Selective Diphosphine Ligand Chelation and Bond Coordination in CoRu(CO)7(
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- 作者：Simon G. Bott ; Kaiyuan Yang ; Jian Cheng Wang ; and Michael G. Richmond
- 刊名：Inorganic Chemistry
- 出版年：2000
- 出版时间：December 25, 2000
- 年：2000
- 卷：39
- 期：26
- 页码：6051 - 6055
- 全文大小：78K
- 年卷期：v.39,no.26(December 25, 2000)
- ISSN：1520-510X
文摘
Thermolysis of CoRu(CO)7(
-PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands2,3-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(-P-P)(-PPh2) [where P-P = bma (3a), bpcd (3b)]along with trace amounts of the known complex CoRu(CO)6(PPh3)(-PPh2) (4). The requisite pentacarbonylintermediates CoRu(CO)5(-P-P)(-PPh2) [where P-P = bma (2a), bpcd (2b)] have been prepared by separateroutes (mild thermolysis and Me3NO activation) and studied for their conversion to CoRu(CO)4(-P-P)(-PPh2).The penta- and tetracarbonyl complexes have been isolated and fully characterized in solution by IR and NMRspectroscopy. The kinetics for the conversion of 2a 
3a and of 2b 3b were measured by IR spectroscopy inchlorobenzene solvent. On the basis of the first-order rate constants, CO inhibition, and the activation parameters(2a 3a, 
H
= 29.2 ± 1.4 kcal mol-1 and S = 8.2 ± 3.8 eu; 2b 3b, H = 27.7 ± 0.6 kcal mol-1 andS = 1.4 ± 1.6 eu), a mechanism involving dissociative CO loss as the rate-limiting step is proposed. Thesolid-state structure of CoRu(CO)4(-bma)(-PPh2) (3a), as determined by X-ray crystallography, reveals thatthe two PPh2 groups are bound to the ruthenium center while the maleic anhydride 
bond is coordinated to thecobalt atom.
-PPh2) (1) in refluxing 1,2-dichloroethane in the presence of the diphosphine ligands2,3-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(-P-P)(-PPh2) [where P-P = bma (3a), bpcd (3b)]along with trace amounts of the known complex CoRu(CO)6(PPh3)(-PPh2) (4). The requisite pentacarbonylintermediates CoRu(CO)5(-P-P)(-PPh2) [where P-P = bma (2a), bpcd (2b)] have been prepared by separateroutes (mild thermolysis and Me3NO activation) and studied for their conversion to CoRu(CO)4(-P-P)(-PPh2).The penta- and tetracarbonyl complexes have been isolated and fully characterized in solution by IR and NMRspectroscopy. The kinetics for the conversion of 2a 3a and of 2b 3b were measured by IR spectroscopy inchlorobenzene solvent. On the basis of the first-order rate constants, CO inhibition, and the activation parameters(2a 3a, H = 29.2 ± 1.4 kcal mol-1 and S = 8.2 ± 3.8 eu; 2b 3b, H = 27.7 ± 0.6 kcal mol-1 andS = 1.4 ± 1.6 eu), a mechanism involving dissociative CO loss as the rate-limiting step is proposed. Thesolid-state structure of CoRu(CO)4(-bma)(-PPh2) (3a), as determined by X-ray crystallography, reveals thatthe two PPh2 groups are bound to the ruthenium center while the maleic anhydride bond is coordinated to thecobalt atom.