Electronic structure and bonding energetics of a complex undergoing intramolecular disproportionation: ab initio two-configuration SCF and CI investigation on O3ReReCl2(H2PCH2PH2)2

Ab initio calculations on O3ReReCl2(H2PCH2PH2)2 were performed to determine whether the ReCl2(dmpm)2 fragment is a sigma donor toward the trioxorhenium or if a different bonding mechanism is in effect. Results revealed that the pentagonal pyramid structure adopted by the ReCl2(dmpm) moiety leads to a charge transfer toward a 5d(sub z super 2)/6s hybrid orbital of the trioxorhenium orbital. As a consequence, the polarized metal-metal bond may be considered as a sigma donation from the trioxorhenium fragment to the ReCl2(dmpm)2 unit.