A DIHYDROGEN COMPLEX, [OS(ETA(2)-H-2)(CO)(QUS)(PPH(3))(2)](+), IN EQUILIBRIUM WITH ITS COORDINATED THIOL TAUTOMER (QUS=QUINOLINE-8-THIOLATE)

The mixture of two isomers of the new complex Os(H)(CO)(quS)(PPh(3))(2) 3 reacts with HBF4 . Et(2)O at -80 degrees C to form the complexes [Os(eta(2)-H-2)(CO)(quS)(PPh(3))(2)](+) With dihydrogen trans to sulfur 4a or nitrogen 4b along with tautomeric thiol complexes [Os(H)(CO)(quSH)(PPh(3))(2)](+) 4c,d; the tautomeric equilibria shift with temperature.