Synthesis of Neutral and Anionic Uranyl Aryloxide Complexes from Uranyl Amide Precursors: X-ray Crystal Structures of UO2(O-2,6-i-Pr2C6H3)2(py)3 and [Na(THF)3]2[UO2(O-2,6-Me2C6H3)4

Abstract

Reaction of anhydrous UO{sub 2}Cl{sub 2} with 2 equiv of KN(SiMe{sub 3})2 in THF leads to formation of the neutral bis(amido) complex UO{sub 2}[N(SiMe{sub 3})2]2 (1), whereas the use of 2, 3, or 4 equiv of NaN(SiMe{sub 3})2 in an analogous reaction produces the tetrakis (amido) salt [Na(THF){sub 2}]2[UO{sub 2}[N(SiMe{sub 3})2]4] (2). Alcoholysis of 1 with 2 equiv of HO-2,6-i-Pr{sub 2}C{sub 6}H{sub 3} in the presence of pyridine gives the bis(aryloxide) complex UO{sub 2}(O-2,6-i-Pr{sub 2}C{sub 6}H{sub 3})2(py){sub 3} (3) (py=C{sub 5}H{sub 5}N), whereas alcoholysis of 2 with 4 equiv of HO-2,6-Me{sub 2}C{sub 6}H{sub 3} in THF produces the tetrakis (aryloxide)salt [Na(THF){sub 3}]2[UO{sub 2}(O-2,6-Me{sub 2}C{sub 6}H{sub 3})4] (4) The molecular structures of 3 and 4 have been determined by means of single-crystal X-ray diffraction studies. Compound 3 exhibits pentagonal bipyramidal geometry, with the uranyl oxygen atoms occupying the axial positions and the aryloxide atoms and 2.197 (9) {Angstrom} for the aryloxide ligands, while U-N distances to the pyridine ligands average 2.616 (7) {Angstrom}. Compound 4 is comprised of a uranium metal center coordinated in a pseudo-octahedral fashion by six oxygen atoms, with two sodium cations each coordinated to one uranyl oxygen atom and one oxygen atom of an aryloxide ligand. U-Omore » bond distances to the uranyl oxygens average 1.814(5) {Angstrom}, while distances to the aryloxide ligands average 2.204(8) {Angstrom} for the two aryloxide ligands not involved in coordination to the sodium cations and 2.288(5) {Angstrom} for the aryloxide ligands forming U-O-Na interactions.« less