Actinide structural studies. 16. Dinitratodioxobis(pyridine)uranium(VI)

Bis(1,3-dimethyl-1,3-diazinan-2-one)dinitratodioxidouranium(VI)

The title compound, [U(NO₃)₂O₂(C₆H₁₂N₂O)₂], exhibits a hexa­gonal–bipyramidal geometry around the U^VI ion, which is situated on an inversion centre and coordinated by two oxide ligands in the axial positions, and four O atoms from two bidentate NO₃⁻ and two O atoms from two 1,3-dimethyl-1,3-diazinan-2-one (DMPU) ligands in the equatorial plane. These ligands are located in trans positions. The –(CH₂)₃– moiety in the DMPU ligand is disordered over two positions in a 0.786 (11):0.214 (11) ratio.

A Structural and Theoretical Investigation of Equatorial cis and trans Uranyl Phosphinimine and Uranyl Phosphine Oxide Complexes UO2Cl2(Cy3PNH)2 and UO2Cl2(Cy3PO)2

Phosphinimine ligands (Cy3PNH) readily react with UO2Cl2(THF)3 (THF=tetrahydrofuran) to give UO2Cl2(Cy3PNH)2, which contains strong U-N interactions and exists as cis and trans isomers in the solid and solution state. Solution NMR experiments and computational analysis both support the trans form as the major isomer in solution, although the cis isomer becomes more stabilized with an increase in the dielectric constant of the solvent. Mayer bond orders, energy decomposition analysis, and examination of the molecular orbitals and total electron densities support a more covalent bonding interaction in the U-NHPCy3 bond compared with the analogous bond of the related U-OPCy3 compounds.

Easy access to stable pentavalent uranyl complexes

Reaction of UO2I2(THF)3 with 1 molar equivalent of KC5R5 (R = H, Me) in pyridine led to the uranyl(V) compound {[UO2(Py)5][KI2(Py)2]}(infinity), which is an infinite 1D polymer in its crystalline form; the UO2X(THF)n (X = I, OSO2CF3) complexes were obtained by reduction of their U(VI) parents with TlC5H5 or KC5R5 in THF.