Pyridine-2-thiolate binding of osmium(III). Geometrical isomers of [Os(C5H4NS)2(PPh3)2]PF6.nH2O (n = 1,0)

Oxidation of OsL 2 (PPh 3 ) 2 by cerium(IV) has afforded the first osmium(III) complex of pyridine-2-thiol (HL), [OsL 2 (PPh 3 ) 2 ]PF 6 .nH 2 O, in two geometrically isomeric forms of green (n=1) and red (n=0) color, the latter being a minor (∼1%) constituent. It is proposed that the oxidation process preserves the original isomer population present in solutions of the osmium(II) precursor in the form of stereorigid osmium(III).