Chalcogenides of aluminium(III) and gallium(III) derived from Lewis base adducts of alane and gallane

Abstract

Reductive cleavage of (ER)₂ by [GaH₃L], L = NMe₃ or P(C₆H₁₁)₃, afforded [Ga(TePh)₃(NMe₃)], [Ga(SeEt)₃(NMe₃)] and [Ga(TePh)₃{P(C₆H₁₁)₃}]; the latter was also prepared by the reaction of [GaH₂Cl{P(C₆H₁₁)₃}] with LiTePh. They have slightly disordered tetrahedral metal centres, established in the solid for [Ga(TePh)₃(NMe₃)] and [Ga(TePh)₃{P(C₆H₁₁)₃}], and in the structure of the aluminium analogue, [Al(SePh)₃(NMe₃)], which was also determined. Reaction of [GaH₂Cl{P(C₆H₁₁)₃}] with Li₂Se afforded dinuclear trans-[{GaCl(µ-Se)[P(C₆H₁₁)₃]}₂] (minor product) which is centrosymmetric with distorted tetrahedral metal centres associated with a planar Ga₂Se₂ ring system. Treatment of trans-[{AlH(µ-Se)(NMe₃)}₂] with tmen (=N,N,N′,N′-tetramethylethane-1,2-diamine), or [{AlH₃(tmen)}_∞] with elemental selenium, afforded polymeric [{[AlH(µ-Se)]₂(tmen)}_∞]. Cleavage of (EPh)₂ by trans-[{AlH(µ-Se)(NMe₃)}₂] gave trans-[{Al(µ-Se)(EPh)(NMe₃)}₂], E = S, Se or Te, also as centrosymmetric dinuclear species with planar Al₂Se₂ ring systems. Reaction of trans-[{AlH(µ-Se)(NMe₃)}₂] with 2 equivalents of NH(SiMe₃)₂ or 6-methyl-2-trimethylsilylaminopyridine gave the secondary amine metallated products trans-[{Al(µ-Se)[N(SiMe₃)₂](NMe₃)}₂] (structurally authenticated as a centrosymmetric dinuclear species) and [{Al(µ-Se)(NC₅H₃NSiMe₃-2-Me-6)}₂].