Unusual dimer formation of cyclometalated ruthenium NHC p-cymene complexes

We present the synthesis and structural characterization of novel ruthenium complexes containing C boolean AND C* cyclometalated N-heterocyclic carbene ligands, eta(6)-arene (p-cymene) ligands and one bridging chlorine ion. Complexes of the general formula [Ru(p-cymene)(C boolean AND C*)Cl] were prepared via a one-pot synthesis using in situ transmetalation from the correspondent silver NHC complexes. These complexes react with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (NaBAr4F) to form dinuclear complexes of the general structure [Ru(p-cymene)(C boolean AND C*)-mu-Cl-(p-cymene)-(C boolean AND C*) Ru](+)[BAr4F](-). Solid-state structures confirm that the pseudo-tetrahedral coordination around the metal center with the eta(6)-ligand aligned perpendicularly to the C boolean AND C* ligand and the i-Pr group "atop" is retained in the bimetallic complexes