Dynamic Dimer-Monomer Equilibrium in a Cycloruthenated Complex of [Re(6-C6h6)2]+

Cycloruthenation is a well known process in organometallic ruthenium chemistry. In this work, we report unprecedented cycloruthenated rhenium bis-arene compounds with planar chirality. In a two-step process, the reaction of acetyl-pyridine with [Re(η6-C6H6)2]+ introduced a pyridinyl-methanol ligand at one of the arene rings. Coordination of [Ru(CO)2Cl2] led to cycloruthenation, and the products were obtained as two diastereomeric pairs of enantiomers. Under basic pH conditions, the two pairs of enantiomers undergo spontaneous and reversible dimerization. The cycloruthenated monomers were fully characterized, and the dimerization process was studied by NMR, IR spectroscopy, and DFT calculations.