Reactions of 1,2,3-triphenyl-1,2,3-triphosphaindan with activated triosmium carbonyl clusters: characterization and crystal structure of the products

Abstract

Reaction of 1,2,3-triphenyl-1,2,3-triphosphaindan (I) with [Os₃(CO)₁₁(NCMe)] at room temperature afforded two clusters: mono-substituted trinuclear [Os₃(CO)₁₁{1-C₆H₄(PPh)₃}] 1 and bridged bis-trinuclear [{Os₃(CO)₁₁}₂{μ-1,3-η²-C₆H₄(PPh)₃}] 2, which can also be prepared by further reaction of 1 with an equimolar amount of [Os₃(CO)₁₁(NCMe)]. The reaction at 100 °C gave, apart from cluster 2, a di-substituted bridged cluster, [Os₃(CO)₁₀{μ-1,3-η²-C₆H₄(PPh)₃}] 3, and that at 140 °C formed a linked pentanuclear cluster, [Os₂(CO)₆{μ₃-η³-PPhC₆H₄(PPh)₂}Os₃(CO)₁₁] 4 and a trinuclear cluster with only two M–M bonds, [Os₃(CO)₉{μ₃-η³-PPhC₆H₄(PPh)₂}] 5 together with 3. Similarly [Os₃(CO)₁₀(NCMe)₂] reacted with I at room temperature to afford 3 in good yields. The conversion of cluster 1 into 3 can be achieved through pyrolysis of a solution of 1. Cluster 4 exhibits stereochemical non-rigidity in the solution state and exists as two isomers at low temperature. All the new compounds were characterized by spectroscopic and analytical techniques and their structures established by X-ray crystallography.