The first nitrosyl derivatives of high nuclearity carbonyl clusters: Synthesis and X-ray analysis of the [(Ph3P)2N]+ salts of the anions [Os10C(CO)24(μ2-NO)]− and [Os10C(CO)23(NO)]−

The carbido dianion Os₁₀C(CO)₂₄]^2? reacts with NOBF₄ in MeCN to give OS₁₀C(CO)₂₄(μ₂-NO)]^? (1) in which the nitrosyl ligand adopts a novel bonding mode bridging the wingtips of a “butterfly” indentation of metal atoms. The anion 1 undergoes rearrangement and CO loss in solution to give OS₁₀C(CO)₂₃(NO)]^? (2); the overall molecular geometry of 2 is close to that previously found for the dianion Os₁₀C(CO)₂₄]^2? with the nitrosyl ligand bonded in a terminal fashion to the tetrahedral Os₁₀ metal skeleton. Crystals of the (Ph₃P)₂N]⁺ salt of 1 are triclinic, space group P$\text{1}$, with a 20.389(4), b 14.670(3), c 12.333(3) Å, α 99.55(3), β 94.43(3), γ 103.03(3)°, Z = 2, refinement of atomic parameters using 2699 absorption corrected data converged at R = 0.0952. The (Ph₃P)₂N]⁺ salt of 2 crystallises with one molecule of CH₂Cl₂ in the triclinic space group P$\text{1}$, with a 19.374(3), b 16.813(3), c 11.791(2) Å, α 85.00(3), β 101.81(3), γ 99.43(3)°, Z = 2, refinement of atomic parameters using 8736 absorption corrected data converged at R = 0.0943.