New Carbaalanes − (AlMe)8(CCH2Me)5(C≡C−Me) and the THF Adduct (AlMe)8(CCH2Me)5H·2THF

The hydroalumination of Me2Al−C≡C−Me with a large excess of Me2AlH afforded the arachno-carbaalane (AlMe)8(CCH2Me)5H (4) by the release of AlMe3. 4 is almost insoluble in noncoordinating solvents and could not be purified by recrystallization. On an attempt to recrystallize 4 from a THF solution, the adduct (AlMe)8(CCH2Me)5H·2THF (5) was isolated as the first stable ether adduct of a carbaalane. Crystal structure determination revealed a cube of eight aluminium atoms, five faces of which are bridged by C−CH2Me groups. The sixth face is µ2-bridged by a hydrogen atom, and two opposite aluminium atoms of this face are coordinated by one THF ligand each. When the excess of dimethylaluminium hyd…