Metal-metal multiple bonds with “half-bond” components in paramagnetic organometallics of f-block metals: Cyclopentadienyluranium carbonyls as molecular relatives of diuranium

The low-energy Cp2U2(CO)n (n = 2, 3, 4) structures have entirely or almost entirely bridging η2-μ-CO groups and do not exhibit CO coupling. Spin states from singlet to quintet are observed as well as a variety of UU bonding modes including formal multiple bonds containing one-electron half-bonds in paramagnetic structures.107