A Salt Metathesis Route To Ruthenium Carbene Complex Isomers With Pyridine Dicarboxamide-Derived Chelate Pincer Ligands

Reaction of the doubly deprotonated pyridine 2,6-dicarboxamido ligand (1) with (PCy Cl Ru=CHPh (3a) in THF gave a mixture of (lig)(PCy )Ru=CHPh isomers (4). The pentane soluble N,N,O-4 isomer was isolated by extraction and characterized by X-ray diffraction. The O,N, O-4 isomer was identified in the residue. Single crystals of the closely related complex (lig)(NHC) Ru=CHPh, O,N,O-5, were obtained from the reaction of 1 with (NHC)(PCy )Cl Ru=CHPh (3b) and used for the X-ray crystal structure analysis of the system Chelate Ligand, Salt Metathesis, Ruthenium Carbene Complexes, Isomeric Coordination Compounds