A Deeper Look into Thiophene Coordination Prior to Oxidative Addition of the C−S Bond to Platinum(0): A Computational Study Using DFT and MO Methods

Abstract

The reaction of thiophene with a zerovalent platinum bisalkylphosphine fragment yields a highly stable thiaplatinacycle derived from cleavage of the C−S bond. Calculations on the [Pt(dmpe)] model system using Density Functional Theory are consistent with experimental results obtained with [Pt(dippe)] in that the reaction is exothermic overall and furthermore predict that the initial η2-coordination of thiophene through the C═C double bond is energetically more favorable than coordination through the sulfur atom (ΔG = 9.3 kcal/mol). There are three well-defined transition states along the pathway to the oxidative addition product from both of these coordination modes. Two of these lead to a higher energy η2-C,S-coordinated intermediate, while the third one leads to cleavage of the C−S bond from the η2-C,S complex. As the reaction was carried out in a polar solvent (THF), the effect of solvation was taken into account by using the polarizable continuum model. The thermodynamic preference for the initial coo...