Narrow Results

The synthesis and reactivity of uranium complexes supported by a bis(aryloxide) cyclam ligand are surveyed. The hemilability of this ligand proved to be particularly appropriate to stabilize highly reactive uranium(III) and uranium(IV) complexes that were able to activate different unsaturated molecules. Of note are the reductive cleavage of azobenzene with the unprecedented formation of a trans-bis(imido) uranium(VI) complex and its reaction with carbon dioxide to generate a trans-oxido-imido uranium(VI) complex and phenyl isocyanate. The formation of a trans-dioxido uranium(VI) (uranyl) complex was also observed in the reaction of uranium(IV) complexes with sodium nitrite. Quantum chemical computations and solution ¹⁵N NMR spectroscopy were employed to evaluate bond covalency in the three {E=U=E}²⁺ complexes (E = O, NR).

The electronic states of silver halides and sodium halides are calculated by the DV-Xα cluster method to get more microscopic evidence for the p – d hybridization and the covalency in noble metal halides. The calculations are carried out for the A₁₃B₁₄ (A = Ag or Na ion, B = halogen ion) clusters. It is found that both components of anti-bonding and bonding exist in the diagram of overlap population (DOP) for AgX (X = halogen) and these two components are made up of the 4d band of Ag ion and the p band of halogen ion, which form the p – d hybridization. The covalency of noble metal halides is in the border between that of the fourfold coordinated compounds and that of the sixfold coordinated compounds. These calculation results on the covalency support the tendency of the Phillips's ionicity.