Preparation and characterization of some ruthenium(III) porphyrins, including the crystal structure of bromo(octaethylporphinato)(triphenylphosphine)ruthenium(III)

Abstract

Some ruthenium(III) complexes Ru(porp)(L)X and [Ru(porp)L2]X, (porp = dianion of octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP); L = PPh3, P″Bu3; X = Br, Cl) have been prepared from the precursor complexes Ru(porp)L2 or Ru(porp)(CO)L using as oxidant the halogens, or air in the presence of the hydrogen halides. The X = PF6 salts can be made using Et3O+PF6− as oxidant. Ruthenium(II) porphyrin π-cation radical intermediates have sometimes been detected. The X-ray crystal structure of Ru(OEP)(PPh3)Br, the first reported for a ruthenium(III) porphyrin, reveals that metal is displaced 0.049 Å from the plane of the pyrrole N atoms towards the phosphine. The Ru(OEP)(py) Br and [Ru(OEP)(py)CH3CN]PF6 complexes have been synthesized from Ru(OEP)(CO)py. The ruthenium(III) complexes are low-spin as shown by magnetic and esr data. Optical and 1H nmr data, the latter showing large paramagnetic shifts, are also presented.