The trans influence of the pyridine ligand on ruthenium(II)-porphyrin-carbene complexes

In the two ruthenium(II)-porphyrin-carbene complexes (dibenzoylcarbenyl-kappaC)(pyridine-kappaN)(5,10,15,20-tetra-p-tolyl- porphyrinato-kappa(4) N)ruthenium(II), [Ru(C15H10O2)(C5H5N)(C48H36N4)], (I), and (pyridine-kappaN)(5,10,15,20-tetra-p-tolylporphyrinato-kappa(4)N)[bis(3-trifluoromethylphenyl)carbenyl-kappaC]ruthenium(II), [Ru(C15H8F6)(C5H5N)(C-48 H36N4)], (II), the pyridine ligand coordinates to the octahedral Ru atom trans with respect to the carbene ligand. The C(carbene)-Ru- N(pyridine) bonds in (I) coincide with a crystallographic twofold axis. The Ru-C bond lengths of 1.877 (8) and 1.868 (3) Angstrom in (I) and (II), respectively, are slightly longer than those of other ruthenium(II)-porphyrin-carbene complexes, owing to the trans influence of the pyridine ligands.