CRYSTAL AND MOLECULAR-STRUCTURE OF MONOMERIC YTTRIUM(III) DIPIVALYLMETHANATE - ARRANGEMENT OF ADSORBED LAYERS

Crystal structure of monomeric yttrium(III) dipivalylmethanate, YO6C33 H57, has been studied by X-ray diffraction. Crystal data: a = 17.868(3 ), b = 9.977(2), c = 10.633(2) Angstrom, V = 1895.7 Angstrom(3), space group Pmn2(1), Z = 2, d(calc) = 1.116; d(exp) = 1.119 g/cm(3). The co mpound has a molecular structure and consists of monomeric molecules w ith a proper symmetry plane m. In the metallocycle lying in this plane , Y-O interatomic distances and O-Y-O bond angles markedly differ from the similar distances and angles in the other two planes. The average Y-O, O-C, and C-C distances are 2.22, 1.25, and 1.46 Angstrom, respec tively. As a result of comparative crystal-chemical analysis carried o ut for related compounds, the coordination polyhedra around the yttriu m atoms were found to be trigonal prisms formed by sir oxygen atoms of three bidentate ligands. Layers similar to 1 mu m thick were obtained by vapor condensation of the complex on different supports; the layer s were investigated by XRD. Irrespective of the type of support, the l ayers are oriented polycrystalline films with [001] texture axes. Arra ngement of the adsorbed molecules of the complex is analyzed. The laye rs are self-organized into close-packed structures with C(CH3)(3) grou ps oriented toward supports.