Reactivity of Triosmium Carbonyl Clusters with 1,8-Diaminonaphthalene ? Synthesis and Structural Characterization of Amido, Diamido, and C-Metalated Trinuclear Derivatives

The compounds [Os3(CO)12] and [Os3(?-H)2(CO)10] do not react with 1,8-diaminonaphthalene (H2dan) under thermal conditions (110 C, 30 min). However, [Os3(CO)10(MeCN)2] reacts with H2dan (THF, reflux temperature) to give two isomers of [Os3(?-H)(?-Hdan)(CO)9] (1 and 2). In toluene at reflux temperature, these reagents afford [Os3(?-dan)(CO)10] (3). Compound 2 can be converted into 3 under thermal conditions, but no interconversion between 1 and 2 has been observed. The three compounds have been characterized by X-ray diffraction methods. Compound 1 arises from the C-metalation of H2dan in a position adjacent to an NH2 group; this generates a hydride and a ligand that interacts with the three metal atoms through one of the NH2 groups, through the metalated carbon atom (which spans an Os?Os edge), and through one of the C=C bonds of the metalated ring. In compound 2, the hydride arises from the oxidative addition of an N?H bond of H2dan; the resulting ligand interacts with two of the three metal atoms through the amido NH fragment (bridging position) and through the remaining NH2 group. Compound 3 is derived from the transformation of both NH2 groups of H2dan into amido NH groups and consists of a 50-electron trinuclear cluster with the longest edge doubly-bridged by both amido groups.