[UO2Cl2(phen)2], a Simple Uranium(VI) Compound with a Significantly Bent Uranyl Unit (phen = 1,10-phenanthroline)

A simple synthesis based on UO2Cl2·n(H2O) and 1,10-phenanthroline (phen) resulted in the formation of a new uranyl(VI) complex [UO2Cl2(phen)2] (1), revealing a unique snub disphenoid coordination geometry around the uranium centre with significant bending of the robust linear arrangement of the uranyl (O─U─O) unit. Quantum chemical calculations on complex 1 indicated that the weak but distinct interactions between the uranyl oxygens and the adjacent hydrogens of phen molecules play an important role in forming the snub disphenoid geometry that fits to the crystal structure of 1, resulting in the bending the uranyl unit. The uranyl oxygens in 1 are highly activated as compared with those in the linear uranyl unit and, hence, complex 1 is anticipated to be one of the rare uranyl(VI) complexes with readily reactive uranyl oxygens.