PtIPtI bond energy in dinuclear PtI complexes. A theoretical study

The metal-metal bond of [Pt2Cl2(CO)4] and [Pt2Cl4(CO)2]2− is investigated with the ab initio MO/MP2 method. The PtIPtI bond energy (ΔE) is calculated to be 39–58 kcal/mol, being much larger than those for Pt0Pt0 and PtIIPtII reported previously. In [Pt2Cl4(CO)2]2−, a negative ΔE is obtained without considering a countercation. The effect of the cation can be simulated by a positive point charge, and the point-charge dependence of ΔE can be derived by considering the electrostatic interactions by perturbation theory. Thus, it is concluded that an electrostatic potential due to countercations must be taken into account to estimate correctly the PtPt bond energy.