Ligand substitution in the halo-bridged diruthenium compound [Ru(CO)3Cl2]2 by 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Synthesis, spectral properties, and X-ray diffraction structures of cis(CO), trans(Cl)-RuCl2(CO)2 (bpcd) and cis(CO)-RuCl[C(O)Et](CO)2(bpcd)

The reaction between 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and the chlorobridged diruthenium complex Ru(CO)₃Cl₂]₂ (1) proceeds readily at room temperature in CH₂Cl₂ to give the new ruthenium compounds cis(CO),trans(Cl)-RuCl₂(CO)₂(bpcd) (2) and cis(CO)-RuClC(O)Et](CO)₂(bpcd) (3) as the major and minor products, respectively. Compound 2 was isolated and fully characterized in solution, and the molecular structure was established by X-ray diffraction analysis. cis(CO),trans(Cl)-RuCl₂(CO)₂(bpcd) crystallizes in the triclinic space P-1, a = 9.931(5) Å, b = 12.093(7) Å, c = 13.529(7) Å, α = 72.886(9)°, β = 74.739(9)°, γ = 76.851(9)°, V = 1478.2(1) ų, Z = 2, and d _calc = 1.556 mg/m³; R = 0.0841, R _w = 0.1880 for 4137 reflections with I > 2σ(I). The chlorine atoms in 2 adopt a trans geometry at the octahedral ruthenium center, with the two CO groups exhibiting a cis orientation and trans to the bpcd ligand. cis(CO)–RuClC(O)Et](CO)₂(bpcd) crystallizes as two independent molecules in the unit cell in the triclinic space P-1, a = 9.941(2) Å, b = 14.867(2) Å, c = 22.414(3) Å, α = 80.257(3)°, β = 84.796(2)°, γ = 75.207(3)°, V = 3152.6(8) ų, Z = 4, and d _calc = 1.504 mg/m³; R = 0.0428, R _w = 0.0962 for 8242 reflections with I > 2σ(I). The two CO groups are situated cis to each and are opposite to chlorine and phosphine moieties. The production of the minor propionyl compound 3 is discussed with respect to the trace amount of EtOH that is present in the CHCl₃ solvent that is used in the preparation of Ru(CO)₃Cl₂]₂.