Complexes of osmium(VI) with catechol and substituted catechols

Osmium tetraoxide reacts with catechols, R(OH)2-o, to give the tris(catecholato)-species [Os(O2R)3] and the polymers [{OsO(O2R)2}n], while in the presence of pyridine or substituted pyridines (L)trans-[OsO2(O2R)L2] complexes are formed. Reaction of cis-[OsO4(OH)2]2– or trans-[OsO2(OH)4]2– with catechols yields salts of trans-[OsO2(O2R)2]2–. The Raman, i.r., 1H and 13C n.m.r., and mass spectra of the products are reported and the structures deduced. The relevance of some of these complexes to the reaction of OsO4 with phenolic material in plant tissue is briefly discussed.