Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (03): 745-750.doi: 10.3866/PKU.WHXB20100326

• QUANTUM CHEMISTRY AND COMPUTATION CHEMISTRY • Previous Articles     Next Articles

Mechanism of the Model Reaction between CpRu(PH3)2SH and HNCS

ZHAO Yi, DONG Dong-Dong, BI Si-Wei   

  1. School of Chemical Engineering, Shandong University of Technology, Zibo 255049, Shandong Province, P. R. China; School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, Shandong Province, P. R. China
  • Received:2009-11-02 Revised:2009-12-31 Published:2010-03-03
  • Contact: BI Si-Wei E-mail:siweibi@126.com

Abstract:

Reaction mechanisms for the reaction between CpRu(PPh3)2SH (Cp=cyclopentadienyl) and RNCS (R = Ph, 1-naphthyl) were investigated by density functional theory using the model reaction between CpRu(PH3)2SH and HNCS. Two possible mechanisms are proposed. First, one PH3 ligand dissociates from CpRu(PH3)2SH to give a 16e intermediate upon which hydrogen migration occurs giving the product. Second, hydrogen migration occurs before the dissociation of a PH3 ligand, giving the product. Based on our calculations, the second mechanism is more favorable. From the potential energy curves for the two possible mechanisms, the rate-determining step for the reaction is hydrogen migration. The overall reaction activation energy for the first mechanism is markedly higher than that for the second mechanism. Therefore, we predict that this reaction tends to experience hydrogen migration before the dissociation of PPh3 from the metal center. In the second mechanism, the product is eventually obtained because of an increase in entropy but the product is thermally less stable than the intermediate that directly connects to the product.

Key words: Density functional theory, PH3 dissociation, Hydrogen migration, HNCS, Reaction mechanism

MSC2000: 

  • O641