CO substitution in Ru₃(CO)₁₂ by 2,3-bis(diphenylphosphino)-N-phenyl-maleimide (bppm). X-ray diffraction structure of Ru₂(CO)₆(bppm)

Abstract

The cluster Ru₃(CO)₁₂ reacts with the diphosphine ligand 2,3-bis(diphenylphosphino)-N-phenyl-maleimide (bppm) in toluene solution at 100^○C by fragmentation to give a 2:1 mixture of the donor–acceptor complex Ru₂(CO)₆(μ-bppm) and the phosphido-bridged species Ru₂(CO)₆ $[\mu {\text{ - }}{\text{(O)](}}\mu _{\text{2}} {\text{ - PPh}}_{\text{2}} )$, respectively. The new diruthenium compounds have been isolated by chromatography and characterized in solution by IR and NMR (¹H and ³¹P) spectroscopies, in addition to X-ray diffraction analysis in the case of Ru₂(CO)₆( μ₂ -bppm). Ru₂(CO)₆( μ₂ -bppm), which exists as two crystallographically independent molecules in the unit cell, crystallizes in the orthorhombic space group Pbca, a = 18.8441(9), b = 21.352(2), c = 36.510(2) Å, V = 14,690(1) ų, z = 16, D _calc = 1.649 g/cm³; R = 0.0356, and R _w = 0.0812 for 17732 observed reflections. The reactivity of the bis(diphenylphosphino)-N-phenyl-maleimide ligand with Ru₃(CO)₁₂ under thermolysis conditions is contrasted with the related diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd).