Chemical, electrochemical, and structural aspects of the ruthenium complexes Ru(η-arene)Cl2(P) (where arene = benzene, [2.2]paracyclophane and P = triphenylphosphine, rac-[2.2]paracyclophanylphosphine)

Reaction of diphenyl[2.2]paracyclophanylphosphine, rac-PPh2(C16H15) (1), with [Ru(eta-arene)Cl-2](2) (where arene = C6H6, [2.2]paracyclophane (C16H16)) in a 2:1 ratio affords the half-sandwich complexes Ru(eta-arene)Cl-2(PPh2(C16H15)) (arene = C6H6 (2), C16H16 (3)) in high yield. In solution, the structures of 2 and 3 have been probed and assigned using 2D NMR spectroscopy and the structure of the [2.2]paracyclophane derivative, 3, has been established in the solid-state by single-crystal X-ray diffraction. Cyclic voltammetry and steady-state voltammetry of 2 in 0.25 M [(Bu4N)-Bu-n] [PF6]/CH2Cl2 shows that the complex undergoes a chemically reversible, one-electron oxidation and an irreversible, two-electron reduction. The voltammetry of the related complex [Ru(eta(6)-C6H6)Cl-2(PPh3)] (4), recorded under analogous conditions, is similar both in terms of the processes displayed and the potentials at which they occur.