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-ME(2)C(6)H(3))(4)]

Reaction of anhydrous UO2Cl2 With 2 equiv of KN(SiMe(3))2 in THF leads to formation of the neutral bis(amido) complex UO2[N(SiMe(3))(2)](2)( THF)(2) (1), whereas the use of 2, 3, or 4 equiv of NaN(SiMe(3))(2) in an analogous reaction produces the tetrakis(amido) salt [Na(THF)(2)]( 2){UO2[N(SiMe(3))(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 w ith 4 equiv of HO-2,6-Me(2)C(6)H(3) in THF produces the tetrakis(arylo xide) salt [Na(THF)(3)](2)[UO2(O-2,6-Me(2)C(6)H(3))(4)] (4) The molecu lar structures of 3 and 4 have been determined by means of single-crys tal X-ray diffraction studies. Compound 3 exhibits pentagonal bipyrami dal geometry, with the uranyl oxygen atoms occupying the axial positio ns and the aryloxide and pyridine ligands lying in the equatorial plan e. U-O bond lengths average 1.789(5) Angstrom for the uranyl oxygen at oms and 2.197(9) Angstrom for the aryloxide ligands, while U-N distanc es to the pyridine ligands average 2.616(7) Angstrom. Compound 4 is co mprised of a uranium metal center coordinated in a pseudo-octahedral f ashion by six oxygen atoms, with two sodium cations each coordinated t o one uranyl oxygen atom and one oxygen atom of an aryloxide ligand. U -O bond distances to the uranyl oxygens average 1.814(5) Angstrom, whi le distances to the aryloxide ligands average 2,204(8) Angstrom for th e two aryloxide ligands not involved in coordination to the sodium cat ions and 2.288(5) Angstrom for the aryloxide ligands forming U-O-Na in teractions. Crystal data for 3 (at -70 degrees C): Monoclinic, space g roup P2(1), a = 11.582(2) Angstrom, b = 13.975(3) Angstrom, c = 12.322 (2) Angstrom, beta = 103.67(3)degrees, V = 1937.9(6) Angstrom(3), Z = 2, D-calc =1.477 g cm(-3). Crystal data for 4 (at -70 degrees C): Tric linic, space group P ($) over bar 1, alpha = 12.830(2),Angstrom, b = 1 3.574(2) Angstrom, c = 18.382(3)Angstrom, alpha = 93.401(1)degrees, be ta = 98.12(1)degrees, gamma = 106.21(1)degrees, V= 3027(2) Angstrom(3) , Z= 2, D-calc = 1.35 g cm-3.