Synthesis of Neutral and Anionic Uranyl Aryloxide Complexes from UranylAmide 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]

Article abstract of DOI:10.1021/ic00120a011

Reaction of anhydrous UO2Cl2 with 2 equiv of KN(SiMe3)2 in THF leads toformation of the neutral bis(amido) complex UO2[N(SiMe3)2]2(THF)2 (1), whereas the use of 2, 3, or 4 equiv of NaN(SiMe3)2 in an analogous reaction produces the tetrakis(amido) salt [Na(THF)2]2{UO2[N(SiMe3)2]4} (2). Alcoholysis of 1 with 2 equiv of HO-2,6-i-Pr2C6H3 in the presence of pyridine gives the bis(aryloxide) complex UO2(O-2,6-i-Pr2C6H3)2(py)3 (3) (py = C5H5N), whereas alcoholysis of 2 with 4 equiv of HO-2,6-Me2C6H3 in THF produces the tetrakis(aryloxide) salt [Na(THF)3]2[UO2(O-2,6-Me2C6H3)4] (4). The molecular structures of 3 and 4 have been determined by meansof single-crystal X-ray diffraction studies. Compound 3 exhibits pentagonal bipyramidal geometry, with the uranyl oxygen atoms occupying the axial positions and the aryloxide and pyridine ligands lying in the equatorial plane. U-O bond lengths average 1.789(5) ? for the uranyl oxygen atoms and 2.197(9) ?. for the aryloxide ligands, while U-N distances to the pyridine ligands average 2.616(7) ?. 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-O bond distances to the uranyl oxygens average 1.814(5) ?, while distances to the aryloxide ligands average 2.204(8) ? for the two aryloxide ligands not involved in coordination to the sodium cations and 2.288(5) ?for the aryloxide ligands forming U-O-Na interactions. Crystal data for3 (at -70°C): Monoclinic, space group P21, a = 11.582(2) ?, b = 13.975(3) ?, c = 12.322(2) ?, β = 103.67(3)°, V = 1937.9(6) ?**3, Z = 2, Dcalc = 1.477 g cm**-3. Crystal data for 4 (at -70°C): Triclinic, space group P1-, a = 12.830(2) ?, b = 13.574(2) ?, c = 18.382(3) ?, α = 93.40(1)°, β= 98.12(1)°, γ = 106.21(1)°, V = 3027(2) ?**3, Z = 2, Dcalc = 1.35 g cm**-3.