SYNTHETIC, SPECTROSCOPIC, AND X-RAY CRYSTALLOGRAPHIC STUDIES ON THE URANYL(VI) COMPLEXES OF THE BETA-DIKETOPHENOL LIGANDS 1-(2-HYDROXYPHENYL)-1,3-BUTANEDIONE AND 1-(2-HYDROXYPHENYL)-3-PHENYL-1,3-PROPANEDIONE

The preparation of the mononuclear complexes [UO2(HL1)(2)(MeOH)] and [ UO2(HL2)(2)(EtOH)], the heterobinuclear complexes [UO2Mn(L-1)(2)(EtOH) ]. 1.5H(2)O and [UO2Mn(L-2)(2)(EtOH)]. 2H(2)O, and the oxo-ligand addu cts [UO2(HL1)(2)(Ph3AsO)]. 2H(2)O, [UO2(HL2)(2)(Ph3PO)] and [UO2(HL2)( 2)(Ph3AsO)] (H2L1 = 1-(2-hydroxyphenyl)-3-butanedione and H2L2 = 1-(2- hydroxyphenyl)-3-phenyl-1,3-propanedione) is described. The complexes have been characterized by a variety of physicochemical techniques and the crystal structures of [UO2(HL1)(2)(EtOH)] and [UO2(HL2)(2)(EtOH)] . EtOH determined. Crystals of the former an triclinic, space group P1 , a = 8.076 (1), b = 8.131 (1), c = 10.161 (1) Angstrom, alpha = 108.4 9 (1), beta = 112.26 (1), gamma = 89.89 (1)degrees and Z = 1. The latt er is also triclinic, space group P (1) over bar, a = 12.184 (3), b = 15.578 (5), c = 9.035 (2) Angstrom, alpha = 91.05 (2), beta = 103.20 ( 2), gamma = 73.21 (2)degrees and Z = 2. Both complexes contain seven-c oordinate uranium(VI) in a pentagonal bipyramidal geometry in which th e two bidentate beta-diketonato ligands and the coordinated ethanol ma ke up the equatorial pentagonal plane. For the complex [UO2(HL1)(2)(Et OH)] the HL1 ligands are in a trans arrangement with respect to one an other, whereas for the [UO2(HL2)(2)(EtOH)]. EtOH complex the HL2 ligan ds adopt a cis arrangement. However, in solution variable temperature H-1 NMR spectra indicate that the cis and trans isomers are in equilib rium for both complexes. (C) 1998 Elsevier Science S.A. All rights res erved.