Facile oxidative addition/reductive elimination of HX (X=Cl, Br, I) on (μ-H)2Os3(CO)10

The addition of an HX molecule (X=Cl, Br, I) to (μ-H)2Os3(CO)10 yields four novel trihydride complexes of formula H(μ-H)2Os3(CO)10(X), which differ in the position occupied by the terminal hydride on the osmium atom. The reaction takes place even at 183 K, and can be followed by NMR spectroscopy. At room temperature elimination of HX yields (partially) the original starting material. This reaction appears to be catalyzed by a base. This observation prompted us to investigate the reaction between H(μ-H)2Os3(CO)10(X) and ammonia. The product of the latter reaction is a mixture of isomers whose structures are related to those of the parent H(μ-H)2Os3(CO)10(X).