Reaction of tris[(diphenylphosphino)dimethylsilyl]methane with molybdenum hexacarbonyl and deprotonation to give a salt with a planar carbanion. Crystal structures of (Ph2PMe2Si)3CH and [Li(tmen)2][C(SiMe2PPh2)3], tmen = N,N,N′,N′-tetramethylethane-1,2-diamine

Abstract

The compound (Ph₂PMe₂Si)₃CH I reacted (i) with [Mo(CO)₆] to give cis-[Mo(CO)₄{(Ph₂PMe₂Si)₃CH}] 1 in which two phosphine groups are co-ordinated to molybdenum and one is free, and (ii) with LiBu in the presence of N,N,N′,N′-tetramethylethane-1,2-diamine (tmen) to give [Li(tmen)₂][C(SiMe₂PPh₂)₃] 2, which contains discrete planar carbanions and no Li–P co-ordination. The crystal structures of compounds I and 2 have been determined and 1 has been characterised spectroscopically.