Bonding modes in bis(benzene)beryllium(0): A density functional and Møller-Plesset computational investigation

[Display omitted] •Bis(benzene)beryllium(0) structures were investigated with density functional and Møller-Plesset methods.•The most stable structure is (1,2-η2-benzene)(1,2,3,4-η4-benzene)beryllium(0).•The bis(benzene)beryllium(0) structures are unlikely to interconvert or to be fluxional at room temperature. Density functional calculations at the B3LYP/6-311+G∗∗ and ωB97X-D/6-311+G∗∗ levels of theory and Møller-Plesset calculations at the MP2/6-311+G∗∗ level of theory predict that bis(benzene)beryllium(0) may adopt three different structures: syn- and anti-bis(1,2-η2-benzene)beryllium(0) and (1,2-η2-benzene)(1,2,3,4-η4-benzene)beryllium(0); the latter is the most stable structure. Significant charge transfer from the beryllium atom to the benzene rings is observed in all structures. Due to the relatively large energy differences between the three different structures, the molecules are unlikely to be fluxional at room temperature.