82544-74-9Relevant academic research and scientific papers
Selective diphosphine ligand chelation and π bond coordination in CoRu(CO)7(μ-PPh2): Kinetics and X-ray structure of CoRu(CO)4(μ-bma)(μ-PPh2)
Bott,Yang,Wang,Richmond
, p. 6051 - 6055 (2000)
Thermolysis of CoRu(CO)7(μ-PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands 2,3-bis(diphenylphosphino)maleic anhydride (bma) and 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) furnishes the new mixed-metal complexes CoRu(CO)4(μ-P-P)(μ-PPh2) [where P-P = bma (3a), bpcd (3b)] along with trace amounts of the known complex CoRu(CO)6(PPh3)(μ-PPh2) (4). The requisite pentacarbonyl intermediates CoRu(CO)5(μ-P-P)(μ-PPh2)[where P-P = bma (2a), bpcd (2b)] have been prepared by separate routes (mild thermolysis and Me3NO activation) and studied for their conversion to CoRu(CO)4(μ-P-P)(μ-PPh2). The penta- and tetracarbonyl complexes have been isolated and fully characterized in solution by IR and NMR spectroscopy. The kinetics for the conversion of 2a → 3a and of 2b → 3b were measured by IR spectroscopy in chlorobenzene solvent. On the basis of the first-order rate constants, CO inhibition, and the activation parameters (2a → 3a, ΔH? = 29.2 ± 1.4 kcal mol-1 and ΔS? = 8.2 ± 3.8 eu; 2b → 3b, ΔH? = 27.7 ± 0.6 kcal mol-1 and ΔS? = 1.4 ± 1.6 eu), a mechanism involving dissociative CO loss as the rate-limiting step is proposed. The solid-state structure of CoRu(CO)4(μ-bma)(μ-PPh2) (3a), as determined by X-ray crystallography, reveals that the two PPh2 groups are bound to the ruthenium center while the maleic anhydride π bond is coordinated to the cobalt atom.
