Reaction of cyclopentadienyl ruthenium complexes with a carborane anion: Effect of the spectator ligands on the substitution site

The reaction of cyclopentadienyl ruthenium complexes of the type [RuCI(Cp)L1L2] (L-1,L- L-2 = PPh3, PMe2Ph, PMePh2; L1L2 = dppe; L1L2 = COD; L-1 = CO, L-2 = PPh3) with Licarb (Hcarb = 2-Me-1,2dicarba-closo-dodecaborane) gives two types of complexes, [Ru(H)(C5H4-carb)L1L2] or [Ru(carb)(Cp)L1L2], depending on the nature of the coordination set. The structures of [Ru(carb)(Cp)(PMe2Ph)2] and [RuCl(eta(5)-C5Me4H)(PMe2Ph)(2)] have been determined by single-crystal crystallography. The role played by the ligand set on the site of nucleophilic attack is discussed in light of the steric crowding and electronic density at the metal center.