Klaus Rohbock

Metallkomplexe mit tetrapyrrol-liganden : IX. Octaäthylporphinato-osmium(II)-carbonyl-komplexe mit trans-ständigen donator-liganden

Abstract By reaction of octaethylporphine [(OEP)H2] with osmium tetroxide in diethyleneglycil monomethyl ether at temperatures about 200°C, new octaethylporphinatoosmium (II) carbonyl complexes of the type (OEP)Os(CO)X are obtained in good yield after addition of a Lewis base X[where X = MeOH, EtOH, THF, C5H5N, PPh3, and AsPh3]. Treatment of these complexes with P(OMe)3 yields (OEP)Os[P(OMe)3]2, both axial ligands (CO and X) being replaced. All compounds are fully characterized by elemental analyses, electronic absorption, IR, NMR and mass spectra. The ligand X exerts a trans-effect on the carbonyl group: as the back-bonding capacity of X increases the carbonyl stretching frequency rises, indicating diminishing back bonding to the CO group. IR data show that back bonding onto the CO-ligand increases in the porphinatometal carbonyls (P)M(CO)X for different metals M in the order Fe