A comparative study of the behaviour of N-trimethylsilyl and N-neopentyl-anilines and 1,2-diaminobenzenes towards trimethylalane; X-ray structures of nine Al–N compounds

The reactions of a pair each of monosubstituted anilines PhNHR1 and disubstituted 1,2-diaminobenzenes C6H4(NHR1)2-1,2 (R1= SiMe3= R, or R1 = CH2But= R) with 1 or 2 equivalents of trimethylalane have been investigated. The trimethylsilyl derivatives were more reactive than the neopentyl analogues. The following crystalline compounds were obtained at ambient temperature or (1) gentle heating: trans-[AlMe2(mu-NRPh)] 21, [AlMe3{NH(R)Ph}]2, [(AlMe2)2{mu-(NR)2C6H4-1,2}]4, [(AlMe2){mu-(NR)2C6H4-1,2}]5, [(AlMe){N(R)C6H4NR-mu-1,2}]26 and [AlMe2{N(R(C6H4N (H)R}]7, while prolonged heating was required in order to obtain [AlMe2(mu-NRPh)]23 and [(AlMe{N(R)C6H4NR-mu-1,2}]28. The amine adducts 2 and 7, were identified as intermediates to 3 and 8, respectively. Treatment of C6H4(NHR)2-1,2 with successively 2 LiBun and 2 AlCl3 afforded [AlCl{N(R)C6H4NR-mu-1,2}]29. The diamine adduct [C6H4{N(H)R(AlMe3)}2-1,3]10 was obtained from C6H4(NHR)2-1,3 and 2 AlMe3; while the same diamine with successively 2 LiBun, 2 AlClMe2 and 2 tmen yielded a compound tentatively formulated as [C6H4{N(R)AlMe2(tmen)}2-1,3] 11. The X-ray structures of 1–7, 9 and 10 are presented.