Chemical structures from the analysis of domain-averaged Fermi holes. Nature of the Mn-Mn bond in bis(pentacarbonylmanganese)

Because of conflicting and contradictory classification based on traditional AIM characteristics, the nature of the Mn-Mn bond has been and still is the subject of continuing discussions. To overcome the existing inconsistencies in the interpretation of the nature of this bond, the bonding in Mn-2(CO)(10) has been analyzed and discussed in terms of new recently proposed methodology known as the analysis of domain-averaged Fermi holes. It has been shown that this analysis is able to reconcile the conflicting conclusions of earlier AIM-based studies with traditional anticipations based on simple electron counting rules. According to Fermi hole analysis, the Mn-Mn bond has the character of the more or less ordinary covalent single sigma, bond, but the analysis also brings clear evidence in favor of Mn . . . (CO) intramolecular interactions between the metal atom and the ligands bonded to the other metal atom. These interactions could be responsible for the observed decrease of electron density at the bond critical point detected in AIM studies.