Alane phosphine adducts

H3A1 NMe3,53 whose structure has been determined by X-ray diffraction.54 Since these initial studies, comparable reactions were observed for alanes, gallanes and indanes R3M (M = Al, Ga, In R = H, halogen) with amines and phosphines, yielding bis-amine, bis-phosphine and mixed amine/ phosphine adducts. Figure 13 presents the different coordination modes that have been observed so far. 

Gallane-tertiary amine or -tertiary phosphine adducts 106, L-GaH3 (L = Me3N, quinuclidine, ( -G6Hn)3P), reduce a carbonyl group and other unsaturated functional groups. The selectivities are different to those observed for similar alane... 

Treatment of solutions of lithium aluminium hydride in ether with the hydrochloride salts of bulky trialkylphosphines provides a route to stable tertiary phosphine adducts of alane, AlH,." ... 

Adenosine triphosphate alkali metal complexes, 34 vanadyl complexes, 568 Alane, 123 amine adducts, 107 phosphine adducts, 111 Alane, alkoxy-, 124 Alane, amino-, 109 Alane, imino-, 109 Alkali metal complexes, 1-70 acid anions, 30 acid salts, 30 bipyridyl, 13 crown ethers cavity size, 38 cryptates... 

The reaction between a Lewis acid R3M and a Lewis base ER3, usually resulting in the formation of a Lewis acid-base adduct R3M—ER3, is of fundamental interest in main group chemistry. Numerous experiments, in particular reactions of alane and gallane MH3 with amines and phosphines ER3, have been performed [14]. Several general coordination modes, as summarized in Fig. 2, have been identified by X-ray diffraction. 

The phosphine-alane is expected to displace PPh at Ni, but no reaction takes place in the absence of substrate due to strong intramolecular P Al interactions. Lewis bases such a triethylamine are able to split the head-to-tail phosphine-alane dimer and consistently, further increase catalytic activity. The precise role of the Lewis acid moiety in the catalytic cycle remains unknown. It is supposed to interact with the methyl group at Ni and to facilitate methyl/silyl exchange. The key active species 36a could not be characterized, but its Lewis base adduct 36b was identified by NMR (Figure 19). 

Trialkyl and triaryl alanes give stable 1 1 adducts with neutral donor molecules (e.g., ethers, thioethers, tertiary amines, tertiary phosphines) ... 

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