(eta6-Biphenyl)tricarbonylchromium and mu-(eta6:eta6)-biphenyl-bis(tricarbonylchromium).

The title compounds, [Cr(C(12)H(10))(CO)(3)] and [Cr(2)(C(12)H(10))(CO)(6)], serve as a fundamental standard of comparison for other mono- and polysubstituted (eta(6)-biphenyl)tricarbonylchromium compounds. (eta(6)-Biphenyl)tricarbonylchromium has a typical piano-stool coordination about the Cr center, and the dihedral angle between the planes of the phenyl rings is 23.55 (5) degrees . The corresponding angle in mu-(eta(6):eta(6))-biphenyl-bis(tricarbonylchromium) is 0 degrees because the molecule occupies a crystallographic inversion center; the Cr atoms reside on opposite sides of the biphenyl ligand. Density functional theory and natural bonding orbital theory analyses were used to scrutinize the geometry of these and closely related compounds to explain important structural features.