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Gallazanes and related compounds 1971

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GALLAZANE3 Aril) RELATED COK?OUHi)S ALLEN DA^II) PENIAT'D B.Sc. (Hons.) University of British Columbia. 1969 A THESIS SUBMITTED IN PARTIAL FULFILi/EEI?! OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In The Department of Chemistry V/e accept this thesis as conforming to the required standard The university of British Columbia J u l y 1971 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make i t freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It i s understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver 8, Canada ABSTRACT Th i s work involved preparat ion of c y c l i c a l dimeric or t r ime r i c ga l lazanes of general formula: (RNHGaHg) where n= 2 or 3 and R = E t , P r " , P r 1 , Bu", EuV s t Bu , or Bu . The e f f e c t of l a rger R group on r i n g s ize ( n value ) was de te r - mined. Some, deuterated analogues of these compounds were a l so prepared. These were (EtNHGaD ) , (BuSffiC-al)^, and (PrHffiGaP ) 2 . Attempted prepara t ion of j#NHGaH2 r e su l t ed i n i s o l a t i o n of Ji^NH.GaH^.Me^. React ions were undertaken with jfeH. GaH 2 . NMe.j and i t p a r t i a l l y deuterated analogue ^KITGaD9.IIf-Ie^, and shown to involve proton t rans fe r through a '+-centre t r a n s i t i o n s t a te . Add i t i ona l work on the e f f e c t s of R group on the n i t rogen w i th in the ga l lazanes involved preparat ion o f d imer ic ga l lazanes of general formula ((CE 2) y.lT.GaH 2) where x = 2,3,k or 5. Add i t i ona l work on double r i n g systems invo lved preparat ion o f analogous alazanes o f general formula ( ( d l ) x N . A l H 2 ) n where x = 2,3,^,5 and n = 2 or 3. S im i l a r borazanes were l ikewise prepared and were o f general formula : ( (CH 2 ) x l I . BH 2 ) n where x = 2,3,'+, 5 and n = 2 or 3. Adducts of general formula: ' (CH^NH.EMe^ where E = B, A l , Ga, In , were a lso prepared. Upon p y r o l y s i s these adducts y i e l d methane p lus mater ia ls of the general formula: ((CH )2N.EMe2)-j where E = Al,C-a, In . Cha rac t e r i za t i on of these mate r i a l s as wel l as gaseous r ea c t i on products was accomplished by i n f r a r ed spectroscopy. A d d i t i o n a l data was obtained by 60MHz and 100MHz ' H nmr as wel l as mass spectrometry. Molecular weights were determined c r y o s c o p i c a l l y i n benzene and analyses f o r ga l l u im , aluminum or h y d r o l y s a b l e / hydrogen ca r r i ed out by standard means. - i i i - Table of Contents: '• Page I. Title Page i II. Abstract 1 1 III. Table of Contents i i i IV. List of Tables v V . List of Figures vi VI. Acknowledgement ix VII. Introduction 1 VIII. Experimental 6 A, Experimental Techniques 6 (a) Desiccation ... 6 (b) Reaction-Filtration Apparatus 10 (c) Molecular Weight 10 (d) Spectroscopy . 15 (e) Elemental Analysis 16 B. Preparative 17 (a) Preparation of Gallium Trichloride ............ 17 (b) Preparation of Lithium Gallium Hydride.,.,...'. 19 (c) Preparation of Trimethylamine Gallane 20 (d) Preparation of Alkylamino Gallazanes 21 Preparation of Ethylamino Gallazane .......... 22 (e) Reaction of Mê NGall-j with aniline 23 Reaction of j&TKOal̂ NMê  with Methylamine 23 (f) Preparation of Cyclic Imino Gallazanes 25 Preparation of Aziridino Gallazane ........... 25 - IV - Page (g) Preparation of Cyclic Imino Alazanes 25 Preparation of Pyrrolidine Alazane 27 (h) Preparation of CyclicImino Borazanes 27 Preparation of Purrolidino Borazane 27 i (i) Preparation of Aziridino Borazane j 29 (j) Preparation of Aziridine Gallium Trimethyljand Aziridino Gallium Dimethyl 30 (k) Preparation of Aziridine 30 Preparation of Azetidine 32 IX. Discussion •• 33 Part 1. Alkyl Cyclogallazanes 33 Trimeric Cyclogallazanes 35 Dimeric Cyclogallazanes 2̂ I.r. Spectra of Cyclogallazanes 51 Part. 2 Reaction of tfê NGaR"̂  with Aniline 53 Part 3 Imino Gallazanes 58 Part k Imino Alazane s 66 Part 5 Imino Borazanes 72 Part 6 Reactions of Imine Bases with EKe^ 77 X. References 81 LIST OF TABLES: Table 1 Analytical data for cyclogallazane compounds 2h Table 2 Analytical data for imino cyclogallazanes 26 Table 3 Analytical data for imino cycloalazane compounds.... 28 Table h Analytical data for imin© trimethyl and imino metal dimethyl compounds........ 31 Table 5 Ions of high m/e in mass spectrum of (Pr^THGaB^^... 50 Table 6 Infrared spectra of some cyclogallazanes in benzene solution 52 - vi - List of Figures Page Figure 1 Drying Pistol.' 7 Figure 2 Sublimer | 8 Figure 3 Mê NC-aĤ  Sublimer .• 9 Figure k Vacuum Line, Part A... J 11 Figure k' Vacuum Line, Part E 12 Figure 5 Filtration-Reaction Apparatus 13 Figure 6 Molecular V/eight Apparatus . 1̂ Figure 7 Gallium Trichloride Apparatus '.. 18 Figure 8 Hydrogen elimination scheme for gallazanes, alazanes and borazanes 3k Figure 9 Conformations of Trimeric Gallane Species 36 Figure 10 lOOMc/s *H n.m.r. spectrum of EtNHGaH9 in.benzene solution..... 38 Figure 11 'H n.m.r. of some cis and trans trimers .̂0 Figure 12 100 Mc/s 'H n.m.r. spectrum of EtMGaH2 in benzene solution. ^1 Figure 13 100 Mc/s 'K n.m.r. spectrum of EtNHGaD2 in benzene solution • ...' 3̂ Figure 1^ 100 Mc/s >H n.m.r. spectrum of i-PrNHGaH2 in benzene solution.. ,. kk - v i i - Page Figure 15 60MHz 'H n.m.r. spectrum c f neat a PrilTHGaHj and b Pr^NHGa,]^ k6 F i g u r e 16 Conformations of Dimeric Gallane Species ^7 F i g u r e 17 60Mc/s 'H n.m.r. spectrum of neat sec-BuNIIGaH2... ^9 Fig u r e 18 60Mc/s 'H n.m.r. spectrum of ̂ NHGaH2 .NMe-j i n benzene s o l u t i o n F i g ure 19 I n f r a r e d s p e c t r a o f : a a n i l i n e ; b MeNHGaH2; c a n i l i n e & MeNITGaH2 56 F i g u r e 20 S t r u c t u r e of A z i r i d i n o G-allazane 59 Figure 21 60Mc/s 'H n.m.r. spectrum of (CH 2) 2NGaH 2 i n benzene s o l u t i o n 61 Figure 22 60Mc/s 'H n.m.r. spectrum of ( C H ^ l T G a J ^ i n benzene s o l u t i o n 63 Figure 23 60Hc/s 'H n.m.r. spectrum of (CH2)it,NGaH2 i n benzene s o l u t i o n 6k F i g u r e 2k 60Mc/s 'H n.m.r. spectrum of (CH?) NGaII? i n benzene s o l u t i o n . . 65 Figure 25 60 Hc/s 'H n.m.r. spectrum of (CH 2) 2NAIH 2 i n benzene s o l u t i o n 67 F i g u r e 26 60Mc/s »H n.m.r. spectrum of (CH 2) 2NAIH 2 i n benzene s o l u t i o n 68 Figure 27 60Mc/s 'H n.m.r. spectrum of (CH 2)-jNAIH 2 i n benzene s o l u t i o n . 70 - v i i i - Page Figure 28' 60Mc/s 'IT n.m.r. spectrum of (CH^ItfAIHg in benzene solution 71 Figure 29 60Mc/s 'H n.m.r. spectrum of (CE2)^K3H2 in benzene solution 73 Figure 30 60Mc/s *H n.m.r. spectrum of (CH^^NBH^ in benzene solution 7̂ Figure- 31 60Mc/s 'H n.m.r. spectrum of (CH2)^IJBH2 in benzene • solution 75 Figure 32 60Nc/s 'H n.m.r. spectrum of (CH2_)2N.BH2 in benzene solution 76 Figure 33 60Mc/s 'H n.m.r. spectrum .of H"3B.NH(CH2)2 in benzene solution 78 Figure 3^ 60Mc/s 'H n.m.r. spectrum of Me^B.NH(CH2)2 in benzene solution 79 Figure 35 60Mc/s 'H n.m.r. spectrum of Me^Ga.I\fH(CH2)2 in benzene solution 80 - i x - ACKNOWLEDGEMENT I would l i k e to express my s ince res t thanks to my research d i r e c t o r Dr . A lan S t o r r , fo r h i s invalua.ble adv i ce , guidance, and en l i gh ten ing d i scuss ions throughout the course of t h i s work. I would a lso l i k e to thank Dr . B. S. Thomas fo r h i s help with some of the more d i f f i c u l t - preparat ive procedures encountered dur ing the course of t h i s work. INTRODUCTION The chemistry of gallium hydride has developed quickly since the discovery of the stable adduct, Me^N.GaH^, trimethy1amine gallane (1). Previous to t h i s there had been a long search f o r uncoordinated gallium hydride and i t s d e r i v a t i v e s . Free gallium hydride, although o r i g i n a l l y believed to be a temperature stable dimer d i g a l l a n e . Ga 0H (2), has recently been shown to be a viscous polymeric l i q u i d which disproportionates at -15°C in t o gallium and hydrogen (3). On the basis that, t h i s material was benzene i n s o l u b l e , these workers suggested that i t was not dimeric, but rather, polymeric l i k e aluminum hydride. IR spectroscopy showed the -1 -1 c h a r a c t e r i s t i c strong oGa-H at 1980 cm and AGa-H at ca. 700 cm f o r th i s compound. In add i t i o n , analysis showed a gallium to hydrogen r a t i o of one to three, proving that t h i s was the long sought a f t e r (4) hydride of gallium. By a procedure analogous to that used f o r the preparation of gallium hydride, monochloro gallium hydride (GaH^Cl)^ was prepared and characterized as polymeric (5). Subsequently di c h l o r o gallium hydride ( G a H C ^ ^ w a s prepared (6) by a d i f f e r e n t route and shown to be dimeric rather than polymeric. Lithium gallium hydride, LiGaH^, was f i r s t i s o l a t e d by F i n h o l t , Bond and Schlesinger (7) by the r e a c t i o n : Et 0 4LiH(s) + GaCl 3(s) — — - LiGaH^ + 3LiCl(s) . This compound i s the only complex metal gallium hydride which i s stable 2 at' room temperature, and then only as an ether s o l u t i o n . Two other unstable analogues, both d i s p r o p o r t i n a t i n g at below -15°C, are AgGall. (8) andTl(GaH,)„ (9). The reaction of LiGaH, with water causes 4 4 3 4 vigorous evolution of four moles of hydrogen. Hence anhydrous conditions are necessary for preparation and storage of t h i s compound. The GaH^ moeity forms complexes with a number of organo compounds of the group V and group VI elements, i n addition to adducts formed with the hydride ion (H ), as found.in LiGaH^. The preparation of these compounds i s summarized i n a recent review on gallium hydride and d e r i v a t i v e s (10). Trimethylamine. gallane, Me^N.GaH^, i s , i n comparison with other gallium hydrides, f a i r l y temperature stable and can r e a d i l y be sublimed at room temperature. It can be prepared e a s i l y by the reaction of excess l i t h i u m gallium hydride with timethylamine hydrochloride i n the following manner: LiGaH. (s) + Me 0NHCl(s) »- Me„N.GaH (s) + L i C l ( s ) 4- Ht<8^ 4 3 3 3 This compound was the f i r s t metal hydride to have s u f f i c i e n t vapor pressure to enable the gas phase IR spectrum to be recorded (11). The gas phase IR spectrum exhibited strong absorptions due. to \5 Ga-H at 1853 cm ^ and SGa-H at 758 cm These assignments were confirmed by deuteration of the protons on the gallium atom. The s h i f t of the Ga-H s t r e t c h i n g and deformation, v i b r a t i o n s to lower frequency was by a factor of , as expected. Trimethylamine gallane has been shown by tensiometric t i t r a t i o n to add a molar equivalent of trimethylamine gas and form a 2:1 adduct (11). Upon warming to room temperature t h i s m a t e r i a l reverted back to the s t a r t i n g m a t e r i a l with evolution of trimethylamine gas. Dimethylamine gallane was prepared recently by transamination of trimethylamine gallane with dimethylamine gas (12). Me2NH(g) + Me N.GaH (s) =• Me 3N(g) + Me^H.GaH (s) 2Me2NH#'GaH (s) —»• 2H 2 + Me2N - GaH 2 H 2Ga - NMe2 Over a period of a few weeks Me2NHGaH evolved one molar equivalent of hydrogen to give the gallazane shown i n the second equation (above). I t was shown that t h i s adduct was dimeric in.benzene s o l u t i o n . From con- s i d e r a t i o n of the gas phase IR spectrum, i t was concluded, however, that this compound was monomeric i n the gas phase, having C 2 symmetry (12). The transamination r e a c t i o n with gaseous ammonia has recently been shown to proceed v i a hydrogen e l i m i n a t i o n to give a q u a n t i t a t i v e y i e l d of the polymeric s o l i d (NH^GaH,^)^ (13) according to the following r e a c t i o n : Me 3N.GaH 3(s) +• NH (g) -a- H^N.GaH^s) + Me N(g) + E^g) . A s i m i l a r r e a c t i o n with methylamine gas gave a mixture of two isomers of t r i m e r i c (MeNH.GaH2) according to the o v e r a l l equation: Me3N.GaH (s) + MeNH^g) — * MeNH.GaH^s) +'Me N(g) + H 2(g).. The present study involved an extension of t h i s s e r i e s of gallazanes, (RNH.GaH^^, i n an attempt to eluc i d a t e the various factors which govern the value of n, the degree of a s s o c i a t i o n . In a d d i t i o n to the use of primary alkylamines [R = E t , P r 1 1 , P r 1 , Bu 11 , Bu^", B u S , Bu 1 "], the t r a n s a m i n a t i o n r e a c t i o n using a n i l i n e was al s o i n v e s t i g a t e d . The second part of t h i s work was concerned w i t h a study o f the r e a c t i o n of c y c l i c i m i n e s , [ (CI^) NH where x = 2, 3, 4 or 5] w i t h t r i - methylamine g a l l a n e . The imino g a l l a n e products [(CH ) NGaH„] , were expected to i n v o l v e some double r i n g s t r a i n and an i n v e s t i g a t i o n of t h i s e f f e c t was undertaken. A f u r t h e r extension of t h i s l a t t e r study i n v o l v e d the p r e p a r a t i o n and c h a r a c t e r i z a t i o n of s i m i l a r boron [CH^^NBB^]^ and aluminum [ ( C I ^ ^ A I H ] compounds. The r e a c t i o n of imine bases w i t h diborane to y i e l d adducts w i t h the g e n e r a l f o r m u l a , [CH^^NH.BH^, where x = 2, 3, 4, 5 was s t u d i e d i n 1956 by Burg and Good ( 1 4 ) . Three of these adducts gave, on hydrogen e l i m i n a t i o n , m a t e r i a l s of composition:-(CI^) N.BI^ [where x = 3, 4, 5 ] . However, the a z i r i d i n e compound, x = 2, appeared to give ring-opened, polymeric p r o d u c t s , and was not i s o l a t e d . In 1969 S. A k e r f e l d t et a l (15) prepared the adduct a z i r i d i n e borane, as w e l l as a z i r i d i n o borazane. The l a t t e r compound was u n t i l then b e l i e v e d unpreparable. Simultaneously, a c r y s t a l s t r u c t u r e of the adduct (CI^^NH'M^ w a s reported ( 1 6 ) , i n a d d i t i o n t o a "*"H nmr and i n f r a r e d study of both the adduct and the a z i r i d i n o borazane (17). This l a t t e r study r e j e c t e d the previous p.NH2 f o r m u l a t i o n of a r i n g opened product,! \ , i n the p r e p a r a t i o n of the L_BH adduct. (18) The p r e p a r a t i o n of a z i r i d i n o alazane and r e l a t e d c y c l i c imino alazanes has r e c e i v e d some recent a t t e n t i o n . The f i r s t p r e p a r a t i o n of the c y c l i c compounds dates back to 1962, when some I t a l i a n workers i s o l a t e d the p i p e r i d i n o and p y r o l i d i n o alazanes (19). Their preparation of a z i r i d i n o alazane was hampered by the fac t that t h i s m a t e r i a l decomposed with some violence at room temperature i n the absence of solvent. More r e c e n t l y , E h r l i c h (20) discussed i n d e t a i l the preparation and subsequent r i n g opening of t h i s m a t e r i a l ; which he suggests i s polymeric. The present study on c y c l i c imino boremones and alaiemev has a twofold purpose. F i r s t l y , as i n d i c a t e d p r e v i o u s l y , to compare these compounds with the gallium d e r i v a t i v e s ; and secondly to reinv e s t i g a t e and extend the previous s t u d i e s . The f i n a l part of t h i s work involved preparing the a z i r i d i n o metal dimethyl d e r i v a t i v e s , [ (CH^^^MM^^ where M = B, A l , Ga, In, i n order to i n v e s t i g a t e the e f f e c t , on the degree of as s o c i a t i o n , of rep l a c i n g the hydrogens on the group I I I atom with methyl groups. EXPERIMENTAL . . A. Experimental Techniques (a) Desiccation A l l gases were dried f i r s t by f r a c t i o n a t i n g under high vacuum through a trap at -20°C, to remove large amounts of water, and then condensed at-196°C into one limb of a drying p i s t o l , see Figure 1, packed with a mixture of glass-wool and phosphorus pentoxide. The gas i s passed through the phosphorus pentoxide by a l t e r n a t e l y cooling one limb and then the other limb. The dried gases are then stored at less than one atmosphere i n large glass bulbs attached to the vacuum l i n e . A l l solvents were drie d and r e d i s t i l l e d before use; d i e t h y l ether over l i t h i u m aluminum hydride, benzene and cyclohexane over molten potassium. The amine ligands which were commercially a v a i l a b l e were dried by r e f l u x i n g over CaR^ followed by d i s t i l l a t i o n . S o l i d components were p u r i f i e d by sublimation, e i t h e r by vacuum bulb-to-bulb sublimation or as with trimethylamine hydrochloride, sublimed to the cooled c e n t r a l f i n g e r of the apparatus shown i n Figure 2. Trimethylamine gallane was sublimed, under dynamic vacuum from the f l a s k to the large v e r t i c a l tube, marked as A, of the apparatus, which was cooled to -80°C, shown i n Figure 3. A l l glassware was washed with acetone, oven dri e d , evacuated and f i l l e d with nitrogen before use. A l l nitrogen used was Canada Li q u i d A i r "L" grade, p u r i f i e d nitrogen. ^ The hydride and a l k y l d e r i v a t i v e s , because of t h e i r r e l a t i v e i n s t a b i l i t y and extreme r e a c t i v i t y with oxygen or water vapour were Figure 1 Drying Pistol B I 4 n. Figure 2 Sublimer Me 3NGaH 3 Sublimer Figure 3 a l l p r e p a r e d and h a n d l e d i n e i t h e r a h igh-vacuum sys t em o r a n i t r o g e n f i l l e d d r y b o x . The h i g h vacuum sys tem d e v e l o p e d f o r t he work i s shown i n F i g u r e 4 . A d o u b l e - s t a g e r o t a r y o i l pump (Welch S c i e n t i f i c C o . ) and an e l e c t r i c a l l y h e a t e d s i n g l e s t a g e mercu ry d i f f u s i o n pump were used to -4 o b t a i n a vacuum o f g r e a t e r t han 10 mm of Hg . The d r y box (Kewaunee S c i e n t i f i c Equ ipment ) had a s p e c i a l f o r t chamber t h a t c o u l d be e v a c u a t e d by a d o u b l e - s t a g e r o t a r y o i l pump and t h e n f i l l e d w i t h d r y n i t r o g e n t o e n s u r e the p u r i t y o f the a tmosphere i n the b o x . . The d ry box i s a l s o c o n n e c t e d t o a c i r c u l a t i n g pump wh ich c i r c u l a t e s the b o x ' s a tmosphere t h rough a d r y i n g t r a i n c o n t a i n i n g m o l e c u l a r s i e v e ( F i s h e r t ype 5A) and a c o p p e r f u r n a c e t o remove any oxygen . _ (b) R e a c t i o n - F i l t r a t i o n A p p a r a t u s The a p p a r a t u s shown i n F i g u r e 5 f ound e x t e n s i v e use i n our wo The a p p a r a t u s i s e v a c u a t e d , f i l l e d w i t h d r y n i t r o g e n , and the r e a c t a n t s a re p l a c e d i n f l a s k A . A d d i t i o n a l r e a g e n t s may be added d u r i n g the cou o f a r e a c t i o n by r o t a t i n g the dumper tube B_, the r e a c t i o n m i x t u r e i s s t i r r e d by a m a g n e t i c b a r C_. The p r o d u c t s , i f gaseous may be removed b a T o p l e r pump t h r o u g h one o f the s t o p c o c k s , o r i f i n s o l u t i o n can be f i l t e r e d t h rough the s i n t e r e d d i s c p_ (medium p o r o s i t y ) by c o o l i n g o r e v a c u a t i n g the r e c e i v e r f l a s k Ê . (c ) M o l e c u l a r We igh ts M o l e c u l a r w e i g h t s were d e t e r m i n e d by the c r y o s c o p i c method , t he d r y box an a c c u r a t e l y known w e i g h t o f p u r e compound was d i s s o l v e d i a we ighed sample o f pu r e benzene (about 10 m l ) . The benzene s o l u t i o n was p o u r e d i n t o the m o l e c u l a r w e i g h t a p p a r a t u s , see F i g u r e 6, and remov Vacuum L i n e , P a r t A Figure 4 from P a r t A Figure 5 14 M o l e c u l a r Weight Apparatus Figure 6 from the.dry box. A slow stream of pure nitrogen was flushed through the apparatus as i t was cooled i n an i c e bath. The fre e z i n g point of the s o l u t i o n was recorded and compared with that of pure benzene solvent and with standard s o l u t i o n s of biphenyl i n benzene solvent. The following e m p i r i c a l formula was used to c a l c u l a t e the molecular weights. [K^]X[weight of sample (gms)] molecular weight = [weights of benzene solvent (gms)]X [change i n temperature (°C)] K.£ = f r e e z i n g point depression constant 5.20°C per molal. (d) Spectroscopy : I n f r a r e d spectroscopy was used throughout t h i s work f o r semi- q u a n t i t a t i v e a n a l y s i s and for s t r u c t u r a l determination of compounds. Infrared s p e c t r a were recorded on a Perkin-Elmer Model 457 spectrometer (4000 - 250 cm The observable range f o r both l i q u i d and gas samples was between 4000 and 400 cm ^ because KBr windows were used. For gaseous or v o l a t i l e samples a 10 cm gas c e l l was used with KBr windows. For l i q u i d or s o l u t i o n samples a 0.05 cm f i x e d path length s o l u t i o n c e l l with KBr windows was used and a variable-thickness c e l l f i l l e d with pure solvents (usually benzene) was placed i n the reference beam to. compensate f o r solvent absorption. Because of the i n s t a b i l i t y of most of the hydride adducts prepared, a l l i n f r a r e d s o l u t i o n c e l l s were loaded i n the dry box and a spectrum run as r a p i d l y as p o s s i b l e . As with i n f r a r e d spectroscopy, nuclear magnetic resonance spectroscopy, NMR, was used as a t o o l to i n v e s t i g a t e reactions and f o r s t r u c t u r a l determination. The instruments used were a Varian A-60 and Varian T̂ -60 both operating with a radiofrequency of 60 megacycles per 16 second and a Varian HA-100 which operates at a radiofrequency of 100 megacycles per second. Most samples were run i n benzene s o l u t i o n with a concentration of about 0.1 M to 1 M. The benzene proton s i g n a l was used as an i n t e r n a l , standard and was defined as T = 2.840 p.p.m. Tetra- methylsilane, TMS, was used as an external standard on several samples and i s defined as = 10.000 p.p.m. The NMR sample tubes were s p e c i a l l y f i t t e d with a flame-seal c o n s t r i c t i o n and a B-10 q u i c k - f i t cone so that the samples could be loaded and sealed under an atmosphere of nitrogen. As with the i n f r a r e d samples, the NMR spectra were run as r a p i d l y as possible since steady decomposition at room temperature often impeded prolonged i n v e s t i g a t i o n . (e) Elemental Analysis (i ) Active Hydrogen: Active hydrogen was measured by pla c i n g a small weighed amount of compound i n a round bottom f l a s k i n the dry box, attaching a stopcock adaptor and evacuating on the vacuum l i n e . A small volume of degassed, d i l u t e aqueous HNO^ s o l u t i o n was then condensed onto the s o l i d at -196°C. The mixture was allowed to reach room temperature and l e f t to react f o r about one hour with s t i r r i n g . Me 3NGaH 3 + 3H + — Me3N + G a + 3 + 3H 2 The volume of hydrogen gas, non-condensable at -196°C, was then measured using a Topler pump. The amount of active hydrogen i n the compound was then cal c u l a t e d . This aqueous s o l u t i o n was made up to.a known volume and an aliqu o t was used i n the determination of gallium as i n d i c a t e d below. 17 ( i i ) Gallium (Aluminum): A measured aliquot of the s o l u t i o n prepared i n section ( i ) was measured out into a beaker. The s o l u t i o n was f i r s t made n e u t r a l with d i l u t e ammonia s o l u t i o n , then was made s l i g h t l y a c i d i c , pH 5-7, with d i l u t e aqueous HC1. The s o l u t i o n was then heated to 80°C and!a s l i g h t excess of a 5% s o l u t i o n of 8-hydroxyquinoline i n g l a c i a l a c e t i c acid was added followed by an aqueous s o l u t i o n of saturated ammonium acetate u n t i l pre- c i p i t a t i o n of Ga(C H NO) i s complete. A f t e r digestion at 80°C f o r one hour, the yellow p r e c i p i t a t e was c o l l e c t e d i n a f i l t r a t i o n c r u c i b l e and the p r e c i p i t a t e washed, f i r s t with hot, then cold water. The p r e c i p i t a t e was then d r i e d at 120°C, weighed and i t s gallium content c a l c u l a t e d from the formula Ga(CgHgNO)^ which i s 13.89% g a l l i u m b y weight. This method has been found to give accurate determinations f o r a minimum concentration of 10 mg of gallium i n 50 ml of s o l u t i o n . Aluminum was determined s i m i l a r l y as i t s 8-hydroxyquinolate. B. Preparative (a) Preparation of Gallium T r i c h l o r i d e (23) GaCl^ Gallium t r i c h l o r i d e xjas prepared by d i r e c t combination of the elements. Pure chlorine gas (Matheson Ltd.) was dried by passing through concentrated sulphuric acid i n a bubbler and was then passed into the a l l glass apparatus shown i n Figure 7. The gallium metal, about 15 gms, (A l f a Inorganics Inc.) placed i n A soon melted on warming with a bunsen burner, and reacted with the c h l o r i n e , f i r s t to give a colo u r l e s s l i q u i d , g a l l i u m t e t r a c h l o r o g a l i a t e (21), Ga 2Cl^ (melting point 170.5°C (22)). On adding more chlorine t h i s l i q u i d Ga 9Cl, disappeared and the l i q u i d gallium Gallium Trichloride Apparatus Figure 7 ca burned w i t h a grey-white flame g i v i n g a v o l a t i l e white s o l i d , g a l l i u m t r i c h l o r i d e G a C l^, (melting p o i n t 79°C). 2Ga(l)'+ 2 C l 2(g) ^ (Ga +)(GaCl 4") i +  1 (Ga ) ( G a C l 4 )(1) + C l 2 ( g ) — — * G a 2 C l 6 The r a t e of flow of c h l o r i n e gas and r a t e of he a t i n g the molten g a l l i u m were adjusted so that most of the v o l a t i l e GaCl^ was deposited i n the cooled r e c e i v e r boat C!. A f t e r a l l the g a l l i u m had reacted ( e s s e n t i a l l y 100%) , any sublimate i n A was d r i v e n i n t o C_ by warming and then flame s e a l i n g the c o n s t r i c t i o n at B_. The apparatus was then evacuated and flame se a l e d at F_. The crude h a l i d e was then resublimed i n t o the ampoules E_ and then these were sealed at t h e i r c o n s t r i c t i o n s . The g a l l i u m t r i c h l o r i d e was found to remain s t a b l e i n d e f i n i t e l y when st o r e d t h i s way. (b) P r e p a r a t i o n of L i t h i u m G a l l i u m Hydride ( 7 ) , LiGaH^ Et 0 4LiH + GaCl_ = *• LiGaH. + 3 L i C l 3 room Temp. 4 An ampoule of GaCl^, was weighed and broken open i n the dry box and p l a c e d i n a c o n i c a l f l a s k . The g a l l i u m t r i c h l o r i d e was then d i s s o l v e d i n d i e t h y l ether and the ampoule washed s e v e r a l times to ensure q u a n t i t - a t i v e removal of GaCl^. The empty ampoule was reweighed and the weight of GaCl^ determined. The e t h e r e a l s o l u t i o n of GaCl^ and a l l the washings were now added to the n i t r o g e n f i l l e d r e a c t i o n - f i l t r a t i o n apparatus (see F i g u r e 5) and the s o l u t i o n brought up to about 150 m l . From the weight of GaCl c a l c u l a t e d , (8.59 gms; 48.8 mmoles) ,20 the weight of about 16 molar e q u i v a l e n t s of f i n e l y ground l i t h i u m hydride (7.45 gms; 938 mmoles) ( A l f a Inorganics I n c . ) , enough f o r a f o u r - f o l d e x c e s s , was weighed out under n i t r o g e n i n t o the dumper tube. The r e a c t i o n f l a s k was cooled to -50°C i n an a c e t o n e - s o l i d C0 o bath and the dumper tube r o t a t e d upwards to permit the slow a d d i t i o n of Li H to the r e a c t i o n f l a s k over a p e r i o d of about t h i r t y minutes. A bubbler was attached to the apparatus so that the r e a c t i o n could be c a r r i e d out under a constant pressure of one atmosphere of n i t r o g e n . The coolant was allowed to warm up to room temperature and the mixture was s t i r r e d f o r about f i f t y hours to ensure.complete r e a c t i o n . The r e s u l t i n g r e a c t i o n mixture was f i l t e r e d through the g l a s s s i n t e r e d d i s c and a c l e a r c o l o u r l e s s f i l t r a t e r e s u l t e d . This f i l t r a t e was then t r a n s f e r r e d , i n the dry box, to a c o n i c a l f l a s k f i t t e d w i t h a break s e a l and an extended neck which was flame sealed f o r s t o r a g e . The LiGaH^ ether s o l u t i o n was observed to be i n d e f i n i t e l y s t a b l e i f st o r e d i n ' a l l g l a s s ampoules under a n i t r o g e n atmosphere and cooled below 0°C. L i t h i u m g a l l i u w d e u t e r i d e , LiGaD^, was prepared and s t o r e d i n e x a c t l y the same manner as LiGaH^, only l i t h i u m d e u t e r i d e , L i D , ( A l f a I n o rganics Inc.) was s u b s t i t u t e d i n the p r e p a r a t i o n f o r l i t h i u m h y d r i d e , (c) P r e p a r a t i o n of Trimethylamine Gallane ( 1 ) , Me^NGaH^ Et 0 LiGaH. + Me NHC1 * Me NGaH + L i C l + H 0 4 3 room temp. 3 3 2 A known amount of l i t h i u m g a l l i u m hydride (2.38.gms; 29.4 mmoles) i n ether s o l u t i o n was placed i n the r e a c t i o n - f i l t r a t i o n apparatus, see Figure 5. S l i g h t l y l e s s than the s t o i c h i o m e t r i c amount of trimethylamine h y d r o c h l o r i d e , Me_NHCl, (2.644 gms; 27.6 mmoles) ( A l f a Inorganics Inc.) 2f d r i e d and p u r i f i e d by sublimation, was placed i n the dumper tube of the re a c t i o n vessel which contained a nitrogen atmosphere. The ether s o l u t i o n of LiGaH, was f i r s t cooled to -50°C i n a drv- 4 * i c e cooled acetone bath, as the trimethylamine hydrochloride was added over a period of about 10 minutes. Then the s o l u t i o n was allowed to warm up to room temperature and s t i r r e d f o r about four hours' to ensure complete reactio n . The s o l u t i o n was next f i l t e r e d through the glass s i n t e r and the receiver f l a s k containing the c l e a r ether s o l u t i o n was attached to the sublimation apparatus, see Figure 5. This apparatus was attached to the vacuum l i n e and the ether was pumped o f f at -50°C. When most of the ether was removed, the residue was allowed to warm up to room temperature while the large bulb part of the sublimation apparatus was immersed i n an acetone-solid CO^ slush bath. The pure trimethylamine gallane was vacuum sublimed as long needle l i k e c r y s t a l s i n t o the cooled r e c e i v e r . The. o v e r a l l y i e l d i n going from gallium t r i c h l o r i d e to trimethylamine gallane was about 60%. „ i The deuterated compound, trimethylamine t r i d e u t e r o g a l l a n e , Me^NGaD^ was prepared i n the same manner only l i t h i u m gallium deuteride was s u b s t i t u t e d for l i t h i u m gallium hydride. Trimethylamine alane , Me^NAlH^, was also obtained s i m i l a r l y from commercially a v a i l a b l e L i A l H ^ and t r i - methylamine hydrochloride. (d) Preparation of Alkylamino Gallazanes (RNHGaH^^ As the procedures are s i m i l a r f or preparation of a l l the gallazane compounds, only the procedure for the ethylamino compound w i l l be given as an example. 23 benzene. A weighed q u a n t i t y of this; s o l u t i o n was removed from the cryo- s c o p i c molecular weight apparatus and h y d r o l y s e d . The volume of hydrogen evolved on h y d r o l y s i s was then determined. The g a l l i u m content was determined g r a v i m e t r i c a l l y by standard procedures. The d e u t e r i o d e r i v a t i v e , (EtNHGaD^)^*  w a s  obtained by an e x a c t l y s i m i l a r procedure to the above, but u s i n g Me^NGaD^ as the s t a r t i n g m a t e r i a l . Experimental d e t a i l s f o r the other alkylamino g a l l a z a n e s are summarized i n t a b l e 1. (e) Reaction of Me„NGaH„ w i t h a n i l i n e (C,HCNH„) J J p J z A n i l i n e (.405 g, 4.352 mmoles) was condensed onto trimethylamine g a l l a n e (.573 g, 4.351 mmoles) at -196°C and allowed to warm to room temperature A f t e r complete r e a c t i o n (about two days) the f l a s k was cooled to -196°C and the volume of evolved hydrogen measured (Found: 92.5 ml; C a l c . 97.8 m l ) . The mixture was then allowed to warm t o room temperature and a t r a c e of Me^N was gas d e t e c t e d . The white s o l i d p roduct, Me^NGaH^NH , was mono-' meric i n benzene (Found: 224, C a l c . 223) and gave the f o l l o w i n g a n a l y s i s : Ga: Found: 31.9%, C a l c : 31.2%. > H a c t i v e : Found: 1.12%, C a l c : 1.12%. Reaction of a two m o l a l q u a n t i t y of a n i l i n e l e d to an i n s o l u b l e polymeric m a t e r i a l . I t evolved a 2 molal q u a n t i t y of hydrogen as w e l l as a m o l a l q u a n t i t y of Me^N. Reaction of c^NHGaR^NMe^ w i t h Methylamine A measured amount of methylamine gas (42.8 ml) was condensed onto a weighed q u a n t i t y of (JiNHGaH^NMe^ (.426 g, 1.878 mmoles) at -196°C and t h i s mixture was then permitted t o warm to room temperature. No hydrogen was e v o l v e d . The volume of trimethylamine gas was measured (Found: 92.4 m l , C a l c : 91.8 ml) a n d . i t s p u r i t y was checked by gas phase i n f r a r e d s p e c t r o s c o p y . This product, as w e l l as the products r e s u l t i n g Table 1 A n a l y t i c a l d a t a ' f o r c y c l o g a l l a z a n e compounds prepared by the r e a c t i o n : - Me.NGaH. + RNH„ (RNHGaH.) + H_ + Me.N j j / 2. n l J Compound Phase Moles H 2 per Moles Me3N Degree of assoc- A n a l y s i s at 25°C mole RNH2 • per mole RNH2 i a t i o n , n Found % (RNHGaH?) r e q u i r e s 7J Ga Hydrolysable hydrogen Ga Hydrolysable hydrogen EtNHGaH2 Viscous l i q u i d 1.01 1.01 2,92 60.1 1.73 60.2 1.73 Pr n KHGaH 2 Viscous l i q u i d 0.98 1.02 2.64 53.5 1.53 53.7 1.54 Bu I1 NHGaH2 Viscous l i q u i d 1.00 1.09 2.57 48.4 1.37 48.5 1.39 Pr X NHGaH 2 Mobile l i q u i d 0.92 0.98 1.91 53.6 1.55 53.7 1.54 Bu X NHGaH2 Viscous l i q u i d 0.95 1.03 2.15 48.4 1.38 48.5 1.39 • Bu S NHGaH2 Mobile l i q u i d . 0.92 1.02 1.83 48.5 1.40 48.5 1.39 Bu t NHGaH2 White s o l i d 0.97 1.02 1.83 48.4 1.37 48.5 1.39 from the reac t i o n s : a n i l i n e plus Me^NGaD^, a n i l i n e plus Me NGaH , methylamine plus (^NHGaD^NMe^, and methylamine plus (JlNHGaH^NMe^ were characterized by i n f r a r e d and ̂"H nmr spectroscopy. (f) Preparation of C y c l i c Imino Gallazanes Since the procedure f o r the preparation of these "double r i n g s t r a i n " gallazanes i s standard throughout the s e r i e s , and since the I technique, and apparatus are e s s e n t i a l l y the same as those used i n pre- paration of the simple gallazanes, only a short, procedure for a z i r i d i n o gallazane w i l l be given as an example. Preparation of A z i r i d i n o Gallazane . A z i r i d i n o gallazane was prepared by condensing a z i r i d i n e gas (23.8 ml; 1.50 mmoles) onto trimethylamine gallane (0.140 g; 1.60 mmoles at -196°C, and allowing the mixture to warm slowly to room temperature. A f t e r complete reaction (about 1 h) the f l a s k was cooled to -196°C, and the volume of evolved hydrogen measured (Found: 23.6 ml, Calc: 23.8 ml). The mixture was again brought to room temperature and.the volume of trimethylamine gas was measured (Found: 24.4 ml, Calc: 23.8 ml). The pur i t y of the Me^N was checked by i t s gas phase i . r . spectrum. The white, c r y s t a l l i n e s o l i d product was analysed for hydrolysable hydrogen and f o r gallium by the previously discussed methods. The a n a l y t i c a l dat for the compounds prepared i n t h i s s e r i e s are given i n table 2. (g) Preparation of C y c l i c Imino Alazanes The procedure for the preparation of t h i s s e r i e s of alazane compounds i s standard throughout the s e r i e s . Hence the p y r r o l i d i n o alazane preparation, only i s given as an i l l u s t r a t i v e example. Tabie 2 Analytical data for imine cyclogallazane compounds prepared by the reaction:- . Me3NGaH3 • + (dft2)xNH ===== ((CTI2)x1lGaII2)n + H2 + Meyi Compound Phase Moles H2 per mole imine Moles MeoN Degree of association ,1 Analysis at 25*C per mole imine n. Found % Theory % 1 Ga IJydrol. j hydrogen Ga Hydrol. hydrogen 'CH2)2NGaH2 White solid 1.01 . 1.00 2.00 (2.56) i \ • 62.1 1.76 61.1* 1.76 (CH2)3NGaH2 White solid 0.99 1.01 2.00 5̂ .1 1.55 5̂ .5 1.56 ;CH2)^IGaH2 White solid 0.99 0.99 2.02 |̂ 9.0 ! i 1.38 '+9.2 l.'H ;CH2)5NGaH2 White solid 0.99 0.98 1.89 |̂ 3.9 1.26 1.28 * Degree of association immedtately after dissolving imine cyclogallazane in benzene. \ 27 Preparation of P y r r o l i d i n o Alazane (CH„).NA1H„ t t- 4 2 The b i s trimethylamine alane used i n the reaction was prepared by condensing excess Me^N gas onto trimethylamine alane at -196°C. Af t e r e q u i l i b r a t i o n pf t h i s system at room temperature, the excess trimethylamine was removed at -20°C, leaving the b i s adduct. P y r r o l i d i n e (35.0 ml, 1.559 mmoles) was condensed onto b i s trimethylamine alane (0.228 g; 1.542 mmoles) dissolved i n 5 ml of dry benzene. This mixture was permitted to warm to room temperature. A f t e r the evolution of hydrogen had ceased, the f l a s k was cooled to -196°C and the volume of hydrogen measured (Found: 35.2 ml; Calc: 35.0 ml). The benzene solvent and trimethylamine gas from the reaction were then removed at -20°C to leave a white c r y s t a l l i n e s o l i d i n the reaction v e s s e l . Analyses for aluminum and hydrolysable hydrogen were performed only on the a z i r i d i n o alazane since most of these compounds had been previously prepared and analysed (23). Experimental data for t h i s s e r i e s of compounds i s summarized i n table 3. (h) Preparation of C y c l i c Imino Borazanes The procedure for the preparation of these borazane compounds i s standard for three of the d e r i v a t i v e s , (CH ) NBH where x = 3, 4, 5 and therefore the preparation of p y r r o l i d i n o borazane only w i l l be given. The preparation of a z i r i d i n o borazane d i f f e r s s l i g h t l y and w i l l be described l a t e r . Preparation of P y r r o l i d i n o Borazane P y r r o l i d i n o borazane was prepared by condensing p y r r o l i d i n e (100 ml, 4.45 mmoles) on a previously condensed sample of diborane (50 ml, 2.22 mmoles) i n a 500 ml break-seal f l a s k . The mixture was Table 3 A n a l y t i c a l data f o r iminC cycloalazane; compounds prepared by the r e a c t i o n : - (Me 3N) 2AlH 3 + (CH 2) XNH - ((CH 2) xKAlH 2) n+ H 2 + 2 M e 3 N Compound Phase, at 2$*C Moles H per' mole imine Molecular .. j weight i j Degree of a s s o c i a t i o n n (CH 2) 2NA1H 2 White s o l i d 1.02 298 4.20 (3.14*) (CH 2) 3?LA1H 2 White s o l i d 1.00 263* 3.06* (CH^NAIIL. White s o l i d 1.01 308 3.10 (CH 2) 5NA1H 2 White s o l i d 0.98 243 2.17 A n a l y t i c a l data f o r imino cycloborazane compounds prepared by the r e a c t i o n : - H H 6 + (CH 2) XMI (( C H 2 ) y H B H ? ) n + H 2 Compound Phase at 25*C j Holes IT2 per i mole imine ! Molecular weight Degree of a s s o c i a t i o n , n CCH 2) 2KBH 2 White s o l i d — 165 3.00 (CH 2) 3NBJI*' White s o l i d 0.97 134 1.9*+ (CH 2)^JB.H 2 White s o l i d 1.03 166 2.00 (CH 2)ra.H 2 White s o l i d 1.08 196 2.02 • * Private communication Dr. B. S. Thomas. allowed to warm to room temperature to form the l i q u i d adduct. The bulb was then cooled and sealed o f f under vacuum. I t was then placed i n an oven at 128°C f o r 3 1/2 hours to pyrolyse the adduct. A f t e r p y r o l y s i s was com- ple t e , the f l a s k was attached to the vacuum l i n e , cooled to -196°C and the f r a g i l e break-seal ruptured with a bar magnet. The evolved hydrogen was measured (Found: 103 ml, Calc: 100 ml). The product was then warmed to room temperature and checked for non-condensibles. Experimental data f o r these compounds i s given i n the lower part of table 3. ( i ) Preparation of A z i r i d i n o Borazane This compound was prepared by condensing a z i r i d i n e (100 ml, 4.45 mmoles) onto a sample of diborane (50 ml, 2.22 mmoles) at -196°C. About 5 ml of s t r i c t l y dry d i e t h y l ether was condensed onto t h i s mixture and the mixture warmed to -130°C. At t h i s point the mixture was per- mitted, by means of a propane slush bath, to warm slowly to -78°C. The ether was removed g i v i n g a product, which when solvent free was a white c r y s t a l l i n e s o l i d . The i n f r a r e d and "̂H nmr spectra of t h i s adduct agreed with those found i n the l i t e r a t u r e (18). The adduct was dissolved i n benzene and refluxed under an atmosphere of dry nitrogen f o r three to four hours. The a z i r i d i n o borazane product was separated by removing the benzene solvent at -20°C. The IR and nmr spectra recorded f o r the a z i r i d i n o borane obtained by t h i s method, agreed with those found i n the l i t e r a t u r e (18). Attempts to prepare t h i s complex by a p y r o l y s i s method using the reaction of a z i r i d i n e with e i t h e r Me^N.BH^ or diborane f a i l e d to give the desired product. These reactions were non-stoichiometric, y i e l d i n g 40% of the t h e o r e t i c a l hydrogen and 77% of the Me^N i n the f i r s t case and only 54% of hydrogen i n the l a s t . The products i n each of these cases gave l i q u i d plus s o l i d but were not soluble i n benzene to any s i g n i f i c a n t extent. (j) Preparation of A z i r i d i n e Gallium trfmethyl and A z i r i d i n o Gallium dimethyl The adduct a z i r i d i n e gallium trimethyl was prepared by condensi: a z i r i d i n e (75.5 ml, 3.36 mmoles) onto gallium trimethyl (75.5 ml, 3.36 mm< at -196°C and warming to room temperature. The adduct was a clear mobile l i q u i d which was stable to methane e l i m i n a t i o n at room temperature. The a z i r i d i n o gallium dimethyl was prepared by pyrolysing a 0.413 g sample of the previously prepared adduct at 110°C f o r 5 hours i n a break-seal bulb. A f t e r the f i v e hour reaction time the bulb, now con- t a i n i n g a white s o l i d (mp 184°C).was connected to the high vacuum l i n e , cooled to -196°C, the glass break seal ruptured and the methane measured (Found: 56.8 ml, Calc: 58.8 ml). The product was then warmed to room temperature and checked for the presence of condensibles. The a n a l y t i c a l data for the other compounds of t h i s s e r i e s i s given i n table 4. (k) Preparation of A z i r i d i n e ^NM Since commercial samples of a z i r i d i n e were not a v a i l a b l e the preparation of t h i s m a t e r i a l was undertaken using the following route. The methods of Wenker (24) Leighton (25) and Reeves (26) were a l l t r i e d but gave lower y i e l d s than the following method. 96% H 2 S 0 4 ( 1 0 9 - 9 S» 1 > 0 ^ m ° l e s ) w a s added d i r e c t l y to a s t i r r e d sample of ethanolamine (65.7 g, 1.07 moles). This mixture was then heated to 100°C under water a s p i r a t o r vacuum to give a q u a n t i t a t i v e y i e l d of ethonolamine s u l f a t e according to the following scheme: Table 4 A n a l y t i c a l data f o r imine metal trimethyl and imino metal dimethyl compounds prepared by the following: (CHg) NH IZZZZ Me 3M.HH(CK 2) 2 Me3M.KH(CH ) 2 (Me 2M.N(CH 2) 2) n + CH^ Compound Phase at 25*C Moles methane per mole imine ; j P y r o l y s i s : temperature Degree of as s o c i a t i o n n Me 3GaM-l(CH 2) 2 ; mobile l i q u i d 110*C,5h Me 2GaH(CH 2) 2 | white : ! s o l i d 0.97 2.88 Me 3EKH(CH 2) 2 • '. mobile l i q u i d • 180 C,12h Me 2EN(CH 2) 2 v/hite s o l i d 0.68 polymeric s o l i d s and l i q u i d s M e 3 A l M ( C H 2 ) 2 mobile, l i q u i d evolves CH^ : at r . t . 60*,4h Me 2AlK(CH 2) 2 v/hite . s o l i d . " " 0.88 ! • | 2.96 iMeoInKH(CH ) 0 i i ?  1 mobile l i q u i d evolves CH^ • at r . t . 80'c,12h Me In!Sf(CII ) i 2 2 2 white s o l i d ' 0.70 ' '3.00* *Private communication Dr. B. S. Thomas. - H0CH 2CH 2NH 2 + H2SO The white s o l i d product was ground with 95% EtOH, suction f i l t e r e d and dried i n a vacuum descicator over The ethonolamine s u l f a t e was then placed i n a 1000 ml round bottomed f l a s k surmounted by a s t i l l head and water condenser set for downward d i s t i l l a t i o n and o v e r l a i d with a 40% NaOH s o l u t i o n (95 g NaOH, 143 g H 20). The f l a s k was heated with an open flame and the d i s t i l l a t e c o l l e c t e d r a p i d l y i n a w e l l cooled 500 ml rece i v e r . Once d i s t i l l a t i o n was complete, enough KOH to obtain a saturated s o l u t i o n was added and the f l a s k stored i n the f r i d g e overnite. The upper organic layer was then removed and dried over CaH2/K0H. The product, when water and ethanol free was stored over CaH 2 at +5° u n t i l required. ( Y i e l d ~ 1 5 % ) . Azetidine (27) f CHH • Azetidine was prepared by the same procedure as above but s t a r t i n g with propanolamine instead of ethanolamine. The y i e l d was about 1%. H 20 + CH 2-CH 2 O.-SO3- N 1 I3 DISCUSSION Part 1 The ease of intramolecular hydrogen e l i m i n a t i o n from adducts of the type MeNH^, EH^, where E i s B, A l or Ga follows 1' the sequence B < Ga < A l as i l l u s t r a t e d i n fi g u r e 8. Note that 90° |(28) i s required i for hydrogen e l i m i n a t i o n with boron* MeNH^GaH^ eliminates hydrogen at room temperature (13) , while MeNH^AlH^ eliminates two molar equivalents of hydrogen at -20° (29). Stone (30) explains t h i s sequence i n terms of the r e l a t i v e e l e c t r o - n e g a t i v i t y values of the atoms involved. 5+H H5- 6+H H5-| I V S Me-N >- G-H y Me-N > E ~H _ >- Me-N — E - H + H I \ * I \ \ A I 2 H H . H H H H In the above scheme the hydrogen attached d i r e c t l y to the nitrogen atom i s considered to lose e l e c t r o n density on formation of an el e c t r o n donor bond by the donor moeity. Hydrogen attached to the acceptor atom, E, simultaneously increases i n ele c t r o n density and an e l e c t r i c a l s t r a i n i s thus created i n the adduct. The s t r a i n i s r e l i e v e d when hydrogen e l i m i n a t i o n occurs. On the basis that the diff e r e n c e s between the Allred-Rochow (31) e l e c t r o - n e g a t i v i t i e s of the E atoms and that of hydrogen (at 2.1)increase i n the order B, Ga, Al,the hydxidic character i n EH^, and hence the ease of hydrogen e l i m i n a t i o n should decrease i n the order A l through Ga.to B }as observed. The factors a f f e c t i n g the as s o c i a t i o n of the products from - hydrogen e l i m i n a t i o n are believed to be the following (32). ( i ) S t e r i c E f f e c t - With the same donor and acceptor atoms B (2.01) R / H,B«-N-H 3  \ H BORANE 9 0° , 1 Hr. H R I I -B-N-It n BORAZANE 9 0° , 10 Hr. T R I B=N- BORAZINE Ga (1.82) / H_Ga<-N-H 3  \ K GALLANE r . t . , 1 day H R I I -Ga-N- I I H H n GALLAZANE" DECOMP. (GALLAZINE) A l (1.47) H.A1«£— N-H 3  \ ALANE -20 c (ALAZANE) -20° H R I I -Al-N- POLYMERIC NETWORK IMINO ALANE (ALAZINE) Figure 8 -35 increased s i z e of R groups on the E atom cause a shift, to lower oligomers. ( i i ) Valency angle s t r a i n - Dimers contain more s t r a i n than trimers, but this i s easier to t o l e r a t e with larger donor and acceptor atoms, ( i i i ) Entropy - Prefers monomer over dimer and dimer over trimer. (iv) Nature of rea c t i o n intermediates. | The cyclogallazanes prepared i n t h i s study ranged from white s o l i d s to mobile l i q u i d s and a l l had s a t i s f a c t o r y analyses f o r gallium and hydrolysable hydrogen; a l l were soluble i n common organic solvents. As i s evident from Table 1, increasing the s i z e of the R group coincides with the formation of lower oligomers. Thus, s t e r i c i n t e r a c t i o n s i n cyclohexane-type trimers become too large and a preference f o r the angularly-strained, dimers, with lower s t e r i c requirements, becomes apparent. With both the t r i m e r i c and dimeric species the p h y s i c a l data ( i . r . and '̂ H nmr spectra) i n d i c a t e the presence of at le a s t two con- f i g u r a t i o n a l isomers i n benzene s o l u t i o n . T rimeric Cyclogallazanes (RNHGaH^)^ A cyclohexane-type ri n g structure f o r t r i m e r i c cyclogallazanes, (RNHGaH^)^, i s proposed on evidence c o l l e c t e d from "̂H nmr data and from supplementary evidence from i . r . spectroscopy measurements. As observed with the methyl d e r i v a t i v e , (13) at l e a s t two co n f i g u r a t i o n a l isomers are present i n benzene solutions of the new trimers. Figure 9. The most s t a b l e isomer, on s t e r i c grounds, i s the one i n which a l l three N-alkyl groups occupy equ a t o r i a l p o s i t i o n s on the r i n g . The next most^ stable isomer, s t e r i c a l l y , i s one i n which one N-alkyl group i s a x i a l and the remaining two N- a l k y l groups e q u a t o r i a l to the (Ga-N) r i n g . Ga R' N H Tsl — Ga H Ga N — R H CIS Ga R' .N H 'N~-Ga Ga N — H R T R A N S Conformations of Trimeric Gallane Species Figure 9 -37 These isomers w i l l be termed c i s and trans r e s p e c t i v e l y . (EtNHGaH^)^ - 1,3,5-Triethylcyclpgallazane, a viscous l i q u i d at room temperature, i s t r i m e r i c i n benzene s o l u t i o n . The p a r t i a l "*"H nmr spectrum of the benzene s o l u t i o n at 100 MHz (Figure 10) shows c l e a r l y the presence of a number of non-equivalent ^-CH^ groups. 'The s i g n a l s from these groups consist of three well-defined t r i p l e t s (J,.!™, ca. 7 Hz). The. HCOH pattern of s i g n a l s suggests that the t r i p l e t s A and B a r i s e from ^-CH^ groups i n s i m i l a r environments whereas the t r i p l e t C, at higher f i e l d , appears unique. It i s therefore tempting to assign t r i p l e t s A and C to the trans-isomer.(ca. 2:1 r a t i o ) , and the t r i p l e t B to the cis-isomer. The t r i p l e t s A and B, both assigned to e q u a t o r i a l p-CE^ groups, occur very . close together which i s to be expected since l i t t l e change i n e q u a t o r i a l "CH^ environment w i l l occur between the two isomers. These assignments would i n d i c a t e that the trans-isomer i s i n greater abundance, which i s somewhat s u r p r i s i n g f o r a cyclohexane-type ri n g on purely s t e r i c arguments. S i m i l a r t r i m e r i c borazanes, (33) however, show t h i s same preference f o r trans-isomer formation. An alternate explanation i s to assign the t r i p l e t A to the cis-isomer and the t r i p l e t s B and C (ca. 1:2 r a t i o ) to a twist conformation s i m i l a r to the one recently reported for the ethyleniminodimethyl- aluminium trimer (34). In the twist conformation one could again obtain yS-CH^ groups i n d i f f e r e n t environments i n a 1:2 r a t i o , the unique /3'CĤ group being attached to the nitrogen on the two-fold axis of the molecule. This alternate explanation would then i n d i c a t e the s t e r i c a l l y favoured cis-isomer i n greater abundance. I f the chair-type model i s accepted for the t r i m e r i c gallazanes, i t i s i n t e r e s t i n g to note the appearance of the a x i a l ^3-CH^ s i g n a l i n (EtNHGaH^)^ at higher f i e l d than the e q u a t o r i a l 1 a 9 . 0 6 9 . 0 8 . 9 . 2 7 Fig. 10 lOOMc/s 'H n.m.r. spectrum of E t N H G a H in benzene solution 39 s i g n a l s . This i s i n contrast to the a x i a l NMe s i g n a l i n the trans-(MeNHGaH^)^ trimer, which appears at.lower f i e l d than the equ a t o r i a l s i g n a l s (13). I t seems that t h i s downfield s h i f t f o r methyl groups a x i a l to- cyclohexane-type rings i s quite common, occurring i n a va r i e t y of inorganic r i n g systems, (MeNHBH^)3» (35) (MeCH.S)^, (36) (MeCH.CH 2) 3, (37) and (MeCH.O)3, (38) two of which are shown i n Figure 11. Perhaps, t h i s phenomenon can be accounted for by invoking van der Waals deshielding due to 1,3-axial i n t e r a c t i o n s . With the /?-CH 3 groups of (EtNHGaH 2) 3 the proximity to a x i a l hydrogens on the nitrogen atoms i s evidently not s u f f i c i e n t to give t h i s type of deshielding. The methylene protons i n (EtNHGaR^).^ do not give w e l l resolved signals but overlapping quintets are apparent i n the "4l nmr spectra (J ?r J ) (Figure 12), rlCiUrl HNCH presumably a r i s i n g from the a x i a l and e q u a t o r i a l environments i n the di f f e r e n t isomers. The NH resonance i s p a r t l y 'hidden' under the fl-CR^ signals i n the hydride compound occurring at ca t 9.3, but i t appears as a broad t r i p l e t (J . --7 Hz) at higher f i e l d ( t 9.52) i n the spectrum of the de u t e r i o d e r i v a t i v e , (EtNHGaD 2) 3, at 100 MHz (Figure 13). Signals due to GaH protons were not observed p r i n c i p a l l y because of low concentrations but also perhaps because of nuclear quadrupole broadening (39, 40). The "4l nmr spectra of the remaining t r i m e r i c gallazanes (R = Pr 1 1 and Bu11) are l e s s c l e a r l y resolved, even at 100 MHz. The V -CH 3 proton s i g n a l s i n • (Pr^JHGa^) 3 appear as a se r i e s of t r i p l e t s ( J H C C H ca. 7.2 Hz) centred at t-9.43, 9.44, and 9.46 again i n d i c a t i n g the presence of at least two isomers. These t r i p l e t s are t e n t a t i v e l y assigned to c i s - and trans-isomers, the t r i p l e t at higher f i e l d being   assigned to the a x i a l J*-CH^ group of the trans-isomer. The H nmr spectra of the n-butyl d e r i v a t i v e are very complex, even at 100 MHz, and no assign- ment i s attempted. Dimeric Cyclogallazanes, (RNHGaH ) ! i i Dimeric cyclogallazanes, (RNHGaH^^ may e x i s t as c o n f i g u r a t i o n a l isomers with the N-alkyl groups c i s or trans on the r i n g [ ( I l a ) and ( l i b ) r e s p e c t i v e l y ] . A number of a d d i t i o n a l v a r i a t i o n s are possible i f the (Ga-N)^ r i n g i s nonplanar, which has been shown to be the case f o r numerous analogous substituted cyclobutane d e r i v a t i v e s (41, 42). Non- planar configurations may be expected more e s p e c i a l l y i n the cis-isomer, to r e l i e v e s t e r i c i n t e r a c t i o n s between adjacent, bulky, R groups. (Pr NHGaH 2) 2 - 1,3-Di -isopropylcyclogallazane i s a mobile l i q u i d at room temperature and i s r e a d i l y sublimed. In benzene s o l u t i o n i t s molecular weight corresponds to a dimer. The .''"H nmr spectrum i n benzene s o l u t i o n consists of a s e r i e s o f doublets i n the "5"-CĤ  region of the spectrum (Figure 14). The major doublets, D and E (J o r,„ 1 T 6.3 Hz) at HL.Cn tr 9.14 and 9.15 are assigned to the c i s - and trans-isomers of the dimer. The remaining small doublets i n t h i s region may be due p a r t l y to NH signals (JJJ^QJ 6.3 Hz) or to the presence of small amounts of other oligomers. Attempted f r a c t i o n a l d i s t i l l a t i o n , however, f a i l e d to separate any components and a l l f r a c t i o n s when dissolved i n benzene gave s i m i l a r spectra to that shown i n Figure 14. The p o s s i b i l i t y of r e s t r i c t e d r o t a t i o n of the is o p r o p y l groups i n one isomer leading to both the major doublets A and B i n the spectrum was investigated by obtaining spectra at a s e r i e s of temperatures (0 - 60°). Although the separation between the two doublets decreased s l i g h t l y at higher temperatures there was no OJ D E A 8 C I I I I I I L . 1 • ' 1 I I I I , 44 8 . 8 6 8 . 8 9 8 . 9 3 9.14 9.15 9.32 Fig.14 IOO Mc/s H n.m.r. spectrum of i— P r N H G a H 2 in benzene solution. 45 i n d i c a t i o n . o f a co l l apse to j u s t one doublet and therefore the assignment of A and B to c i s - and trans-isomers i s p r e f e r r ed . The neat l i q u i d (P^NHGaR^^ and i t s deuterio'analogue gave the nove l *H nmr spec t ra shown in F igure 15. Here, f o r the f i r s t t ime, the GaH s igna l s are c l e a r l y seen as broad resonances at tr 4.71 and 4.88. The s igna l s are f i e l d dependent and i nd i ca te the presence of d i f f e r e n t i environments f o r hydrogens on ga l l ium atoms. These s igna l s a re , of course, absent i n the spectrum of the deu te r i o-de r i va t i v e , thus conf i rming the assignment. In a d d i t i o n , the CH mu l t i p l e t ( J u _ n u = J T T _ 7 „ . T ) , centred at f 6 . 3 4 , and the broad NH resonance at T 7.94 are c l e a r l y d i s t i ngu i shed . The remaining doub le ts , A and B, (J 6.4 Hz) due to ft -CH groups are HL.CH ' 3 centred at T 8.15 and 8.32. Again a mixture of c i s - and trans-dimers (F igure 16) i s pos tu la ted and i t i s seen as fo r tu i tous that the r a t i o of the y3-CH^ doublets i s approximately 1:2. The presence of the t r imer i n the l i q u i d form, which could give r i s e to th i s r a t i o , i s d iscounted on the mass spec t ra data obtained fo r the deuterio-compound, (Fr^NRGaT)^)2' The ions of h igh m/e values are l i s t e d i n Table 5 and correspond to the pa t te rn expected from the dimer (Pr^HGaD^) ^ taking in to account the 69 i s o t o p i c d i s t r i b u t i o n of ga l l ium atoms in the molecules [ Ga(60%), ^Ga(40%) ] . Molecu lar- ion peaks, although weak, occur i n the mass spectrum i n add i t i on to peaks due to the more abundant ions which have l o s t deuterium from ga l l i um. The most intense peak in the spectrum occurs at m/e = 44 and may correspond to the propane ion C 0 H o + . The spectrum gave no i n d i c a t i o n of the presence of t r ime r i c u n i t s , and s ince i t i s u n l i k e l y fo r the dimer to be converted in to t r imer i n going from vapour to l i q u i d , a d imer ic c o n s t i t u t i o n fo r the neat compounds i s 2.84 471 4.88 6.34 7.94 ' 8 32 60MHz 'H n.m.r. spectrum-of neat a Pr'NHGaH2 and b Pr'NHGaO, R Ga ,R Conformations of Dim eric Gallane Species. Figure 16 p r e d i c t e d . s (Bu NHGaH^)^ ~ 1,3-Di-s-butylcyclogallazane i s a mobile l i q u i d at room temperature. I t i s dimeric i n benzene s o l u t i o n and i n t h i s solvent i t has a *H nmr spectrum which exhibits two strong doublets (J ca. 6.6 Hz) HCCH at T 9.13 and 9.16 which are assigned to the 3 -CH^ groups i n the c i s - and trans-dimers. Signals due to the V -CH^ protons appearj at higher f i e l d but the t r i p l e t s expected on a f i r s t - o r d e r basis are poorly resolved. The nmr spectrum of the neat l i q u i d showed e s s e n t i a l l y the same pattern as the s o l u t i o n spectrum but once again, i n ad d i t i o n , the GaH signals are c l e a r l y v i s i b l e at T4.64 and 4.81 (Figure 17). (Bu NHGaH ) - 1 , 3 - D i - i s o b u t y l c y c l o g a l l a zane i s a viscous l i q u i d at room temperature and i n s o l u t i o n probably e x i s t s as a mixture of dimers and trimers. Branching of the hydrocarbon chain of the R group at the £ -carbon atom po s s i b l y reduces the s t e r i c i n t e r a c t i o n s u f f i c i e n t l y to lead . to both dimer and trimer formation. Four well-defined doublets (Junnu ca. 6.6 Hz) at TT 9.27, 9.30, 9.31, and 9.38 appear i n the high f i e l d region of the ''"H nmr spectrum i n benzene s o l u t i o n at 100 MHz. These are assigned to p 8 r o u P s b u t no further assignment i s attempted. (B^NHGaH^)^ - 1,3-Di-t-butylcyclogallazane i s a white s o l i d at room temperature, dimeric i n benzene s o l u t i o n , and di s p l a y i n g three y'S-CĤ s i g n a l s i n i t s "̂H nmr spectrum i n t h i s solvent. Two of these si g n a l s are close together at t 8.96 and 8.97, and a t h i r d , much weaker s i g n a l , occurs at higher f i e l d ( f 9.15). The signals are a l l f i e l d dependent and therefore not due to coupling. The major signals are assigned to the c i s - and trans-dimers, the t h i r d weaker s i g n a l , accounting f o r ca. 5% of the t o t a l i n t e g r a l , i s pos s i b l y due to monomer i n s o l u t i o n . 0 Hz > i l • I I • I i I I I I I I I I L_J 1 I I j I I I I I I ! 1 I ! L _ H i I I I I i I i i[ ij I 1 I I I I I I I I I L I , I I I I I I I L _ 2.84 4.64 5.81 Fig.17 60Mc/s 'H n.m.r. spectrum cf neat sec-BuNHGaH2- Table 5 Ions of high m/e in mass spectrum of (Pr NHGaD ) m/e Relative Abundance 266 0.5 265 0.5 264 5.0 • 263 2.5 262 17.5 261 3.7 260 27.7 259 12.5 258 16.0 257 • 0.5 • 44 100.0 51 I.'r. Spectra of Cyclogallazanes (RNHGaH) 2 n I.r. spectra of the cyclogallazanes (RNHGaH„) , and t h e i r L n deuterio-derivatives (RNHGaD„) i n some cases, i n benzene s o l u t i o n were 2 n recorded i n the range 4000 - 250 cm As observed previously with gallane d e r i v a t i v e s (5, 11), the strongest absorptions were a t t r i b u t a b l e to the Ga-H and Ga-D s t r e t c h i n g and deformation modes. Selected absorption bands are l i s t e d and assigned i n Table 6 for the et h y l and iso p r o p y l d e r i - vatives which are representative of the t r i m e r i c and dimeric cyclogallazanes r e s p e c t i v e l y . As expected on amass e f f e c t the r a t i o V(Ga-H)/ -0(Ga-D) i s close to 1.4. The NH s t r e t c h i n g abosrptions are i n t e r e s t i n g i n that three bands occur i n t h i s region f o r t r i m e r i c species but two bands only, f o r dimeric species. Presumably the d i f f e r e n t p o s s i b l e environments f or the NH u n i t i n the various c i s - and.trans-isomers lead to the observed v i b r a t i o n s but i s i s noteworthy that the band at 3280 cm ^ i n the e t h y l d e r i v a t i v e s i s concentration dependent, decreasing i n r e l a t i v e i n t e n s i t y on d i l u t i o n . Perhaps hydrogen bonding of the type invoked recently by Brown et a l (43), to explain the i . r . spectra of similar.cycloborazanes at various concentrations, could be operative, a l s o , i n these gallium systems. The i . r . spectra of neat (Pr^HGaH^)^ and i t s deuterio-analogue were also recorded. In each spectrum the NH s t r e t c h i n g v i b r a t i o n occurred as a broad band at 3270 cm S i m i l a r l y , Ga-H(D) s t r e t c h i n g v i b r a t i o n s appeared as broad bands at 1875 and 1825 (1350) cm The -1 Ga-H(D) deformation modes occurred at 725 and 690 (510, 493) cm and absorptions a t t r i b u t a b l e to r i n g v i b r a t i o n s came i n the region 540 - 590 cm"1. Table 6 Infrared spectra of some cyclogallazane derivatives in benzene solution EtM.GaH2 EtN-H.GaD2 Gall GaD Assignment 3338 w 3318 m 3280 s 3338 w 3316 m 3280 s N-H stretch 1875 vs 1825 vs 1350 vs • 1335 vs 1.37'+ Ga-F.(D) stretch 745 vs 502 vs 496 vs 1.404 Ga-H(D) defn. 580 s 550 s 510 m 542 s . 522 s Ring modes PrHlHGaH^ 3 3 2 0 m 3283 s Pr1NHGaD2 3 3 2 0 w 3283 m Gall GaD Assignment N-H stretch 1875 vs 1820 vs 1355 vs 1330 s 1.3 64 Ga-H(D) stretch 745 vs 508 vs J+97 vs 1.465 Ga-H(D) defn. 586 s 560 m 4-90 m 596 s 552 s 536 m Ring modes Bt̂ NHGaTTg 3307 v 3208 vs EutKKGaD2 3 3 1 2 s 3264 s GaH GaD Assignment N-H stretch 1890 vs 1820 m 1318 vs 1.408 Ga-H(D) stretch 745 s 538 vs 5 2 1 vs 1.402 Ga-H(D) stretch 598 s 554 s Ring modes 53 Part 2 The reaction of a n i l i n e with trimethylamine gallane proceeded as indi c a t e d i n the following equation: Me 3N.GaH 3(s) + <$NH2(g) -—» 4>NH.GaH .NMe (s) + H fg) The monomeric m a t e r i a l , <^NH.GaH2.NMe3, giv i n g the \l nmr shown i n Figure 18, was somewhat unexpected since with the primary alkylamine reactions d i s - cussed i n part 1, complete e l i m i n a t i o n of trimethylamine occurred with the production of a gallazane (Ga-N) r i n g species. In the present case i t n appears that due to some electron withdrawing e f f e c t of the phenyl r i n g a c y c l i c gallazane was not formed. This e f f e c t seems to have reduced the donor properties of the lone p a i r on the a n i l i n e nitrogen atom, and hence prevents coordination to a second gallium and consequent r i n g formation. I t was beli e v e d that in t r o d u c t i o n of a strong acceptor would remove the trimethylamine from the complex, ̂ NH.GaH^.NMe^, since a strong donor such as nitrogen always prefers a strong acceptor over a weak acceptor. . • The acceptor of choice was diborane since i t i s both a strong acceptor and would not undergo any unwanted side reactions such as might occur i f the (oron t r i f l u o r i d e , BF , acceptor were used. However, the reaction of diborane with 4NH.GaH^.NMe^ re s u l t e d , not i n production of the desired gallazane, d)NH.GaH2, but i n decomposition into gallium, hydrogen, a n i l i n e as w e l l as the expected trimethylamine borane. The ̂ following sequence of reactions summarizes these experimental observations:" 2.84 'Fig: 18'60Mc/s 'H n.m.r. spectrum of (J)NHGaH2-NMe3 in benzene solution 55 Me N.GaH .NH$ + 1/2B.H, * Me.N.BH + (ĵ NHGaH 5 L L o 5 5 L 4)NHGaH2 > <j>NH + Ga + 1/2H It seems l i k e l y that when the ' r^NH.GaH^' i s formed i n the reac t i o n , the donor strength of the nitrogen connected'to the phenyl r i n g i s so reduced that formation of a sta b l e c y c l i c gallazane does not occur. The monomeric unit i s evidently unstable, when formed and decomposes to i t s components even below 0°C. I t was of further i n t e r e s t to react ctNH.GaH^.NMe^ with methyl- amine i n the hope that displacement of trimethylamine would occur and y i e l d a novel c y c l i c gallazane on hydrogen e l i m i n a t i o n according to the following sequence of reactions: '(J>NH.GaH2.NMe3 + MeNH^ *• Me^ + <j>NH.GaH2,NH Me <p NH. GaH 2. NH2Me ' $ NH. GaH. NHMe' + H 2 The a c t u a l mixture of products obtained was i d e n t i f i e d by nmr and i n f r a r e d spectroscopy. Figure 19 shows the N-H str e t c h i n g region f o r each of a n i l i n e and methyl-gallazane as w e l l as the reac t i o n mixture. I t should be noted that the two upper spectra combine to give the lower spectrum. Hence, although trimethylamine was displaced as expected, the eli m i n a t i o n of a n i l i n e and production of the f a m i l i a r (MeNH.GaH,^)^ trimer occur as follows: Me3N.GaH2.NH<$> + MeNH£ + t}>NH2+ 1/3[MeNH.GaH2] Fig. 19 Infrared spectra of: a aniline; b MeNHGaH2 ; ,c aniline & MeNHGaH2 57 The p r o d u c t s were i d e n t i f i e d a l s o by means o f t h e i r c h a r a c t e r i s t i c "*"H nmr s p e c t r a . I t was o f i n t e r e s t to t hen e s t a b l i s h the mechanism o f h y d r o g e n t r a n s f e r . The two most p r o b a b l e mechanisms f o r t h i s t r a n s f e r a r e i l l u s t r a t e d b e l o w : H H H 0-N-—-Ga - NMe — > 0 N H 2 + GaH .NHMe H H H B. 0-N*3-GaH I t Me 5NHMe In the f i r s t mechan i sm, the p r o t o n wh i ch t r a n s f e r s to the a n i l i n e comes f rom the g a l l i u m . In the second mechanism a f o u r c e n t r e i n t e r m e d i a t e i s formed w i t h the h y d r o g e n atom f o r a n i l i n e p r o d u c t i o n coming f r om the me thy l am ine n i t r o g e n . The d e u t e r a t e d compound, <f> NH. G a D 2 .NMe^ was t h e r e f o r e p r e p a r e d and r e a c t e d w i t h m e t h y l a m i n e . The i n f r a r e d s p e c t r u m of-, the p r o d u c t s d i d n o t d i s p l a y e i t h e r a N-D s t r e t c h f o r a n i l i n e o r a Ga-H s t r e t c h f o r the g a l l a z a n e , thus e l i m i n a t i n g mechanism A as a p o s s i b l e r o u t e to t he p r o d u c t s . I t t h e r e f o r e seems l i k e l y t h a t mechanism B i s the a c t u a l mode o f p r o t o n t r a n s f e r . 58 P a r t 3 Imino.Gallazanes The r e a c t i o n of a z i r i d i n e , a z e t i d i n e , p y r r o l i d i n e and p i p e r i d i n e w i t h trimethylamine g a l l a n e y i e l d s compounds of. the type [ (CR^^NGaH^ ] where x = 2, 3, 4 or 5; f o l l o w i n g e l i m i n a t i o n of molar e q u i v a l e n t s of i hydrogen and t r i m e t h y l a m i n e . Cryoscopic measurements on c e n t r i f u g e d benzene s o l u t i o n s i n d i c a t e t h a t a l l these m a t e r i a l s arej d i m e ric (Table 2) i n benzene. R e c e n t l y , however, an x-ray c r y s t a l l o g r a p h i c study (45) on a s i n g l e c r y s t a l of a z i r i d i n o g a l l a z a n e produced by s u b l i m a t i o n under about 5 - 7 cm of n i t r o g e n p r e s s u r e , r e s u l t e d i n the c h a r a c t e r i z a t i o n of t h i s compound as a t r i m e r i n which the (Ga-N)^ r i n g . i s i n the c h a i r conformation (Figure 2 0 ) . The mean dimensions, found were Ga-N 1.97, N-C 1.54, C-C 1.55A; N-Ga-N = 1 0 0°, Ga-N-Ga = 121, Ga-N-C = 116°; w h i l e the angles i n the t h r e e membered r i n g s were c l o s e to 6 0°. This s t r u c t u r e , although confirming the p r e d i c t i o n s i n p a r t 1 concerning the c o n f i g u r a t i o n of the (Ga-N) r i n g , i s somewhat unexpected i n view of the c r y o s c o p i c molecular weight i n benzene s o l u t i o n . The r e s o l u t i o n of t h i s apparent dilemma could be the f o l l o w i n g . I t has been found that f r e s h l y d i s s o l v e d samples of a z i r i d i n o g a l l a n e , whether f r e s h l y prepared or n o t , g i ve degrees of a s s o c i a t i o n of 2.55 to 2.65. Samples d i s s o l v e d i n benzene and s t o r e d f o r a few days give a degree of a s s o c i a t i o n of 2.00. Since the s o l i d i s t r i m e r i c , i t would seem t h a t the c r y o s c o p i c r e s u l t s i n d i c a t e the gradual formation of dimer i n the benzene s o l v e n t . I t was a l s o observed that a s i g n i f i c a n t amount of i n s o l u b l e m a t e r i a l was formed on d i s s o l v i n g the s o l i d . The f o l l o w i n g mechanism seems p l a u s i b l e : C1' C1 S t r u c t u r e o f A z i r i d i n o Gallazane Figure 20 60 ( A z i r G a H 2 ) 3 ( A z i r G a H ^ + ( A z i r ' G a H ) ( A z i r GaH ) 2 x Thus the t r i m e r g i v e s u n s t a b l e monomer which p o l y m e r i z e s , l e a v i n g the dimer i n s o l u t i o n . Another p o s s i b l e mechanism appears to be the f o l l o w i n g : ( A z i r G a H 2 ) 3 ( A z i r G a H 2 ) 2 ( A z i r GaH n ) 2 x where two competing rearrangements o c c u r , one g i v i n g po lymer , the o ther dimer . I f the degree of a s s o c i a t i o n of g a l l a z a n e s i n benzene i s not n e c e s s a r i l y an i n d i c a t i o n of the a s s o c i a t i o n i n the s o l i d or neat l i q u i d phase , p o s s i b l y the neat nmr spectrum of i s o p r o p y l a m i n o g a l l a z a n e ( F i g u r e 15) c o u l d be a l s o r a t i o n a l i z e d i n terms of a t r a n s t r i m e r c o n f i g u r a t i o n , i n agreement w i t h the observed i n t e n s i t y r a t i o of 2 :1 f o r the . |3.-CH p r o t o n s i g n a l s . The nmr spectrum of a z i r i d i n o g a l l a z a n e ( F i g u r e 21) shows o n l y a sharp s i n g l e t , i n d i c a t i n g a s i n g l e i s o m e r i c c o n s t i t u t i o n which i s expected on the b a s i s of a p l a n a r (GaN) 2 r i n g w i t h a l l hydrogens e q u i v a l e n t . F i g u r e 22 shows the ^"H nmr spectrum of d i m e r i c a z e t i d i n o g a l l a z a n e , w i t h i n t e g r a l s of the two areas of resonance i n the r a t i o of 2 : 1 . The s p l i t t i n g observed i s tha t expected on the b a s i s of a p l a n a r (GaN) 2 r i n g , a t r i p l e t f o r the f o u r c< pro tons and a q u i n t e t f o r the two /3 p r o t o n s . 1 1 1 1 1 1 1 1 1 1 1 ' 1 1 1 1 | 1 1 I 1 I I I ! 1 1 1 1 [ I I I 1 1 1 . 1 i i ' 1 1 ' 1 i ' . 500 1 ' I 400 1 1 1 1 • 1 | i 1 i. 1 1 1 1 300 1 ' I l l ' 1 200 • i 1 1 1 1 1 1  1 100 i I- i i 1 i 1 r i ) Hz J L I I I I I J L I I I l I I I I _ I _ J L I I I 2.84 ... 8.44 Fig.21 60Mc/s H n.m.r. spectrum of (CHANGahL in benzene solution > - H > J L <4> Figures 23 and 24 show the H nmr spectra of p y r r o l i d i n o gallazane ( i n t e g r a t i o n of 1:1 as expected for the four oc and four (3 protons) and p i p e r i d i n o gallazane ( i n t e g r a t i o n of 4:6 for ©C : f$ + o~ proton m u l t i p l e t s ) . The l a t t e r two spectra are no longer simple, with evidence of complicated spin-spin i n t e r a c t i o n .  I I 1 1 1 1 1 1 1 I I 1 I I I ! 1 1 1 1 1 1 1 1 i 1 1 I- 1 1 1 1 1 1 1 1 1 j ' 1 1 1 • 1 1 1 1 1 i 1 1 1 1 500  1  400 1 I. 1 1 I I 1 3( 1 ' 1 1 1 )0 1 1 1 1 1 1 » 1 200 1 i 1 1 I I I 100 1 1 1 1 1 c 1 ) ~ H > I I 1 I I 1 I I 1 I I 1 1 1 1 i | I I I I • 1 1 1 1 i i i ! 1 1 1 1 1 1 1 1 1 1 • I - I 1 1 1 1 500 1 i 1 l | I I 400 1 1. | | 1 i 1 I I I 1. 300 i ; 1 1 200 ! 1 1 1 I i i 100 1 1 1 1 1 I I i 1 Q Hz 2.84 \ 712 8.76 Fig.24 60Mc/s 'H n.m.r. spectrum of (CH2)BNGaH2 in benzene solution 66 P a r t 4 Imino Alazanes The r e a c t i o n between ethylenimine ( a z i r i d i n e ) and b i s t r i m e t h y l - amine alane was f i r s t attempted i n 1962 by Marconi (19). These workers d i d not i s o l a t e the a z i r i d i n o alazane product. A more recent d i s c u s s i o n of t h i s r e a c t i o n product (20) suggests th a t r i n g opening of the a z i r i d i n e r i n g occurs on solvent removal y i e l d i n g an average degree of a s s o c i a t i o n of n = 10. The product prepared i n t h i s study gave i n i t i a l l y the nmr spectrum of f i g u r e 25. Since t h i s spectrum contains a h i g h f i e l d t r i p l e t and evidence of a lower f i e l d q uartet the previous f o r m u l a t i o n (20) of r i n g opening to g i v e e t h y l groups seems f a i r l y c o n c l u s i v e . However, the spectrum a few hours l a t e r (Figure 26) showed an increased i n t e n s i t y of the high f i e l d t r i p l e t w i t h respect, to the broad s i n g l e t f o r the a z i r i d i n e r i n g s . The f o l l o w i n g day, a f t e r storage at +5°CJ) :., the nmr spectrum showed the h i g h f i e l d t r i p l e t to be even more in t e n s e than p r e v i o u s l y . These r e s u l t s i n d i c a t e that r i n g opening occurs at a f a i r l y steady r a t e at o o 5 - 25 C. The i n i t i a l aluminum to a c t i v e hydrogen r a t i o was found to be A l - H„ w h i l e the a n a l y s i s of the same product l e f t at room temperature f o r three days under dry n i t r o g e n was found to be A l ^ QQ H^ These r e s u l t s i n d i c a t e t h a t i n the l i m i t , complete a z i r i d i n e r i n g opening could occur to give a l l N - e t h y l groups i n an i n s o l u b l e polymeric product. I t was of i n t e r e s t to see what the degree of a s s o c i a t i o n would » be i f r i n g opening could be h e l d to a minimum. Thus the degree of a s s o c i a t i o n of f r e s h l y prepared a z i r i d i n o alazane was determined i n 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I | 1 1 I 1 | 1 1 I I 1 1 1 1 1 1 1 1 1 1 1 . 1 . 1 1 1 1 500 1 . 1 1 I I 400 M | | l 1 3C I 1 1 )0 1 1 | 1 1 1 1 1 I - I 1 200 1 1 I 1 1 100 I 1 1 I I 1 ) Hz Fig.25 6.0M.C/S 'H n.m.r. spectrum of (CH )2NAIH2 in benzene'solution Fig.26 60Mc/s 'H n.m.r. spectrum of (CH2)2NAIH2 in benzene solution , w . 0 0 69 benzene s o l u t i o n with a minimum of delay. This worker was able to obtain a minimum value of n = 4.2 w h i l s t a co-worker was able to obtain n = 3.14. These r e s u l t s suggest that the degree of association before r i n g opening sets i n , i s l i k e l y n = 3. This i s . t h e expected degree of a s s o c i a t i o n i n view of the r e s u l t s f or the other alazanes of table 3. The product from the reaction of the b i s trimethylamine alane with a z e t i d i n e did not give up a l l i t s trimethylamine, some of which remained coordinated to i t (Figure 27). Pumping at 0°C removed most of t h i s trimethylamine to give the spectrum of Figure 28. The i n t e g r a t i o n r a t i o i s 2:1 f o r the or: <5 protons. The molecular weight i s consistent with the formulation of t h i s compound as a trimer. S i m i l a r l y the 'Hi nmr spectrum of t r i m e r i c p y r r o l i d i n o alazane shows two areas of resonance i n the r a t i o of 1:1. One resonance i s centred at 1 = 7.10 and the other at T = 8.50. The p i p e r i d i n o alazane appears to be mainly dimer i n benzene s o l u t i o n (n = 2.17) p o s s i b l y r e s u l t i n g from the l a r g e r s t e r i c requirements of the p i p e r i d i n o r i n g . The nmr spectrum f o r t h i s compound shows two resonances i n the r a t i o of 6:4 at Tr = 8.61 and at = 7.18 r e s p e c t i v e l y . These correspond to (&+ T~ and o< proton resonances. I t appears that t r i m e r i c species are common with the imino alazanes and i n t h i s respect they d i f f e r from the dimeric imino gallazanes. Since the bond lengths of Al-N and Ga-N are known to be almost i d e n t i c a l , the reason f o r t h i s d i f f e r e n c e probably l i e s more i n the nature of the reaction intermediate leading to these species than i n s t e r i c or other e f f e c t s . P o s s i b l y t h i s d i f f e r e n c e i s due to the r e l a t i v e ease with which aluminum can go 5-coordinate i n the intermediate, but t h i s i s highly speculative as no mechanism u t i l i z i n g a 5-coordinate aluminum has a c t u a l l y been demonstrated. 2.84 F i g 6.46 785 792 Fiq.27 60Mc/s *H n.m.r. spectrum of (CH2)3NAIH2 in benzene solution  72 Part 5 Imino Borazanes The f a c t that azetidino, p i p e r i d i n o and p y r r o l i d i n o borazane are dimeric i n benzene i s not s u r p r i s i n g since boron-nitrogen systems generally p r e f e r a monomeric or dimeric state to that of trimer. The nmr spectra of these three compounds are given i n Figures 29, 30 and 31 and are a l l i n agreement with the formulation of these compounds as having planar (B-N)^ rings and containing each a s i n g l e isomeric form. The a z i r i d i n o borazane prepared by the method of Akerfeldt (17) gave a s i n g l e t f o r the a z i r i d i n o r i n g hydrogen i n agreement with the l i t e r a t u r e (18) (Figure 32). The adduct, prepared by the Burg method (14) gave the nmr spectrum of f i g u r e 33 i n agreement with the l i t e r a t u r e (18). The a z i r i d i n o borazane has a t r i m e r i c c o n s t i t u t i o n i n contrast to the remaining members of t h i s s e r i e s . The reasons for t h i s d i f f e r e n t c o n s t i t u t i o n may be a r e s u l t of the preparative route used to obtain the compound. I I f ; • • i i i | i i i i 1 1 1 1 1 1 1 1 1 1 > 1 1 1 1 1 1 1 1 1 | 1 1 1 1 i | i | ' i I 1 " 1 i i 1 i i 500  1  400 1 i . l | M 1 . 3( M i l l DO I M I M 1 200 M M 1 1 | | 1 1 1 1 100 I i 1 f I ) Hz 2.84 7 6 2 8.33 Fig;29 60Mc/s 'H n.m.r. spectrum of (CH2)3NBH2 in benzene solution CO i i i 1 1 i 1 1 i i — i — i — r i | i I i i 1 1 1 I I I I ! i 1 1 i 1 7 ! • 1 1 1 1 500 i I i i [ i 1 | I I i i i i | i I i i 1—1—| ! • i 1 i l l 1 ' 400 1 3( Hr i | i .i • 1 1 I | i ' 30 1 I 200 1 1 I 1 1 i I r i 100 i I 1 I I I ! 0 Hz Fig.30 60.Mc/s 'H n.m.r. spectrum of (CH 2 ) 4NBH 2 j n benzene solution -4 1 1 1 1 1 1 1 1 1 i 1 1 1 1 • . 1 1 | 1 1 1 1 ) 1 | I i 1 1 1 I I I I | 1 1 I- i 1 I 1 1 ' 1 500 1 1 1 1 | I I 400 1 i . I | l 1 I i ! 1 300 1 1 1 1 1 1 1 I 200 1  1 1 I 1 1 1 1 1 100 l 1 1 i 1 I 1 0 Hi t 1 i 1 i 1 1 ! i 1 I 1 1 1 I i 1 1 1 I I 1 1 1 1 [ ! 1 1 1 1 l l l i M i l 1 i I l l ; 1 | 1 - -1 1 I- 1 1 1 1 1 I 1 1 1 1 1 I 1 l | 1 1 1 1 1 II 1 1 1 1 1 I I I ! ! 2.84 . 746 8.69 Fig.31 60Mc/s 'H n.m.r. spectrum of ((5hOft3H9 in benzene solution ~ i — r 400 300 1 i 1 1 i I 1 1 1 l 1 1 1 1 I 1 ! j " 1 1 1 i 1 1 I 1 200 ! 1 ' I M ' 10Q 1 i i ! i I i . 1 O H s J L J__L .1. . . I L_ 9.63 l__l_L± I I ! I I I I ! I ! I Fig.32 60I\/Sc/s 'H n.m.r. spectrum of (CK,). N* B H ! in benzene solution Part 6 Reactions of Imine Bases with EMe E = B, A l , Ga, In Reaction of EMe^ with a z i r i d i n e gave, on methane e l i m i n a t i o n , compounds which were t r i m e r i c i n benzene s o l u t i o n . Since the hydrido analogues previously prepared were t r i m e r i c as w e l l , t h i s r e s u l t suggests that the groups about the E atom have l i t t l e e f f e c t i n determining the f i n a l degree of ass o c i a t i o n of the complexes studied here. The compound Ke^B^(CE^)^ was not i s o l a t e d , as the high temperatures necessary to achieve methane el i m i n a t i o n from the adduct also cause polymerization. The nmr spectra of the two stable adducts Me^BNR^CH^^ (Figure 34) and Me^GaNH(CH^)^ (Figure 35) are c h a r a c t e r i s t i c but very d i f f e r e n t . The a z i r i d i n e r i n g protons of the boron compound give r i s e to a s i n g l e t at low f i e l d - probably the r e s u l t of nitrogen in v e r s i o n or f a s t exchange reactions i n s o l u t i o n . The higher f i e l d s i n g l e t i s the resonance of the boron methyl protons. The a z i r i d i n e r i n g protons of the gallium adduct, on the other hand, appear to be s p l i t into a m u l t i p l e t . This complex s p l i t t i n g i s believed to be the r e s u l t of not only primary but also second order magnetic coupling of the hydrogen nuclei- on the a z i r i d i n e r i n g , . ) . The three methane e l i m i n a t i o n products had simple and very s i m i l a r nmr spectra. These spectra consisted of a lower f i e l d s i n g l e t for the a z i r i d i n o protons and a high, f i e l d s i n g l e t for the methyl groups of the E atoms. r r — " r T 1 ! 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