a n o l a m i n e borate ( 2 0 ) , and 1 .638 A i n ( E t 2 N B F 2 ) 2 ( 3 0 ) . The two phenyl r i n g s are planar w i t h i n experimental e r r o r (see Table 1 8 ) . The e i g h t phenyl hydrogen atoms l i e i n the r e s p e c t i v e mean planes while the boron and f l u o r i n e atoms 47 T a b l e 18 W e i g h t e d l e a s t - s q u a r e s mean p l a n e s (a) D i s t a n c e s (A) o f r e l e v a n t a t o m s f r o m t h e mean p l a n e s Atom d <V<r A torn d <V<r P l a n e 1: C ( 3 ) - C ( 8 ) P l a n e 2 : C ( 9 ) - C (14) C(3) - 0 . 0 0 5 1.6 C (9) - 0 . 0 0 7 2 . 4 C (4) 0 . 0 0 3 0 . 8 C(10) 0 . 0 1 0 2 . 3 C(5) 0 . 0 0 0 0.1 C (11) 0 . 0 0 0 0 .0 C (6) 0 . 0 0 0 0 . 0 C(12) - 0 . 0 0 7 2.1 C(7) - 0 . 0 0 5 1.1 C (13) 0 . 0 0 7 1.6 C (8) 0 . 0 0 8 2 . 0 C(14) 0 . 0 0 4 1.0 B - 0 . 0 3 1 9 . 5 B - 0 . 0 5 9 18. 4 F ( 1 ) - 0 . 0 5 9 2 4 . 1 F (2 ) - 0 . 0 0 8 3.1 H(4) 0 .091 2 . 4 H (10) - 0 . 0 0 4 0 . 1 H (5) - 0 . 1 2 8 2 . 5 H(11) 0 . 123 2 . 0 H(7) . 0 . 0 3 9 0 .8 H (13) - 0 . 0 0 3 0 . 1 H{8) 0 . 0 0 5 0 . 1 H(14) 0 . 0 7 9 2 . 0 (b) E q u a t i o n s o f p l a n e s : Vk + mY + nZ = jo, where X , Y , and Z a r e o r t h o g o n a l a n g s t r o m c o o r d i n a t e s d e r i v e d a s f o l l o w s : I-XT r a 0 0 T r X i III = I 0 b 0 I IYl t-ZJ L 0 0 c J « - Z J P l a n e m n 1 - 0 . 2 7 5 5 0 . 1 0 6 8 - 0 . 9 5 5 4 - 6 . 8 5 4 6 2 - 0 . 9 7 4 3 - 0 . 2 2 1 7 - 0 . 0 3 9 5 - 1 1 .3654 The d i h e d r a l a n g l e b e t w e e n p l a n e n o r m a l s i s 7 4 ° 48 i are s i g n i f i c a n t l y d i s p l a c e d from the planes, F(1) and B by -0.06 and -0.03 A from the C(3)-C(8) plane and F(2) and E by -0.01 and -0.06 A from the C(9)-C(14) plane. T h i s i s probably a r e s u l t of i n t r a - and i n t e r m o l e c u l a r s t e r i c f o r c e s . The d i h e d r a l angle between the plane normals i s 74° compared to 100° i n J . The two f l u o r o p h e n y l groups are not e q u i v a l e n t , the r i n g s being unequally r o t a t e d about the E-C tends. The d i h e d r a l angles C (8) [ C (3)-B ]0 and C (10) [ C (9)-B ]0 are 21.7(3) and 30.2(3)° compared to values of 78.0(2) and 7.0(2)° i n J.. The d i f f e r e n c e i n the o r i e n t a t i o n of the phenyl groups i n the two s t r u c t u r e s i s a r e s u l t of packing c o n s i d e r a t i o n s , among which the C(14)-H (14)...F (1) hydrogen bond may be an important f a c t o r . The c o r r e c t e d C-C bond l e n g t h s i n the phenyl groups range from 1.374 to 1.416 A with a mean value of 1.390 A. There i s a s i g n i f i c a n t v a r i a t i o n i n the i n d i v i d u a l bond d i s t a n c e s , the bond lengths decreasing as they are removed from the boron s u b s t i t u e n t . The mean valu e s f o r the three 0 groups are 1.403, 1.391, and 1.378 A, s i m i l a r to the corresponding values f o r 1 (co r r e c t e d f o r l i b r a t i o n ) of 1.403, 1.394, and 1.380 A. The B-C d i s t a n c e s , mean 1.621, are c s l i g h t l y longer than the va l u e of 1.616 A i n 1 and s h o r t e r than i n the t e t r a p h e n y l borate anion (1 .631-1.648(8) A) (19). The angles i n the phenyl r i n g s have a mean value of 120° but the i n d i v i d u a l values, ranging from 116.3 to 123.4°, show s i g n i f i c a n t d e v i a t i o n s ' f r o m 120°. The mean angle at the carbon atom c a r r y i n g the boron s u b s t i t u e n t i s 116.4° and the 49 other mean values are 122.4, 118.3, and 122.2° f o r atoms 2£tho , meta , and £ara to the boron group r e s p e c t i v e l y . These v a r i a t i o n s have been e x p l a i n e d i n terms of the e l e c t r o n e g a t i v i t i e s of the s u b s t i t u e n t groups (31). The angles a t C(6) and C(12) c a r r y i n g the f l u o r i n e atoms, mean 122.2°, are as expected f o r an e l e c t r o n withdrawing group. The angles at C(3) and C (9), mean 116.4°, c a r r y i n g the boron s u b s t i t u e n t are i n d i c a t i v e t h a t t h i s group i s r e l e a s i n g e l e c t r o n d e n s i t y i n t o the aromatic system. The d i s t r i b u t i o n of bond le n g t h s i s i n agreement with t h i s o b s e r v a t i o n , i n d i c a t i n g s m a l l r e s i d u a l p o s i t i v e charge a t atoms ortho to F and n e gative charge ortho to B, the o v e r a l l donating and withdrawing e f f e c t s of the para s u b s t i t u e n t s c a n c e l l i n g each other to r e s u l t i n e l e c t r o n i c n e u t r a l i t y of the aromatic TT systems. There i s both t h e o r e t i c a l and p h y s i c a l evidence which i n d i c a t e s that i n s p i t e of the N-»B d a t i v e bond, the boron atom remains more p o s i t i v e l y charged than the n i t r o g e n atom as a r e s u l t of charge r e d i s t r i b u t i o n s o c c u r r i n g i n the remainder of the molecule (30,32). T h i s o f f e r s an e x p l a n a t i o n f o r the smal l d i f f e r e n c e s between the B-C, B-0, C-N, C-0, and C(1)-C(2) bond lengths i n t h i s s t r u c t u r e and those i n 1_, where the negative charges which occur at the f l u o r i n e atoms i n t h i s s t r u c t u r e r e s u l t i n d e l o c a l i z a t i o n e f f e c t s i n the o molecule. The mean C-F d i s t a n c e of 1.371 A i s c l o s e to that of 1.368 A i n o - f l u o r o b e n z o i c a c i d (33) but s i g n i f i c a n t l y longer than the mean C ( a r ) - F d i s t a n c e of 1. 328 A i n r e f . 18. The mean bond angles at t e t r a h e d r a l l y and t r i g o n a l l y c o o r d i n a t e d atoms are 109.4 and 119.9°. There are a number of 50 Table 19 (a) S e l e c t e d i n t r a - and i n t e r m o l e c u l a r c o n t a c t s I n t r a m o l e c u l a r I n t e r m o l e c u l a r * atoms d i s t a n c e atoms d i s t a n c e 0.. ,C(8) 2. 888 (4) F (1) . ..F (2) i 3.229 (4) 0. . .C (10) 2.961 (4) F(1) . . .C (1 1) z 3.484 (5) N • • . C (14) 3.084 (4) F (1) . ..C(12) * 3. 400 (4) N...C (8) 3. 489 (4) F (1) . 3. 446 (4) F (2) . ..C(7) * 3.451 (5) C (6) . ..C (11) 2 3.477 (5) C (1) . . ,H(N2) 5 2.96 (4) C (5) . . . H (1 1 ) 2 2.98 (7) C (6) . ..H(1 1) 2 2.79 (7) C (6) . . . H (14) 3 2.88 (4) C (7) . . . H ( 1 3) 6 2.99 (5) C (13) ...H (11) * 2.92(6) C(13) ...H(7) * 2.94 (5) H (7). . . H (13) 6 2. 16 (7) (b) Hydrogen- bond data ( d i s t a n c e s i n 0 A and angles i n deg) D-H.. .A H. .. A D. . . A ^DHA ^X AH N-H (N2) .. .08 1.96 (5) 2.941 (3) 176 (4) 122 (1 ) ,129 (1) N-H (N1) .. . F (2) 7 2.35 (4) 3. 171 (4) 155(3) 140(1 ) C(14)-H(14) ...F (1) 9 2.34 (4) 3.318 (5) 165 (3) 99 ( 1) • S u p e r s c r i p t s r e f e r t o atoms a t p o s i t i o n s : 1 1/2-x 1/2-2 1-2 6 X 1+y. 2 2 2-x 1/2+1 3/2-2 7 3/2-x -2 z- 1/2 3 2-x V2+I 1/2-2 e 3/2-x 1-2 2-1/2 * X 1-1 2 9 2-2 2-1/2 1/2-z S 3/2-x 1-1 1/2 + 2 51 s i g n i f i c a n t d e v i a t i o n s from the mean values r e s u l t i n g from s t e r i c and e l e c t r o n i c e f f e c t s . I n t e r i o r angles i n the r i n g s have a l r e a d y been d i s c u s s e d . Asymmetry of the packing appears t o be r e s p o n s i b l e f o r s i g n i f i c a n t d i f f e r e n c e s between corresponding angle p a i r s 0-B-C, N-B-C, and C-C-F. The C (3)- B-C(9) angle i s equal to t h a t i n J to with i n experimental e r r o r . The mean C(sj>3)-H, C(ar)-H, and N-H d i s t a n c e s of 0.95, 0.96, and 0.93 A are as expected f o r X-ray data. The bond angles i n v o l v i n g the hydrogen atoms are g e n e r a l l y as expected. There are s i g n i f i c a n t d i f f e r e n c e s between the C-C-H angles at C(13) and C(14) which are probably a r e s u l t of van der Waals c o n t a c t s F(1)...H(14) and H(7)...H(13) (see Table 19) . PART 3 CRYSTAL AND MOLECULAR STRUCTURE OF 4,4-DIMETHYL-2,2-DIPHENYL-1,3-DIOXA- 4-AZONIA-2-BORANATACYCLOPENTANE 53 I N T R O D U C T I O N From the r e a c t i o n of N-hydroxydialkylamine Q) and formaldehyde an a d d i t i o n can be expected e i t h e r a t the n i t r o g e n or at the oxygen atom to g i v e 2 or 4. The a d d i t i o n products, o r i g i n a l l y regarded as N-hydrcxymethyl- o x y d i a l k y l a m i n e s (4) by Z i n n e r and R i t t e r (34,35), r e a c t with d i p h e n y l b o r o n - s u p p l y i n g reagents ( P l ^ B - X ) to y i e l d c r y s t a l l i n e compounds which were i n i t i a l l y a s s i g n e d the s t r u c t u r e 5 c o n t a i n i n g i n t r a m o l e c u l a r N—»B c o o r d i n a t i o n . T h i s assignment was based on the e a r l i e r s t u d i e s of the • b o r o x a z o l i d i n e s • by Weidmann and Zimmerman (36-38) and was subsequently employed f o r compounds of t h i s type (39-43). R ^ O H 11 0© 0=CH, \ 0 0—'H R R X '0 I Pĥ B-X - HX + Ph^B-X -HX -Ph Ph R- C H , R = C H 3 Ph-- C 4 H S X = a) 0-BPh2 b) Ph c) 0-CH4-CHt-NH2 d) 0-CH2-CH2-N(CH3)t R . R ' P,h 7Ph N c H r C H z R \ @ / C H * C ^ /N 0 R V © / 0—B—Ph / 7 Ph There i s , however, some evidence which i n d i c a t e s t hat the a l t e r n a t e s t r u c t u r e s 2 and 3 are probably favored over 54 the o r i g i n a l l y proposed s t r u c t u r e s 4 and 5: 1. The a l k y l a t i o n of N-hydroxydialkylamines normally leads to t e r t i a r y amine o x i d e s . 2. N-Oxides show st r o n g e r b a s i c i t y and possess b e t t e r n u c l e o p h i l i c or donor g u a l i t i e s than the i s o m e r i c N- alkyloxyamines (44,45). & hydrogen bridge c h e l a t e of the type 2 should t h e r e f o r e be more s t a b l e than 4. 3. I f both forms 2 and 4 e x i s t e d , p o s s i b l y i n a s t a t e of e q u i l i b r i u m , the r e a c t i o n with an e l e c t r o p h i l i c reagent such as Ph2B-X should s h i f t the ( h y p o t h e t i c a l ) e q u i l i b r i u m to the s i d e o f the b e t t e r donor molecule, i . e . the N-oxide (2). 4. The N-oxide form not only f a c i l i t a t e s the approach of the Lewis a c i d Ph 2B-X to the donor (oxygen) atom but a l s o r e s u l t s i n a s t e r i c a l l y favored c h e l a t e s t r u c t u r e (3) . 5. Ethanolaroine e s t e r s of d i p h e n y l b o r i n i c a c i d are i n t r a m o l e c u l a r N—»B c o o r d i n a t e d c y c l i c complexes (6), as r e c e n t l y proved c o n c l u s i v e l y f o r Ph 2B-0-CH 2CH 2NH 2 (Part 1) and (£-FC 6H^) 2B-0-CH 2CH 2NH 2 (Part 2). Despite the s t a b i l i t y of these * b o r o x a z o l i d i n e s ' (9,36-38) the r e c h e l a t i o n of the a p p l i e d examples (6, E = H, CH^) was p o s s i b l e with the formaldehyde adduct. This a l s o 55 supports s t r u c t u r e s 2 and 3 s i n c e i t i s not very p l a u s i b l e that a weakly b a s i c N-hydroxymethyl- ox y d i a l k y l a m i n e HO-CH2ONR2 {4) i n an equimolar q u a n t i t y can d i s p l a c e the i s o s t e r i c but more b a s i c aminoalcohol H0-CH 2CH 2Ni<2- 6, F i n a l l y there e x i s t s an analogy between 3 and the di p h e n y l boron c h e l a t e s (7) of N - ( 2 - h y d r o x y a l k y l ) - d i a l k y l a m i n e - N - o x i d e s and other s i m i l a r c y c l i c boron- n i t r o g e n - b e t a i n e s (46-50) which are c l o s e l y r e l a t e d to 3 both i n means of p r e p a r a t i o n and i n t h e i r chemical and p h y s i c a l behavior. These c o n s i d e r a t i o n s and a l s o the chemical and p h y s i c a l data obtained to date are c o n s i s t e n t with the betai n e - t y p e c h e l a t e 3, but do net provide unambiguous proof. To t h i s end the f u l l X-ray c r y s t a l l o g r a p h i c study of the homologue with R = CH^ has been c a r r i e d out. EXPERIMENTAL HJ.1Z ge th Y 1 1 2 L 2 - d iphgny_ 1- 1 F_ 3 - dio xa- A s o l u t i o n of N-hydroxydimethylamine (5 mmole) i n 5 ml of e t h a n o l was mixed with an aqueous s o l u t i o n of formaldehyde (40%, 5 mmole). A f t e r a d d i t i o n o f : a) 2.5 mmole oxybisdiphenylborane c r b) 5.0 mmole t r i p h e n y l b o r a n e or 56 c) 5.0 mmole B-(2-aminoethyloxy)diphenylborane or d) 5.0 mmole B-(2-dimethylaminoethyloxy)diphenylborane the mixture was heated u n t i l i n i t i a l b o i l i n g and then allowed to c o o l . During the c o o l i n g or a f t e r the d i s s o l u t i o n of the boron component the p r e c i p i t a t i o n began. Y i e l d s : a) 99%, b) 90%, c) 98%, d) 85% m.p. 191-192° C ( a c e t o n i t r i l e ) ; L i t . (6): m.p. 191-192° (ethanol) C 1 5 H18 B N 02 (255.1) C a l c . C 70.62 H 7.11 B 4.24 N 5.49 Found 70.96 7.21 4.18 , 5.45 1H-NMR (100 MHz, d6"DMSO/TMS) (ppm) : 6.84 s (6, CH^), 5.25 s (2, CH2) , 2.6-3.1 m (10, Ph) 11B-NMR (32.1 MHz, DMSO) : SjBF^OEt^) = -11.1 ppm C r y s t a l s s u i t a b l e f o r X-ray a n a l y s i s were obtained by r e c r y s t a l l i z a t i o n from 3:1 acetone-carbon t e t r a c h l o r i d e . The c r y s t a l used f o r data c o l l e c t i o n was bounded by the (001), (010), and (100) planes a t d i s t a n c e s of 0.14, 0.35, and 0.14 mm from an i n t e r n a l o r i g i n and was mounted with b p a r a l l e l to the go n i o s t a t a x i s . D n i t - c e l l and space group data were obtained from f i l m and d i f f r a c t o m e t e r measurements. The u n i t - c e l l parameters were r e f i n e d by a l e a s t - s q u a r e s treatment of sin 2© values f o r 27 r e f l e x i o n s measured on a d i f fractometer with Cu K,*. r a d i a t i o n . C r y s t a l data are: 57 C 1 5 H 1 8 B M 0 2 f , w * = 2 5 5 . 1 O r t h o r h o m f c i c , a = 1 7 . 0 4 3 ( 3 ) , b = 6 . 2 8 9 ( 1 ) , c = 1 3 . 0 2 4 ( 2 ) A , V = 1 3 9 5 . 9 (5) A 3 , Dm = 1 .225 ( f l o t a t i o n i n a q u e o u s K I ) , Z = 4 , Dx = 1 .214(1 ) g c m - 3 , F (000) = 544 ( 2 0 ° C , Cu K * , fl = 1 .5418 A , /x. - 6 . 4 c m - 1 ) . A b s e n t r e f l e x i o n s : 0 k / , k + * 2n g and h 0 ^ , h # 2 n , s p a c e g r o u p Pna2^ (P-̂ v' N o* 3 3 ) * I n t e n s i t i e s were m e a s u r e d on a D a t e x - a u t o m a t e d G e n e r a l E l e c t r i c XKD 6 d i f f r a c t o m e t e r , w i t h a s c i n t i l l a t i o n c o u n t e r , Cu r a d i a t i o n ( n i c k e l f i l t e r and p u l s e h e i g h t a n a l y s e r ) , and a +3-29 s c a n a t 2 ° m i n - 1 o v e r a r a n g e o f ( 1 .80 + 0. 86 t a n 9) d e g r e e s i n 2 9 , w i t h 20 s b a c k g r o u n d c o u n t s b e i n g m e a s u r e d a t e a c h end o f t h e s c a n . D a t a were m e a s u r e d t o 29 = 1 4 5 ° (minimum i n t e r p l a n a r s p a c i n g 0 .81 A ) . The r . m . s . d e v i a t i o n o f t h e i n t e n s i t y o f t h e c h e c k r e f l e x i o n , m e a s u r e d e v e r y 40 r e f l e x i o n s t h r o u g h o u t t h e d a t a c o l l e c t i o n , f r o m i t s i n i t i a l v a l u e was 2 .4%. T h e f i n a l i n t e n s i t y was 1 .045 t i m e s t h e i n i t i a l v a l u e . L o r e n t z , p o l a r i z a t i o n , and a b s o r p t i o n c o r r e c t i o n s were a p p l i e d , a n d s t r u c t u r e a m p l i t u d e s were d e r i v e d . O f 1450 i n d e p e n d e n t r e f l e x i o n s m e a s u r e d , 324 had i n t e n s i t i e s l e s s t h a n 3<r(l) a b o v e b a c k g r o u n d where <rz (I) = S + B + ( 0 . 0 6 S ) 2 w i t h S = s c a n c o u n t and B = b a c k g r o u n d c o u n t , c o r r e c t e d t o t i m e o f s c a n . T h e s e r e f l e x i o n s were n o t i n c l u d e d i n t h e r e f i n e m e n t . S t r u c t u r e A n a l y s i s The s p a c e g r o u p was a s s u m e d t o be Pna2^ f r o m s y s t e m a t i c a b s e n c e s and t h e number o f m o l e c u l e s i n t h e u n i t - c e l l (Z = 58 4) . The s t r u c t u r e was solved by d i r e c t methods, 158 r e f l e x i o n s with normalized s t r u c t u r e f a c t o r |E| > 1.55 being used i n the symbolic a d d i t i o n procedure f o r non- centrosymmetric c r y s t a l s (21). The phases of the 5 5 0, 8 3 0, and 14 2 1 r e f l e x i o n s were f i x e d t o d e f i n e the o r i g i n and the enantiomorph was f i x e d by a l l o w i n g one of the symbol phases to take o n l y values between 0 and 500 mc. During a manual expansion, c a r r i e d out among the 75 r e f l e x i o n s with l a r g e s t |E| v a l u e s , i t became apparent that there were e i g h t r e f l e x i o n s from which the t h r e e symbol phases could be chosen. A f t e r s e v e r a l u n s u c c e s s f u l runs, a combination of symbol phases which gave a promising s e t of t r i a l phases was found. The three symbol phases; 1 1 11, 3 1 13, and 1 4 8; along with the o r i g i n determining phases comprise the b a s i c s t a r t i n g group given i n T a b l e 20. Eig h t s t a r t i n g s e t s were generated by a l l o w i n g symbols a and b to have i n i t i a l values of ±250 mc and c to have i n i t i a l v a lues of 125 and 375 mc (thereby f i x i n g the enantiomorph). These s e t s were used as i n p u t to a computer program which determines phases using the tangent formula (22,23). The values of o v e r a l l t, o v e r a l l * , Q, and Rk on the f i n a l c y c l e f o r each of the s e t s are given i n Table 21. Set 4, which had the lowest value of Rk, was expanded to 185 r e f l e x i o n s with |E| > 1.50 by s t a r t i n g with the same symbol values as i n set 4. The f i n a l value of Rk was 0.23 with 180 phases assigned. An E-map based on these 180 phases gave p o s i t i o n s f o r the 19 non-hydrogen atoms among the 40 h i g h e s t peaks. Table 20 B a s i c s t a r t i n g s e t of r e f l e x i o n s f o r Ci^H^gBNC^ h k I I I phase (mc) 5 5 0 3.28 8 3 0 2. 07 1 Of o r i g i n determining i 14 2 1 1.99 1 0-> 1 1 11 2.66 a 3 1 13 2.62 b 1 4 8 2.44 c 60 Table 21 Results for the eight s t a r t i n g sets in the phase determination procedure set a {toe) b (mc) c (mc) t Rk 1 1 250 250 125 0.69 158 0. 30 0.30 146 2 250 250 3 75 0.72 158 0.27 0.31 144 3 250 -250 125 0. 69 165 0. 30 0. 35 14 1 4 250 -250 375 0.68 160 0.31 0.24 154 5 -250 250 125 0.69 160 0.30 0.30 145 6 -250 250 375 0.71 163 0.28 0.34 143 7 -250 -250 125 0.71 163 0. 28 0.28 149 8 -250 -250 375 0.58 135 0.41 0.36 141 61 Two c y c l e s of f u l l - m a t r i x l e a s t - s g u a r e s refinement of the p o s i t i o n a l and i s o t r o p i c thermal parameters of the non- hydrogen atoms gave R 0.156. T h i s was f o l l o w e d by two c y c l e s of a n i s o t r o p i c refinement which reduced R to 0. 103. A d i f f e r e n c e map at t h i s point r e v e a l e d the p o s i t i o n s of seven of the ten phenyl hydrogen atoms. The remaining hydrogen atom p o s i t i o n s were c a l c u l a t e d and a l l 18 hydrogen atoms were i n c l u d e d i n subsequent c y c l e s of refinement with i s o t r o p i c thermal parameters. The refinement was concluded at R 0.071 f o r 1100 r e f l e x i o n s with I > 3<r(I) (26 r e f l e x i o n s were given z e r o weight i n the f i n a l stages of refinement due to suspected e x t i n c t i o n or counter e r r o r s ) . The s c a t t e r i n g f a c t o r s f o r the non-hydrogen atoms were taken from r e f . 12 and those f o r the hydrogen atoms from r e f . 13. The weighting scheme: w = 1/<r2(F) where <rz (F) i s d e r i v e d from the p r e v i o u s l y d e f i n e d <rz (I) , gave constant average v a l u e s of w(Fo-Fc) 2 over ranges of |Fo| and was employed i n the f i n a l stages of refinement. On the f i n a l c y c l e of refinement no parameter s h i f t was g r e a t e r than 0.33(rfor non- hydrogen atoms except f o r the y_ c o o r d i n a t e s of methyl carbon atoms C(2) and C(3) which s h i f t e d by 0.80 <r". The s h i f t s were l e s s than 1.5 <r f o r the methyl hydrogens and l e s s than 1.0<r f o r the remaining hydrogen atoms. The f i n a l p o s i t i o n a l and thermal parameters appear i n Tables 22 and 23 r e s p e c t i v e l y . Observed and c a l c u l a t e d s t r u c t u r e amplitudes are a v a i l a b l e on request. THERMAL MOTION AND CORRECTION OF MOLECULAR GEOMETRY 62 Table 22 F i n a l p o s i t i o n a l parameters ( f r a c t i o n a l x 10* t x 10 3 f o r H atoms) with estimated standard d e v i a t i o n s i n parentheses Atom x j z 0 (1) 3418 (2) 4469 (6) 1466 (4) 0 t2) 3126 (2) 962 (6) 915 N 3315 (2) 977 (7) 1968 (4) C{ [D 3207 (4) 3249 (14) 2300 (6) c (2) 4138 (4) 108(17) 2051 (7) c [3) 2771 (5) -431 (22) 2513 (6) c (4) 2139 (3) 3904 (9) 385 (4) c (5) 1578 (4) 2389 (11) 255 (7) c (6) 801 (3) 2872 (13) 39(7) c (7) 571 (3) 4941 (1 1) -20 (5) c (8) 1100 (3) 6539 (13) 91 (6) c (9) 1907 (3) 6006 (10) 308 (5) c (10) 3584 (3) 3654 (9) -463 (5) c (11) 3659 (3) 1995 (10) -1166 (5) c (12) 4062 (4) 2244 ( 13) -2085 (6) c (13) 4409 (4) 4265 (14) -2305 (6) c (14) 4327 (4) 5879 (14) - 1610 (7) c (15) 3922 (3) 5542 (12) -688 (6) B 3054 (3) 3323 (1 1) 570 (5) H d&) 354 (4) 364 (11) 307 (6) H (1B) 255 (4) 340 (12) 255 (5) H (2A) 434 (5) 129 (11 ) 159 (8) H (2B) 422 (9) 2(21) 298 (14) H (2C) 425 (5) -177 (14) 170 (7) H <3A)- 242 (11) -13 (29) 228 (16) H (3B) 311 (4) -248 (10) 226 (5) H (3C) 285 (7) -43 (16) 336 (10) H (5) 170 (3) 99 (9) 23 (4) H (6) 47 (3) 149 (7) -25(4) H (7) 5(4) 525 (11) -25 (5) H (8) 9 1 (3) 796 (9) 12(4) H (9) 220 (6) 706 (17) 53 (8) H (11) 342 (5) 50 (12) -116(7) H (12) 404 (3) 129 (9) -259 (5) H (13) 479 (5) 459 (11) -292 (7) H (14) 443 (6) 776 (13) -186 (7) H (15) 384 (4) 685 (10) -33(5) 63 Table 23 F i n a l thermal parameters and t h e i r estimated standard d e v i a t i o n s 0 (a) A n i s o t r o p i c thermal parameters (U. . x 100 A 2) Atom %1 2 2 2 u 3 3 % 2 . % 3 u 2 3 0(1) 4.7 [2) 7. 5 < 3) 4.6 (2) -1.2(2) -1.3(2) 0.3 ( 2) 0(2) 4.6 ( 2) 6. 8 | 3) 3.8 (2) -0.4 (2) -1.0 (2) 0.3 | 2) N 3.5 (2) 6.0 | 3) 3. 4 (2) 0.2(2) -0.5(2) 0.5 ( 2) C(1) 6.7 ( 4) 10. 1 6) 5.7 (4) -0. 1 (4) -0.9 (3) 0. 3 | 4) C (2) 4.8 [3) 14. 2 | 7) 6.0 (4) 3.9(4) -1.8(3) -0.4 ( 5) C(3) 6.5 ( 4) 18.7 | 11) 4.6 (4) -3.3 (6) 1.4 (3) 2.6 | 5) C (4) 3.7 [2) 5.9 | 3) 3. 3 (2) -1. 1 (2) 0.1 (2) -0. 1 ( 2) C(5) 5.1 ( 3) 4.4 | 4) 10.4 (5) 0.3 (2) -1.9 (3) 1. 4 4) C (6) 3.8 [3) 8.7 | 5) 10. 1 (5) -1. 1 (3) -1.8(3) 1. 1 ( 4) C(7) 3.4 ( 2) 8.0 4) 4.7 (3) 0.2 (3) -0.6 (2) 0.0 3) C (8) 4.5 [3) 8. 4 [5) 6.6 (4) 2.3(3) -0.5(3) - 1.3 ( 3) C(9) 3.9( 3) 5.7 5.8 (3) 0.4 (2) -0,4 (2) -0.5 3) C{10) 2.9 [2) 6. 7 < 3) 4. 2 (3) 0. 3 (2) -1.1 (2) 1. 1 ( 3) C(11) 4.1 | 3) 5.6 4) 4.9 (3) 0.9 (2) -0.3 (2) 0.5 3) C (12) 5.3 (3) 8. 5 < 5) 5.8(4) 2. 9 (3) 0.2(3) 0.6 ( 4) C(13) 3.9( 3) 12.3 | 6) 6.0 (4) 1. 2 (4 ) 1.3 (3) 1.4 4) C (14) 4.5 [3) 9. 1 5) 8. 6 (5) 0. 0 (3) 1.7(3) 2.9 ( 4) C(15) 4.1 | 3) 7.5 | 4) 5.6 (3) -1.0 (3) -0.8 (2) 1. 1 3) B 3.7 (3) 5. 2 | 3) 4.2(3) -0.7(2) -0.5(2) 0,3 ( 3) (b) I s o t r o p i c thermal parameters Atom B(A 2) Atom B (A 2) H(1A) 3.8 (16) H (6) 2.0 (9) H <1B) 5. 3(15) H(7) 5. 1 (13) H(2A) 6.0(18) H (8) 3.1(11) H (2B) 15.0 (44) H(9) 11.9 (27) H (2C) 8.8 (21) H (11) 5.6 (16) H (3 A) 22.2 (67) H(12) 3.0 (12) H(3B) 4.3 (14) H (13) 7. 1 (17) H (3C) 11.2 (30) H(14) 9. 2 (25) H(5) 2.5(9) H (15) 4.4 |13) 64 F i g u r e 7 A s t e r e o s c o p i c view of the molecule showing c r y s t a l l o g r a p h i c numbering scheme. 50% p r o b a b i l i t y e l l i p s o i d s are shown f o r the non-hydrogen atoms. The e l l i p s o i d s of thermal motion f o r the non-hydrogen atoms are shown i n F i g u r e 7 . The thermal motion has been analysed i n terms of the r i g i d - b o d y modes of t r a n s l a t i o n (T), l i b r a t i o n (L) , and screw ( S ) motion u s i n g the computer program MGTLS ( 1 4 ) . Four a n a l y s e s were c a r r i e d out: the 1 9 non-hydrogen atoms were c o n s i d e r e d f i r s t ; then each of the phenyl groups along with the boron atom; and f i n a l l y the five-membered r i n g and at t a c h e d carbon atoms which f a i l e d to g i v e a p o s i t i v e - d e f i n i t e L tensor. The r e s u l t s of the a n a l y s e s of the two phenyl groups appear i n Table 2 4 . The r.m.s. standard d e v i a t i o n i n the temperature f a c t o r s e U|i i s 0.C035 A 2 which i n d i c a t e s that the mclecule as a whole (r.m.s. AU±j = 0.0124 A 2) i s not a good r i g i d - b o d y whereas the thermal motion of the phenyl groups i s adegu.itly 65 Table 24 Rigid-body thermal parameters 1 C(4)-C (9) , B C (10)-C (15) , B r104 (17)-18 (7) 26(10)-, r 23(9) -2(5) -12(9) n L ( a e g 2 ) | 9(7) -5(5) | | 13(6) 0(6) | «- 17(5) J «• 33(14 )J P r i n c i p a l axes of 1 r, m. s. Amplitude D i r e c t i o n c o s i n e s (x10 3) 10.7° 949 -171 264 6.4° -562 26 827 3.0 268 2 -963 4.0 -702 512 -495 2.5 165 985 48 3.5 -436 -859 -269 P r i n c i p a l axes of reduced T r.m.s. Amplitude D i r e c t i o n c o s i n e s (x10 3) 0.22 A 45 -998 36 0.22 A 152 -857 -492 0.19 998 46 32 0.20 407 508 -759 0.17 -33 35 999 0.14 901 -84 426 Displacement of axes from i n t e r s e c t i n g (A) P a r a l l e l to 0.74 1.60 P a r a l l e l to I 2 0.13 0.55 P a r a l l e l to 0.40 -0.03 0 E f f e c t i v e screw t r a n s l a t i o n s (A) P a r a l l e l to 0.014 0.002 P a r a l l e l to L 2 -0.005 0.000 P a r a l l e l to "ij -0.053 -0.004 F r a c t i o n a l c o o r d i n a t e s of unique o r i g i n (x10*) x 2412 3051 I 4353 3786 z 329 -388 F r a c t i o n a l c o o r d i n a t e s of c e n t r e of g r a v i t y (x10*) x 1572 3871 • y. 4296 3851 z 227 -1132 r.m.s. 4UJJ^ 0.0052 0.0046 A 2 iAxes of r e f e r e n c e are orthogonal angstrom axes. E.s.d.'s of components of L are given i n parentheses i n u n i t s of the l a s t p l a c e s shown, 66 d e s c r i b e d by the r i g i d - b o d y parameters (r.m.s. A U^j = 0.0052 0 and 0.0046 A 2 ) . Both groups show somewhat a n i s o t r o p i c t r a n s l a t i o n a l motion and a n i s o t r o p i c l i b r a t i o n a l motion, p a r t i c u l a r l y the C( 4 ) - C ( 9 ) , B group (see Table 24). The p r i n c i p a l axes of L are o r i e n t e d as expected: the l a r g e s t o s c i l l a t i o n s , , correspond to r o t a t i o n s about the B-C bonds, the angles between the axes and the B-C bonds being 7.3 (C(4)) and 8.9° (C(10)). The unigue o r i g i n s (14) are i n the expected l o c a t i o n s f o r both groups, l y i n g between the B and a t t a c h e d phenyl C atoms. The a p p r o p r i a t e bond d i s t a n c e s and angles i n the phenyl groups have been c o r r e c t e d f o r l i b r a t i o n (15,16) using shape parameters cj 2 of 0.08 f o r a l l atoms. Both c o r r e c t e d and uncorrected bond lengths and angles appear i n Tables 25 and 26 r e s p e c t i v e l y . RESULTS AND DISCUSSION The X-ray a n a l y s i s has shown that the betaine-type s t r u c t u r e (3) i s c o r r e c t . F i g u r e 7 shows a g e n e r a l view of the molecule and the c r y s t a l l o g r a p h i c numbering scheme. Fi g u r e 8 shows the packing arrangement viewed along b. I n t r a - annular t o r s i o n angles d e f i n i n g the conformation of the f i v e - membered r i n g are gi v e n i n Tab l e 27 and some weighted l e a s t - squares mean planes through the molecule i n Table 28. Non- bonded i n t r a - and i n t e r m o l e c u l a r c o n t a c t s are l i s t e d i n Table 29. Henceforth, the molecules (C^H^)gBCCHgCHgNHg and (p- F C 6 H 4 ) 2 B 0 C H 2 C H 2 S H 2 (Parts 1 and 2 ) w i l l be r e f e r r e d to as 6a 67 Table 25 0 Bond le n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms uncorr. c o r r . Atoms uncorr. c o r r . 0 ( 1 ) - C (1) 1. 378 (9) C(5)- C(6) 1. 388 (9) 1. 391 0( 2 ) - N 1. 409 (5) C(6) - C (7) 1. 361 (10) 1. 377 0( 1 ) - B 1. 506 (7) C(7)- C(8) 1. 359 (10) 1. 372 0 ( 2 ) - B 1. 556 (8) C (8)-C (9) 1. 443 (8) 1. 446 C (4)-B 1. 620 (7) 1 .624 C(10) -C (11) 1. 394 (8) 1. 402 C(10) -B 1. 634 (8) 1 .639 C(10) -C (15) 1. 353 (9) 1. 363 C (1 )-N 1. 505 (10) C(11) -C(12) 1. 390 (9) 1. 396 C(2)- N 1. 509(7) 1 .551* C (12) -C (13) 1. 431 (10) 1. 441 C (3)- N 1. 467 (9) 1 .520* C(13) -C (14) 1. 367 ( 1 1) 1. 374 C(4)- C(5) 1. 360 (8) 1 .373 C (14) -C (15) 1. 401 (10) 1. 406 C{4)~ C{9) 1. 383 (8) 1 . 399 (b) Bonds i n v o l v i n g hydrogen atoms Atoms d i s t a n c e Atoms d i s t a n c e C O ) -H (1A) 1. 18(7) C(6)- H(6) 1. 10 (5) C(1) -H(1B) 1. 17(7) C (7)-H (7) 0.95 (7) C (2) -H (2A) 1. 02 (9) C(8)- H(8) 0.95 (6) C(2) -H(2B) 1. 22 (18) C (9)-H (9) 0.88 (11) C(2) -H (2C) 1. 28 (9) C (11) -H(11) 1.02 (8) C(3) -H (3A) 0. 70 (20) C (12) -H (12) 0.89 (6) C (3) -H (3B) 1. 45 (6) C(13) -H(13) 1.05 (9) C(3) -H(3C) 1. 11 (13) C (14) -H (14) 1.24 (8) C(5) -H (5) 0. 90 (5) C(15) -H(15) 0. 96 (6) • r i d i n g motion c o r r e c t i o n o nly. 68 Table 26 Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms uncorr. Atoms uncorr. c o r r , C{1) -0(1)-B 103.8 (4) B-C (4) -C (5) 122. 5 (5) 122. 1 N-0(2)-B 107. 1 (4) B-C (4) -C (9) 120. 1 (4) 119. 9 0(2) -N-C(1) 105.0 (4) C(9)-C(4)-C(5) 117. 4 (5) 118. 0 0 (2) -N-C (2) 106. 4 (4) C(4)-C(5)-C(6) 122. 8 (6) 122. 5 0 (2) -N-C(3) 108.8 (5) C (5)-C (6)-C (7) 119. 7 (6) 1 19. 5 C(1) -N-C (2) 115.9 (6) C(6)-C(7)-C(8) 120. 7 (5) 121. 2 C(1) -N-C(3) 110.9 (7) C(7)-C (8)-C(9) 118. 8 (6) 118. 5 C (2) -N-C (3) 109.6 (7) C (8) -C (9) -C (4) 120. 5 (6) 120. 3 0(1) -B-0 (2) 101.5 (4) B-C (10)-C (11) 119. 7 (5) 119, 6 0(1) -B-C (4) 113.8 (5) B-C (10) -C (15) 121. 8 (5) 121. 7 0(1) -B-C ( 10) 110.5 (4) C (15) -C (10)-C (11 ) 118. 4 (6) 118. 5 0 (2) -B-C (4) 109.5 (4) C (10) -C (1 1) -C ( 12) 121. 8 (6) 121. 7 0(2) -B-C( 10) 108.4 (4) C (11) -C (12)-C (13) 118. 5 (7) 118. 5 C (4) -B-C (10) 112.4 (4) C(12) -C(13)-C(14) . 119. 0 (6) 119. 1 0(1) -C(1)-N 105.7 (6) C (13) -C (14)-C (15) 120. 4 (7) 120. 3 C (14) -C (15) -C (10) 121. 9 (7) 121. 9 (b) Angles i n v o l v i n g hydrogen atoms Atoms value Atoms value 0 (1 ) - C (1) - H (1 A) 1 16 (4) C ( 5 ) - C ( 6 ) - H ( 6 ) 113 (2) 0 ( 1 ) - C ( 1 ) - H (1B) 115 (3) c ( 7 ) - C ( 6 ) - H (6) 126 (2) N - C (1 ) - H (1A) 112 (4) c ( 6 ) - C ( 7 ) - H ( 7 ) 118 (4) N - C (1) - H ( IB) 106 (4) c ( 8 ) - C ( 7 ) - H ( 7 ) 120 (4) H ( 1 A ) - C ( 1 ) - H (1B) 102 (5) c ( 7 ) - C ( 8 ) - H ( 8 ) 118 (3) N - C ( 2 ) - H ( 2 A ) 90 (4) c ( 9 ) - C ( 8 ) - H (8) 123 (3) N - C ( 2 ) - H (2B) 101 (7) c ( 8 ) - C ( 9 ) - H (9) 122 (7) N - C { 2 ) - H (2C) 1 16 (4) c ( 4 ) - C(9) - H ( 9 ) 116 (7) H (2A) - C (2) - H (2B) 126 (9) c (10) - C (1 1 ) - H (11 ) 130 (5) H ( 2 A ) - C ( 2 ) - H (2C) 115 (6) c (12) - C ( 1 1 ) - H ( 1 1 ) 108 (5) H (2B) - C ( 2 ) - H (2C) 107 (8) c (11) - C ( 1 2 ) - H (12) 123 (4) N - C ( 3 ) - H (3A) 100 (16) c (13) - C ( 1 2 ) - H ( 1 2 ) 118 (4) N - C ( 3 ) - H (3B) 100 (2) c (12) - C ( 1 3 ) - H (13) 126 (4) N - C ( 3 ) - H (3C) 1 14 (6) c (14) - C (13) - H (13) 1 15 (4) H ( 3 A ) - C ( 3 ) - H ( 3 B ) 119 (17) c (13) - C (14 ) - H (14) 121 (4) H ( 3 A ) - C ( 3 ) - H (3C) 122 (17) c (15) - C (14) - H ( 14) 116 (4) H ( 3 B ) - C ( 3 ) - H ( 3 C ) 100 (6) c (14) - C ( 1 5 ) - H ( 1 5 ) 126 (4) C ( 4 ) - C ( 5 ) - H (5) 121 (3) c (10) - C ( 1 5 ) - H (15) 1 11 (4) C ( 6 ) - C ( 5 ) - H (5) 1 15 (3) Table 27 I n t r a - a n n u l a r t o r s i o n angles (cleg) Five-membered r i n g Bond obs. c a l c . B-0(1) 34.3 (5) 36. 4 0(1)-C(1) -42.3 (5) -43.9 C (1)-N 33.7 (5) 34. 8 N-0 (2) -10.5 (5) -12.3 0 (2)-B -13.4 (4) - 15.0 70 and 6b r e s p e c t i v e l y . The c o n f o r m a t i o n o f t h e f i v e - m e m b e r e d r i n g i s n e a r l y t h e same a s t h a t o f t h e i s o s t e r i c • b o r o x a z o l i d i n e * r i n g i n 6 b , f o u r o f t h e f i v e t o r s i o n a n g l e s b e i n g e q u a l w i t h i n e x p e r i m e n t a l e r r o r w h i l e t h e l a s t d i f f e r s by 2 . 5 ° (4 s t a n d a r d d e v i a t i o n s ) . A toms C ( 1 ) a n d N b o t h l i e on t h e same s i d e o f o t h e OBO p l a n e , d i s p l a c e d - 0 . 7 5 and - 0 . 3 1 A f r o m t h e p l a n e . T h e o b s e r v e d t o r s i o n a n g l e s i n the r i n g a r e i n good a g r e e m e n t w i t h t h o s e o b t a i n e d f r o m e n e r g y m i n i m i z a t i o n c a l c u l a t i o n s f o r ui i = 1 0 ° ( 1 7 ) , a l s o g i v e n i n T a b l e 2 7 . The o b s e r v e d m a g n i t u d e s o f t h e t o r s i o n a n g l e s a r e s l i g h t l y s m a l l e r t h a n t h e c a l c u l a t e d v a l u e s s i n c e t h e mean a n g l e i n t h e r i n g , 1 0 4 . 6 ° , i s s l i g h t l y g r e a t e r t h a n t h e c a l c u l a t e d v a l u e o f 1 0 4 . 2 ° b u t i n good a g r e e m e n t w i t h the v a l u e s o f 104 .8 and 1 0 4 . 9 ° i n t h e s t r u c t u r e s 6a and 6 b . T h e i n d i v i d u a l v a l u e s r a n g e f r o m 1 0 1 . 5 ( 4 ) a t B t o 1 0 7 . 1 ( 4 ) ° a t 0 ( 2 ) . The a n g l e a t B i s s l i g h t l y , b u t s i g n i f i c a n t l y , g r e a t e r t h a n t h e mean v a l u e o f 9 9 . 8 ( 1 ) ° i n t h e b o r o x a z o l i d i n e s . T h e bond d i s t a n c e s i n t h e f i v e - m e m b e r e d r i n g d i f f e r f rom t h e i r e x p e c t e d v a l u e s a s a r e s u l t o f s t e r i c s t r a i n and e l e c t r o n d i s t r i b u t i o n i n t h e m o l e c u l e , a n a l o g o u s t o t h a t o c c u r r i n g i n s y s t e m s w i t h N—>B i n t e r a c t i o n s (see e g . 12 and 3 2 ) . T h e 0 ( 1 ) - C ( 1 ) b o n d , 1 .378 (9) A , i s s i g n i f i c a n t l y s h o r t e r t h a n t h e u s u a l v a l u e o f 1 .426 A a s w e l l a s t h e v a l u e s o f 1 .413 i n 6a a n d 1 .418 A i n 6 b . T h e C ( 1 ) - N b o n d , 1. 505(10) A , i s somewhat l o n g e r t h a n t h o s e i n 6a and 6b ( 1 . 4 8 5 and 1.491 0 A) b u t i s n o t s i g n i f i c a n t l y l o n g e r t h a n a n o r m a l C ( s p 3 ) - 71 N (sp 3) bond. The N-0 (2) distance of 1.409(5) A i s 0 s i g n i f i c a n t l y longer than the sum of covalent r a d i i (1.36 A) but l i e s in the range of 1.34-1.44 A usually observed for N-0 single bonds (18,51). The two B-0 distances, 1.506(7) and 1.556(8) A, are s i g n i f i c a n t l y d i f f e r e n t . The pattern of one o bond close to the normal value and one on the order of 0.1 A longer than normal also occurs i n the boroxazolidines 6a and 6b where B-0 distances are 1.484 and 1.471 A and the B-N o o bonds are 1.653 and 1.652 A, each about 0.1 A longer than normal. The exocyclic C-N distances have been corrected for r i d i n g motion and are egual within experimental error. Bearing i n mind that the r i d i n g model approach usually overcorrects, i t s t i l l appears that these bonds are somewhat longer than normal (see Table 25). The two phenyl rings are planar within experimental error (see Table 28). Two hydrogen atoms, H (6) and H(14), are s i g n i f i c a n t l y displaced from th e i r respective mean planes, probably as a' r e s u l t of inaccuracy in the hydrogen atom positions due to thermal e f f e c t s . The boron atom i s s i g n i f i c a n t l y displaced from both phenyl mean planes, by 0.07 from the C(4)-C(9) plane and by 0.11 A from the C(10)-C(15) plane, representing a s l i g h t folding of the phenyl groups away from each other. The dihedral angle between the mean planes i s 74°. The two phenyl groups are not equivalent, the rings being rotated unequally about the E-C bonds. The dihedral angles C (9) [ C (4)-B ]0 (1) , C (15) [C (10 )-B ]0 (1) , C (5)[C (4)-B ]0 (2) , and C (11) [ C (10)-B ]0 (2) are -52.1(6), 39.9(6), 17.9(6), and -33.4(6)° respectively. The orientation 72 Table 28 Weighted l e a s t - s q u a r e s mean planes (a) 0 D i s t a n c e s (A) of r e l e v a n t atoms from the mean planes Atom d <V<r Atom d <V«r Plane 1: C(U)-C(9) Plane 2: C (10) -C (15) C(4) -0.001 0.1 C (10) 0.005 0.5 C (5) -0.004 0.5 C (11) 0.006 0.0 C(6) 0.012 1.3 C (12) -0.007 0. 1 C (7) -0.009 1. 3 C{13) -0.007 0.4 C(8) 0.007 0.8 C (14) 0.007 1.2 C (9) 0.000 0.0 C(15) -0.006 1.1 B 0.070 10.5 B 0.105 18.0 H (5) 0.088 1.6 H(11) 0.062 0.8 H(6) 0.285 6.1 H (12) 0. 143 2.5 H(7) 0. 116 1.7 H(13) -0.137 1.7 H(8) -0. 104 1.9 H (14) 0.357 3.7 H (9) -0.195 1.8 H(15) 0. 150 2.5 (b) Equations of planes: JLX + mY + nZ = £, where X, Y, and Z are o r t h o g o n a l angstrom c o o r d i n a t e s d e r i v e d as f o l l o w s : I H = r a 0 | 0 b >- 0 0 0 0 c 1 III J LzJ Plane m n 2 1 0.1930 -0.0163 0.9811 0. 1760 2 -0.8458 0.29 17 -0.4468 -4.2290 The d i h e d r a l angle between the planes i s 74°. 73 Table 29 S e l e c t e d i n t r a - and i n t e r m o l e c u l a r c o n t a c t s I n t r a m o l e c u l a r I n t e r m o l e c u l a r * Atoms d i s t a n c e Atoms d i s t a n c e 0(1) • • .H(2A) 2.55 (7) C (3) .. .C (11) i 3. 393 (9) 0(1] • • ,C(2) 3. 100 (8) C (3).. .C (12) * 3.488 (10) 0 (1] * • • C(9) 3. 137 (7) 0(1) .. , H ( 3B) z 2.24 (6) 0(1) • • • C(15) 3.013 (8) C (1) . . . H (3B) 2 2.69 (6) 0 (2) • • . H(2A) 2. 26 (8) C(4) .. . H ( 3C) 3 2.67 (12) 0 (2) * • » H(3A) 2.26 (19) C (7) .. . H (2B) 3 2.63 (19) 0 (2) * • • H (5) 2. 58 (5) C (9) .. . H(3C) 3 2.73 (13) 0(2) * * • C(5) 2.916 (8) H (2C) . . .H(14) * 2.46 (1 1) 0 (2) • • .C(11) 2. 932 (7) H (5) . . .H (8)5 2.34 (7) C(1) • • • C(4) 3. 1 17 (9) H (6) . . . H(8)s 2.39 (7) * S u p e r s c r i p t s r e f e r to atoms at p o s i t i o n s : 1 V 2-X 1 - 1 / 2 1 / 2 *z * 1-x -j 1/2+z 2 x 1+Y z 5 x _y-1 z 3 1/2 -x 1/2+1 1 - 1 / 2 74 F i g u r e 8 The packing arrangement viewed along b, hydrogen atoms have been omitted f o r c l a r i t y . of the phenyl groups r e p r e s e n t s a m i n i m i z a t i o n of i n t r a - and i n t e r m o l e c u l a r s t e r i c i n t e r a c t i o n s . The c o r r e c t e d C-C bond l e n g t h s i n the phenyl groups range from 1.363 to 1.446 with a mean va l u e of 1.395 A. There i s a s i g n i f i c a n t v a r i a t i o n i n the i n d i v i d u a l bond d i s t a n c e s , the C(10)-C(17) bond, 1.363 A, being s i g n i f i c a n t l y s h o r t e r and the C ( 8 ) - C ( 9 ) , 1 .446, and C(12)-C(13), 1.441 A, bonds s i g n i f i c a n t l y l onger than the normal value of 1.394 A (18,51). The means over c h e m i c a l l y e q u i v a l e n t groups of bonds (as they are removed from the boron s u b s t i t u e n t ) are 1.384, 1.410, and 1.391 A. T h i s p a t t e r n i s d i f f e r e n t from t h a t observed in the two b o r o x a z o l i d i n e s t r u c t u r e s (Parts 1 and 2) where the bond l e n g t h s decrease as they are removed from the boron s u b s t i t u e n t . The B-C d i s t a n c e s are equal w i t h i n 75 experimental e r r o r and t h e i r mean value, 1.632 A, i s longer than i n the s t r u c t u r e s 6a (1.616) and 6b (1.621) but s h o r t e r than i n the t e t r a p h e n y l borate anion (1.631-1.648(8) A) (19). The angles i n the phenyl r i n g s have a mean value of 120.0°, but the i n d i v i d u a l v a l u e s , ranging from 118.0 to 122.5°, show some s i g n i f i c a n t d e v i a t i o n s from 120°. The mean angle at the carbon atom c a r r y i n g the bcron group i s 118.3° and the other mean values are 121.6, 119.2, and 120.2° f o r atoms o r t h o x meta A and £ara to the boron group. These angular d e v i a t i o n s have the same p a t t e r n as those i n 6a and 6b but the magnitudes of the d i s t o r t i o n s are one-half as g r e a t . These v a r i a t i o n s have been e x p l a i n e d i n terms of the e l e c t r o n e g a t i v i t i e s of the s u b s t i t u e n t groups (31). The angl e s a t C(4) and C(10), mean 118.3°, c a r r y i n g the boron s u b s t i t u e n t i n d i c a t e t h a t t h i s group i s weakly e l e c t r o n r e l e a s i n g . The o v e r a l l geometry of the molecule suggests t h a t the formal charges on B and H i n 3 are d e l o c a l i z e d i n a way such t h a t , f o r m a l l y , the B and 0(2) c a r r y p a r t i a l negative charges while N and 0(1) c a r r y p a r t i a l p o s i t i v e charges. T h i s i s i n accord with the observed p a t t e r n of bond d i s t a n c e s , p a r t i c u l a r l y the d i f f e r e n c e between the two B-0 d i s t a n c e s . The mean bond angles i n the molecule are as expected. There are a number of s i g n i f i c a n t d e v i a t i o n s from the mean values r e s u l t i n g from s t e r i c and e l e c t r o n i c e f f e c t s . I n t e r i o r a n g l e s i n the r i n g s have a l r e a d y been d i s c u s s e d . The C (4)-B- C(10) angle, 112.4(4)°, i s s i g n i f i c a n t l y s m a l l e r than i n 6a 76 and 6 b , b u t i s g e n e r a l l y a s e x p e c t e d . Asymmetry i n t h e p a c k i n g a r r a n g e m e n t a p p e a r s t o be r e s p o n s i b l e f o r s i g n i f i c a n t d i f f e r e n c e s b e t w e e n c o r r e s p o n d i n g a n g l e p a i r s 0 - B - C and C - N - C . The g e o m e t r y i n v o l v i n g h y d r o g e n a t o m s i s a s f o l l o w s : O 0 mean C ( a r ) - H , 0 . 9 9 A , mean C ( s j 3 3 ) - H , 1.14 A , mean C ( a r ) - C ( a r ) - H , 1 1 9 ° , mean H - C ( S £ 3 ) - H , 1 0 7 ° , and mean H- C ( s j 3 3 ) - H , 1 1 3 ° . T h e d i s t a n c e s a r e l o n g f o r X - r a y d a t a , p r o b a b l y a s a r e s u l t o f r e l a t i v e l y l a r g e t h e r m a l m o t i o n i n t h e s a m p l e . The c r y s t a l s t r u c t u r e c o n s i s t s o f d i s c r e t e m o l e c u l e s s e p a r a t e d by n o r m a l van d e r W a a l s d i s t a n c e s , t h e s h o r t e s t o f w h i c h a r e l i s t e d i n T a b l e 2 9 . 77 PART U CRYSTAL AND MOLECULAR STRUCTURE OF THE N-METHYLDIETHANOLAMINOGALLAN E DIMER 78 INTRODUCTION Trimethylamine-gallane i s known to react with compounds containing active hydrogen to eliminate molecular hydrogen and trimethylamine and form coordinatively unsaturated intermediates which then undergo c y c l i z a t i o n to give oligomers whose size depends upon a balance between s t e r i c , mechanistic, and valency angle e f f e c t s (52-54). The present work i s part of an extension of t h i s type of reaction involving aminoalcohols where the active hydrogen i s attached to oxygen and/or nitrogen atoms. The t i t l e compound i s derived from N-methyldiethanolamine and trimethylamine- gallane reacted in 1:1 molar r a t i o . In the t i t l e compound four-coordination about the gallium atom can be achieved in monomer units, analogous to similar boron compounds (9,20,Parts 1 and 2), by coordination of two oxygen atoms, one nitrogen atom, and the remaining hydrogen atom, after elimination of two moles of hydrogen and one mole of trimethylamine from the reaction sphere. The metal i s indeed coordinated to these atoms but instead of discrete monomer units a novel dimerization through bridging oxygen atoms i s r e a l i z e d , to give a distorted t r i g o n a l bipyramidal arrangement about each five-coordinate* gallium atom (_1). 1 A preliminary report of the structure of the f i v e - coordinate complex chlorobis-(8-hydroxy-2-methylquinolin- ato)gallium (III) by K. Dymock and G. J. Palenik, Chem. Comm., 884 (1973) appeared during the preparation of this thesis. The amount of s t r u c t u r a l information therein does not warrant inclusion of t h i s data in the discussion. 79 1 EXPERIMENTAL The N-methyldiethanclaminogallane dimer was prepared by r e a c t i n g N-methyldiethanolamine (0.226 g; 1.9 mmoles) with t r i m e t h y l a m i n e - g a l l a n e (0.250 g; 1.9 mmoles) i n benzene. Hydrogen (84.5 ml; 3.77 mmoles) was evolved at room temperature to l e a v e the product i n benzene as a c l e a r s o l u t i o n : MeN (CH 2CH 2OH) 2 + Me^NGaH^ > MeN (CH 2CH 20 ) 2GaH + 2H 2 + Me^N Removal of a l l v o l a t i l e s gave a white a i r - s e n s i t i v e s c l i d . [ A n a l y s i s : r e g u i r e d f o r MeN (CH 2CH 20) 2GaH: Ga, 37.1??; h y d r o l . H, 0.535? found: Ga, 36.9??; h y d r o l . H, 0.54%.] The compound was r e d i s s o l v e d i n benzene and the s o l u t i o n c o o l e d to 5° C. Large c o l o r l e s s c r y s t a l s were d e p o s i t e d from s o l u t i o n a f t e r a prolonged p e r i o d of time. C r y s t a l s s u i t a b l e f c r X-ray a n a l y s i s were p o s i t i o n e d i n c a p i l l a r i e s under a n i t r o g e n 80 atmosphere to avoid the r a p i d h y d r o l y s i s which occ u r r e d i n c o n t a c t with moist a i r . The c a p i l l a r i e s were then flame s e a l e d . The c r y s t a l chosen f o r study was mounted with the [2 1 1] vector p a r a l l e l to the g o n i o s t a t a x i s and had dimensions of ca. 0.3 x 0.3 x 0.5 mm. U n i t - c e l l .and space group data were obtained from f i l m and d i f f r a c t o m e t e r measurements. The u n i t - c e l l parameters were r e f i n e d by a l e a s t - s q u a r e s treatment of s i n 2 9 values f o r 30 r e f l e x i o n s measured on a d i f f r a c t o m e t e r with Cu r a d i a t i o n . C r y s t a l data are: C 1 0 H 2 4 G a 2 N 2 0 ^ f.w. = 375.8 Orthorhombic, a = 19.112(4), b = 9.947 (2), c = 7.709 (2) A, V = 1465.5 (5) A 3 , Z = 4, Dx = 1.703 (1) g cm~3, F(000) = 768 (20° C, Cu K^, 9\ = 1.5418 A, ^tU. = 49.7 cm-*). Absent r e f l e x i o n s : hOO, h * 2n, OkO, k * 2n, and 00^, £ * 2n d e f i n e ii, uniguely the space group P2 12^2 1 (Dg, So. 19). I n t e n s i t i e s were measured on a Datex-automated General E l e c t r i c XRD 6 d i f f r a c t o m e t e r , with a s c i n t i l l a t i o n counter, Cu r a d i a t i o n ( n i c k e l f i l t e r and pulse height a n a l y s e r ) , and a 9-20 scan at 2° m i n - 1 over a range of (1.80 + 0.86 tan 9) degrees i n 29, with 20 s background counts being measured at each end of the scan. Data were measured to 29 = 145° 0 (minimum i n t e r p l a n a r spacing 0.81 A). A check r e f l e x i o n was monitored every 40 r e f l e x i o n s throughout the data c o l l e c t i o n . The r.m.s. d e v i a t i o n of the i n t e n s i t y of the check r e f l e x i o n 81 from i t s i n i t i a l value was 2.2% and the f i n a l i n t e n s i t y was 1.014 times the i n i t i a l value. L orentz and p o l a r i z a t i o n c o r r e c t i o n s were applied., and the s t r u c t u r e amplitudes were d e r i v e d . No a b s o r p t i o n c o r r e c t i o n was attempted due t o the i r r e g u l a r i t y of the c r y s t a l s u r f a c e (in p a r t i c u l a r r e - e n t r a n t a n g l e s ) . Of the 1697 independent r e f l e x i o n s measured, 180 had i n t e n s i t i e s l e s s than 3<r(I) above background where <rz (I) = S + B + (0.05S) 2 with S = scan count and B = background count, c o r r e c t e d t o time of scan. These r e f l e x i o n s were not i n c l u d e d i n the refinement. S t r u e t u r e A n a l y s i s The p o s i t i o n s of the two g a l l i u m atoms were determined from the three-d i m e n s i o n a l P a t t e r s o n f u n c t i o n , Three c y c l e s of f u l l - m a t r i x l e a s t - s q u a r e s refinement of the p o s i t i o n a l and i s o t r o p i c thermal parameters of the g a l l i u m atoms gave R 0.27. A d i f f e r e n c e map r e v e a l e d the p o s i t i o n s of a l l the C, N, and 0 atoms. A l l the non-hydrogen atoms were r e f i n e d i s o t r o p i c a l l y f o r three c y c l e s g i v i n g R 0.096 and then a n i s o t r o p i c a l l y f o r two c y c l e s g i v i n g R 0.076. A d i f f e r e n c e map r e v e a l e d the p o s i t i o n s of the g a l l i u m H atoms and 12 of the 16 methylene protons. The remaining hydrogen atoms were assigned c a l c u l a t e d p o s i t i o n s . The hydrogen atoms were i n c l u d e d i n a l l subsequent c y c l e s of refinement with i s o t r o p i c temperature f a c t o r s . The refinement was concluded a f t e r four more c y c l e s with R = 0.056 f o r 1477 r e f l e x i o n s with I > 3<r(I) . 82 The absolute c o n f i g u r a t i o n of the complex (for the p a r t i c u l a r c r y s t a l used) has been determined through the anomalous s c a t t e r i n g of the non-hydrogen atoms. Enantiomorph (A) i s represented by the c o o r d i n a t e s i n Table 31 r e f e r r e d to a right-handed a x i a l system and enantiomorph (B), the mir r o r image of (A), was generated by changing the x c o o r d i n a t e s of (A) to 1-x. Both enantiomorphs were r e f i n e d and Hamilton's t e s t (24) a p p l i e d to the r e s u l t i n g R f a c t o r r a t i o s . Enantiomorph (A) was c l e a r l y i n d i c a t e d as c o r r e c t . The r e s u l t s of Hamilton's t e s t are compiled i n Table 30. The s c a t t e r i n g f a c t o r s of r e f . 55 were used f o r the non- hydrogen atoms and those of r e f . 13 f o r the hydrogen atoms. Anomalous s c a t t e r i n g f a c t o r s from r e f . 56 were used f o r Ga, 0, N, and C atoms. The weighting scheme: w = 1 i f |Fo| < 11; w = (11/1Fo | ) 2 i f |Fo | > 11, and w = 0.49 f o r the weak r e f l e x i o n s gave constant average values of w(Fo-Fc) 2 over ranges of |Fo| and was employed i n the f i n a l stages of refinement. On the f i n a l c y c l e of refinement the mean parameter s h i f t was 0.29<r, the l a r g e s t s h i f t s were 0.85<r- f o r non-hydrogen and 1.70<*~for hydrogen atoms, both of which were a s s o c i a t e d with the C{10) methyl group. The f i n a l p o s i t i o n a l and thermal parameters are given i n T a b l e s 31 and 32 r e s p e c t i v e l y . Measured and c a l c u l a t e d s t r u c t u r e amplitudes are a v a i l a b l e on request. THERMAL MOTION AND CORRECTION OF MOLECULAR GEOMETRY The e l l i p s o i d s of thermal motion f o r the uon-hydrogen 83 Ta b l e 30 R e s u l t s of Hamilton's Test Parameter compared Value f o r enantiomorph S i g . (ft) (B) (B/A) l e v e l 1 C o n v e n t i o n a l R (3<r data) 6. 126 6. 210 1. .0137 >99, .5 Conventional R ( a l l F) 6. 491 6. 573 1. .0125 >99. .5 Weighted R (3<r data) 8. 738 8. 878 1. .0161 >99. .5 Weighted R ( a l l F) 9. 162 9. 232 1. .0145 >99. ,5 * T h i s i s the 5? p r o b a b i l i t y t h a t enantiomorph (A) i s the c o r r e c t a b s o l u t e c o n f i g u r a t i o n . T a b l e 31 F i n a l p o s i t i o n a l p a r a m e t e r s ( f r a c t i o n a l x 1 0 * f Ga x 1 0 s , H x103) w i t h 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 p a r e n t h e s e s Atom X 2 z Ga(1 ) 41623 (5) 20988 (9) 38421 (13 ) Ga (2) 40777 (5) 27950 (8) 76738 (12) 0 (1 ) 4292 (3) 1238 (5) 6085 (7) 0 (2) 329 1 (4) 2739(6) 3234 (10) 0 (3) 4335 (3) 3645 (5) 5470 (8) 0 (4 ) 3170 (4) 2235 (6) 8000 (9) N (1) 3704 (4) 126 (7) 3277 (10) N (2) 3662 (4) 4807 (7) 8153 (11) C (1) 3999 (6) - 7 9 4 (8) 4579 (14) C (2) 4036 (6) - 9 7 ( 8 ) 6316 (13) C (3) 2961 (5) 424 (9) 3574 (18) C (4 ) 2800 (5) 1779 (9) 2715 (16) C (5) 3837 (9) - 3 4 3 (12) 1516 (18) C (6) 4032 (5) 5690 (8) 6919(15) C (7) 4118 (6) 4996 (8) 5206 (13) C (8) 2928 (5) 4611 (9) 7696 (15) C (9) 2686 (5) 3265 (9) 8447 (17) C (10) 3763 (7) 5237 (1 1) 9954 (16) H (Ga l ) 475 (5) 217 (9) 282 (1 1) H (Ga2) 461 (4) 268 (7) 899 (9) H (1A) 445 (5) - 9 0 (10) 430 (14) H (1E) 365 (5) - 1 5 1 (9) 463 ( 12) H (2A) 426 (8) -81 (14) 713 (18) H (2B) 353 (5) 5(11) 653 (15) H (3A) 290 (6) 34 (12) 476 (18) H (3B) 258 (6) - 2 7 (10) 312(13) H (4A) 273 (4) 165 (8) 141 (11) H (4B) 241 (10) 194 (17) 304 (26) H(5A) 342(10) - 1 0 2 (20) 142 (29) H (5B) 380 (8) 32 (18) 76 (22) H (5C) 426 (5) -41 (10) 131 (13) H (6 A) 460 (6) 566 (13) 735 ( 15) H (6B) 375 (7) 641 (13) 679 (17) H (7A) 443 (7) 548 (14) 467 (18) H (7B) 377 (7) 490 (12) 460 (15) H (8A) 289 (5) 434 (11) 629 (17) H (8B) 276 (11) 516 (19) 359 (28) H (9A) 263 (6) 318(11) 997 (15) H (9B) 213 (6) 290 (11) 795 (14) H (10A) 334 (8) 598 (19) 990 (22) H(10B) 340 (9) 453 (17) 1086 (24) H (10C) 431 (6) 548 (12) 1021 (15) 85 T a b l e 32 F i n a l t h e r m a l p a r a m e t e r s and t h e i r 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 (a) A n i s o t r o p i c t h e r m a l p a r a m e t e r s (U« * x 100 A 2 ) Atom h i P-22 533 "12 P-13 H23 Ga(1 ) 5 . 4 7 (6) 3. 23 (5) 4 . 9 0 (6) - 0 . 3 0 ( 4 ) 0 . 3 6 (4) 0 . 20 (4) Ga (2) 5 . 1 6 ( 6 ) 2 . 8 6 (5) 4 . 9 7 (6) 0 . 0 8 (4 ) - 0 . 27 (4) 0 . 14 (4) 0 ( 1 ) 5 . 8 (3) 3 . 1 (2) 4 . 7 (3) 0 . 5 (2) 0 . 0 ( 3 ) 0 .2 (2) 0 (2 ) , 7 . 5 ( 4 ) 2 .9 (3 ) 8.1 (4) - 0 . 1 (3) - 1 . 9 (3) 1. 4 (3) 0 (3) 6 . 3 (3) 2. 8 (2) 5 . 1 (3) - 0 . 9 (2) 0 . 1(3) 0 . 2 (2) 0 (4 ) 6 . 5 ( 3 ) 3 .1 (3) 7 . 5 (4) - 0 . 1 (3) 1.0 (3) 0 . 4 (3) N (1) 5 . 7 (4) 3. 1 (3) 5 . 5 (4) - 0 . 1 (3) - 0 . 5 ( 3 ) 0 . 3 (3) N (2) 5 . 6 ( 4 ) 2 .9 (3) 6 . 3 (4) 0 . 1 (3) 0 . 5 (3) 0 . 5 (3) C ( 1 ) , 6 . 5 ( 6 ) 3. 2 (4) 6 . 5 ( 5 ) 0 . 7 (4) - 0 . 9 (5) - 0 . 1 (4) C(2) 6 . 8 ( 6 ) 3 . 6 (4) 5 . 3 (5) - 0 . 1 (4) - 0 . 6 (4) 0 . 6 (4) C ( 3 ) 5 . 8 (5) 3 . 7 (4) 9 . 0 (8) - 0 . 1 (4) - 0 . 5 ( 5 ) 0 . 7 (5) C (4) 5 . 9 ( 5 ) 4.2 (4) 8 . 3 (7) - 0 . 1 (4) - 1 . 8 (5) 1. 1 (4) C ( 5 ) 9 . 3 (10) 4 . 9 (5) 7 . 1 (7) - 0 . 4 (6) 0 . 6 ( 7 ) - 0 . 8 (5) C(6) 6 . 3 ( 6 ) 2 .7 (4) 7 . 6 (6) - 0 . 5 (4) 0 . 7 (5) 0 . 0 (4) C ( 7 ) 6 .3 (5) 3 . 7 (4) 6 . 0 (5) - 0 . 7 (4) 1 .0 (5) 1.0 (4) C (8) 5 . 8 ( 5 ) 3 . 5 (4) 7.1 (6) - 0 . 5 (3) 0 . 5 (4) 0 . 9 (4) C (9) 6 . 0 (5) 3. 8 (4) 9 . 0 (7) 0 . 6 (4) 1 .8 (5 ) 1 .4(4) C(10) 10 .1 (9) 4.2 (5) 6 . 6 (6) 0 . 5 (5) - 0 . 4 (6) - 1 . 4 (5) (b) I s o t r o p i c t h e r m a l p a r a m e t e r s o Atom B ( A 2 ) Atom B ( A 2 ) H (Ga1) 3 . 9 (19) H (Ga2) 2. 3(13) H(1A) 4 . 3 (21) H (6A) 7 . 0 (29) H (1 B) 3 .0 (17) H (6B) 5 . 4(28) H (2A) 8 . 8 (30) H (7A) 6 . 5 (29) H (2B) 3 . 6 (21) H(7B) 4 . 3 (28) H(3A) 4 . 8 (27) H (8A) 2 . 6 (23) H (3B) 4 .0 (20) H (8B) 11 .9 (52) H (4A) 1 .7 (12 ) H (9A) 3 . 0 (24) H (4B) 12. 3 (51) H (9B) 1 0 . 2 ( 2 3 ) H(5A) 17 .4 (50) H (10A) 1 3 . 7 (44 ) H (5B) 8 .0 (40) H (10B) 4 . 7(47) H(5C) 2.1 (18) H (10C) 5 . 2 (24) 86 H<2A> F i g u r e 9 A s t e r e o view of the molecule a l o n g the C a a x i s showing the atom numbering and 50% p r o b a b i l i t y thermal e l l i p s o i d s f o r the non-hydrogen atoms. Broken l i n e s show p o s s i b l e C-H...0 hydrogen bonds. atoms are shown i n F i g u r e 9. The thermal motion has been analysed i n terms of the r i g i d - b o d y modes of t r a n s l a t i o n (T), l i b r a t i o n ( L), and screw (S) motion using the computer program MGTLS (14). The r.m.s. standard d e v i a t i o n i n the temperature f a c t o r s ^ i s 0.0042 A 2 which i n d i c a t e s t hat the thermal motion of the molecule as a whole (r.m.s. A . = 0.0054 A 2) i s adequately d e s c r i b e d by the r i g i d - h o d y parameters i n Table 33. The i n d i c a t e d modes of motion are p h y s i c a l l y r e a s o n a b l e ; the t r a n s l a t i o n a l and l i h r a t i c n a l motions are both somewhat a n i s o t r o p i c . The o r i e n t a t i o n of the p r i n c i p a l axes of L i s n e a r l y c o i n c i d e n t with that of the p r i n c i p a l axes of i n e r t i a , the l a r g e s t l i b r a t i o n a l motion o c c u r r i n g about the l e a s t a x i s of i n e r t i a . Table 33 Rigid-body thermal parameters 1 87 a l l non-hydrogen atoms r 49(9) -14(9) -4(8) 1 L (x 10 deg 2) | 157 (21) 46 (13) | «- !, 69 (15) J P r i n c i p a l axes of L r.m.s. Amplitude D i r e c t i o n c o s i n e s (x10 3) 4.2° -108 914 392 2.2 -506 288 -813 2.2 -856 -286 430 P r i n c i p a l axes of reduced T r.m.s. Amplitude D i r e c t i o n c o s i n e s (x10 3) 0.23A -1 -268 -963 0.22 997 -73 20 0.16 -76 -960 267 Displacement of axes from i n t e r s e c t i n g (A) P a r a l l e l to 0.65 P a r a l l e l to Ig -0.53 P a r a l l e l to L3 -0.32 o E f f e c t i v e screw t r a n s l a t i o n s (A) P a r a l l e l to 0.036 P a r a l l e l to L 2 -0.039 P a r a l l e l to -0.031 F r a c t i o n a l c o o r d i n a t e s of unique o r i g i n (x10*) x 3862 jr 2358 z 5740 F r a c t i o n a l c o o r d i n a t e s of c e n t r e of g r a v i t y (x10 A) x 3818 2 2462 z 5721 r.m.s. A 0 j j _ (A 2) 0.0054 JAxes of r e f e r e n c e are orthogonal angstrom axes. E.s.d.*s of components of L are given i n parentheses i n u n i t s of the l a s t p l a c e s shown. 83 The a p p r o p r i a t e bond d i s t a n c e s and angles have been c o r r e c t e d f o r l i b r a t i o n (15,16) , using shape parameters q 2 of 0.08 f o r a l l the atoms i n v o l v e d , and appear i n Tables 34 and 35 r e s p e c t i v e l y . RESULTS AND DISCUSSION The X-ray a n a l y s i s has provided the f i r s t known c r y s t a l l o g r a p h i c example of pentacoordinate g a l l i u m as well as the f i r s t r e p o r t e d Ga-H d i s t a n c e s . The numbering scheme i s shown i n Figure 9, i n which the molecule i s viewed along i t s approximate C 2 a x i s . F i g u r e 10 shows the c o o r d i n a t i o n about the g a l l i u m atoms and F i g u r e s 11 and 12 show the c r y s t a l s t r u c t u r e viewed along c and b r e s p e c t i v e l y . Ga-N and Ga-0 bond d i s t a n c e s i n r e l a t e d four and s i x - c o o r d i n a t e s t r u c t u r e s are compiled i n Table 36. Some weighted l e a s t - s q u a r e s mean planes through the molecule are given i n Table 37 and the d i h e d r a l angles i n the f i v e fused r i n g s of the molecule i n Table 38, S e l e c t e d i n t e r - and i n t r a m o l e c u l a r c o n t a c t s are l i s t e d i n Table 39. The molecule has C 2 symmetry w i t h i n the l i m i t s of experimental e r r o r . The bond d i s t a n c e s , valence angles, and d i h e d r a l angles averaged assuming C 2 symmetry a l s o appear i n the a p p r o p r i a t e t a b l e s and w i l l be employed i n the d i s c u s s i o n o f the molecular geometry. The molecule e x h i b i t s , i n p a r t , the s t r u c t u r e expected f o r the monomeric boron analogue (on the b a s i s of the s t r u c t u r e s of t r i e t h a n o l a m i n e borate * (20), B , B - d i p h e n y l b o r o x a z o l i d i n e (Part 1), and B,B-bis(£- fl u o r o p h e n y l ) b o r o x a z o l i d i n e (Part 2), and s u p p o r t i n g 89 Table 34 o Bond le n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses (a) Non-hydrogen atoms Atoms uncorr. c o r r . Atoms uncorr. c o r r . mean* Ga (1) -0 (1) 1. 945 (6) 1. 952 Ga(2) -0(3) 1. 960 (6) 1. 967 1. 960 (8) Ga(1) -0(2) 1. 843(7) 1. 848 Ga (2) -0 (4) 1. 839 (7) 1. 845 1. 847 (2) Ga (1) -0 (3) 2. 012 (6) 2. 016 Ga (2) -0 (1) 2. 016 (6) 2. 019 2. 018 (2) Ga(1) "N (1) 2. 193 (7) 2. 196 Ga (2) -N(2) 2. 184 (7) 2. 187 2. 192 (5) 0 ( 1 ) - C(2) 1. 427 (10) 1. 429 0 (3)-C (7) 1. 422 (10) 1. 424 1. 427 (3) 0 (2)-C(4) 1. 398 (11) 1. 399 0 ( 4 ) - C(9) 1. 422 (1 1) 1. 424 1. 412 (13) N(1)- C{1) 1. 471 (12) 1. 475 N (2)-C(6) 1. 475 (12) 1. 479 1. 477 (2) H (D-C (3) 1. 468 (13) 1. 471 N(2)- C(8) 1. 460 (12) 1. 464 1. 468 (4) N(1)- C(5) 1. 458(15) 1. 460 N(2)- C(10) 1 .466 (14) 1. 468 1. 464 (4) C (1)-C{2) 1. 510 (14) 1. 512 C(6) -C(7) 1. 499 (14) 1. 501 1. 507 (6) C(3)- C(4) 1. 533(13) 1. 535 C (8)-C (9) 1. 531 (12) 1. 533 1. 534 (1) (b) Bonds i n v o l v i n g hydrogen atoms Atoms d i s t a n c e Atoms d i s t a n c e Ga(1) -H (Ga1) 1.37 (8) Ga (2) -H (Ga2) 1. 45 (7) C (1)-H (1&) 0.90 (10) C(6)- H (6A) 1. 14 (12) C(1)- H(1B) 0.98(9) C(6)- H (6B) 0. 90 (13) C ( 2 ) - H (2A) 1.04 (14) C (7)-H (7A) 0. 87 (14 ) C (2)- H (2B) 0.99 (10) C(7) - H(7B) 0. 82 (12) C ( 3 ) - H ( 3A) 0.93 (14) C (8)-H (8A) 1. 12 (13) C(3)- H (3B) 1.06 (11) C(8)- H (8B) 0. 94 (20) C(4)- H (4A) 1.02(8) C (9)-H (9A) 1. 18 (11) C (4)-H (4B) 0.81 (19) C(9)- H(9B) 1. 20 (11) C(5)- H (5A) 1.05 (20) C (10) -H (10A) 1. 10 (13) C(5)- H (5B) 0.89 (18) C (10) - H(10B) 1. 21 (16) C(5)- H (5C) 0.83 (9) C (10) -H (10C) 1. 09 (12) •Average of bonds r e l a t e d by the £2 a x i s , number i n parentheses i s r.m.s. d e v i a t i o n from the mean. T a b l e 35 Bond a n g l e s (deg) w i t h 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 p a r e n t h e s e s (a) N o n - h y d r o g e n a t o m s Atoms u n c o r r . c o r r . A toms u n c o r r . c o r r . m e a n * 0 (1 0(1 0(1 0 (2 0 (2 0 ( 3 Ga (1) Ga (1) Ga (2) Ga ( Ga ( Ga ( Ga ( C(1 C ( 1 C(3 N(1 N(1 C(1 C ( 3 •Ga( 1 Ga (1 •Ga{ 1 Ga (1 Ga (1 Ga (1 - 0 ( 1 - 0 ( 1 - 0 ( 1 - 0 ( 2 - N (1 - N ( 1 - N ( 1 N (1) N (1) N (1) C(1) C (3) C(2) C (4) - 0 ( 2 ) - 0 (3) - N (1) - 0 ( 3 ) - N (1) - N ( 1 ) - G a (2) - C (2) - C ( 2 ) - C ( 4 ) - C (1) - C ( 3 ) - C { 5 ) C (3 ) C(5 ) C(5 ) C(2) C (4) 0 (1) 0 (2 ) 1 19. 5 (3 7 6 . 2 (2 8 0 . 4 (3 9 2 . 5 (3 84 . 1 (3 1 5 0 . 9 (3 100 .1 (2 1 1 8 . 5 ( 5 1 2 4 . 8 (5 1 1 6 . 4 ( 5 1 0 5 . 6 (5 100 .1 (5 1 1 3 . 7 (7 1 1 3 . 0 (8 1 1 1 . 6 ( 8 1 12 .2 (9 1 0 9 . 7 (7 1 0 7 . 7 (8 1 0 9 . 5 ( 7 1 10 .0 (8 1 1 9 . 5 0 ( 3 ) - Ga (2) - 0 (4) 1 1 9 . 1 (3) 119. 1 1 1 9 . 3 (2) 7 6 . 2 0 ( 3 ) - Ga (2) - 0 ( 1 ) 7 5 . 8 (2) 7 5 . 7 76 . 0 (3) 8 0 . 4 0 ( 3 ) - Ga (2) - N ( 2 ) 8 0 . 9 (3) 80 . 9 80 . 7 (3) 9 2 . 5 0 ( 4 ) - Ga (2) - 0 (1) 9 2 . 4 (3) 9 2 . 4 9 2 . 5 (1) 8 4 . 0 0 ( 4 ) - Ga (2) -N (2) 8 4 . 9(3) 8 4 . 9 84 . 5(5) 1 5 0 . 8 0 ( 1 ) - Ga (2) - « (2) 151 . 6 (3) 15 1. 6 1 5 1 . 2 (4) 100 . 2 Ga (2) - 0 (3) - G a (1) 9 9 . 7(2) 9 9 . 8 100. 0 (2) 1 1 8 . 5 Ga (2) - 0 ( 3 ) - C (7) 117 . 3 (6) 117. 3 117. 9 (6) 124 . 7 Ga (1) - 0 (3) - C ( 7 ) 125. 8(6) 125. 7 125. 2(5) 1 1 6 . 4 Ga (2) - 0 (4 ) - C (9) 115 . 4 (5) 115. 3 1 15. 9 (6) 105 . 5 Ga (2) -N (2) - C ( 6 ) 105. 2 (5) 105. 2 105 . 4 (2) 1 0 0 . 1 Ga (2) - N (2) - C ( 8 ) 100 . 7 (5) 10 0 . 8 100. 5 (4) 113. 6 Ga (2) - N (2) - C (10) 112 . 3 (6) 112. 3 1 13 .0 (7) 112. 9 C ( 6 ) - N (2)" C(8) 112. 6(8) 112. 6 1 1 2 . 8 (2) 1 1 1 . 7 C (6) -N (2 ) - C (10) 112 . 0 (8) 112. 0 111 .9 (2) 112. 3 C ( 8 ) - M (2 ) - C(10) 113. 2(9) 113. 2 1 1 2 . 8 (5) 1 0 9 . 8 N ( 2 ) - C (6 ) - C (7) 110 . 2 (7) 110. 3 1 10. 1 (3) 107 . 7 N (2) -C ( 8 ) - C(9) 108. 4 (8) 108. 4 108. 1 (4) 1 0 9 . 4 C ( 6 ) - C (7 ) - 0(3) 1 0 9 . 9(8) 109. 9 109. 7 (3) 110. 1 C ( 8 ) - C (9 ) - 0 (4) 110 . 0 (8) 110. 0 110 .1 (1 ) c o n t i n u e d . (b) Angles i n v o l v i n g hydrogen atoms Atoms value Atoms va lue 0 (1) -Ga (1 )-H (Ga1) 115 (4) 0 (3) -Ga (2) -H (Ga2) 118 (3) 0 (2) -Ga (1)-H(Ga1) 125 (4) 0 (4) -Ga (2) -H (Ga2) 123 (3) 0 (3)-Ga (1 )-H (Ga1) 10 1 (4) 0 (1)-Ga (2)-H (Ga2) 103 (3) N (1) -Ga (1)-H (Ga1) 105 (4) N (2) -Ga (2) -H (Ga2) 102 (3) N ( 1)^C(1) -H(1A) 106 (7) N (2)-C (6)-H (6A) 105 (6) N (1 )-C (1 )-H (1B) 102 (5) N (2) -C (6)-H (6B) 104 (8) C (2)-C ( 1)-H (1A) 103 (7) C (7) -C (6)-H (6A) 98 <6) c (2)-C (1) -H (1 B) 109 (5) C (7) -C (6) -H (6B) 109 (8) H (1A) -C (1)-H(1B) 126 (8) H (6 A) -C (6) -H (6E) 129 (10) 0 (1 )-C (2) -H (2A) 125 (8) 0 (3)-C(7)-H(7A) 113 (9) 0 (1) -C (2) -H (2B) 103 (6) 0 (3) -C(7)-H (7B) 102 (9) c (1)-C(2) -H(2A) 104 (7) C (6)-C (7)-H (7A) 104 (9) c (1)-C (2)-H (2B) 100 (7) C (6) -C(7) -H (7B) 118 (8) H (2A) -C (2)-H (2B) 113 (11) H (7A) -C (7) -H (7B) 1 10 (12) N (1 )-C (3) -H (3A) 105 (7) N (2) -C (8) -H (8A) 109 (5) N (1)-C(3) -H(3B) 118 (6) N (2) -C (8) -H (8B) 94 (12) C (4)-C (3) -H (3A) 119 (8) C (9)-C(8)-H (8A) 98 (6) C (4) -C(3) -H (3B) 107 (5) C (9)-C (8)-H (8B) 98 (12) H (3A)-C (3)-H (3B) 101 (9) H (8A) -C (8) -H (8B) 146 (15) 0 (2) -C (4) -H (4A) 117 (4) 0 (4)-C (9)-H (9A) 104 (6) 0 (2)-C (4) -H (4B) 114 (13) 0 (4)-C (9)-H (9B) 107 (5) C (3) -C (4)-H (4A) 110 (4) C (8) -C(9)-H (9A) 118 (6) C (3) -C (4) -H (4B) 103 (13) C (8)-C (9)-H (9B) 1 15 (5) H (4A)-C (4)-H (4B) 103 (15) H (9A) -C (9) -H (9B) 103 (8) N (1) -C (5) -H (5A) 98 (12) « (2) -C (10) -H (10 A) 94 (9) H (1 )-C (5) -H (5B) 111 (10) N (2) -C(10) -H (10B) 107 (9) N (1)-C(5) -H(5C) 112 (7) N (2)-C (10) -H (10C) 1 1 1 (6) H <5A)-C (5)-H (5B) 111 (14) H (10A)-C(10)-H(10B) 89 (11) H (5A) -C (5)-H (5C) 133 (13) H (10A)-C (10) -H (10C) 124 (11) H (5B)-C (5)-H (5C) 91 (12) H (10B)-C (10)-H (10C) 125 (10) •mean of c o r r e c t e d angles r e l a t e d by the a x i s , number i n parentheses i s the r.m.s. d e v i a t i o n from the mean. 92 chemical evidence (9)) i n t h a t the MeN (CH^CH^C^ ac t s as a t r i d e n t a t e l i g a n d , the n i t r o g e n and two oxygen atoms a l l being c o o r d i n a t e d to the same g a l l i u m atom. Here the s i m i l a r i t y to the boron compounds ends as d i m e r i z a t i o n occurs through b r i d g i n g oxygen atoms, c r e a t i n g a four-membered Ga^C^ r i n g which r e s u l t s i n the formation of a molecule possessing a system of f i v e fused r i n g s . A polymeric s t r u c t u r e might be expected of the compound produced by the r e a c t i o n of t r i m e t h y l a m i n e - g a l l a n e and N-methyldiethanolamine even though g a l l i u m has a high tendency to form four-membered r i n g s with oxygen (57,58). Thus p o l y m e r i z a t i o n through n i t r o g e n or oxygen atoms ( i e . the MeN ( C H 2 C H 2 O ) 2 a c t i n g as a b r i d g i n g l i g a n d ) to form l a r g e h e t e r o c y c l e s with t e t r a h e d r a l c o o r d i n a t i o n about the g a l l i u m atoms was o r i g i n a l l y s u spected. The r e s u l t i n g s t r u c t u r e c o n t a i n s pentacoordinate g a l l i u m atoms with d i s t o r t e d t r i g o n a l b i p y r a m i d a l geometry. The n i t r o g e n and two oxygen atoms of each MeN (CH 2CH 20) 2 l i g a n d occupy r e s p e c t i v e l y an a x i a l and two e g u a t o r i a l p o s i t i o n s about the a s s o c i a t e d g a l l i u m atom. One of the oxygen atoms bri d g e s the two g a l l i u m atoms, occupying an a x i a l p o s i t i o n of the second g a l l i u m atom. The remaining e g u a t o r i a l s i t e i s occupied by the hydrogen atom (see F i g . 10). o The a x i a l Ga-N d i s t a n c e of 2.192(5) A i s longer than the e observed d i s t a n c e s f o r t e t r a h e d r a l (mean 1.97 A) and f o r o c t a h e d r a l g a l l i u m (mean 2.12 A) shown i n Table 3 6 . The d i s t a n c e compares w e l l with a s t e r i c a l l y s i m i l a r bond i n Figure 10 A view of the coordination about the gallium atoms. octahedral GaH (EOTA) . H20 (59) of 2.182(5) A and the a x i a l A l - N distance of 2.18 A in AlH^(NMe^) 2 (60). The bond nevertheless appears to be be weaker than a normal single bond as a result cf s t e r i c s t r a i n as in the related aminoalcohol boron compounds (20,Parts 1 and 2). The three types of Ga-0 bonds are a l l s i g n i f i c a n t l y d i f f e r e n t . The equatorial non-bridging distance i s 1.847(2) A and for the bridging oxygen the equatorial distance i s 1.960(8) and the a x i a l i s 2.018(2) A. The equatorial bonds involve ££ 2 hybrids at the gallium atoms which reduces the covalent radius of gallium to 1.21 A for these bonds. The expected equatorial Ga-0 distance i s then about 1.87 A. The mean Ga-0 distances in related four-coordinate and octahedral complexes are 1.96 and 1.959 A respectively. In t h i s structure the 1.847 A •terminal 1 Ga-0 distance corresponds to a strong bond while 94 T a b l e 36 C o m p a r i s o n o f G a - O and G a - N bond d i s t a n c e s Compound Ga C o o r d , n o . G a - O Ga -N r e f . GaN 4 1.94 62 ( H 2 G a N C H 2 C H 2 ) 3 4 1 .97 53 [ D 2 G a (N 2C3H3) ] 2 4 1 .980 54 [ (CH3) 2 GaOH ]4 4 1 . 9 4 ,1 . 9 8 63 (CH3)3NGaH3 4 1 .97 64 [ C H 3 N ( C H 2 C H 2 0 ) 2 G a H ] 2 5 1 . 8 4 3 - 2 . 0 1 9 2 . 1 8 7 , 2 . 1 9 6 * [ G a 2 ( 0 H ) 2 C 1 2 (C 1 2 4 .H 1 7 N3) 2 ] C 1 2 . H 2 0 6 1. 9 0 8 , 2 .0 17 2 . 0 8 3 - 2 . 132 58 GaH(EDTA) . H 2 0 6 1 . 9 2 4 - 1 . 9 9 6 2 . 0 9 7 , 2 . 182 59 [ G a C l 2 ( b i p y ) 2 ] + [ G a C l ^ ] - 6 2 . 0 9 7 , 2 . 105 65 GaCl3 ( t e r p y ) 6 2 . 0 3 4 - 2 . 1 1 5 66 • t h i s work 95 the bridge bonds, 1.960 and 2.018 A, seem to be of n e a r l y egual s t r e n g t h c o n s i d e r i n g t h a t one i s a x i a l and the other e q u a t o r i a l and both these d i s t a n c e s are w i t h i n the range of p r e v i o u s l y r e p o r t e d Ga-0 bond lengths (see Table 36). Using 0 an e f f e c t i v e r a d i u s of 0.23 A f o r hydrogen (61), the expected Ga-H bond l e n g t h i s 1.44 A i n good agreement with the mean Ga-H d i s t a n c e of 1.41(4) A. The d i s t o r t i o n o f the t r i g o n a l bipyramid occurs as a deformation of the angle between the a x i a l groups from the i d e a l 180° t o 151.2(4)°. The e q u a t o r i a l GaOOH groups are both pl a n a r within experimental e r r o r (see Table 37) and the mean O-Ga-O, 119.3(2)°, and O-Ga-H angles, 120.3°, are c l o s e to the expected 120°. The e q u a t o r i a l - G a - a x i a l angles range from 76° (in the four-membered ring) to 104° (mean N-Ga-H), each 14° from the i d e a l 90°. The angular d i s t o r t i o n s are a r e s u l t of the s t e r i c c o n s t r a i n t s i n h e r e n t i n the fused r i n g system. The four-membered G a 2 0 2 r i n g i s non-planar with a l l i n t r a - a n n u l a r d i h e d r a l angles equal w i t h i n experimental e r r o r , the mean value being 21.6°. Angles i n the r i n g are 76.0(3) a t Ga and 100.0(2)° at 0. The r i n g i s d i f f e r e n t from the p l a n a r centrosymmetric G a 2 0 2 r i n g i n the o c t a h e d r a l complex [ Ga 2 (OH) 2 C l 2 (C^^H^yN^) 2 ] C l 2 . H 20 (16) i n which there 0 i s one s t r o n g and one weak Ga-0 bond (1.908 and 2.017 A). The d i f f e r e n c e between the • t e r m i n a l ' and ' b r i d g i n g 1 oxygen atoms i s c a r r i e d i n t o the five-membered GaOCCN r i n g s which have d i s t i n c t geometries which may be a s c r i b e d to s t e r i c and e l e c t r o n i c d i f f e r e n c e s between the two c l a s s e s of 96 T a b l e 37 I n t r a - a n n u l a r t o r s i o n a n g l e s (deg) (a) F i v e membered r i n g s Bond o b s . Bond o b s . mean c a l c . G a { 1 ) - 0 (1) 2 . 1 (5) Ga (2) - 0 (3) 3 .4 (5 ) 2 . 8 ( 7 ) 5 . 0 0 ( 1 ) - C ( 2 ) - 2 5 . 0 (8) 0 ( 3 ) - C (7) - 2 6 . 4 (8) - 2 5 . 7 (7) - 2 9 . 8 C ( 2 ) - C ( 1 ) 4 3 . 3 (8) C ( 7 ) - C (6) 4 4 . 1 (8) 4 3 . 7 (4) 4 3 . 0 C (1 ) -N (1) - 3 9 . 8 (7) C ( 6 ) - N ( 2 ) - 3 9 . 2(7) - 3 9 . 5 ( 3 ) - 4 0 . 0 N ( 1 ) - G a (1) 2 1 . 4 (5) N (2) - G a (2) 2 0 . 1 (5) 2 0 , 8 (7) 21 . 8 Bond o b s . Bond o b s . mean c a l c . Ga ( 1 ) - 0 (2) 1.2 (5) Ga (2) - 0 ( 4 ) 2 . 7(5) 2 . 0(8) 1 .3 0 ( 2 ) - C ( 4 ) - 2 7 . 5 (8) 0 ( 4 ) - C (9) - 2 8 . 3 (8) - 2 7 . 9 (4) - 2 7 . 1 C ( 4 ) - C ( 3 ) 5 0 . 3 (9) C ( 9 ) - C (8) 4 9 . 6 (9) 5 0 . 0 (4) 42 . 3 C (3 ) -N (1) - 4 4 . 1 (7) C (8) - N(2) - 4 2 . 6(7) - 4 3 . 4(8) - 4 1 . 6 N ( 1 ) - G a (1) 2 5 . 3 (6) N ( 2 ) - Ga (2) 2 3 . 5 (5) 2 4 . 4 (11) 2 5 . 0 (b) F o u r - m e m b e r e d r i n g Bond o b s . Ga (1) - 0 ( 1 ) -21 .3 (2) 0 ( 1 ) - Ga (2) 22 . 0 ( 2 ) Ga (2) - 0 ( 3 ) -21 .2 (2) 0 ( 3 ) - Ga(1) 21 . 9 ( 2 ) 97 T a b l e 38 W e i g h t e d l e a s t - s q u a r e s mean p l a n e s (a) D i s t a n c e s (A) o f r e l e v a n t a toms f r o m t h e mean p l a n e s Atom d d/o- Atom d d / ^ 1: G a ( 1 ) , 0 ( 1 ) , 0 ( 2 ) , H (Ga 1) 2: G a ( 2 ) , 0 ( 3 ) , 0 ( 4 ) , H (Ga2) G a ( 1 ) 0 . 0 0 0 0 . 0 G a ( 2 ) , 0 . 000 0 . 0 0 (1) 0 . 0 0 0 0 . 0 0 (3) 0 . 0 0 0 0 . 0 0 (2) 0 . 0 0 0 0 . 0 0 (4) 0 . 000 0 . 0 H(Ga1) 0 . 0 0 5 0 . 1 H(Ga2) 0 . 0 4 2 0 . 6 E q u a t i o n s o f p l a n e s : Jrl * El * nZ = £ , where X , Y , and a r e o r t h o g o n a l a n g s t r o m c o o r d i n a t e s d e r i v e d a s f o l l o w s : I-XT r a 0 0 I I I = I 0 b 0 1 I I I 0 0 c P l a n e m n 1 0 . 2 2 4 0 0 . 8 8 5 7 0 . 4 0 6 6 4 . 8 3 5 5 2 - 0 . 2 3 3 1 0 . 8 9 5 9 0 . 3 7 8 3 2 . 9 1 1 7 T h e a n g l e be tween t h e p l a n e n o r m a l s i s 2 6 . 5 ° 98 r i n g s . The mean d i h e d r a l angles i n each type of r i n g are compared with those obtained from energy minimization c a l c u l a t i o n s (17) i n Table 38. The co n f o r m a t i o n a l d i f f e r e n c e s between the two types of five-membered r i n g s are s m a l l yet the r i n g s with the ' b r i d g i n g ' oxygen atoms (A rings) have a conformation which i s c l o s e s t to that c a l c u l a t e d f o r w = 5.0° while those c o n t a i n i n g the ' t e r m i n a l ' oxygens (E rings) have a conformation nearest to t h a t c a l c u l a t e d f o r u)^ = 25.0°. Both r i n g types show some s t r a i n r e l a t i v e to the minimum energy conformations but the B r i n g s show higher s t r a i n (4.0° r.m.s. d e v i a t i o n between ^ obs a n ^ " ^ c a l c compared to 2.4° f o r the A r i n g s ) , t h i s o c c u r r i n g p r i m a r i l y i n the t w i s t about the C-C bonds. Bond angles i n the A r i n g s range from 80.7(3)° at Ga to 117,9(6)° at 0 and i n the B r i n g s from 84.5(5)° at Ga to 115.9(6)° a t 0 with mean v a l u e s of 104.8 and 103.8° i n A and B r i n g s r e s p e c t i v e l y compared to the c a l c u l a t e d value of 104.2° (17) and observed values i n BOCCN r i n g s of 104.8° (Part 1) and 104.9° (Part 2 ) . The C-0, C-C, and C-H d i s t a n c e s are 1. 427(3), 1.507 (6), and1.477(2) A i n the A r i n g s and 1.412 (13), 1.534 (1), and 1.468 (4) A i n the B r i n g s . The d i f f e r e n c e s i n the bond l e n g t h s and angles i n the two types of r i n g s are a r e s u l t of s t e r i c and e l e c t r o n i c d i f f e r e n c e s between the corresponding atoms i n the r i n g , and to some exte n t are i n d i c a t i v e of the charge d i s t r i b u t i o n i n the molecule. The mean C-0, C-C, and C-N d i s t a n c e s i n the two s t r u c t u r e s with BOCCN r i n g s (Parts 1 and 2) are 1.416(3), 1.500 (6), and 1.488 (3) A. The mean N-C(methyl) d i s t a n c e o f 99 1.164(4) A i n the present s t r u c t u r e i s as expected. The mean angle at n i t r o g e n i s 109.4° but the i n d i v i d u a l angles a l l d i f f e r s i g n i f i c a n t l y from the mean and range from 100 . 5(4)° f o r Ga-N-C(B ring) to 113.0(7)° f o r Ga-N-C (methyl) . The angle a t N between the A and B r i n g s i s 112.8(2)°. The d i s t o r t i o n o f the n i t r o g e n t e t r a h e d r o n r e s u l t s from s t e r i c c o n s t r a i n t s imposed by the f u s e d - r i n g system. 0 The mean C-H d i s t a n c e of 1.00(13) A i s as expected f o r X-ray data (61). A l l angles i n v o l v i n g hydrogen atoms (R-C-H, R = N#0,C,H) are w i t h i n three standard d e v i a t i o n s of the mean value of 109°. Fig u r e 11 The packing arrangement viewed along c. The c r y s t a l s t r u c t u r e c o n s i s t s of d i s c r e t e [ CH3N (CH2 CH20)2GaH ] 2 molecules which are separated by normal i 100 F i g u r e 12 The packing arrangement viewed along b. van der Waals d i s t a n c e s , the s h o r t e s t of which are l i s t e d i n Table 3 9 , except f o r one C-H . . .0 i n t e r a c t i o n (C...C = 3 . 1 4 ( 1 ) • A) which may correspond to a weak hydrogen bond. There are a l s o two p o s s i b l e i n t r a m o l e c u l a r C-H . . .0 hydrogen bonds present ( r e l a t e d by the tw o - f o l d r o t a t i o n a x i s ) which are i n d i c a t e d by broken l i n e s i n F i g u r e 9 . The g e o m e t r i c a l data f o r these C-H . . .0 i n t e r a c t i o n s are given i n Tab l e 3 9 . The asymmetry i n t r o d u c e d by the i n t e r m o l e c u l a r 0 (4) . . .H (3B)-C (3) i n t e r a c t i o n i s a reasonable e x p l a n a t i o n f o r the d i f f e r e n c e between the C ( 4 ) - 0 ( 2 ) , 1. 3 9 9 , and C ( 9 ) - 0 ( 4 ) , 1 . 424 A, bond d i s t a n c e s (which r e p r e s e n t s the l a r g e s t d e v i a t i o n from symmetry i n the molecule). The non-bonded c o n t a c t s i n the g a l l i u m c o o r d i n a t i o n spheres and other i n t r a m o l e c u l a r non- bonded c o n t a c t s which correspond to s t e r i c i n t e r a c t i o n s w i t h i n the molecule are a l s o l i s t e d i n Tab l e 3 9 . 101 Table 39 (a) S e l e c t e d i n t r a - and i n t e r m o l e c u l a r c o n t a c t s I n t r a m o l e c u l a r I n t e r m o l e c u l a r * Atoms d i s t a n c e Atoms d i s t a n c e C(2) . • • C(3) 2. 99 (2) 0 (4) . ..C (3) i 3.44 (D C (7). • • C(8) 3. 00 (D Ga(1) ...H (10C) 2 3.4 1 (12) C(4) . • * C(5) 3. 04 (2) Ga(2) ...H(6A) 2 3. 30 (12) C (9) . • • C(10) 3. 07 (2) Ga (2) . . H (5B) 3 3. 46 (18) C(2). H (3A) 2. 52 (12) Ga (2) ...H(2A) * 3.48 (15) C (7) . * • H (8A) 2. 58 (11) 0 (1) . ..H (6 A) 2 2, 50 (12) C (3). • • H (2B) 2. 55 (11) 0(2) . ..H(10B) s 2.57 (17) C(9) . • * H(10B) 2. 68 (18) C (4) . . . H (9 A) 5 2.56 (11) H (2B) • • .H (3A) 1. 84 (17) C(9) . ..H(4A) 3 2.79 (8) H(7B) • • .H (8A) 2. 20 (16) H (1B) .. .H(9B) i 2. 40 (14) H (9A) • • . H (10B) 2. 10 (19) H (4A) . . . H (9A) 5 1.90 (15) (b) Gallium c o o r d i n a t i o n sphere Atoms d i s t a n c e Atoms d i s t a nee Ga (1) 0(1) 0 (1) 0(2) 0(2) 0 (1) 0(2) 0(3) H (1) . .Ga (2) .0(2) • N(1) .0(3) .H (Ga1) .H (Ga1) .H (Ga1) . H (Ga1) 3.038 (2) 3.273 (8) 2.678 (10) 2.787 (9) 2.716 (9) 2.82 (8) 2.86 (9) 2.63 (8) 2.87 (9) 0(1) 0 (3) 0 (3) 0 (4) 0 (4) 0 (3) 0 (4 ) 0 (1) N (2) .0(3) .0(4) • N (2) • 0(1) .N (2) . H (Ga2) .H (Ga2) . H (Ga2) .H (Ga2) 2.442 (8) 3. 275 (9) 2.695 (10) 2. 785 (9) 2.728 (9) 2.92 (7) 2.90 (8) 2.73 (7) 2.86 (7) (c) P o s s i b l e C-H...0 hydrogen bonds D- H . . . A H. .. A D...A /DHA /X AH C (7) - H (7B) . .. 0 (2) 2.56 (12) 3.14(1) 129 (10) C (2)-H (2B)...0(4) 2.55(11) 3.13(1) 118(8) C (3)-H(3B) . . .0 (4) i 2.43 (1 1) 3.44(1 ) 160 (8) 82 (3) , 158 (3) 88 (3) , 154 (2) 144 (3) ,10 1 (3) The H...0...H angle a t 0(4) i s 59(3)° • S u p e r s c r i p t s r e f e r to atoms at p o s i t i o n s : 1 1/2-x ' 2 1-x 3 X -1 1-1/2 1 z-1/2 3/2-z 1 + z 4 5 1-x 1/2+y, 3/2-z x y z-1 102 The i n f r a r e d spectrum of the t i t l e compound i n benzene s o l u t i o n showed a very s t r o n g Ga-H s t r e t c h i n g a b s o r p t i o n a t 1900 cm-1 with a weak shoulder at 1810 cm - 1. A medium i n t e n s i t y band at 770 cm - 1 i s assigned to the Ga-H wagging mode. The low frequency spectrum d i s p l a y e d a number of a b s o r p t i o n s a t t r i b u t a b l e to * Ga-O1, 'Ga-N * and r i n g modes (615 sh, 595 vs, 540 vs, 510 vs, 420 s, 390 s, 380 sh) but no assignment of t h i s p a r t of the spectrum i s attempted at t h i s time. Coates and Hayter (57), by chemical t e s t s , p o s t u l a t e d t h a t d i m e r i z a t i o n i n [MegNCR^C^OGaMeg ]g probably occurs v i a a four-membered Ga202 r i n g l e a v i n g the g a l l i u m atoms f o u r - c o o r d i n a t e and the normally s t r o n g e r n i t r o g e n donor atoms not u t i l i z e d i n c o o r d i n a t e - t y p e bonding. I t i s tempting, as a r e s u l t of the present study, to p o s t u l a t e that i n the above dimer f i v e - c o o r d i n a t e g a l l i u m atoms might again be f e a t u r e d , the bonding about the metal atoms again i n v o l v i n g both n i t r o g e n and oxygen atoms t o give a f u s e d - r i n g system. T h i s p o s s i b i l i t y i s under study f o r the analogous g a l l a n e dimer, [ Me2NCH2CH2OGaH2 ] 2 . 103 PART 5 CRYSTAL AND MOLECULAR STRUCTURE CF (PENTAHAPTOCYCLOPENTADIENYL) HYDRIDOMOLYBDENUM-/-- DIMETHYLALUMINUM->5t-[METHYLALUMINUfi-DI- (/<-PENTAHAPTO (MONOHAPTO) CYCLOPENTADIENY.L) DIMETHYLALUMINUM ] (PENTAHAPTO CYCLOPENTADIENYL)HYDRIDOMOLYBDEN UM 104 INTRODUCTION An e a r l i e r r e p o r t (67) i n d i c a t e d t h at slow decomposition of the adduct CP2M0H2.AlMe^ occurs i n benzene s o l u t i o n at room temperature. Methane i s l i b e r a t e d and e v e n t u a l l y a s o l i d i s deposited from s o l u t i o n . From one such s o l u t i o n a small amount of c r y s t a l l i n e m a t e r i a l was produced s u i t a b l e f o r X-ray a n a l y s i s and an i n v e s t i g a t i o n was c a r r i e d out to determine the extent of the expected Mo-Al network i n the c r y s t a l s . The novel* s t r u c t u r e which r e s u l t e d (shown i n F i g . 13) contained two molybdenum and three aluminum atoms per molecular u n i t . EXPERIMENTAL The s m a l l amount of c r y s t a l l i n e m a t e r i a l deposited as a r e s u l t of the slow methane e l i m i n a t i o n from benzene s o l u t i o n s of the parent compound, Cp 2M0H2.AlMe^, was s u f f i c i e n t only f o r the c r y s t a l s t r u c t u r e i n v e s t i g a t i o n and consequently no c h e m i c a l analyses are r e p o r t e d . The molecular formula given i n the t i t l e was d erived from the experimental X-ray data c o l l e c t e d on the sample. The a i r - s e n s i t i v e c r y s t a l s were mounted i n g l a s s 1 During the p r e p a r a t i o n of t h i s t h e s i s a p r e l i m i n a r y r e p o r t of t h i s s t r u c t u r e by Dr. C. K. Prout and co-workers appeared i n Chem. Comm., 426 (1973). Correspondence with Dr. Prout, who w i l l i n the f u t u r e p u b l i s h an account on both t h i s s t r u c t u r e and that of the symmetric complex [ (Ĉ H/j.) ̂ MoH]2Al£j,Me6, i s acknowledged.' 105 c a p i l l a r y tubes under a n i t r o g e n atmosphere and subsequently s e a l e d o f f . An i r r e g u l a r l y shaped c r y s t a l with dimensions of ca. 0.15 x 0.15 x 0.15 mm was mounted with the [0 1 1 ] v e c t o r p a r a l l e l t o the g o n i o s t a t a x i s . U n i t - c e l l and space group data were ob t a i n e d from f i l m and d i f f T a c t o m e t e r measurements. The u n i t - c e l l parameters were r e f i n e d by a l e a s t - s g u a r e s treatment of s i n 2 6 v a l u e s f o r 30 r e f l e x i o n s measured on a d i f f r a c t o m e t e r with Mo r a d i a t i o n . C r y s t a l data are: c 25 H 35 A l 3 M o 2 f * w * = 608.a Orthorhombic, a = 19.398 (4), b = 14.438(9), c = 9.035 (2) k, V = 253 1 (2) A 3, Z = 4, Dx = 1. 597 (1) g cm" 3, F(000) = 1232 (20° C, Mo K*, 7\ = 0.71069 A, /<: = 10.9 c m - » ) . Absent r e f l e x i o n s : hOO, h # 2n, OkO, k * 2n, and OOi, JL * 2n d e f i n e k uniquely the space group V2^2^2^ (P2 , No. 19). I n t e n s i t i e s were measured on a Datex-automated General E l e c t r i c XRD 6 d i f f r a c t o m e t e r , with a s c i n t i l l a t i o n counter, Mo K<* r a d i a t i o n (zirconium f i l t e r and pulse height a n a l y s e r ) , and a f)-26 scan at 2° m i n - 1 over a range of (1. 80 + 0.86 tan 9) degrees i n 20, with 20 s background counts being measured at each end of the scan. Data were measured to 29 = 45° (minimum i n t e r p l a n a r spacing 0.93 A). L a t e r data f o r /. = 0 t o 7 were c o l l e c t e d between 29 = 45 and 50° (minimum i n t e r p l a n a r spacing 0.84 A). Data c o l l e c t i o n i n the 20 = 45-50° s h e l l was d i s c o n t i n u e d at £ = 7 due to a very low percentage of r e f l e x i o n s with I > 3cr(I). A check r e f l e x i o n was monitored every 40 r e f l e x i o n throughout the data c o l l e c t i o n . The i n t e n s i t y of the check r e f l e x i o n remained wi t h i n 1095 of i t s 106 o r i g i n a l value during the data c o l l e c t i o n , the f i n a l measurement g i v i n g 95% of the o r i g i n a l count, L o r e n t z and p o l a r i z a t i o n c o r r e c t i o n s and check r e f l e x i o n s c a l i n g were a p p l i e d i n d e r i v i n g the s t r u c t u r e amplitudes. No a b s o r p t i o n c o r r e c t i o n was made i n view of the r e l a t i v e l y small value of JU+ Of the 2352 independent r e f l e x i o n s measured, 1113 had i n t e n s i t i e s l e s s than 3<r[l) above background where <r2 (I) = S + B + (0.03S) 2 with S = scan count and B = time averaged background count. These r e f l e x i o n s were not i n c l u d e d i n the refinement. S t r u c t u r e A n a l y s i s The p o s i t i o n s of the two molybdenum atoms were determined from the t h r e e - d i m e n s i o n a l Patterson f u n c t i o n . One c y c l e of i s o t r o p i c f u l l - m a t r i x l e a s t - s q u a r e s refinement gave R 0.25. A subsequent d i f f e r e n c e map r e v e a l e d three l a r g e peaks, two of which were c l e a r l y the b r i d g i n g aluminum atoms. The t h i r d peak was thought to be anomalous at the time and was l e f t out of the c a l c u l a t i o n s . The molybdenum and two aluminum atoms were r e f i n e d i s o t r o p i c a l l y f o r one c y c l e and a second d i f f e r e n c e F o u r i e r was c a l c u l a t e d . The R f a c t o r at t h i s p o i n t was 0.200. The d i f f e r e n c e map showed the same l a r g e peak as the p revious one, which was deduced to be a t h i r d aluminum atom, as w e l l as probable p o s i t i o n s f o r s i x t e e n carbon atoms. The molybdenum atoms were then r e f i n e d a n i s o t r o p i c a l l y and the three aluminum and s i x t e e n carbon atoms i s o t r o p i c a l l y f o r one c y c l e , g i v i n g R 0.130. A f t e r one a d d i t i o n a l c y c l e of refinement and d i f f e r e n c e F o u r i e r 107 s y n t h e s i s a l l 25 carbon atoms had been l o c a t e d . Refinement with a n i s o t r o p i c carbon atoms gave an R value of 0.051 but three carbon atoms had n o n - p o s i t i v e d e f i n i t e temperature f a c t o r s . S ince the number of strong r e f l e x i o n s was r e l a t i v e l y low i t was decided to r e f i n e the s t r u c t u r e with i s o t r o p i c thermal parameters f o r the carbon atoms. Hydrogen atom p o s i t i o n s were c a l c u l a t e d with C-H = 0.97 0 A f o r the methyl and c y c l o p e n t a d i e n y l groups. The hydrogen atoms were assigned i s o t r o p i c temperature f a c t o r s o approximately 1.5 A 2 l a r g e r than the mean B f o r the carbon atom type to which they are bonded. D i f f e r e n c e maps did not unambiguously r e v e a l the p o s i t i o n of the molybdenum hydrogen atoms. With the 33 methyl and c y c l o p e n t a d i e n y l hydrogen atoms f i x e d , the remainder of the s t r u c t u r e was r e f i n e d to convergence with the carbon atoms i s o t r o p i c , Mo and Al atoms a n i s o t r o p i c . The f i n a l agreement f a c t o r s were R 0.066 and Rw 0.063 f o r 1213 r e f l e x i o n s with I > 3<r(l) . The a b s o l u t e c o n f i g u r a t i o n of the complex (for the p a r t i c u l a r c r y s t a l used) has been determined through the anomalous s c a t t e r i n g of the molybdenum and aluminum atoms. Enantiomorph (A) i s r e p r e s e n t e d by the c o o r d i n a t e s i n Tables 40 and 42. Enantiomorph (B) was generated by changing the x c o o r d i n a t e s of (A) to 1-x. (B) was then r e f i n e d to convergence and Hamilton's t e s t (24) was a p p l i e d to the r e s u l t i n g R f a c t o r r a t i o s . The r e s u l t s , summarized i n Table 43, i n d i c a t e that enantiomorph (A) i s most probably the c o r r e c t a b s o l u t e c o n f i g u r a t i o n , assuming the data to be f r e e 1 0 8 of s y stematic e r r o r . The s c a t t e r i n g f a c t o r s of r e f . 12 were used f o r the non- hydrogen atoms and those of r e f . 13 f o r the hydrogen atoms. C o r r e c t i o n s f o r anomalous s c a t t e r i n g have been made f o r the molybdenum and aluminum atoms(13). A standard e r r o r s weighting scheme was used (see P a r t 3) g i v i n g constant average v a l u e s of w (Fo - F c ) 2 over ranges of |Fo| i n the f i n a l s t ages of refinement. On the f i n a l c y c l e of refinement the l a r g e s t parameter s h i f t was 0.310"; F i n a l p o s i t i o n a l parameters appear i n Table 40 and thermal parameters i n Table 41. The c a l c u l a t e d p o s i t i o n s of the hydrogen atoms and t h e i r assigned temperature f a c t o r s appear i n Table 42. In the f i n a l stages of refinement 26 r e f l e x i o n s b e l i e v e d to be s u f f e r i n g from counter e r r o r s or which had r a t i o s of g r e a t e r than 10:1 between the two background counts were given zero weight. Observed and c a l c u l a t e d s t r u c t u r e amplitudes are a v a i l a b l e on request. RESULTS AND DISCUSSION Bond d i s t a n c e s and angles appear i n Tables 44 and 45 r e s p e c t i v e l y . Weighted l e a s t - s q u a r e s mean planes are given i n Table 46 and some important non-bonded c o n t a c t s i n Table 47. Table 48 g i v e s s t r u c t u r a l data f o r r e l a t e d molybdenum c y c l o p e n t a d i e n y l complexes. S t e r e o s c o p i c views of the s t r u c t u r e viewed along the c and b axes are shown i n F i g u r e s 14 and 15. The c r y s t a l s t r u c t u r e c o n s i s t s of d i s c r e t e molecular 109 T a b l e 40 F i n a l p o s i t i o n a l p a r a m e t e r s ( f r a c t i o n a l x 10* ) w i t h 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 p a r e n t h e s e s Atom X 2 z Mo (1) 4031 (D 9007 (D 5698 (2) Mo (2) 2971 (D 6488 (D 3182 (2) A l (1) 3720 (2) 8025 (4) 3296 (7) A l ( 2 ) 3440 (3) 7152 (4) 6166 (6) A l (3) 5033 (3) 7308 (4) 2544 (8) C (1) 3610 (8) 8777 (11) 1476 (20) C (2) 2652 (9) 7157 (12) 7586 (21) C (3 ) 4111 (9) 6284 (11) 7097 (19) C (4) 53 11 (12) 7847 (17) 585 (30) C(5) 5728 (10) 6463 (15) 3457 (24) C (11) 4825 (8) 8301 (12) 4091 (20) C (12) 4980 (10) 8119 (14) 5585 (26) C (13) 5159 (10) 8891 (15) 6371 (22) C (14) 5093 (11) 9578 (15) 5439 (27) C (15) 4895 (9) 9309 (12) 4061 (22) C (21) 4121 (8) 6588 (12) 2430 (18) C (22) 3675 (9) 6443 (14) 1167 (20) C (23) 3358 (11) 5571 (15) 1344 (24) C (24) 3548 (10) 5133 (13) 2729 (24) C(25) 4013 (9) 5804 (11) 3290 (20) C (3 1) 2859 (10) 9264 (12) 6137 (20) C (32) 3082 (12) 9808 (15) 494 1 (25) C (33) 3592 (12) 10424 (17) 5446 (30) C (34) 3646 (12) 10331 (17) 6871 (3 1) C (35) 3220 (11) 9617 (15) 74 15 (25) C (4 1) 1845 (11) 6082 (16) 3250 (30) C (42) 1906 (10) 6793 (14) 4219 (25) C (43) 2123 (12) 7557 (15) 3564 (26) C (44) 2152 (10) 7337 (13) 2022 (25) C(45) 1967 (11) 6402 (15) 1954 (26) 110 Table 41 F i n a l thermal parameters and t h e i r estimated standard d e v i a t i o n s 0 (a) A n i s o t r o p i c thermal parameters (U^^ x 100 A 2) Atom U 11 "22 u 3 3 2l2 2l 3 y 23 Mo(1) 2. 7(1) 2.8(1) 3.5 (1) 0.3 (1) 0 .3 (1) -0. 5 (1) Mo (2) 2. 4 (1) 3. 2(1) 3.9(1) -0.4(1) - 0 .1(1) - o . 2(1) a i d ) 3. 1 (3) 2.6 (3) 3.4 (4) -0.1 (2) 0 .0 (3) 0. 3 (3) Al<2) 3. 9 (4) 5.0 (4) 2.4 (4) 0.7(3) 0 .3(3) 1. 1 (3) Al(3) 3. 2(3) 5.6(4) 6.5 (4) -0.4 (3) 1 .6 (3) -2. 0 (4) (b) I s o t r o p i c thermal parameters A torn B (A 2) Atom B (A 2) C (1) 3.3 (4) C(23) 5.0(5) C(2) 3.3 (4) C (24) 4.2 (5) C (3) 3.4 (4) C(25) 3.1(4) C(4) 7.1 (6) C (31) 3.4 (4) C (5) 5.5 (5) C(32) 5.4(6) C(11) 2.6 (4) C (33) 6.5 (6) C (12) 4.5 (5) C(34) 6.8(6) C(13) 4.4 (5) C (35) 5.0 (5) C (14) 4.9 (5) C (41) 5.8(6) C(15) 3.4 (4) C (42) 4.6 (5) C (2 1) 2.7 (4) C(43) 5.8(6) C(22) 3.9(4) C (44) 4.5 (5) C(45) 5.1 (5) ( 111 T a b l e 42 (a) C a l c u l a t e d hydrogen atom p o s i t i o n s * ( f r a c t i o n a l x 10*) and assigned i s o t r o p i c temperature f a c t o r s Atom X 2 z B (A *) H (1 A) 3164 9078 1488 5.0 H (1B) 3971 9244 1440 5.0 H(1C) 3646 8379 616 5.0 H (2A) 2290 7572 7195 5.0 H (2B) 2475 6554 7715 5.0 H (2C) 2808 7417 8529 5.0 H {3A) 4507 6213 6454 5.0 H (3B) 4256 6531 80 4 4 5.0 H (3C) 3892 5687 7242 5.0 H (4A) 5718 8229 720 7.5 H (4B) 5413 7349 -98 7.5 H (4C) 4938 8221 201 7.5 H(5A) 6135 6817 3719 7.5 H (5B) 5533 6179 4328 7.5 H(5C) 5852 5987 2743 7.5 B (12) 4965 7499 60 12 5.5 H (13) 5300 8922 7400 5.5 H (14) 5177 10220 5704 5.5 H(15) 4817 9712 3216 5.5 B (22) 3605 6870 349 5.5 H (23) 3 051 5296 617 5. 5 B (24) 3399 4547 3149 5.5 H(25) 4243 5719 4232 5.5 H (31) 2527 8758 61 10 6.5 H (32) 2917 9764 3930 6.5 fl (33) 3856 10854 4843 6.5 B (34) 3945 10705 7501 6.5 B (35) 3 175 9405 8432 6.5 H (41) 1723 5446 3483 6.5 B (42) 1808 6742 5264 6.5 H (43) 2233 8144 4034 6.5 B (44) 2277 7747 1212 6.5 H (45) 1935 6046 1038 6.5 continued... 112 (b) C y c l o p e n t a d i e n y l r i n g c e n t r o i d c o o r d i n a t e s ( f r a c t i o n a l x 10 4) Ring x y z R (1) R (2) R(3) R (4) 4990 3743 3280 1999 8840 5908 9889 6834 5109 2192 6162 3002 * The hydrogen atoms are l a b e l l e d as f e l l o w s : the c y c l o p e n t a d i e n y l hydrogens have the same number as the carbon atom to which i t i s bonded, e.g. H(12) i s bonded to C(12); the methyl hydrogens are denoted by a numeral r e f e r r i n g to the carbon atom to which i t i s bonded and by A, E, or C to d i s t i n g u i s h between the three d i f f e r e n t hydrogens a s s o c i a t e d with each carbon. 1 1 3 Table 43 R e s u l t s of Hamilton's Test Parameter compared Value f o r enantiomorph S i g . (A) (B) (E/A) l e v e l * C onventional R (3<r data) 6.56 6 .58 1. 0030 97. 5 Conv e n t i o n a l B ( a l l F) 14.34 14 .39 1. 0035 99. 5 Weighted R (3<rdata) 6.31 6 .32 1. 0022 95.0 Weighted 1 ( a l l F) 6.51 6 .52 1. 0021 99. 5 1 T h i s i s the % p r o b a b i l i t y that enantiomorph (A) i s the c o r r e c t a b s olute c o n f i g u r a t i o n . 1 1 4 u n i t s with normal van der Waals c o n t a c t s between u n i t s . The c l o s e s t i n t e r m o l e c u l a r c o n t a c t s , i n c l u d i n g those f e r hydrogen atoms i n c a l c u l a t e d p o s i t i o n s , are l i s t e d i n Table 47. F i g u r e 13 A s t e r e o s c o p i c view of the C25H3^Al 3Mo2 molecule. 50% p r o b a b i l i t y e l l i p s o i d s are shown f o r Mo and A l atoms. Carbon atoms ar e r e p r e s e n t e d by e q u i v a l e n t spheres. The molecular s t r u c t u r e e x h i b i t s s e v e r a l unusual and novel f e a t u r e s . The three aluminum atoms i n the molecule are of d i f f e r e n t s t r u c t u r a l types, one of them, A l ( 2 ) , was of the p r e d i c t a b l e dimethylaluminum type, b r i d g i n g two molybdenum atoms. The d i s t a n c e s Mo(1)-Al(2) and Mo(2)-Al(2) are 2.944(6) and 3.003(6) A. The Mo ( 1 ) - A l (2) - Mo (2) angle i s 106.2(2)° while the o p p o s i t e angle C (2)-Al (2)-C (3) i s 103.9(7)°. Thus the c o o r d i n a t i o n about Al(2) i s that o f a d i s t o r t e d t e t r a h e d r o n . Other angles at Al(2) range from 110.5 to F i g u r e 14 The s t r u c t u r e viewed down c. F i g u r e 15 The s t r u c t u r e viewed along b. 116 Table 44 Bond le n g t h s (A) with estimated standard d e v i a t i o n s i n parentheses Atoms d i s t a n c e Atoms d i s t a n c e M O (1 ; -Al(1) 2. 662 (6) Al(1) -C (1). 1.98 (2) M o (2) -Al{1) 2.655 (5) A l (1) -C (11) 2.30 (2) M O (1 ] - A l (2) 2. 944 (6) A l (1) -C (21) 2.35 (2) M o (2 - A l (2) 3.003 (6) A l (2) -c (2) 2.00 (2) M O (1) -C (11) 2. 35(2) Al (2) - c (3) 1.99 (2) M o (1 ] -C (12) 2. 25 (2) Al (3) -c (4) 2.01 (3) M O M i -C (13) 2.28 (2) Al (3) -c (5) 2.00 (2) M O (11 -C (14) 2. 23 (2) Al (3) -c (11) 2.04 (2) M o -C (15) 2.28 (2) Al (3) - c (21) 2.05 (2) M o -C (31) 2. 34 (2) C (1 1] -c (12) 1.41 (3) M o ( i : -C (32) 2.28 (2) C (12] -c (13) 1.37 (3) M o (1 i -C (33) 2. 23 (2) C(13) - c (14) 1.31 (3) M o (1) -C (34) 2.31 (2) C (14] -c (15) 1.36 (3) M O -C (35) 2. 38 (2) C (15] -c (11) 1.46 (2) M o (2) -C (21) 2.34 (2) C (21 ) -c (22) 1.45 (2) M o (2 l-C (22) 2. 28 (2) C(22) -c (23) 1.41 (3) M o (2) -C (23) 2.25 (2) C (23) -c (24) 1.45 (3) M o <2' l-C (24) 2. 29 (2) C (24) - c (25) 1.42 (2) M o (2) -C (25) 2.25 (2) C (25] -c (21) 1.39 (2) M o (2 |-C (41) 2. 26 (2) C(31) -c (32) 1.40 (2) M o (2) -C (42) 2.31 (2) C (32] -c (33) 1.4 1 (3) M O (21 l-C (43) 2.28 (2) C (33) -c (34) 1.30 (3) M o (2] -C (44) 2.26 (2) C (34] -c (35) 1.41 (3) M o (2 l-C (45) 2. 25 (2) C (35) -c (31) 1.44 (3) M o (1) -R (1) 1.95 C (41] -c (42) 1.35 (3) M o (2 |-R (2) 1.94 C (42] -c (43) 1.32 (3) M o (1] -R (3) 1.98 C (43] -c (44) 1.43 (3) M o (2 |-R (4) 1. 96 C (44] -c (45) 1.40 (2) C (45' -c (41) 1.28 (3) 1 1*7 Table 45 Bond angles (deg) with estimated standard d e v i a t i o n s i n parentheses atoms angle atoms angle a i ( i ) -Mc(1) -Al (2 ) 62. 9(2) C 15) - C (11) - C (12) 101 2) a l (1) -Mo (1) -E (1) 85. 9 C i 15) - C (11) - A l (1) 105 D a i ( i ) -Mo (1) -R (3) 110. 4 C i 15) - C (11) - A l (3) 132 ( D Al(2) -MO (1) -B(1) 107. 3 c (12) - C (11) - A l (1 ) 1 18 D A l (2) -Mo (1) -R (3) 105. 5 C ( 12) - C (11) - A l (3) 1 19 ( 1) R (1 ) - Mo (1)- R(3) 147. 1 Al (D - C (11) - A l (3) 81. 3 (6) A l (1 ) -Mo (2) -Al (2 ) 62. 1 (2) C ( 25) - C (21) - C (22) 104 ( 2) a i d ) -Mo (2) -R (2) 87. 5 C [25] - C (21) - A l (1 ) 1 19 1) Al{1) -MO (2) -R (4) 108. 5 C | 25) - C (21) - A l (3) 121 1) Al(2) -Mo (2) -R (2) 108. 6 c I 22) - C (21) - A l (1) 10 1 | 1) a i (2 ) -MO (2) -R(4) 106. 6 c (22] - C (21) - A l (3) 129 D H (2)-Mo (2)- R (4) 144. 8 Al (D - C (21) - A l (3) 79. 6 (6) C{1) - A 1 ( D - Mo (1) 1 14. 2 (5) C (11] - c (12) - C (13) 1 14 2) c (1)- A l (1)-•Mo (2) 111. 5 (5) c I 12) - c (13) - C (14) 105 ( 2) C ( 1 ) - a l ( D - C(11) 105. 4 (7) c 13] - c (14) - C (15) 1 14 2) C (1 )- A l (1 )- C{21) 104. 1 (7) c ( 14] - c (15) - C (11) 107 2) Ho (1) -Al (1 ) -Mo (2) 126. 9 (2) c I 21) - c (22) - C (23) 107 | 2) Mo(1) - A l (1) -C(11) 56. 0 (4) c (22] - c (23) - C (24) 112 (2) Ho (1) - A l (1) - C (21) 131. 8 (5) C ( 23) - c (24) -C(25) 100 2) Mo (2) - A l (1) - C (11) 131. 9 (5) c (24] - c (25) - C (21) 1 17 (2) Mo (2) - A l (1) - C (21) 55. 2 (4) c I [35) - c (31) - C (32) 106 2) C (1 1) - A l (1) -C(21) 87. 1 (6) c 31] - c (32) - C (33) 109 2) MO (1 ) - A l (2) — Mo (2) 106. 2 (2) c ( 32) - c (3 3) - C (34) 108 2) Ho(1) - A l (2) -C(2) 112. 0 (6) c [33] - c (34) - C (35) 112 2) MO (1) " A l (2) -C(3) 112. 3 (5) c (34] - c (35) - C (31) 105 (2) Ho (2) - A l (2) - C (2) 110. 5 (6) c 45) - c (41) - C (42) 108 2) Mo{2) - A l (2) -C(3) 112. 1 (6) c 41 ] - c (42] -C (43) 112 (2) C (2)- A l (2)- C (3) 103. 9 (7) c I 42] - c (4 3) - C (44) 105 2) C (4)- A l ( 3 ) - C(5) 114. 8 (10) c (43] - c (4 4) - C (45) 104 (2) C (4)- A l (3) -•C(11) 1 12. 6 (9) c I 44) - c (45) - C (41) 111 ( 2) C ( 4 ) - A l ( 3 ) - C(21) 112. 6 (9) C (5)- A l (3)- C(11) 106. 2 (8) C ( 5 ) - A l (3)- C(21) 107. 1 (8) C (11) - A l (3) -C(21) 102. 7 (7) 1 1 8 112,3°, the mean angle a t Al(2) being 109,5°. The two remaining aluminum atoms are i n v o l v e d i n the unique s t r u c t u r a l f e a t u r e of t h i s system. Instead of a second b r i d g i n g AIMe 2 u n i t an AlMe group b r i d g e s the two molybdenum atoms and a t the same time i s i n v o l v e d i n a novel m u l t i c e n t r e ; bonding arrangement with the two unique carbon atoms of the C^Hjj, groups, C(11) and C(21), and the remaining aluminum atom, A l ( 3 ) , which occurs as an AlMe 2 u n i t . The two Al(1)-Mo o d i s t a n c e s , 2. 662 (6) and 2.657 (5) A, are equal to within experimental e r r o r . The f a c t t h a t these d i s t a n c e s are more 0 than 0.3 A s h o r t e r than the corresponding Al(2)-Mo bonds has i n t e r e s t i n g s t r u c t u r a l i m p l i c a t i o n s which w i l l be d i s c u s s e d . The Al 2Mo2 b r i d g i n g system i s s i g n i f i c a n t l y non-planar (see Table 46). The angle between the normals to the two AlAlMo planes i s 168.9°. The A l ( 1 ) - A l ( 3 ) and Mo(1)-Mo{2) d i s t a n c e s are 2.935 (8) and 4.757 (2) A r e s p e c t i v e l y , n e i t h e r of which r e p r e s e n t s any d i r e c t i n t e r a c t i o n . The remaining angles i n t h i s system are Mo (1)-Al (1)-Mo (2) , 129.9(2), Al(1)-Mo(1)- A l ( 2 ) , 62.9(2), and A l (1)-Mo (2) - A l (2) , 62.1(2)°. Bond angles at Al(1) i n v o l v i n g the two molybdenum atoms, C ( 1 ) , and A l (3) have a mean value of 108.2°. T h i s i s i n d i c a t i v e t h a t Al(1) i s s p 3 h y b r i d i z e d with three hybrids n e a r l y p a r a l l e l to the two Al(1)-Mo and Al(1)-C(1) bonds, and the remaining h y b r i d , which i s i n v o l v e d i n the m u l t i c e n t r e bonding, d i r e c t e d toward A l ( 3 ) . The A l (1) , C(11), C(21), Al{3) m u l t i c e n t r e bonding arrangement resembles that i n the trimethylaluminum dimer (68), although c l o s e r examination 119 r e v e a l s unique d i f f e r e n c e s . The [ ( C H ^ ^ A l j ^ s t r u c t u r e i s centre-symmetric with a planar b r i d g i n g arrangement; the two independent Al-C (bridge) d i s t a n c e s are 2.125 and 2.123 A, and a A l - C ( t e r m i n a l ) are 1.949 and 1.956 A. The angles i n the bridge p o r t i o n are 75.7° at C and 104.3° at A l . The brid g e system i n the present s t r u c t u r e i s non-planar (see Table 46), the angle between the two A l A l C planes i s 149.7°, and a l s o asymmetric with s h o r t bonds to A l ( 2 ) , mean A l (2)-C (bridge) = 2.05 A, and long bonds to A l ( 1 ) , mean A l (1) -C (bridge) •= 2.33 A. The angles i n the bridge are 87.1(6) at A l ( 1 ) , 102.7(7) a t A l ( 3 ) , 79.7(6) at C(21), and 81.3(6)° a t C (11) . F i g u r e 16 shows a schematic r e p r e s e n t a t i o n of the atomic o r b i t a l s b e l i e v e d to be i n v o l v e d i n the m u l t i c e n t r e bonding: one sp_2 h y b r i d o r b i t a l from each of C(11) and C(21), one s_p3 h y b r i d o r b i t a l from Al(1) and two S £ 3 h y b r i d o r b i t a l s from A l ( 3 ) , Note t h a t Al(1) l i e s twice as f a r from the mean planes of the C5 Hjj. r i n g s (represented by the h o r i z o n t a l dotted l i n e s i n Fi g u r e 16) as does A l ( 3 ) . The bonding scheme represented by Fi g u r e 16 i s adeguate to e x p l a i n the observed geometry of the system, p a r t i c u l a r l y the d i f f e r e n c e between the A l ( 1 ) - C (bridge) and A l (3)-C (bridge) d i s t a n c e s . The c o o r d i n a t i o n about Al(3) i s a somewhat d i s t o r t e d t e t r a h e d r o n , with the angle C (4)-Al (3)-C (5) expanded to 114.8(10)° corresponding to the c o n t r a c t i o n of the opposite angle, C (11)-Al (3)-C (21), to 102.7(7)°. Other angles at Al(3) range from 106.2 t o 112.6°, and the mean of a l l angles at Al(3) i s 109.3°. None of the f i v e Al-C (terminal) d i s t a n c e s o d i f f e r s s i g n i f i c a n t l y from the mean value of 2.00(1) A, which 1 2 0 A i d ) C(R1) A K 3 ) F i g u r e 16 A r e p r e s e n t a t i o n of the bonding i n the A l (1) -C (1 1) -C (21)-A1 (3) b r i d g i n g system. Mean bond d i s t a n c e s are shown. i s equal to the sum of c o v a l e n t r a d i i . The two C 5 H 5 a D C ^ two C^H^ groups are a l l fientahapto to the molybdenum atoms, and, assuming that one hydrogen atom i s a l s o c o o r d i n a t e d to each of the molybdenum atoms, the l a t t e r obey the 1 8 - e l e c t r o n r u l e . I f the Ccj H«j and C^H^ groups are regarded as f o r m a l l y n e g a t i v e l y charged and occupying three c o o r d i n a t i o n s i t e s at the metal atom, the complex may be regarded as a n i n e - c c c r d i n a t e complex cf Mo (II) (assuming the H atom i s a one e l e c t r o n donor). The r e c e n t l y reported s t r u c t u r e of the niobccene dimer [ (C^H^) (C^H^JNbHJg (69) a l s o c o n t a i n s IHonoha^to and pentahapto Cc Hu l i g a n d s . The present 121 T a b l e 46 W e i g h t e d l e a s t - s q u a r e s mean p l a n e s 0 (a) D i s t a n c e s (A) o f r e l e v a n t a toms f r o m t h e mean p l a n e s Atom d Atom d d/<r P l a n e 1 : C (11 ) - C (15) P l a n e 3: C (31) - C (35) C(11) 0 .011 0 . 7 C(31) 0 . 0 1 2 0 . 6 C (12 ) - 0 . 0 1 9 1.0 C (32) - 0 . 0 2 4 1. 1 C (13 ) 0 .011 0 . 6 C(33) 0 . 028 1. 1 C (14 ) 0 . 0 0 0 0 . 0 C (34) - 0 . 0 1 3 0 . 6 C (15) - 0 . 0 0 8 0 . 4 C(35) - 0 . 0 0 5 0 .2 Mo(1) - 1 . 9 5 1 1 2 9 6 . 3 Mo (1) 1 .976 1 3 0 4 . 8 P l a n e 2 : C ( 2 1 ) - C (25) P l a n e 4: C ( 4 1 ) - C ( 4 5 ) C(21) 0 . 0 0 8 0 . 5 C (41) - 0 . 0 2 4 1. 2 C (22) - 0 . 0 1 4 0 . 8 C (42) 0 . 0 2 4 1. 2 C (23 ) 0 . 0 1 6 0 . 8 C(43) - 0 . 0 2 3 1.0 C{24) - 0 . 0 0 6 0 . 3 C (44) 0 . 0 0 7 0 . 3 C (25) - 0 . 0 0 3 0 . 2 C(45) 0 . 0 0 8 0 .4 Mo (2) - 1 .934 1 2 7 8 . 7 Mo (2) - 1 . 9 5 6 1339 .1 P l a n e 5 : M o ( 1 S 2 ) , A l ( 1 S 2 ) P l a n e 6: A l ( 1 & 3 ) , C (11&12) Ho (1) - 0 . 0 1 7 1 1 . 5 A l ( 1 ) 0 . 0 3 3 5 . 7 Mo (2) - 0 . 0 1 7 1 1 . 3 A l (3) 0 . 0 6 4 . 9 . 4 A l ( 1 ) 0 .240 4 9 . 4 C(11) - 0 . 3 9 0 2 2 . 2 A l ( 2 ) 0 . 176 3 0 . 8 C (21) - 0 . 3 7 5 22 . 3 c o n t i n u e d . 122 (b) E q u a t i o n s o f p l a n e s : / X + mY + nZ = £ , where 1, Y , and Z a r e o r t h o g o n a l a n g s t r o m c o o r d i n a t e s d e r i v e d a s f o l l o w s : IH = LZJ r a 0 | 0 b L 0 0 0 i TXT 0 I m c J P l a n e / m n 1 0 . 9 . 6 0 5 - 0 . 1 0 7 0 - 0 . 2 5 7 0 6 . 7 4 6 3 2 0 . 7 5 6 6 - 0 . 4 5 3 9 - 0 . 4707 0 .6892 3 0 . 7 2 7 0 - 0 . 6 6 7 4 - 0 . 1 6 1 2 - 5 . 8 0 1 2 4 - 0 . 9 5 8 4 0 . 2 5 9 6 - 0 . 1189 - 1. 4746 5 0 . 8 8 5 2 - 0 . 4 6 0 8 - 0 . 0 6 3 5 0. 6 188 6 - 0 . 0 0 6 0 0 . 5 1 6 4 - 0 . 8 5 6 3 - 3 . 3572 (c) A n g l e s b e t w e e n p l a n e n o r m a l s P l a n e s a n g l e P l a n e s a n g l e P l a n e s a n g i e ( 1 ) - ( 2 ) 154 ( 2 ) - ( 3 ) 158 ( 3 ) - (5) 164 (1 )~(3) 144 ( 2 ) - (4) 142 ( 3 ) - (6) 102 <1)~(4) 157 ( 2 ) - ( 5 ) 155 ( 4 ) - (5) 164 <D-(5) 156 ( 2 ) - ( 6 ) 81 ( 4 ) - (6) 104 (D - ( 6 ) 81 ( 3 ) - ( 4 ) 148 ( 5 ) - (6) 101 123 Tab l e 47 S e l e c t e d i n t r a - and i n t e r m o l e c u l a r c o n t a c t s I n t r a m o l e c u l a r I n t e r m o l e c u l a r * atoms d i s t a n c e Atoms d i s t a n c e MO (1) • • .Mo (2) 4.757 (2) C(13) .. .C( 14) l 3.29(3) A K D • * - A l (2) 2.935 (8) C(1). • . H (3 5) 2 3.02 Al{1) • • . A l (3) 2.831 (8) C (2). . . H (22) 3 3.14 C (11) • • .C (21) 3.20 (2) C(3) . . .H (14) * 2.87 C(15) • * .C (33) 3.25 (3) C (23) ...H (41) s 2.98 C (23) .C (45) 3.00 (3) C (4 1) ...H(23) 6 2.93 C(33) • • .C (14) 3. 16 (3) H (2B) ...H (24) 6 2.36 C (34) • • .C (14) 3. 28 (3) H (2C) .. .H(22) 3 2.39 C(2) . • • 8(31) 2.66 H (3C) . . . H (4 1 ) 6 2.31 C (2). • • H (42) 2.73 C(3) . • • H(12) 2.60 C (3) . • • H (25) 2.73 C(31) * * .H(43) 2.77 H (1B) • « . H (15) 2.39 H(1C) • * .H (22) 2.19 H (2A) w m .H (31) 2.07 H(2A) w m .H (42) 2.31 H (3a) • • .H (12) 2. 10 H (3a) • • .H (25) 2.19 H (31) • • . H (43 2. 15 • S u p e r s c r i p t s r e f e r to atoms at p o s i t i o n s : 1 1/2+x 3/2-2 1"2 * 1-x .X-1/2 3/2-z 2 x j z-1 s 1/2-x 1-2 z-1/2 3 x 2 z+1 6 1/2-x 1-2 1/2+z 124 Table 48 S t r u c t u r a l data f o r some molybdenum c y c l o p e n t a d i e n y l complexes Compound Mo-C (Cp) C-C (Cp) K o - c e n t r o i d a 2.285 1.389 1.96 b 1.40-1.44 c 2. 333 1.413 d 2.333 1.412 e 2. 310 1.378 f 2.32-2.68 1.347-1.427 g 2.34 1.41 2.08 h 2.30 1.97 i 2. 35 1.42 2.01 j 2.338 1.418 2.00 k 2. 324 1.421 1 1.39 2.02 m 2.289 1. 425 1. 94 n 2.345 1.416 o 2. 38 1.43 2.04 P 2.329 1.391 2.00 g 2.253-2.368 1. 385 1. 999, 1.993 r 2.32-2.39 1.405 s 2.229-2.388 1.396 1.976,2.002 t 1.41 u 2.244-2.396 1. 394 1.980,1.981 V 2.21-2.42 1.40 1.96-2.01 w 2.27-2.36 1.27-1.42 1.986,1.993 x 2.26-2.40 1.40 1.962,1.991 a. C25 H35A I 3 M 0 2' t n i s w o r k b. (C^Hj^) (C5H5) (CO) MoMn (CO)^ , r e f . 72 c. (C5H5) Mo (CO) (PPh^) 2 (NCO) , r e f . 75 d. (C5K5) no (CO) 2 (PPI13) I# r e f . 76 e. Ko(CO) (Ph2PCB2CH2PPh2)Cl, r e f . 76 f . (C5H5) 3 M 0 (NO) , r e f . 77 g. Mo (C5H5) (CO) 2 (CH 2SCH^) , r e f . 78 h. [ Mo ( C 5 H 5 ) ( S C H 3 ) 2 12 ' r e f « 7 9 c o n t i n u e d . . . (C^I!^) Mo (CO) 3CH 2COOH, ref. 80 [PPh k ]+ [ (C 5H 5) Mo{ S 2 C 2 (CN) 2 }2 ]-, ref. 81 (C5H5) Mo (CO) ( P h 2 P C H 2 ) 2 C l , ref. 82 (C^H 5) 2MoS 2C^H k, r e f . 83 (C^H^) 2MoH 2, ref. 71 [ Mo (CO) ̂  ] 2 , ref. 84 (C5H5 ) Mo (CO)3C2He,, r e f . 85 [ (C5H5) Mo(CO) 2 ]2 (H)[ P ( C H 3 ) 2 ], ref. 86 (C5H5)2MoS2C6H3CH3 , r e f . 87 C5H5 (CO) 2MoN (H) NC (C0 2C 2H5) COH, ref. 88 (C5H5) 2MoS (CH 2) 2NH 2I, r e f . 89 (C5H5 (CO) 2MoN. N (CH3) . C (C0 2C 2H5) COH) PFg, ref. H[ (C5H5) 2MoNH 2CH (CH 2S) COO]Cl f ref. 91 H[ (C5H5) 2MoNH 2CH (CH 2S) COO ]PF£, ref. 91 [(C5H5) 2MoNH 2CH 2COO]Cl.H 20, ref. 91 [ (C^H^) 2MoHN(CH3)CH 2COO ]Cl.CH3OH, r e f . 91 126 s t r u c t u r e again demonstrates the v e r s a t i l i t y of the C5 H5 l i g a n d i n that the C^Hk groups d e r i v e d therefrom are £§Si3liapto t o a molybdenum atom and are i n v o l v e d v i a the unique carbon atom i n m u l t i c e n t r e bonding to aluminum atoms. The mean Mo-C d i s t a n c e i s 2.285 A with i n d i v i d u a l 0 d i s t a n c e s ranging from 2.23 to 2.38 A and the mean Mo-R ( r i n g c e n t r o i d ) d i s t a n c e i s 1.96 A. The f o u r c y c l o p e n t a d i e n y l r i n g s are a l l p l a n a r to w i t h i n experimental e r r o r (see Table 46). o The mean C-C bond l e n g t h i n the r i n g s i s 1.389 A and the mean C-C-C angle i s , as expected, 108°. The Mo-C, C- C ( c y c l o p e n t a d i e n y l ) , and Mo-R d i s t a n c e s are i n good agreement with those of r e l a t e d compounds which are compiled i n Table 48. The s t r u c t u r e may be i n t e r p r e t e d i n terms of valence bond theory i n a manner analogous to that d e s c r i b e d f o r the niobocene dimer (69). The l a t t e r approach views s t r u c t u r e s of t h i s type of b i s ( c y c l o p e n t a d i e n y l ) - t r a n s i t i o n metal complex as having canted r i n g s with three h y b r i d o r b i t a l s i n the h o r i z o n t a l m irror plane (70) as shown i n F i g u r e 17. Some s t r u c t u r e s which can be r a t i o n a l i z e d by t h i s scheme are given by Guggenberger (69). Both molybdenum atoms i n the present molecule have A l (2) i n the ^2 p o s i t i o n and A l ( 1 ) i n the p o s i t i o n , the hydrogen atom i s assumed to be i n the ^3 p o s i t i o n . The angles between the C^H^ and C^H^ planes are 32.9° at Mo(1) and 35.2° a t Mo(2), which are s i m i l a r to those i n other molybdenum complexes, e.g. 34° i n CpgMoHg (71) and 35° i n (Cp) (CO) Mo (C^fy) Mn (CO)^ (72). The l e n g t h of the two 127 F i g u r e 17 I d e a l i z e d s t r u c t u r e of b i s ( c y c l o p e n t a d i e n y l ) - t r a n s i t i o n metal complexes with canted Cp r i n g s . e Mo-Al(2) bonds (0.3 A longer than the Mo-Al(1) bonds) suggests the p o s s i b i l i t y of a M'o-H-Al(He)2-H-Mo b r i d g i n g system analogous t o the T i - H - A l E t 2 system i n [ (Cp) (C^H^JTiHAlEtglg (73,74). The three aluminum and f i v e methyl carbon atoms are approximately c o p l a n a r . The hal v e s of the molecule with r e s p e c t to t h i s plane are not e q u i v a l e n t , the most i n t e r e s t i n g d i f f e r e n c e i s t h a t the C^ H5 a n ( ^ groups a s s o c i a t e d with Mo(1) are staggered while those at Mo (2) are e c l i p s e d . T h i s r e s u l t s from s t e r i c i n t e r a c t i o n s between the Ring 3 and Ring 4 hydrogen atoms. The d i s t a n c e between 128 c a l c u l a t e d p o s i t i o n s f o r H(31) and H (43) i s 2.15 A which i s l e s s than the sum of van der Waals r a d i i . I f the conformation of the r i n g s were the same a t both molybdenum atoms there would be even g r e a t e r s t e r i c i n t e r f e r e n c e . I n s p e c t i o n of bond l e n g t h s and angles shows other small d i f f e r e n c e s between the two h a l v e s of the molecule, some of which are s i g n i f i c a n t . o The mean Mo-C (C5 Hij.) d i s t a n c e s are the same, 2.28 A f o r each molybdenum atom, while the Mo-Al(2) d i s t a n c e s d i f f e r by 10 standard d e v i a t i o n s being 3.003 (6) A f o r Mo (2) and 2.944 (6) 0 f o r Mo(1). The mean Mo-C (Cp) a l s o d i f f e r , being 2.31 A at Mo(1) and 2.27 at Mo (2). The corresponding angles at the two molybdenum atoms show s i g n i f i c a n t d i f f e r e n c e s as w e l l , and may be caused by a s m a l l energy d i f f e r e n c e between the staggered and e c l i p s e d conformations of the C^H^ and C ^ H ^ r i n g s . 129 PART 6 THE COMPUTER PROGRAM "SIGCOR" 130 INTRODUCTION T h i s s e c t i o n o f t h e t h e s i s d e s c r i b e s a c o m p u t e r p r o g r a m w h i c h c a l c u l a t e s e s t i m a t e d v a l e n c e bond o r d e r s g i v e n a s e t o f a t o m i c c o o r d i n a t e s . T h e work i s n o t y e t c o m p l e t e d b u t an o p e r a t i o n a l v e r s i o n , w h i c h g i v e s s a t i s f a c t o r y r e s u l t s when t h e h y b r i d i z a t i o n a t b o t h a t o m s i n t h e bond i n v o l v e s c n l y s and 2 o r b i t a l s , w i l l be d e s c r i b e d . I n s t r u c t i o n s f o r t h e u s e o f t h e p r o g r a m a r e g i v e n and t h e s o u r c e d e c k may be o b t a i n e d f r o m t h e a u t h o r . The bond o r d e r i s d e r i v e d f r o m t h e f r a c t i o n a l d i f f e r e n c e b e t w e e n t h e o b s e r v e d i n t e r a t o m i c d i s t a n c e and t h e c a l c u l a t e d s i n g l e b o n d d i s t a n c e . The c a l c u l a t e d v a l u e i s b a s e d on t h e sum o f c o v a l e n t r a d i i (92) c o r r e c t e d f o r (T h y b r i d i z a t i o n e f f e c t s (93-95) and i n some c a s e s f o r e l e c t r o n e g a t i v i t y e f f e c t s (96) . T h e d e p e n d e n c e on e l e c t r o n e g a t i v i t i e s h a s n o t y e t been c o m p l e t e l y worked o u t . The p r o g r a m p r o v i d e s q u a l i t a t i v e l y a c c u r a t e i n f o r m a t i o n a b o u t t h e b o n d i n g and e l e c t r o n d i s t r i b u t i o n i n t h e s t r u c t u r e . I t i s i n t e n d e d t o s e r v e a s a n a i d i n t h e c o m p a r i s o n and a n a l y s i s o f s t r u c t u r a l i n f o r m a t i o n o b t a i n e d f r o m d i f f r a c t i o n and s p e c t r o s c o p i c e x p e r i m e n t s . GENERAL DESCRIPTION The p r o g r a m , w r i t t e n i n FORTRAN 1 7 , i s d i v i d e d i n t o s u b r o u t i n e s t o f a c i l i t a t e m o d i f i c a t i o n a n d e x p a n s i o n . T h e ma in p r o g r a m p e r f o r m s most o f t h e b a s i c o p e r a t i o n s , w h i l e 131 subroutine PABSET i s a l i b r a r y of c o v a l e n t r a d i i and e l e c t r o n e g a t i v i t i e s f o r a number of commonly o c c u r r i n g atoms. A l i s t i s i n c l u d e d i n the s e t of i n s t r u c t i o n s . Subroutine ENCOR a p p l i e s c o r r e c t i o n s to the c o v a l e n t r a d i u s f o r e l e c t r o n e g a t i v i t y d i f f e r e n c e s and f o r formal charges where a p p r o p r i a t e . Subroutine BOND i s the f u n c t i o n which r e l a t e s bond order to the r e l a t i v e c o n t r a c t i o n of the bond d i s t a n c e from i t s c a l c u l a t e d value. F i n a l l y , s ubroutine ANGLE i s o p t i o n a l l y c a l l e d to c a l c u l a t e and p r i n t both the observed valence angles and the c a l c u l a t e d angles between the a p p r o p r i a t e h y b r i d o r b i t a l s . The sequence of o p e r a t i o n s begins with r e a d i n g the input i n f o r m a t i o n . The g e n e r a l atomic c o o r d i n a t e s are transformed to o r t h o g o n a l angstrom c o o r d i n a t e s . The c o v a l e n t r a d i i and e l e c t r o n e g a t i v i t i e s are assigned by subroutine PARSET f o r atoms i n the l i b r a r y or are read from cards with the atomic p o s i t i o n s f o r atoms not i n the l i b r a r y . The i n t e r n a l values may be a l t e r e d f o r any p a r t i c u l a r atom (see i n s t r u c t i o n s ) . These valu e s are s t o r e d i n the a r r a y s BAD (i) and CA (i) . Bonding i n f o r m a t i o n i s read i n and s t o r e d i n the form of a symmetric c o n n e c t i v i t y matrix (97) KB(i,j) where KB ( i , j ) = 1 i f the atoms i and j are bonded to one another and K B ( i , j ) = 0 otherwise. The h y b r i d i z a t i o n s t a t e s of " t e r m i n a l " atoms (those which are u n i v a l e n t ) cannot be c a l c u l a t e d and are assumed to be S£3 . I f the h y b r i d i z a t i o n s t a t e of a t e r m i n a l atom i s known to be d i f f e r e n t from s £ 3 , as i n the case of c a r b o n y l groups, t h i s i n f o r m a t i o n i s read from an o p t i o n a l t e r m i n a l atom c a r d . 132 The bond d i s t a n c e s and d i r e c t i o n c o s i n e s of the bonds are then c a l c u l a t e d and s t o r e d i n a r r a y s DB, DL, CM, and DH. The next step i s the det e r m i n a t i o n of the f r a c t i o n a l s c h a r a c t e r s , S F ( i , j ) , f o r the hyb r i d o r b i t a l at atom i i n v o l v e d i n the bond between atoms i and j . In g e n e r a l , an or t h o g o n a l s e t of non-equivalent h y b r i d o r b i t a l s which f o l l o w the bond d i r e c t i o n s cannot be c o n s t r u c t e d from s and 2 atomic o r b i t a l s o n l y . Since the o r t h o g o n a l i t y c o n d i t i o n s must be met, there are u s u a l l y d i f f e r e n c e s between the i n t e r h y b r i d angles and the observed valence angles i f the hy b r i d s are c o n s t r u c t e d only from s and 2 atomic o r b i t a l s . The general o r t h o g o n a l i t y c o n d i t i o n s may be expressed as: aj_aj + b^ b j c o s = 1 where O^j i s the angle between the non-eguivalent hybrids a^s • b^2 a n f l a j i ? + b-jjO. I t ^ s assumed each of the f u n c t i o n s i s n ormalized. T h i s r e q u i r e s : a z + b 2 = 1 i n which case the f r a c t i o n a l s and jg c h a r a c t e r s are simply a 2 and b 2 . For d i v a l e n t atoms i t i s assumed that the two bonding h y b r i d s are e q u i v a l e n t . In t h i s case the o r t h o g o n a l i t y c o n d i t i o n becomes: 133 a 2 • b 2 (cos 9) = 0 where 9 i s the bond angle. Since the f u n c t i o n i s normalized the f r a c t i o n a l s c h a r a c t e r (a 2) i s given by: SF = cos 9/ (cos 9 - 1) t r i g o n o m e t r i c i d e n t i t i e s transform t h i s e x p r e s s i o n to the e q u i v a l e n t form: SF = 1 - 0 . 5 [ c s c 2 (9/2) ] which i s used i n the program. The r e s u l t i n g h y b r i d o r b i t a l s f o l l o w the bond d i r e c t i o n s . For t r i g o n a l l y c o o r d i n a t e d atoms the values of S F ( i , j ) are c a l c u l a t e d using the same formula as f o r d i v a l e n t atoms. In t h i s case 9 i s taken as the mean valence angle at atom i i n v o l v i n g the bond i - j . T h i s approach y i e l d s non-equivalent hybrid o r b i t a l s which s a t i s f y the o r t h o g o n a l i t y c o n d i t i o n s , i m p l y i n g t h a t the t o t a l s c h a r a c t e r a t a given centre must equal 1. T h i s i n c l u d e s vacant, l o n e - p a i r , or Tf bonding ' o r b i t a l s f o r which the s c h a r a c t e r i s not e x p l i c i t l y c a l c u l a t e d but may be deduced. The c a l c u l a t e d i n t e r h y b r i d a n g l e s are not g e n e r a l l y the same as the observed angles, but d e v i a t i o n s from i d e a l geometry are always i n the same d i r e c t i o n . The approach which g i v e s the best agreement between 1 3 4 c a l c u l a t e d i n t e r h y b r i d angles and bond angles f o r f o u r - c o o r d i n a t e atoms i s based on an i n i t i a l assumption of t h r e e f o l d symmetry. The h y b r i d f o r which the s c h a r a c t e r i s being c a l c u l a t e d i s assumed to be the unigue hy b r i d and the remaining t h r e e are t r e a t e d as i f they were e q u i v a l e n t . Let 9 be the mean bond angle at atom i not i n v o l v i n g atom j . The s c h a r a c t e r i n each of the a r t i f i c i a l l y e q u i v a l e n t hybrid o r b i t a l s i s given by the equation d e r i v e d above. I f we denote t h i s q u a n t i t y by x, o r t h o g o n a l i t y r e q u i r e s t h a t : S F ( i f j ) = 1 - 3x and s u b s t i t u t i o n of the value of x i n the above ex p r e s s i o n g i v e s : S F ( i , j ) = 1 . 5 [ c s c 2 (9/2) ] - 2 Except i n cases of extreme s t e r i c d i s t o r t i o n , a p p l i c a t i o n of the above equation to each of the bonds at a f o u r - c o o r d i n a t e atom y i e l d s a s e t of orthogonal h y b r i d o r b i t a l s . When the sum of the s c h a r a c t e r s i n the four h y b r i d s d i f f e r s by more than 2% from u n i t y , a message to that e f f e c t i s p r i n t e d by the program. The most probable causes f o r such d e v i a t i o n s are severe s t e r i c d i s t o r t i o n s and p o s s i b l e involvement of d (or f) o r b i t a l s i n the makeup of the bonding h y b r i d s , the l a t t e r being most l i k e l y f o r atoms beyond the f i r s t row of the p e r i o d i c t a b l e . As f o r t r i v a l e n t atoms, the h y b r i d s g e n e r a l l y do not f o l l o w the bond d i r e c t i o n s . 135 The d e p e n d e n c e o f t h e s i n g l e bond d i s t a n c e on t h e amount o f s c h a r a c t e r i n t h e h y b r i d o r b i t a l s i n v o l v e d i s a g e o m e t r i c f a c t o r , i n d e p e n d e n t o f t h e t y p e s o f a t o m s i n v o l v e d . S i n c e t h e g r e a t e s t amount o f e x p e r i m e n t a l i n f o r m a t i o n i s a v a i l a b l e f o r C - C b o n d s , t h e y w i l l be u s e d a s a s t a n d a r d . A p l o t o f t h e p e r c e n t c o n t r a c t i o n o f t h e s i n g l e bond d i s t a n c e ( r e l a t i v e t o a n s p 3 - s p 3 bond) v e r s u s t h e f r a c t i o n a l s c h a r a c t e r o f t h e b o n d i n g h y b r i d s i s shown i n F i g u r e 18. The d a t a p o i n t s c o r r e s p o n d t o s i n g l e C - C bond d i s t a n c e s o f 1 . 5 3 7 , 1 . 4 8 6 , and 1 .379 A f o r j s p 3-sj3 3, s p 2 - s p 2 , and s p - s p b o n d s ; g i v i n g t h e f o l l o w i n g r e l a t i o n s h i p b e t w e e n t h e f r a c t i o n a l s c h a r a c t e r , S F ( i , j ) , a n d t h e f r a c t i o n a l c o n t r a c t i o n o f t h e c o v a l e n t r a d i u s o f atom i i n t h e bond i - j , DELTA ( i , j ) : DELTA ( i , j ) = 0 . 4 1 1 2 (SF ( i , j) - 0 . 2500) T h e c o r r e c t e d s i n g l e b o n d d i s t a n c e f o r t h e bond i - j i s g i v e n b y : S I G C 0 R ( i , j ) = (1 - DELTA ( i , j ) ) RAD ( i ) + (1 - DELTA ( j , i ) ) RAD (j) where R A D ( i ) and RAD (j) h a v e been c o r r e c t e d f o r f o r m a l c h a r g e s ( s u c h a s q u a t e r n a r y N and B a toms) and e l e c t r o n e g a t i v i t y d i f f e r e n c e s . The g e n e r a l r e l a t i o n s h i p be tween bond c o n t r a c t i o n and bond o r d e r h a s a g a i n b e e n b a s e d on t h e b e h a v i o r o f C - C b o n d s . The v a l u e s o f 1 . 5 3 7 , 1 . 3 9 4 , 1 . 3 3 5 , and 1 .206 A were u s e d f o r 116 F i g u r e 18 A p l o t o f % c o n t r a c t i o n o f C-C s i n g l e b ond d i s t a n c e s ( r e l a t i v e t o an s p 3 - s_n 3 s i n g l e bond) v s . % s c h a r a c t e r i n t h e b o n d i n g o r b i t a l s . 1 37 Bond Order -5 0 5 % Contract ion F i g u r e 19 A p l o t of valence bond order vs. % c o n t r a c t i o n of the i n t e r n u c l e a r d i s t a n c e r e l a t i v e to the c o r r e c t e d s i n g l e bond d i s t a n c e . f o rmal bond o r d e r s of 1, 1. 5 (aromatic) , 2, and 3 r e s p e c t i v e l y . These values were f i t t e d to the f o l l o w i n g f u n c t i o n : x = 2exp(0.613 TC - 0.693) {TC < 0.47} X = 1 + 1.891 TC 2 - 1.790 TC« + 0.887 TC* {TC > 0.47} where x i s the bond order and TC i s 10 times the f r a c t i o n a l c o n t r a c t i o n of the bond l e n g t h . F i g u r e 19 shows a p l o t of 138 bond order vs. percent c o n t r a c t i o n c a l c u l a t e d from the above e g u a t i o n . The c o n t r a c t i o n i s r e l a t i v e to the c a l c u l a t e d s i n g l e bond d i s t a n c e . The p r i n t e d output begins with a l i s t i n g of the c o n t r o l parameters f o l l o w e d by the t r a n s f o r m a t i o n matrix and i t s i n v e r s e . The o r i g i n a l i n put c o o r d i n a t e s and the transformed c o o r d i n a t e s are l i s t e d next. For each chemical bond the f o l l o w i n g i n f o r m a t i o n i s g i v e n : the observed i n t e r a t o m i c d i s t a n c e , the f r a c t i o n a l s c h a r a c t e r s f o r both of the h y b r i d s i n v o l v e d , the c a l c u l a t e d s i n g l e bond d i s t a n c e , the absolute (A) and percent c o n t r a c t i o n s of the bond r e l a t i v e to the c a l c u l a t e d value, the c o v a l e n t r a d i u s used f o r each of the atoms, the c a l c u l a t e d bond order, and f i n a l l y the d e r i v a t i v e e of the bond order with r e s p e c t to a 0.01 A change i n bond l e n g t h . In summary, the t o t a l c a l c u l a t e d bond order f o r the molecule (excluding bonds i n v o l v i n g H) and the number of bonds i n c l u d e d i n the sum are given. For each ncn-hydrogen atom the c o o r d i n a t i o n number, sum of c a l c u l a t e d s c h a r a c t e r s , and sum of bond o r d e r s are p r i n t e d . The observed valence angles and c a l c u l a t e d i n t e r h y b r i d angles are then ( o p t i o n a l l y ) l i s t e d . A sample of the p r i n t e d output f o l l o w s the symbolic program l i s t i n g . 1 3 9 SIGCOB CALCULATION OF SIGMA HYBBIDIZATION EFFECTS AND APPROXIMATE BOND ORDERS FROM MOLECULAR GEOMETRY INPUT Card I i T i t l e (20A4) 1-80 g e n e r a l t i t l e c a r d Card 2 i C o n t r o l Card (615) 1-5 NA number of atoms to be read i n (max. 100) 6- 10 ND number of cards i n bonding a r r a y 1 1-15 NOUT = 0 f o r normal output, 3 to i n c l u d e angles 16- 20 NC = 0 f o r one card/atom, 1 f o r two cards 21- 25 NTAC number of t e r m i n a l atom cards l 3: C e l l Dimensions i n BUCILS format (6F10.5) 1- 10 a 11- 20 b 21- 30 C (A) 31- 40 alpha 4 1-50 beta 51- 60 gamma (degrees) 140 Card 4j_ Atomic £ositions x c o v a l e n t r a d i i x and Sl§£tronec£ativities (5A2,20X,5F10.6) I f NC = 0 1 card per atom NC = 1 2 cards per atom Covalent r a d i i and e l e c t r o n e g a t i v i t i e s (EN) are s t o r e d i n t e r n a l l y f o r the f o l l o w i n g atoms: atom r EN atom r EN B f (EN) 2.01 Br 1. 14 2.74 C 0.768 2.50 I 1.33 2. 21 H 0.23 2. 20 S i 1. 17 1.74 0 0.652 3.50 Sn 1.40 1.72 N 0.701 3.07 Ge 1. 22 2.02 P 1.069 2.06 Sb 1.41 1.82 As 1.21 2.20 S 1.04 2.44 F 0.64 4.10 Se 1. 17 2. 48 C l 0.99 2.83 Te 1. 37 2.01 These are s e t by the program i f the atomic s ymb r i g h t j u s t i f i e d i n columns 3 and 4 of the c o o r d i n a t e c a r d . For atoms i n the above l i s t the values punched i n the c o v a l e n t r a d i u s and e l e c t r o n e g a t i v i t y f i e l d s of the c o o r d i n a t e card are added to the l i b r a r y values. The above values may t h e r e f o r e be changed by punching the d e s i r e d increment i n the a p p r o p r i a t e f i e l d s (see below). Covalent r a d i u s and e l e c t r o n e g a t i v i t y values must be given i f the chemical symbol i s not i n columns 3 and 4 or i f the atom i s not i n c l u d e d i n the above l i s t . 141 The f i r s t c a r d f o r each atom must c o n t a i n : 1-10 atom i . d . , chemical symbol i n c o l s . 3 and 4 31-40 x 41-50 y 51-60 z ( f r a c t i o n a l c o o r d i n a t e s ) 61-70 c o v a l e n t r a d i u s or change i n c o v a l e n t r a d i u s 71-80 e l e c t r o n e g a t i v i t y The second card may c o n t a i n any form of i n f o r m a t i o n (e.g. temperature f a c t o r s ) and are ignored by the program. Card 5:_ Bonding a r r a y (1613) ND c a r d s of the form: 1-3 I number of r e f e r e n c e atom i n atoms l i s t 4-6 JB (n) , n = 1, 15 7-9 numbers i n atoms l i s t of atoms bonded to 10-12 r e f e r e n c e atom, i f t h i s number i s l e s s 13-15 than I then i t should be l e f t out. Each 16-18 bond i s i n c l u d e d once. e t c . T h i s corresponds to a matrix B ( i , j ) . I f the element B ( i f j) i s non-zero, then the atoms i and j are bonded to each ot h e r . Card i i n the bonding array i n p u t g i v e s the values of j which correspond to non-zero elements i n row i of the matrix. 142 Card 6i_ Terminal atom c o r r e c t i o n s (F10.6,2013) (Omit i f UTAC = 0) The program assumes s p 3 h y b r i d i z a t i o n f o r a l l t e r m i n a l atoms. I f t h i s i s not the case these cards are used t o s e t the f r a c t i o n a l s c h a r a c t e r of the atoms i n qu e s t i o n . SCT i s added to .0.2500 to give the d e s i r e d f r a c t i o n a l s c h a r a c t e r . 1-10 SCT 11-13 numbers i n atoms l i s t of t e r m i n a l 14-16 atoms with h y b r i d i z a t i o n corresponding 17-19 to the value of SCT i n c o l . 1-10 e t c , (up to 20 atoms) For , example, i f SCT = 0.08333 then the atoms corresponding t o the numbers punched i n columns 11-13 e t c . w i l l have s p 2 h y b r i d i z a t i o n s t a t e s . E x ecution time on the IBM/370 are on the order of 0.5 s f o r a t y p i c a l s t r u c t u r e (30 atoms). T o t a l formal bond orders w i l l tend to be too high i f a l i b r a t i o n c o r r e c t i o n has not been made. In most cases t h i s e r r o r w i l l not exceed 5%. At present c o o r d i n a t i o n numbers higher than f o u r cannot be d e a l t with p r o p e r l y although atoms with higher c o o r d i n a t i o n numbers can be i n p u t . S O U R C E L I S T I N G 143 C SIGCOR: A PROGRAM FOR C A L C U L A T I N G ESTIMATED BOND LENGTHS AND BOND C ORDERS CORRECTED FOR SIGF1A H Y B R I D I Z A T I O N EFFECTS C WRITTEN IN FORTRAN I V AT THE U N I V E R S I T Y OF B R I T I S H COLUHBIA, 1972 C R E V I S E D J O L T , 1973 COHHON NA DATA F C , P H R F O , F N , F P , F A S , F F , F C L , F B R , F I , F S I , F G E , F S N , F S B , F S , F S E , P T E / 2 1H C.2H H,2H 0,2H N,2U P,2HAS,2H F,2HCL,2HBR,2H I , 2 H S I , 2 H G E , 2 H S N , 2 H 1SB,2H S,2HSE,2HTE/ DATA FB/2H B/ DIMENSION X ( 1 0 0 ) , 1 ( 1 0 0 ) , Z ( 1 0 0 ) , T I T L E ( 2 0 ) , S I G S (100) DIMENSION CA (100) ,RAD ( 1 0 0 ) , A ( 5 , 1 0 0 ) DIMENSION KB ( 1 0 0 , 1 0 0 ) , D L ( 1 0 0 , 100),DM ( 1 0 0 , 100),DN ( 100, 100) DIMENSION S F ( 1 0 0 , 1 0 0 ) , S I G C O R ( 1 0 0 , 100) , D E L T A ( 1 0 0 , 1 0 0 ) DIMENSION TOR ( 1 0 0 ) , D B ( 1 0 0 , 1 0 0 ) , N T O T (100),NAT ( 2 0 ) , S F T ( 1 0 0 ) , P I C O R (10 ? 0 , 1 0 0 ) , P H I ( 1 0 0 , 1 0 0 ) 90 FORMAT (• T H I S PROGRAM CALCULATES ESTIMATED SIGMA H Y B R I D I S A T I O N E F F 1ECTS AND P I CONTRACTIONS, BASED ON THE FOLLOWING ASSUMPTIONS:*/) 91 FORMAT ( 1 0 X , • 1: H Y B R I D I S A T I O N AT BOTH ATOMS INVOLVES ONLY S AND P 1 0 B B I T A L S •) 92 FORHAT(10X,' 2: THE S I N G L E BOND COVALENT R A D I I ARE THOSE GIVEN I N 1 THE ATOMS L I S T BELOW') 93 FORMAT ('1') 94 F O R H A T ( 1 0 X , * 3: THE AT I O N I C P O S I T I O N S ARE CORRECT, I . E . CONTAIN NO S Y S T E M A T I C ERRORS.',/, 110X,' 4: THE HYDROGEN RADIUS HAS BEEN CONTRACTED TO BE CONSISTENT 1WITH XBAY DATA.',/,10X,' 5: R A D I I OF B AND N ATOMS ARE AUTOMATICAL 1LY ADJUSTED WHEN THESE ATOMS ARE FORMALLY CHARGED.*,/,10X, • 6 : THE 1 RADIUS OF BOBON DEPENDS ON THE ELECTRON EGAT IV ITY OF I T S S U B S T I T U E 1NTS.•,/,10X,' 7: BOND ORDER CALCULATIONS ARE ONLY APPROXIMATE AND 1 FOR BOND ORDERS >2 SMALL ERRORS IN THE BOND DISTANCE',/, 13X, 1 WIL 1L CAUSE LARGE ERRORS I N THE BOND ORDER.') 99 FORMAT (20AU) 100 F ORMAT(6F10.5) 101 FORMAT (//,'OBTHOGONALIZATION MATRIX I S : ' , 3 1 X , ' I N V E R S E MATRIX I S : ' , V ) 102 FORMAT ( 3 F 1 5 . 6 , 1 5 X , 3 F 1 5 . 6 , / ) 103 FORMAT(//) 104 FORMAT (615) 105 F O R H A T ( 5 A 2 , 2 0 X , 5 F 1 0 . 6 ) 106 FORMAT (/,'0BTH0G0NALISED COORDINATES: 34X,'FRACTIONAL COORDINATES 1:',//,' NO. ATOM I D X Y Z',23X 1,'X',10X,'Y',10X,'Z') 107 F O R M A T ( I 5 , 5 A 2 , 3 ( 5 X , F 1 0 . 6 ) ,10X,3 ( 3 X , F 8 . 4 ) ) 108 FORMAT (16 1 3 ) 118 FORMAT (' 1 *, ' ATOM ( I ) ATOM ( J ) LENGTH F S ( I , J ) F S ( J , I ) 1LC0RR PICON RAD ( I ) RAD ( J ) ICON ORDER DORD/DB'//) 119 FORMAT ( 1 0 A 2 , 5 F 1 0 . t t , 2 F 1 0 . 3 , F 8 . 1 , 2 F 8 . 2 ) 120 FORMAT ( F 1 0 . 6 , 2 0 1 3 ) 124 FORMAT (/• END OF CALCULATION') 125 FORMAT ('1',' ATOM SUM FS NO OF BONDS,TOTAL BOND ORDER AT AT XOB COMMENTS') 126 FORMAT(5A2,F10.4,5X,13,F10.3) 130 FORMAT (5A2,F10.4,5X,13,F10.3,7X,'ASSUMPTION 1 MAY NOT HOLD AT T H I S X ATOM') 131 FORMAT(30X.A30) 133 FORMAT('NA=',13,5X,' ND=*, 13,5X,•NOUT A' FI3,5X,•NC=•,13,5X,'NTAC=•,I 13,5X, 'NOPT= ',13) 134 FORMAT(/,• TOTAL BOND ORDER FOR THE ',13,' BONDS NOT INVOLVING H I IN THE ASSYHHETRIC UNIT I S : •,F5.2,/,'THE TOTAL NUMBER OF BONDS I S : 1 '.13) 999 FORMAT (• EXECUTION TERMINATED ON ERROR') PI=3.1415927 PA=0.4111906 144 TOBD=0.00 NBT=0 NBNH=0 WRITE (6,90) WRITE(6,91) WRITE (6,92) WRITE (6, 9U) WRITE (6,93) C READ IN AND PRINT OUT TITLE CARD READ (b,99) (TITLE (H),11=1,20) WRITE(6,99) (TITLE (rl) ,11=1, 20) C READ IN CONTROL CARD READ(S,10U) NA,ND,NOUT,NC,NTAC,NOPT WRITE (6,103) WRITE (6,133) NA,ND,NO0T,NC,NTAC,NOPT C READ IN CELL DIMENSIONS AND SET UP BETA AND INVERSE MATRICES DOUBLE PRECISION C(12),D,V READ(5,100) (C(J),J=1,6) DO 2 J=7,9 D = PI*C (0-3)/180 C(J)=CCOS(D) 2 C(J»3) =DSIN(D) V=DSQBT (1.0»2.0*C(7) *C (8) *C(9)-C (7) **2-C (8) **2-C (9) **2) V=C (1) *C (2) *C (3) *V BA1=C (1) BA2=C (2)*C (9) BA3=C (3) *C(8) BAU=0.0 BA5=C(2) *C(12) BA6=C (3)* (C (7)-C (8)*C (9) )/C (12) BA7=0.0 BA8=0.0 BA9*V/(C(1) *C(2) *C(12)) DA1=1.0/C (1) DA2=-C(9)/(C(1) *C(12) ) DA3 =(BA2*BA6-BA3*BA5)/V DAU-0.0 DA5=1 .0/ (C (2)»C (12)) DA6=-BA6/(BA5*BA9) DA7=0.0 DA8=0.0 DA9=1.0/BA9 WRITE (6, 101) WRITE (6,102) BA1,BA2,BA3,DA1,DA2,DA3 WRITE (6, 102) BAU,BA5,BA6,DA4,DA5,DA6 WRITE(6,102) BA7,BA8,BA9,DA7,DA8,DA9 NE=NA IF (NOPT.EQ.1) GO TO 1 WRITE (6,103) C CLEAR ARBATS 1 DO 8 1*1,BB DO 8 J=»1,HB SF(J,I)*0.0 8 KB(J,I) = 0 DO 9 1=1,NA TOR (I)=0.00 9 RAD(I)=0.00 C READ IN POSITIONS AND COVALENT RADII, IF NEEDED C PRINT ORTHOGONAL COORDINATES AND SINGLE BOND COVALENT RACII WRITE (6,106) DO 14 1*1,IA BEAD (5,105) (A(J,I),J=1,5),XP,YF,ZF,RAD(I),CA (I) IF(IC.EQ.O) GO TO 13 BEAD (5,131) SIGS(I) 13 X (I) =8AmF«BA2*YP*BA3*ZP I (I)=BA5»TP»BA6*ZP Z (I)=BA9*ZF C ASSIGN COVALENT RADII AND ELECTRONEGATIV IT IBS CALL PARSET (A (2, I) ,R,CX) 145 CA (I) =CA (I) + CX BAD (I)=RAD(I) *R WHITE (6,107) I, (A (J,I) ,J=1,5) ,X (I) ,Y (I) ,Z (I) ,XF,YF,ZF 14 CONTINUE WRITE (6,103) C READ IN BONDING INFORMATION AND SET UP CONNECTIVITY ARRAY (KB) 606 FOR NAT (' ATOH NUMBER ',15,' ON CARD 5( ',15,' ) EXCEEDS BONDING ARR X AY DIMENSIONS, I.E. IS GREATER THAN NB') DIMENSION JB(15) L = 0 17 READ (5,108) I, (JB (N),N=1,15) L = L*1 IF (I.GT.NA) GO TO 605 DO 18 N=1, 15 IF (JB (N) .GT. NA) GO TO 607 IF(JB (N) .EQ.O) GO TO 21 KB (JB (N) ,1) = KB (JB (N) , I) • 1 KB (I, JB (N) ) =KB (JB (N) ,1) 18 CONTINUE 21 IF (L. EQ.ND) GO TO 32 GO TO 17 605 WRITE(6,103) WRITE (6,606) I,L GO TO 998 607 WRITE (6,103) WRITE(6,606) JB(N),L GO TO 998 32 IF(NTAC.EQ.O) GO TO 26 C READ TERMINAL ATOH HYBRIDIZATION STATES IF DIFFERENT FROM SP3 DO 12 K=1,NTAC READ(5,120) SCT, (NAT (L),L= 1,20) DO 25 L=1,20 IF(NAT (L).EQ.O) GO TO 12 DO 31 J=1,NB 31 SF (J, NAT (L) ) = SCT 25 CONTINUE 12 CONTINUE C NTOT(M) IS NUMBER OF BONDS FORMED BY ATOH (H) 26 DO 215 1=1,NA N NB=0 DO 214 J=1,NA 214 NNB=NNB*KB(J.I) NTOT (I)=NNB 215 CONTINUE C CALCULATION OF AND STORAGE OF BOND LENGTHS IN ARRAY (DB) M=1 DO 28 1 = 1 ,NB M=H*1 IF (M . GT. NB) GO TO 39 DO 29 J=M,NB N = KB (J,I) IF (N.EQ.O) GO TO 29 DELX=X (J)-X (I) DELY=Y(J)-Y(I) DELZ=Z (J) -Z (I) D£(J,I)= SQRT(DELX**2»DELY**2*DELZ**2) DB (I , J)=DB (J,I) CL (J, I) =DELX/CB (J, I) DL (I,J)=-DL (J,I) DM (J, I) =DELY/DB (J, I) DM(I,J)=-DM (J,I) DN (J, I) =DELZ/CB (J, I) DN (I,J)=-DN (J,I) 29 CONTINUE 28 CONTINUE C CALCULATION OF BOND ANGLES AND S CHARACTER ARRAY ELEMENTS 39 NG= NB- 1 DO 42 J=1,NB DO 4 1 1=1 , NB 146 IF (KB (J, I) . EQ.O) GO TO 41 H = I+ 1 PHI (I,J)=0.00 NN=0 DO 40 K=1,NB IF (KB (K,J).EQ.O) GO TO 40 IF (K.EQ.I) GO TO 40 NN=NN*1 COSANG= (CL (J, 1) *DL (J,K) ) • (Dfl (J,I) *Dfl (J, K) ) • (DN (J, I) *CN (J,K) ) BNGLE = ARCOS (COSANG)*180/PI 44 PHI (I,J)=PHI(I,J) +BNGLE 40 CONTINUE IF(NN.NE.3) GO TO 66 PHI (I,J) = 656. 8-PHI (I* J) PHI(I,J)=PI*PHI(I,J)/(360»HN) GO TO 67 66 IF (NN.EQ.O) GO TO 64 PHI (I ,J) =PI*PHI ( I , J ) / (360 »NN) GO TO 65 64 SF (I,J)=SF(I.J)+0.2500 GO TO 410 65 SF ( I , J)* 1.0000- (0.5/ (SIN (PHI ( I , J ) ) •*2)) GO TO 410 67 SF ( I , J) = (1.5/ (SIN (PHI ( I , J) ) **2)) -2. 000 410 DELTA (I,J)=PA*(SF(I,J)-0.25000) 41 CONTINUE 42 CONTINUE C CALCULATE CORRECTED SINGLE BOND LENGTHS AND APPROXIMATE BOND ORDER WRITE (6,118) H=1 DO 71 1=1,NB H=H*1 IF(H.GT.NB) GO TO 132 DO 70 J=H,NB IF(KB (J, I) . EQ.O) GO TO 70 CALL ENCOR (I,J,A,NTOT,RAD,CA) SIGCOR (J,I) = ( 1. 000-DELTA ( I , J) ) •RAD (J) • (1 .000-DELTA (J,I))*RAD(I) PICOR (J,I)=SIGCOR(J,I)-DB(J,I) PC=100*PICOR(J,I)/SIGCOR(J,I) TC=PC/10 CALL BOND(I,J,SIGCOR,TC,BORD,DORD) IF (A (2,1) . EQ. FH) GO TO 78 IF(A(2,J) .EQ.PH) GO TO 78 TOB (I)=TOR(I)+BOBD TOR (J) =TOR (J) • BORD TORD=TORD*BORD NBNH=NBNH*1 78 PC=PC*0.05 BORD=BORD»0.005 DORD=DORD+0.005 WRITE (6,119) (A(K,I) ,K=1,5) , (A (K,J) ,K=1,5) ,DB (J,I) ,SF (J,I) ,SF ( I , J) 1,SIGCOR (J,I),PICOR (J,I),RAD (I),RAD (J),PC,BORD,DORD NBT=NBT*1 70 CONTINUB 71 CONTINUE 132 TORD=TORD*0.005 WRITE(6,134) NBNH,TORD,NBT WRITE (6,125) DO 74 K=1,NA 74 SFT(K)=0.0 DO 73 1=1,NA IF (A (2,1).EQ.PH) GO TO 73 C Son UP BOND ORDER AND FRACTIONAL S CHARACTER AT EACH NON-HIDROGEN C ATOH. DO 72 J=1,NA IF (KB (J,I) . EQ.O) GO TO 72 SFT (I) *SFT (I) •SF(J.I) 72 CONTINUE IF(NTOT.(I) .LT.4) GO TO 75 147 I F (ABS (1.OOO-SFT (I)).LT.0.02) GO TO 75 WRITE (6, 130) (A(K,I) ,K=1,5) ,SFT(I) , NTCT (I) ,TOR (I) GO TO 73 75 WRITE(6,126) (A (K , I) , K= 1 , 5) , SFT (I) , NTOT (I) ,TOR (I) 73 CONTINUE C PRINT OUT BOND ANGLES AND INTERHYBRID ANGLES IF DESIRED I F (NOUT.NE.3) GO TO 997 CALL ANGLE(KB,DL,DM,DN.SF.A) 997 WRITE (6,12U) GO TO 1000 998 WRITE (6,999) 1000 STOP END SUBROUTINE PABSET (A,B,C) C LIBRARY OF COVALENT RADII AND ELECTRONEGATIVITIES DATA FC,FH,FO,FN,FP,FAS,FF,FCL, FBR, F I , F S I , FGE, FSN,FSB,FS,FSE,FTE/2 1B C,2H H,2H 0,2H N,2H P,2HAS,2H F,2HCL,2HBR,2H I,2HSI,2HGE,2HSN,2H 1SB,2H S,2HSE,2HTE/ I F (A. EQ.FC ) R=0. 768 I F (A. EQ.FH ) R=0. 23 I F (A. EQ.FN ) R=0. 701 I F (A. EQ.FO ) H=0. 652 IF ;A. EQ. FP ) R=1. 069 I F (A. EQ.FAS) H=1. 21 I F (A. EQ.FCL) R=0. 99 I F (A. EQ.FBR) R=1. 14 IF [A. EQ.FSI) 8=1. 17 I F (A. EQ.FSN) R=1. 40 IF (A. EQ.FGE) R=1 . 22 I F (A. EQ.FSB) R=1. 41 I F A. EQ.FS ) R=1. 04 I F [A. EQ.FF ) 8=0. 64 IF A. EQ.FI ) R=1. 33 I F A. EQ.FSB) R=1. 17 I F A. EQ.FTE) R=1. 37 I F A. EQ.FB ) C=2. 01 I F *• EQ.FC ) C=2. 50 I F A. EQ.FH ) C=2. 20 IF (A.EQ.FO ) C=3. 50 I F (A. EQ.FN ) C=3. 07 I F A. EQ. FP ) C=2. 06 I F A. EQ.FP ) C=4. 10 I F A. EQ.FI ) C=2. 21 I F :A. EQ.FS ) C=2. 44 IF (A. EQ.FAS) C=2. 20 IF ;A. EQ.FCL) C=2. 83 IF (A. EQ.FBR) C=2. 74 I F (A. EQ.FSI) C=1. 74 IF (A. EQ.FSN) C=1. 72 I F (A. EQ.FGE) C=2. 02 IF (A. EQ.FSB) C=1. 82 I F (A. EQ.FSB) C=2. 48 IF (A.EQ.PTE) C=2. 01 RETURN END SUBROUTINE ENCOR (I,J,A,NTOT,RAD,CA) C SUBROUTINE FOR ELECTRONEGATIVITY CORRECTIONS C AT A FB/2H B/ DATA FC,FH,FO,FN,FP,FAS,FP,FCL,FBR, PI,FSI,FGE.FSN.FSB.FS,FSE,FTE/2 1H C,2H H,2H 0,2H N.2H P,2HAS,2H F.2HCL.2HBR,2H I,2HSI,2HGE,2HSN,2H 1SB.2H S,2HSE,2HTE/ DATA FB/2H B/ DIMENSION A (5,100),RAD (100),CA (100),NTOT (100) i 148 IF(A(2,I) . EQ.FB) GO TO 68 IF (A (2,1) . EQ.FN) GO TO 69 GO TO 81 68 IF (NTOT (I) .EQ.3) RAD (I) = 0. IF (NTOT (I) •EQ.4) RAD (I) = 0. GO TO 81 69 IF (NTOT (I) .EQ.4) RAD (I) = 0. 81 IF (A (2.J). EQ.FB) GO TO 66 IF(A(2,J) . EQ.FN) GO TO 80 GO TO 67 66 IF (NTOT (J) .EQ.3) RAD (J) = 0. IF (NTOT (J) .EQ.U) RAD (J) = 0. GC TO 67 80 IF (NTOT (J) .EQ.U) RAD (J) = 0. 67 RETURN END 80 3-0. 0 75* A BS (2.01-CA (J) ) 918-0. 064*ABS(2.01-CA(J) ) 708 80 3-0.0 75*ABS (2.01-CA (I)) 918-0.064*ABS (2.01-CA (I) ) 708 SUBROUTINE BOND (I,J,SIGCOR,TC,BORD,DORD) C FUNCTION RELATING PERCENT CONTRACTION TO BOND ORDER DIMENSION SIGCOR (100,100) IF (TC.GE.O.47) GO TO 76 BORD=2.0*(EXP ( (0.612766*TC)-0.69 3)) D0RD=-(0.0612766*BORD)/SIGCOR (J,I) GO TO 77 76 TC2=TC**2 TC4=TC2**2 TC6=TC2*TC4 BORD=1.000* (1.89145589*TC2)- (1.79044767*TC4) •(0.88704 228*TC6) DORD=TC*(-0. 378291 18* (0.71617907*TC2)- (0.53222537*TC4))/SIGCOR (J,I D 77 RETURN END SDBROUTINE ANGLE (KB,DL,DM,DN,SF,A) C SUBROUTINE FOR CALCULATING BOND ANGLES COMMON NA DIMENSION A (5,100),KB (100,100),DL (100,100),DM (100,100),DN (100, 100) DIMENSION SF(100,100) PI=3. 141592 NB=NA 116 FORMAT (• 1 ', ' ATOH (I) ATOH (J) ATOM (K) OBS. ANGLE INTERHYBRID AN 1GLE',/) 117 FORHAT(12A2,5X,F7.3,5X,F5.1) WRITE (6,116) DO 42 J=1,NB DO 41 1=1,NB IF (KB (J , I) . EQ. 0) GO TO 41 H=I*1 DO 40 K=1,NB IF (KB (K,J).EQ.O) GO TO 40 IF(K.EQ.I) GO TO 40 COSANG= (DL(J,I)*DL (J,K) ) • (DM (J,I) *DH (J,K) ) • (Di (J, I) *DN (J , K) ) ANGLE=ARCOS(COSAHG)*180/PI C= (SF (I , J ) *SF (K, J))/ ( (1.000-SF (I , J )) • (1.000-SF (K, J) ) ) IF (C.LT.0.000) GO TO 140 CC—SQRT(C) CANG*ARCOS (CC)*180/P1 CANG=CANG*0.05 GO TO 141 140 CANĜ O.O 141 IF (K.LT.I) GO TO 40 WRITE (6,117) (A (N,I) ,N»1 ,4), (A ( N ,J) ,N«1,4), (A (B,K),N=1,4) ,ANGLE,CA ING 40 CONTINUB 41 CONTINUB 42 CONTINUE RETURN END B.B-r . IPHENYLBOROXAZOLIDINE BOND ORDRR CALCALATICN NA = 13 NE = )7 KOUT = STAC" NOPT= ORTHOGONALIZATION MATRIX IS : 13.8U0230 0.000003 - 1 . 5 6 3 8 0 7 0.0 8.916880 0.000004 0 .0 0 .0 10.048817 INVERSE MATRIX IS: 0.072253 0.0 0.0 -0 .000000 0 . 1121*7 0 .0 0.011244 -O.COOCOO 0.099514 ORTHOGONAL COORDINATES: FRACTIONAL COORDINATES: ATOM ID X 1 Z X T Z 1 B 10.291018 2. 4 14442 3.727608 0.7855 0.2708 0.3709 2 0 9 .467303 3.641119 3.591718 0.7244 0.4083 0.3574 3 N 9 . 329347 1.340697 2.917914 0.7069 0.1504 0.2904 4 C 1 8. 120409 3.297132 3.341392 0.6243 0.3698 0.3325 5 C2 8. 18230 1 2 . 126631 2.397346 0.6182 0.2385 0.2386 6 C3 11.710424 2.655144 3.002817 0.8799 0.2978 0.2988 7 C4 11.902396 2.599992 1. 6239 19 0.8782 0.2916 0. 1616 8 C5 13. 1 16244 2.946305 1.037087 0.9594 0. 3 304,, 0.1032 9 C6 14. 168496 3. 350659 1. 8044 15 1.0440 0.3758 0.1796 10 C7 14.019948 3.417439 3.172863 1.0487 0.3833 0.3157 1 1 C8 12.811918 3.075735 3.747806 0.9678 0.3449 0.3730 12 C9 10.410710 1.881695 5.241000 0.8111 0.2110 0.5216 13 CIO 11.037951 0.676410 5.552895 0.8600 0.0759 0.5526 14 C l 1 1 1.151515 0.219884 6.860044 0.8829 0.0247 0.6827 15 C12 10.660658 0 .968055 7.896218 0.8591 0.1086 0.7858 16 C 1 3 10.037719 2 .156175 7.631754 0.8111 0.2418 0.7595 17 C1U 9.917236 2.596400 6.319348 0.7876 0.2912 0.6289 18 H (1 , 1) 7.661106 3.079945 4.219457 0.6010 0.3454 0.4199 19 H(1 ,2 ) 7 .640915 3. 998204 2.956743 0.5853 0.4484 0.2942 20 H (2 1) 8.46074 1 2 .399273 1.525048 0.6285 0.2691 0.1518 21 H(22) 7 . 385065 1.628079 2.327958 0.5598 0.1826 0.2317 22 H (NI) 8.992624 0.691648 3.582553 0.6900 0.0776 0.3565 23 H (N2) 9.706861 0 .851982 2.332310 0.7276 0.0955 0.2321 24 H (4) 1 1 . 108064 2 .335633 1.030716 0.8142 0.2619 0. 1026 25 H (5) 13.154810 2.897549 0.080189 0.9514 0.3250 0.0080 26 H (6) 15.023149 3.560367 1.404512 1. 1013 0.3993 0.1398 27 H (7) 14.759949 3.700006 3.759905 1.1087 0.4149 0.3742 28 H (8) 12.718121 3.138929 4.716502 0.9720 0.3520 0.4694 29 H (10) 1 1.448815 0 .201407 4.860863 0.8819 0.0226 0.4837 30 H (11) 1 1 .614739 - 0 . 6 2 5 2 4 9 6.975526 0.9176 -0 .0701 . 0.6942 31 H (12) 10.773760 0.663499 8.825694 0.8777 0.0744 0.8783 32 H (13) 9.652521 2.731019 8.318761 0.7910 0.3063 0.8278 33 H (14) 9.462642 3.419044 6. 157130 0.7529 0.3834 0.6127 t o ATOM (I) ATOH (J) LENGTH F S ( I . J ) FS ( J . I ) LCORR PICON RAD (I) RAD (J) ICON ORDER DOBD/DB B B B B 0 H N N CI CI CI C2 C2 CI C3 Ct CU C5 C5 Cb C6 C7 C7 C8 C9 C9 CU) CIO C1 1 CI 1 C12 C12 CI 1 cn CI 4 N a a ci C2 H(N1) H (N 2) C2 H (1, 1) HO.2) H (21) H (22) CU CB CS H(1) C6 H (5) C7 H (6) C8 H (7) H (8) CIO C11 CI 1 H(10) C12 H(11) c n H (12) C11 H (13) H (11) 1.1838 1.6533 1.6118 1.6089 1.1125 1.1817 0.9881 0.8511 1.5050 1.0115 0.9321 0.9551 0. 9128 1. 393 3 1.3917 1.3920 1.0260 1.3636 0.9589 1.3781 0.9666 1.3808 0.9859 0. 9753 1. 391 1 1.3816 1. 3892 0.9315 1.3691 0. 9707 1. 3673 0.9816 1.3895 0.9751 0.9538 0. 1955 0.1707 0.3215 0.3080 0. 2561 0.2529 0. 1719 0.3082 0.2532 0.2570 0. 2580 0.2173 0.3115 0.3322 0. 3181 0.3381 0. 3269 0.3151 0.3512 0.3301 0. 3351 0.3278 0. 3313 0.3231 0. 3253 0.3261 0. 3389 0.3256 0.3165 0.3325 0.3323 0.3351 0. 3203 0.3339 0. 3238 0. 2561 0.2665 0. 3167 0.3175 0.2355 0.1815 0. 2500 0.2500 0. 2571 0.2500 0.2500 0.2500 0. 2500 0.3311 0. 3373 0.3228 0.2500 0.3312 0.2500 0.3378 0. 2500 0.3389 0.2500 0.2500 0. 3311 0.3387 0. 3200 0.2500 0.3325 0.2500 0. 3151 0.2500 0.3371 0.2500 0.2500 1.1915 1.5811 1.5980 1.6027 1.1229 1.1968 0.9607 0.9210 1.5326 0.9958 0.9955 1.0083 0.9691 1.1835 1.1869 1.1851 0.9737 1.1793 0.9721 1.1830 0.9710 1.1833 0.9711 0.9718 1.1857 1.1839 1.1858 0.9711 1.1795 0.9719 1.1800 0.9711 1.1863 0.9715 0.9717 0.0076 -0.0722 -0.0138 -0.0062 0.0105 0.0121 -0.0271 0.0700 0.0276 -0.0187 0.0631 0.0529 0.0262 0.0902 0.0922 0.0931 -0.0523 0. 1 156 0.0131 0.1019 0.0011 0.1025 -0.0115 -0.0001 0.0916 0.0992 0.0966 0.0396 1101 .0013 , 1126 .0135 .0968 -0.0036 0.0209 0.823 0.850 0.887 0.887 0.652 0.708 0.708 0.708 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.768 0.6S2 0.708 0.768 0.768 0.768 0.768 0.230 0.230 0.768 0.230 0.230 0.230 0.230 0.768 0.768 0.768 0.230 0.768 0.230 0.768 0.230 0.768 0.230 0.230 0.768 0.768 0.768 0.230 0.768 0.230 0.768 0.230 0.768 0.230 0.230 0.6 -1.5 -0.8 -0.3 0.8 0.9 -2.8 7.6 1.9 -1.8 6.1 5.3 2.8 6. 1 6.3 6.3 -5.3 7.9 1.1 7. 1 0.5 7.0 -1.1 0.0 6.2 6.7 6.6 1.1 7.5 0.2 7.7 -1.3 6.6 -0.3 2.2 1.01 C.76 0.95 0. 98 1.05 1. C6 0.81 67 12 90 1.53 1.11 1. 19 1.50 1.52 1.53 0.72 1.69 1.09 1.61 1.03 1.60 0. 92 1. C0 1.51 1.57 1.55 1.29 1.66 1.01 1.67 C.92 1.55 0. 98 1. 15 -0.01 -0.02 -0.03 -0.03 -0.01 -0.01 -0.05 -0.11 -0.01 -0.05 -0. 11 -0.11 -0.07 -0.07 -0.07 -0.07 -0.01 -0.07 -0.06 -0.C7 -0.06 -0.07 -0.05 -0.06 -0.07 -0.07 -0.07 -0.08 -0.07 -0.06 -0.07 -0.05 -0.07 -0.06 -0.07 TOTAL BOND ORDER FOR THE 19 BONDS NOT INVOLVING H IN THE ASSYRHETRIC UNIT IS: 25.61 THE TOTAL NUMBER OF BONDS IS: 35 ATOH SUM FS NO OF BONDS,TOTAL BOND ORDER AT ATOM COMMENTS B 0.9957 U 3.713 0 0.S122 2 2.078 N 0.9994 U 1.807 C l 1.0036 4 2. 163 C2 0.9977 It 2.168 C3 0.9970 3 3.961 C4 0.9995 3 3.020 C5 0.9993 3 3.210 C6 0.9997 3 3.299 C7 0.9999 3 3.201 C8 0.9996 3 3.105 C9 0.9992 3 U.053 CIO 0.9986 3 3.056 C l 1 0.9990 3 3. 198 C12 0.9999 3 3.318 C1 3 0.9993 3 3.215 C14 0.9997 3 3.115 ATOM (I) ATOM(J) ATOH(X) OBS. ANGLE INTERRTBRID ANGLE 0 B N 99.739 103.0 0 B C3 108.919 109.9 0 B C9 113.653 109.2 M B C3 112.892 108.3 N B C9 106.792 107.7 C3 E C9 114.011 1 17.4 B 0 Cl 110.136 1 10.2 B N C2 106.099 1 10.6 B N H(N1) 107. 181 106.0 B N H(»2) 116.867 113.8 C2 N H(N1) 108.679 105.4 C2 N H(N2) 113.917 112.9 H(N1) H H (N2) 10 3.697 107.8 0 C1 C2 105.150 108.9 0 C l H(1. 1 109.298 109. 1 0 C1 H(1,2 112.357 109.1 C2 Cl H<1,1 113.268 1 10. 1 C2 Cl H(1,2 110.313 1 10.1 H (1, 1 Cl H(1,2 106.572 1 10. 3 N C2 C1 102.916 106.1 N C2 H<21) 104.242 104.4 N C2 H(22) 113.525 109.9 C l C2 H(21) 111.269 108. 1 C l C2 B(22) 115.001 115.1 H(21) C2 H(22) 109.277 112.4 B C3 CU 124.087 121.0 B C3 C8 120.022 119.9 C« C3 C8 115.579 118.8 C3 C4 C5 121.838 120.5 C3 CD H(«) 118.U06 119.6 C5 CU H(U) 1 19.700 1 19.9 CU C5 C6 120.626 120.1 CU C5 H(5) 116.302 1 19. 1 C6 C5 H(5) 123.063 120.8 C5 C6 C7 119.337 119.9 C5 C6 H(6) 120.918 120.3 C7 C6 H (6) 119.710 120.0 C6 C7 C8 119.721 120.0 C6 C7 H(7) 121.616 120.5 C8 C7 H(7) 118.662 119.7 C3 C8 C7 122.899 120.8 C3 C8 H(8) 118.303 1 19.6 C7 C8 H(8) 118.795 1 19.7 B C9 CIO 122.020 120.5 B C9 CIU 122. 35U 120.6 CIO C9 CIU 115.619 119.0 C9 CIO Cl 1 122.101 120.5 C9 CIO H(10) 118.137 119.5 C1 1 C10 H(10) 119.590 119.9 C10 C11 C12 120.21U 120.0 C10 C11 H ( l l ) 115.918 1 19.0 C12 C11 H(11) 123.8U0 121.0 c n C12 C13 119.460 119.9 C l 1 C12 8(12) 120.281 120.1 C1 3 C12 H(12) 120.244 ' 120. 1 C12 C13 CIU 119.833 119.9 C12 C13 H(13) 123.777 121.0 C l 4 C13 H(13) 116.387 119.1 C9 Cl u C13 122.762 120.7 C9 ciu H(1U) 118.856 119.7 C13 C1U H(14) 118.374 119.6 EM D OF CALCULATION STOP 0 EXECUTION TERMINATED SSIG 153 DISCUSSION The r e s u l t s of bond order c a l c u l a t i o n s f o r < c 6 H 5 ) 2 B O C H 2 C H 2 N H 2 (*» P a r t 1 ) ' (£ _ F C6 H^) 2 B O C H 2 C H 2 N H 2 P a r t 2 ) , and [ CH3N (CH 2CH 20) 2GaH ] 2 ( I I I , P a r t 4) are given as examples i n Table 49. The r e l i a b i l i t y of the c a l c u l a t e d bond o r d e r s depends on the accuracy of the s t r u c t u r a l data as well as on the e r r o r s i n h e r e n t i n the e m p i r i c a l method of c a l c u l a t i o n d e s c r i b e d above. For X-ray and neutron d i f f r a c t i o n data the t o t a l bond order f o r a molecule c a l c u l a t e d by the program tends to be too high i f a l i b r a t i o n c o r r e c t i o n has not been a p p l i e d . T h i s e r r o r i s u s u a l l y l e s s than 5%, the a c t u a l magnitude depending on the degree of thermal motion i n the sample and on the types of bonds present i n the s t r u c t u r e . Neglect of c o r r e c t i o n s f o r thermal motion lea d s t o s m a l l e r r o r s i n the i n d i v i d u a l bond orders f o r weak bonds, but becomes i n c r e a s i n g l y important as the bond order i n c r e a s e s . T h i s e f f e c t can be judged by the magnitude of the d e r i v a t i v e of the bond order with r e s p e c t to a 0.01 A change i n the bond l e n g t h which i s i n c l u d e d i n the output f o r each chemical bond. The e f f e c t . of a p p l y i n g a l i b r a t i o n c o r r e c t i o n on the t o t a l c a l c u l a t e d bond order i s shown i n Table 49 f o r I and I I . Bonds i n v o l v i n g hydrogen atoms are not i n c l u d e d i n the t o t a l . The expected formal bond order f o r a molecule i s f i g u r e d with the assumption t h a t a l l bonds i n v o l v i n g hydrogen atoms have a bond order of 1. I f the mean bond order f o r a l l such bonds i n a s t r u c t u r e i s d i f f e r e n t from 1, then the 154 Table 49 Sample c a l c u l a t i o n s using SIGCOR I I I I I I T o t a l bond order (excluding bonds i n v o l v i n g H) expected (formal) 25 27 14 c a l c u l a t e d (uncorrected) 25.84 28.37 p a r t i a l l i b r a t i o n c o r r e c t i o n 25.10 27.54 f u l l l i b r a t i o n c o r r e c t i o n — — 13.91 Mean d e v i a t i o n between valence and c a l c u l a t e d i n t e r h y b r i d angles f o r 3 and 4 c o o r d i n a t e atoms 1.9 1.8 1.4 I Bond orders i n the X-O-C-C-•N r i n g s A B X-0 1.04 1.10 — 0-C 1.05 1.07 0.88 0.98 C-C 1. 12 1.28 1.12 1.03 C-N 1.06 1.08 0.98 1.09 N-X 0.76 0.73 — — Bond orders i n the phenyl r i n g s * x-o 1.46 1.44 o-m 1 .52 1 .49 m-p 1.59 1.66 mean 1 .52 1.53 *x r e f e r s to the atom bonded to B 155 expected value f o r the remaining bonds w i l l change. For I and I I the l i b r a t i o n c o r r e c t i o n was not a p p l i e d to bonds i n the five-membered r i n g (see P a r t s 1 and 2 f o r d e t a i l s ) . as mentioned p r e v i o u s l y , the c a l c u l a t e d i n t e r h y b r i d a n g l e s and the observed valence angles are g e n e r a l l y not e q u i v a l e n t f o r 3 and 4 c o o r d i n a t e atoms. The magnitude of such d e v i a t i o n s can be judged from the mean d e v i a t i o n s f o r s t r u c t u r e s I - I I I given i n Table 49. The o r t h o g o n a l i t y of the c o n s t r u c t e d h y b r i d o r b i t a l s i s ensured i f the sura cf the f r a c t i o n a l s c h a r a c t e r s i n a l l the h y b r i d s a t a given atom equa l s u n i t y . In cases where the sum was c a l c u l a b l e ( t e t r a h e d r a l or t r i g o n a l - p l a n a r c o o r d i n a t i o n ) the values ranged from 0.994 to 1.004 with a mean value of 1.00 f o r the three sample s t r u c t u r e s . The c a l c u l a t e d bond o r d e r s f o r the X-O-C-C-N (X = B or Ga) r i n g s i n I - I I I and f o r the phenyl r i n g s i n I and II are a l s o given i n Table 49. The values i n d i c a t e s l i g h t l y d i f f e r e n t charge d i s t r i b u t i o n s i n each of the fou r unique c h e l a t e r i n g s as w e l l as i n the phenyl groups i n I and I I . T h i s has been d i s c u s s e d i n P a r t s 2 and 4. The bond orders g i v e more i n f o r m a t i o n than can be deduced from a simple comparison of bond d i s t a n c e s . Caution must be e x e r c i s e d when a n a l y s i n g data produced by the program. Inaccurate c o v a l e n t r a d i i and the neg l e c t of e l e c t r o n e g a t i v i t y c o r r e c t i o n s (which are i n c l u d e d only f o r boron atoms i n the present v e r s i o n of the program) lead to i n c o r r e c t bond o r d e r s . An example of t h i s occurs i n the bonds 156 i n v o l v i n g the phenyl carbon atoms c a r r y i n g the F s u b s t i t u e n t s i n I I . I t i s c l e a r t h a t i n t h i s case the bond or d e r s are too high s i n c e the mean bond order i n the phenyl groups c f I I should be l e s s t h at f o r I (see Part 2). T h i s i s a r e s u l t of not a p p l y i n g an e l e c t r o n e g a t i v i t y c o r r e c t i o n to the r a d i u s of the carbon atom bonded t o the h i g h l y e l e c t r o n e g a t i v e f l u o r i n e atom. ' The determination of the bes t values f o r the s i n g l e bond c o v a l e n t r a d i i , e l e c t r o n e g a t i v i t y c o r r e c t i o n s , and the bond order - bond c o n t r a c t i o n r e l a t i o n s h i p i s a long and t e d i o u s process. S e l l a b l e and s e l f - c o n s i s t e n t parameters can only be obtained i f a great deal of accurate experimental data i s examined. T h i s i s complicated by the n e c e s s i t y that h y b r i d i z a t i o n e f f e c t s must f i r s t be accounted f o r and a l s o by the f a c t t h a t there i s a high c o r r e l a t i o n between the parameters which are being d e r i v e d . Work on the program w i l l c o n tinue i n the f u t u r e , h o p e f u l l y y i e l d i n g an adeguate s e t of e l e c t r o n e g a t i v i t y c o r r e c t i o n s . I t i s a l s o hoped that a method f o r d e a l i n g with hybrids i n v o l v i n g d o r b i t a l s can be found i n order that the program w i l l work f o r atoms with c o o r d i n a t i o n numbers g r e a t e r than 4. 1 5 7 SUMMARY 158 The a im o f t h i s r e s e a r c h h a s b e e n to d e t e r m i n e t h e s t r u c t u r e s o f t h e f i v e m o l e c u l e s p r e v i u o s l y d e s c r i b e d . The s t r u c t u r e s o f t h e t h r e e b o r o n c o m p o u n d s ( P a r t s 1-3) h a v e p r o v i d e d a c c u r a t e g e o m e t r i c d a t a f o r t e t r a h e d r a l b o r o n a t o m s i n o r g a n i c m o l e c u l e s . The a n a l y s i s o f B f B - d i p h e n y l b o r o x a z o l i d i n e ( P a r t 1) p r o v e d t h a t t h e e t h a n o l a m i n e e s t e r s o f d i p h e n y l b o r i n i c a c i d a r e i n t r a m o l e c u l a r N—*B c o o r d i n a t e d c o m p l e x e s . The p - f l u o r o p h e n y l d e r i v a t i v e ( P a r t 2) was f o u n d t o h a v e a c o n f o r m a t i o n d i f f e r e n t f r o m t h a t o f t h e p a r e n t m o l e c u l e , l a r g e l y due t o i n v o l v e m e n t o f t h e f l u o r i n e a toms i n h y d r o g e n b o n d i n g . The two s t r u c t u r e s show s m a l l d i f f e r e n c e s i n t h e bond d i s t a n c e s i n t h e p h e n y l and f i v e - membered BOCCN r i n g s w h i c h i n d i c a t e d i f f e r e n c e s i n c h a r g e d i s t r i b u t i o n a s a r e s u l t o f r e p l a c i n g t h e two h y d r o g e n a t o m s by f l u o r i n e a t o m s . In P a r t 3 t h e compound C 1 5 H l g B N O 2 was shown t o be Ph 2 BOCH 2 NMe 2 6 r a t h e r t h a n P h 2 B O C H 2 O N M e 2 , t h e l a t t e r a n a l o g o u s t o t h e b o r o x a z o l i d i n e s i n P a r t s 1 and 2. T h i s compound h a s B- 0 a n d B - C d i s t a n c e s d i f f e r e n t f r o m t h o s e i n t h e o t h e r two b o r o n c o m p o u n d s . T h i s r e s u l t s f r o m c h a n g i n g one o f t h e s u b s t i t u e n t s a t t h e b o r o n atom f r o m n i t r o g e n t o o x y g e n . T h e bond d i s t a n c e a l t e r a t i o n i n t h e p h e n y l r i n g s has a d i f f e r e n t p a t t e r n and t h e p h e n y l r i n g v a l e n c e a n g l e s i n d i c a t e t h a t t h e b o r o n atom i n t h i s c a s e i s l e s s e l e c t r o n r e l e a s i n g t h a n i n t h e two b o r o x a z o l i d i n e s . The r e l a t e d g a l l i u m c o m p l e x , [MeN (CH^CH^O^ GaH J , ^ p r o v e d t o be one o f t h e f i r s t known c r y s t a l l o g r a p h i c e x a m p l e s o f 159 p e n t a c o o r d i n a t e g a l l i u m ( P a r t 4 ) . T h e r e a r e two d i s t i n c t t y p e s o f GaOCCN c h e l a t e r i n g s i n t h e m o l e c u l e , b o t h o f w h i c h h a v e 0 - C , C - C , and C-N bond l e n g t h p a t t e r n s d i f f e r e n t f r o m t h o s e i n t h e r e l a t e d b o r o n c o m p o u n d s . T h i s c a n be s e e n by e x a m i n a t i o n o f t h e bond o r d e r s i n T a b l e 4 9 , B o t h t h e g a l l i u m a n d h y d r i d o m o l y b d e n u m ( P a r t 5) c o m p l e x e s a r e e x a m p l e s o f c o m p o u n d s i n w h i c h s t e r i c e f f e c t s a r e t h e most p r o b a b l e c a u s e o f u n u s u a l g e o m e t r i e s . The l a t t e r s t r u c t u r e h a s p r o v i d e d an e x a m p l e o f u n i q u e m u l t i c e n t r e b o n d i n g i n v o l v i n g a l u m i n u m a t o m s , F u r t h e r r e s e a r c h w i l l i n c l u d e s t r u c t u r a l a n a l y s e s o f a d d i t i o n a l r e l a t e d c o m p o u n d s . E t h a n o l s o l u t i o n s o f B , B - b i s ( p - f l u o r o p h e n y l ) b o r o x a z o l i d i n e s l o w l y d e c o m p o s e i n l i g h t t o g i v e d a r k l y c o l o r e d c r y s t a l s o f unknown c o m p o s i t i o n , t h e s t r u c t u r e o f wh ich i s now u n d e r s t u d y . O t h e r s t r u c t u r a l s t u d i e s p l a n n e d f o r t h e n e a r f u t u r e a r e t h o s e o f t h e m o n o e t h a n o l a m i n e c o m p l e x [ M e 2 N C H 2 C H 2 O G a M e 2 ] 2 , w h i c h may a l s o f e a t u r e a f i v e - c o o r d i n a t e g a l l i u m a t o m , and e t h y l e n e d i a m i n e c o m p l e x e s o f b o t h b o r o n and g a l l i u m . I t may a l s o be o f i n t e r e s t to d e t e r m i n e t h e s t r u c t u r e o f t h e b o r o n a n a l o g u e o f t h e d i e t h a n o l a m i n e g a l l i u m c o m p o u n d . R e s e a r c h on c o m p o u n d s r e l a t e d t o t h e h y d r i d o m o l y b d e n u m c o m p l e x i n P a r t 5 i s b e i n g done by P r o f . C. K. P r o u t and h i s a s s o c i a t e s a t O x f o r d . 160 REFERENCES 1. G. H. Stout and L. H. Jensen. X-ray S t r u c t u r e Determination: A P r a c t i c a l Guide. The Macmillan Company, London. 1968. 2. H. Lipson and W. Cochran. 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Nowell, Steve Rettig, and James Trotter, "Disordered Crystal Structures of Six Complexes of the Type, Me2XCR1R2CF2XMe2' M(C0K (M=Mc or Cr; X - As or P; R1 = F or H; and R2 = H, CF3, or Cl)", J. Chem. Soc. Dalton, 2381(1972).- Steven J. Rettig and James Trotter, "Crystal and Molecular Structure of B_, B_-Diphenylboroxazol idine (2-Aminoethyl Diphenylborinate), Ph21&0(CH2)2NH2", Can. J. Chem., 51, 1288(1973). Steven J. Rettig and James Trotter, "Crystal and Molecular Structure of Hexakis(dimethylamino) cyclotriphosphazene, [NP(NMe 2) 2] 3", Can. J. Chem., 51, 1295(1973). Steven J. Rettig and James Trotter, "Crystal and Molecular Structure of Potassium trans-1,2-Diaminocyclohexane-N,N-tetraacetatoman- ganate (III) Monohydrate, K(Mn(DCTA)]«H20", Can. J. Chem., 51, 1303(1973). Steven J. Rettig, Alan Storr, Brian S. Thomas, and James Trotter, "Crystal and Molecular Structure of (pentahaptocyclopentadienyl) hydri domolybdenum-u-di methyl a 1umi ni um-u-[methyla 1umi n i um-d i - ( u - pentahapto(monohapto) cyclopentadienyl) dimethylaluminium]- (pentahaptocyclopentadienyl) hydridomolybdenum, [(C 5H 5)(C 5H 4) MoH] 2Al 3(CH 3) 5", Acta Cryst., B30, 666(1974). A l i s t a i r L. Macdonald, Steven J. Rettig, and James Trotter, "Crystal and Molecular Structure of 2-Deacylusnic Acid", Can J. Chem., 52, 723(1974). Steven J. Rettig, Alan Storr, and James Trotter, "Crystal and Molecular Structure of the N-Methyldiethanolaminogallane Dimer, [CH3N(CH2CH20)2GaH]2", Can. J. Chem., 52, in press. Steven J. Rettig and James Trotter, "Crystal and Molecular Structure of B_5B_-Bis(p_-fluorophenyl)boroxazolidine, (£-FC6H^)2 1k)(CH2)2NH2", Acta Cryst., B30, in press. Steven J. Rettig, James Trotter, and W. Kliegel, "Crystal and Molecular Structure of 4,4-Dimethyl-2,2-diphenyl-l,3- dioxa-4-azonia-2-boranatacyclopentane", Can. J. Chem., 52, in press. G.L. Hodgson, D.F. MacSweeney, T. Money, S.J. Rettig, and J. Trotter, "Crystal and Molecular Structure of (±)-7,7-(2,2'-Dimethyl) pentamethylene-1-methyl-norbornane-2-oxime", Can. J. Chem., to be published. S.J. Rettig, A. Storr, and J. Trotter, "Crystal and Molecular Structure of the N^N-Dimethylethanolaminodimethylgallane Dimer, [(CHahNCHzCHzOGatCHahL". in preparation.

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