One-electron metal-metal bond stabilized in dinuclear metallocenes: theoretical prediction of DBe-LiCp (D = C5H5 or C5Me5).

Recently, stimulated by the unexpected synthesis and isolation of a bis-metallic sandwich compound Cp*ZnZnCp* (Cp* = eta(5)-C(5)Me(5)), many studies have focused on various dinuclear metallocenes involving a direct metal-metal (single or multiple) bond. However, we are not aware of any report on the metallocenes incorporating a "one-electron metal-metal bond". Herein, through the good steric and electronic stabilization effect of Cp and Cp*, we for the first time theoretically design a new type of sandwich-like compounds DBe-LiCp (D = Cp or Cp*) associated by an "unaided" one-electron metal-metal bond. Bonding characteristics of CpBe-LiCp were analyzed by natural bond orbital (NBO) theory. To shed more light on the stability of sandwich complexes, the dissociation energies (DBe-LiCp --> DBe + CpLi) and extrusion energies (DBe-LiCp --> DBeCp + Li) were calculated. Through calculation of thermodynamic standard entropies, we predict that these new compounds may be detected in the gaseous phase at appropriate experiment conditions.