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

摘要

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) Å, V=1895.7 Å3, 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 Å, 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)3groups oriented