Reaction of BX2−BX2 (X = H or OH) with M(PH3)2 (M = Pd or Pt). A Theoretical Study of the Characteristic Features

Abstract

The insertion of M(PH3)2 (M = Pd or Pt) into BX2−BX2 (X = H or OH) was theoretically investigated with the ab initio MO/MP4SDQ, SD-CI, and coupled cluster with double substitutions (CCD) methods. The MP4SDQ method provides an activation energy (Ea) and an exothermicity (Eexo) similar to those of the SD-CI and CCD methods (the MP4SDQ values are given here). This reaction proceeds with a moderate Ea of ∼15 kcal/mol and a considerable Eexo of ∼20 kcal/mol for X = OH and M = Pt and a higher Ea of 20 kcal/mol and a higher Eexo of 33 kcal/mol for X = H and M = Pt. It should be noted that the B−B bond, as well as the Si−Si bond, undergoes the insertion reaction of Pt(PH3)2 much more easily than does the C−C bond. However, the insertion of Pd(PH3)2 into B(OH)2−B(OH)2 is difficult, unlike the insertion into the Si−Si bond. The Pt−BH2 and Pt−B(OH)2 bond energies were estimated to be ∼60 kcal/mol, being similar to the Pt−SiH3 bond energy and much greater than the Pt−CH3 bond energy, while the Pd−B(OH)2 bond energy (...