Crystal and molecular structure of monomeric yttrium(III) dipivalylmethanate. Arrangement of adsorbed layers

Abstract

Crystal structure of monomeric yttrium(III) dipivalylmethanate, YO6C33H57, has been studied by X-ray diffraction. Crystal data: a=17.868(3), b=9.977(2), c=10.633(2) A, V=1895.7 A3, space group Pmn21, Z=2, dcalc=1.116, dexp=1.119 g/cm3. The compound has a molecular structure and consists of monomeric molecules with 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 A, respectively. As a result of comparative crystal-chemical analysis carried out for related compounds, the coordination polyhedra around the yttrium atoms were found to be trigonal prisms formed by six oxygen atoms of three bidentate ligands. Layers ∼1 μm thick were obtained by vapor condensation of the complex on different supports; the layers were investigated by XRD. Irrespective of the type of support, the layers are oriented polycrystalline films with [001] texture axes. Arrangement of the adsorbed molecules of the complex is analyzed. The layers are self-organized into close-packed structures with C(CH3)3 groups oriented toward supports.