Carboxylation of a mu(3)-diazo methylidyne triosmium cluster

The unsaturated cluster Os-3(CO)(8)(Ph2PCH2P(Ph)C6H4)(mu -H) (1) reacts wit h CH2N2 at -10 to 25 degreesC to give two novel compounds Os-3(CO)(7)(mu (3 )-CN2)(mu -dppm)(mu -H)(2) (2) and Os-3(CO)(7)(mu (3)-CCO2H)(mu -dppm)(mu - H)(3) (3) characterized by single-crystal X-ray crystallography. Compound 2 is converted to 3 in almost quantitative yield by reaction with CO (atmosp heric pressure) and trace H2O. The reaction of 2 with molecular hydrogen at atmospheric pressure at 80 degreesC yields Os-3(CO)(8)(mu -dppm)(mu -H)(2) (4) and Os-3(CO)(10)(mu -dppm) (5).