Reaction of [Os₃(CO)₁₀(NCMe)₂] with 7-azaindole (L); molecular structures of [Os₃(μ-H)(CO)₁₀(μ-L)] and [Os₃(μ-H)(CO)₉(μ₃-L)]

The reaction of [Os3(CO)10(NCMe)2] with 1 equivalent of 7-azaindole (HL) in CH2Cl2 at room temperature led to two structural isomers (1a and 1b) of formula [Os3(μ-H)(CO)10(μ-L)]; both in 25% yield. A minor product, [Os3(μ-H)(CO)9(μ3-L)] 2 was also isolated in 10% yield. The compounds were characterised by IR, 1H NMR, elemental analysis and structurally by single-crystal X-ray analyses. The co-ordinating 7-azaindole bridges along an edge of the triosmium triangle with both nitrogen atoms bound to two osmium atoms in complex 1a. However, it was found to be orthometallated in complex 1b. The pyridinic and pyrrolic nitrogen atoms co-ordinate to the osmium triangle in a μ3-η2 fashion in complex 2. Formation of 2 from 1a was achieved by thermal, chemical and photochemical means.