REACTIONS OF 1-HYDROXYPYRIDINE-2-THIONE WITH TRIOSMIUM CLUSTERS - PREPARATION AND TRANSFORMATION OF N-OXIDE-CONTAINING OSMIUM COMPLEXES

The reaction of 1-hydroxypyridine-2-thione with Os-3(CO)(11)(NCMe) has yielded three new complexes Os-3(CO)(10)(mu-H)(mu-eta(1)-S-C5H4N(O)) (1, 11% yield), Os-3(CO)(10)(mu-H)(eta(2)-S-C5H4N(O)) (2, 16% yield), and Os-3(CO)(9)(mu-H)(mu-eta(2):eta(1)-SC5H4N(O)) (3, 3% yield). Simil arly, treatment of complex Os-3(CO)(10)(NCMe)(2) with this ligand has produced the major complexes 1 and trace of 3. Prolonging the above tw o reactions increased the yield of 3. Treatment of 1-hydroxypyridine-2 -thione with triosmium isocyanide complexes Os-3(CO)(10)(CNR)(NCMe) (a , R = CH2-Ph; b, R = Pr) has led to the formation of Os-3(Co)(9)(mu-H) (CNR)(eta(2)-SC5H4N(O)) (4), )(10)(mu-eta(1)-C=NHCH(2)Ph)(mu-eta(1)-S- C5H4N(O)) (5), and Os-3(CO)(9)(mu-H)(CNR)(mu-eta(1)-S-C5H4N(O)) (6). T he 4:5 ratio depended upon the nature of the alkyl groups of the coord inated isocyanide. Reaction of either 1 or 2 with Me(3)NO resulted in CO loss and formation of complex 3. Thermolysis of 1 at 80 degrees C g enerated Os-3(CO)(9)(mu-H)(mu(3)-pyS) (7), Os-3(CO)(9)(mu-OH)(mu(3)-py S) (8), and byproduct CO2. Upon being heated at 80 degrees C, 3 was co nverted to 7 and 8 in a ratio of 1:4 as indicated by an in-situ NMR st udy. These observations show that 3 is an intermediate for the formati on of 8 from 1. Crystal structures of 1, 4b, 5a, and 8 were determined by X-ray diffraction analyses. The overall results indicate that the N-oxide group in these complexes exhibits versatile bonding modes on t riosmium clusters.