Synthesis and structural characterization of the complexes [Os₃(CO)₁₀(CON₃Ph)(NCMe)] and [Os₃(CO)₁₀(CON₃Ph)(NC₅H ₅)]

The clusters [Os₃(CO)₁₁ (NCMe)] and [Os₃(CO)₁₁ (NC₅H₅)] have been treated with phenyl azide to give [Os₃(CO)₁₀(CON₃Ph)(L)] [L = NCMe (1) or NC₅H₅ (2)], the structures of which in the solid state were established by X-ray crystallography. Complex (1) crystallises in space group P1̄ with a = 9.029(3), b = 12.720(5), c = 13.433(5) Å, α = 102.69(2), β = 102.52(2), γ = 104.75(2)°, and Z = 2. The structure was solved by a combination of direct methods and Fourier-difference techniques, and refined by blocked-cascade least squares to R = 0.057 for 3 739 unique diffractometer data. Complex (2) crystallises in the monoclinic space group P2₁/n with a = 9.311(4), b = 16.707(11), c = 20.241(15) Å, β = 101.88(5)°, and Z = 4. The structure was solved using the same techniques as for (1), and refined by blocked-cascade least squares to R = 0.080 for 2 566 diffractometer data. In both complexes the Os atoms define a triangle with one edge extended to be non-bonding [3.612(2) Å in (1) and 3.615(2) Å in (2)]. This long edge is bridged by one of the terminal N atoms of the azide. The N atom at the other end of the azide, bound to the phenyl ring, is co-ordinated to the carbon atom of the adjacent equatorial carbonyl group. The other bridged Os atom has an NCMe group [in (1)] or a NC₅H₅ ligand [in (2)] co-ordinated in an axial site.