Cluster-promoted cleavage of a phosphorus-carbon bond under ambient conditions. Synthesis, structure, and stereospecific substitution reactions of the acyl cluster complex Ru3(μ-η2-C(O)(C6H 5))(μ3-η2-P(C6H 5)(C5H4N))(CO)9

Article abstract of DOI:10.1021/ic00251a019

The monosubstituted complex Ru₃(CO)₁₁(PPh₂Py) (1), prepared from Ru₃(CO)₁₂ and diphenylpyridylphosphine PPh₂py by using [PPN]CN as a catalyst, experiences a spontaneous P-C bond-cleavage reaction at 25°C. The expelled phenyl substituent undergoes migratory CO insertion to yield the acyl complex Ru₃(μ-η²-C(O)(C₆H ₅))(μ₃-η²-P(C₆H ₅)(C₅H₄N))(CO)₉ (2) (yield, 85%). The high reactivity observed for 2 is related to a stereospecific labilizing effect of the acyl group toward adjacent carbonyl ligands. This is exemplified by its reaction with several phosphines at 307deg;C, leading to Ru₃(μ-η²-C(O)(C₆H ₅))(μ₃-η²-P-(C₆H ₅)(C₅H₄N))(CO)₈(L) (3) (3a, L = PPh₃; 3b, L = PPh₂H; 3c, L = PCy₂H). The X-ray structures of 2 and 3a are reported. Crystal data for Ru₃(μ-η²-C(O)(C₆H ₅))(μ₃-η²-P(C₆H ₅)(C₅H₄N))(CO)₉ (2): orthorhombic, space group P2₁2₁2₁, a = 10.431 (2) A, b = 15.888 (5) A, c = 17.821 (5) A, V = 2953 A³, Z = 4. Full-matrix least-squares refinement of 379 variables for 2757 reflections with F_o² > 3σ(F_o²) led to R = 0.043 and R_w = 0.049. Crystal data for Ru₃(μ-η²-C(O)(C₆H ₅))(μ₃-η²-P-(C₆H ₅)(C₅H₄N))(CO)₈(P(C ₆H₅)₃) (3a): monoclinic, space group P2₁/n, a = 10.650 (3) A, b = 31.023 (4) A, c = 13,016 (2) A, β = 97.57(2)°, V = 4262 A³, Z = 4. Full-matrix least-squares refinement of 383 variables for 5770 observations with F_o² > 3σ(F_o²) led to R = 0.049 and R_w = 0.087. Both these triangular 50-e cluster complexes are edge double-bridged species, with an acyl group C(O)(C₆H₅) and a phenylpyridylphosphido group P(C₆H₅)(C₅H₄N) spanning the open metal-metal vector Ru(2)-Ru(3). Additional coordination of the nitrogen atom of the pyridyl substituent on phosphorus to the unique ruthenium atom Ru(1) confers on the latter ligand a key role in preserving the integrity of the metal cluster. In the monosubstituted derivatives 3, the phosphine ligand occupies an equatorial coordination site, in a cis position relative to the oxygen of the acyl group.