Formation of new cluster derivatives of triphospholenevia ligand substitution and cleavage of P–P bond(s)

Abstract

At room temperature, triphospholene PhPPhPPhPCPhCPh (L) underwent mono- and di-substitution reactions with [Os₃(CO)₁₁(MeCN)] to afford the following derivatives: mono-substituted cluster [Os₃(CO)₁₁(2-PhPPhPPhPCPhCPh)] 1, di-substituted bridged cluster [Os₃(CO)₁₀(1,3-PhPPhPPhPCPhCPh)] 2, and linked cluster [{Os₃(CO)₁₁}₂(1,3-PhPPhPPhPCPhCPh)] 3. On the other hand, reactions with [Os₃(CO)₁₀(MeCN)₂] gave two isomeric compounds: 2 and [Os₃(CO)₁₀(1,3-PhPPhPPhPCPhCPh)] 4, differing in the orientation of the phenyl group attached to the central unco-ordinated phosphorus atom. At elevated temperatures similar reactions result in cleavage of one P–P bond of the ligand to afford an open cluster [Os₃(CO)₉(μ₃-η³-PhPPhPCPhCPhPPh)] 5, and cleavage of two P–P bonds to give [Os₃(CO)₉(μ₃-PPh)(μ₃-η²-PhPCPhCPhPPh)] 6, arising from the formation of the phosphinidene species. The clusters 1, 2 and 4 can be converted sequentially on heating into 5 and then 6.