Precursors of quadruply bridging phosphorus monoxide ligands: Synthesis and structural characterization of a new family of anionic fluoro and alkoxyphosphinidene clusters

Article abstract of DOI:10.1016/S0022-328X(00)00033-4

A new family of phosphorus functionalized, pentanuclear ruthenium clusters Ru₅(CO)₁₅(μ₄-PR) [R = NⁱPr₂, NCy₂, F, OMe, OEt, OⁱPr, O^-] has been synthesized and representative compounds structurally characterized. The reaction of Ru₄(CO)₁₃(μ₃-PNR₂) (1) (R = Cy, ⁱPr) with Ru₃(CO)₁₂ in refluxing heptane yields H₂Ru₃(CO)₉(μ₃-PNR₂) (2) and Ru₅(CO)₁₅(μ₄-PNR₂) (3). An alternative high-yield synthesis for 3 is the reaction of 1 with Ru(CO)₅ in refluxing hexane. Treatment of 3 with HBF₄·Et₂O produces Ru₅(CO)₁₅(μ₄-PF) (4) in high yield. In contrast, refluxing 3 with HBF₄·H₂O in CH₂Cl₂ yields 4 and [R₂NH₂][Ru₅(CO)₁₅(μ ₄-PO)] (5), a cluster containing a μ₄-phosphorus monoxide (PO) ligand. The reaction of 4 with alcohols affords the series of alkoxy phosphinidene cluster complexes Ru₅(CO)₁₅(μ₄-POR′) (6) (R′ = Me, Et, ⁱPR). The structures of 2a (R = NCy₂), 3a (R = NCy₂), 4 (R = F), and the phosphorus monoxide cluster [H₂NCy₂][Ru₅(CO)₁₅(μ ₄-PO)] (5a and 6a) (R′ = Me) have been determined by X-ray diffraction studies.