CO substitution and diphosphine ligand chelation in the reaction between 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and Re( 2(CO) 8( μ-H)( μ- η1, η2-C  CPh)

Abstract

The reaction between the redox-active diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and the dirhenium compound Re 2(CO) 8( μ-H)( μ- η 1, η 2-C  CPh) in CH 2Cl 2 at room temperature proceeds by CO loss to give the dirhenium complex Re 2(CO) 7(bpcd)( μ-H)( η 1-C  CPh) ( 1). This new complex was characterized in solution by IR and NMR ( 1H and 31P) spectroscopy and in the solid state by X-ray diffraction analysis. Re 2(CO) 7(bpcd)( μ-H)( η 1-C  CPh) crystallizes in the triclinic space group P 1: a = 11.3900(9), b = 13.3921(9), c = 14.275(1) A ̊ , α = 84.280(6)°, β = 89.678(6)° γ = 69.240(6)°, V = 2024.9(3) A ̊ 3, Z = 2, d calc = 1.862 g cm −3 R = 0.0221, R w = 0.243 for 4066 observed reflections. The bpcd ligand in 1 adopts a chelating mode with a linear phenylacetylide ligand being located on the adjacent rhenium center cis to the bpcd ligand. This complex represents the first structurally characterized example of a hydrido-bridged dirhenium complex possessing both a linear acetylide ligand and a chelating diphosphine ligand.