Multiple Bonds between Main-Group Elements and Transition Metals. 123. Re-C Bond Homolysis in Alkyl- and Arylrhenium Trioxides: A Qualitative MO Interpretation

Abstract

In many cases, the decomposition of methyltrioxorhenium (CH 3 RePO 3 , MTO) and other alkyl and aryl derivatives appears occur through the homolytic cleavage of the Re-C bond. Under these circumstances, the already deficient metal [Re(VII)] gives up half of the electron pair donated by the alkyl anion, and the ensuing Re(VI) species has a finite lifetime as a free radical. The problem is tackled from the viewpoint of qualitative MO theory. From a detailed examination of all the orbital interactions between metal and the coordinated atoms in pseudotetrahedral MTO, it is established that the metal receives up to nine electron pairs from the oxygen atoms and CH 3 . Accordingly, the complex is better formulated as an 18- rather than the widely accepted 14-electron species