Rhodium cyclooctadiene complexes of the weakly co-ordinating carborane anion [closo-CB_(11)H_(12]~-.Isolation and crystal structures of [COD)Rh(#eta#~2-CB_(11)H_(12) and [(COD)Rh(THF)_2][CB_(11)H_(12)]

摘要

Reaction of Ag[CB_(11)H_(12) with [Rh(COD)Cl)_2 (COD=1,4-cyclooctadiene)affords the complex [Rh(COD)(#eta#~2-CB_(11)H_(12)](2),which has been characterised by NMR spectroscopy and X-ray crystallography.The solid-state structure shows that the carborane is co-ordinated to the rhodium by two 3c-2e Rh-H-B bonds.The solution fluxional behaviour of the {Rh(COD)} fragment over the surface of the cage is discussed.The carborane ligand in 2 is a structurally characterised model for the active species in [Rh(L_2)(S)_2]~+ (L=bidentate ligand,S-weakly bound solvent)Lewis-acid catalyse dhydrogenation and hydroacylation reactions.It is suggested that the low nucleophility of [CB_(11)H_(12)]~- is an important factor in the isolation of 3.