Dimeric Di(tert-butyl)haloalanes and a Monomeric Di(tert-butyl)phosphino-di(tert-butyl)alane

The di(tert-butyl)aluminum halides, tBu2AlX (X = Br, I) have been prepared in yields ranging from 55 to 64% from AlX3 and LitBu in a 1 : 2 molar ratio in pentane. In the crystal these pyrophoric compounds are dimeric featuring Al–X–Al bridges. The reaction of AlCl3 with LitBu in diethyl ether produced a volatile solvate of composition tBu3Al–Cl–AltBu2(OEt2). Reaction of this species with AlCl3 at 120 ◦C yielded a separable mixture of tBu2AlCl and tBu2AlCl(OEt2). tBu2AlCl and tBu2GaCl react with tBu2PLi to produce the monomeric compounds tBu2E–PtBu2 (E = Al, Ga). The aluminum compound decomposes at 111 ◦C to give a mixture of the cis/trans-isomers of [tBu(H)Al– PtBu2]2 while at 200 ◦C only the trans-isomer is formed.