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 [RuCl(Cp)L1L2] (L1, L2 = PPh3,
PMe2Ph, PMePh2; L1L2 = dppe; L1L2 = COD; L1 = CO, L2 = PPh3) with Licarb (Hcarb = 2-Me-1,2-dicarba-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(η5-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.