Covalences of Be in CpBeX (X=H, Cl, Br, CH3, C CH, center dot center dot center dot) and Cp(2)Be

In this paper, the electronic structures of CpBeH and Cp(2)Be were studied with the methods of DV-X alpha SCC and natural bond orbitals (NBOs), and then the covalences of Be in CpBeX (X=H, Cl, Br, CH3, C=CH, ...) and Cp(2)Be were discussed on the basis of the new definition of covalence proposed by one of the authors, Through the analysis of the occupancies and components of NBOs, it is found that the cyclopentadienyl ring in CpBeX and one of the rings in Cp(2)Be are pi-bonded, and the other ring (the slipped ring) in Cp(2)Be is bonded by the Be(1)-C(7) sigma bond which has slightly delocalized to C(8), C(9), C(10), C(11). Thus the covalences of Be in all these compounds are 6.