title: Synthesis and Characterization of New Alkoxotitanates of Yttrium, Barium, and Copper: Single Crystal X-ray Diffraction Structures of Cl(2)Y{Ti(2)(OPr(i))(9)}, {Ti(OPr(i))(5)}Ba{Ti(2)(OPr(i))(9)}, and ClCu{Ti(2)(OPr(i))(9)}
abstract: The synthesis and characterization of new mixed-metal alkoxides of titanium with yttrium, barium, and copper, achieved via salt elimination and acid-base reactions, is described. The metathesis reactions of KTi(2)(OPr(i))(9) with anhydrous YCl(3) (1:1 and 2:1) and CuCl(2) (1:1) afford chloro-functionalized heterobimetallic alkoxides Cl(2)Y{Ti(2)(OPr(i))(9)} (1), ClY{Ti(2)(OPr(i))(9)}(2) (2), and ClCu{Ti(2)(OPr(i))(9)} (3), respectively, in high yields. The barium-titanium derivatives [Ba{Ti(2)(OPr(i))(10)}](2) (4), {Ti(2)(OPr(i))(9)}Ba{Ti(OPr(i))(5)} (5), and Ba{Ti(2)(OPr(i))(9)}(2) (6) result from the reaction between [Ba(OPr(i))(2)](n) and Ti(OPr(i))(4) in 1:2, 1:3, and 1:4 molar ratios, respectively. All the new derivatives (1-6) have been characterized by elemental analyses, variable-temperature (1)H and (13)C NMR, infrared spectroscopy, cryoscopy, and single crystal X-ray diffraction studies for 1, 3, and 5. The crystallographic study of 1 reveals a mononuclear species where the yttrium atom, coordinated by four alkoxide oxygen atoms of the {Ti(2)(OPr(i))(9)}(-) unit and two chloride ligands, is in a pseudo-octahedral arrangement. The NMR ((1)H and (13)C) and cryoscopic data for 1 indicate that the bioctahedral {Ti(2)(OPr(i))(9)} framework, as observed in the solid state structure, is retained in solution also. The X-ray structure of copper derivative 3 exhibits a triangular heterometallic core CuTi(2)(&mgr;(2)-OPr(i))(3)(&mgr;(3)-OPr(i))(2) with chloride as a terminal ligand on copper. Each titanium bears two terminal OPr(i) groups and displays a distorted octahedral geometry whereas copper has a pseudotrigonal bipyramidal environment. The high-temperature NMR studies for the paramagnetic 3 are in agreement with Curie law behavior; the isotropic shifts indicate that the OPr(i) groups bound directly to the Cu(II) center experience a greater paramagnetic influence in comparison to OPr(i) groups attached to titanium only. Barium titanates reveal an interesting observation of structural and stoichiometry (Ba/Ti) change. The dimeric compound 4 (Ba/Ti, 1:2) reacts with 1 mol of Ti(OPr(i))(4) to offer mononuclear 5 with a Ba/Ti stoichiometry of 1:3; on further addition of 1 mol of Ti(OPr(i))(4), 5 is converted to 6 (Ba/Ti, 1:4). X-ray crystallography performed on 5 shows the molecular structure to be formed by the coordination of monoanionic {Ti(OPr(i))(5)}(-) and {Ti(2)(OPr(i))(9)}(-) units to Ba(2+) in bi- and tetradentate fashion, respectively. The coordination figure of the central atom, barium, corresponds to a trigonal prism distorted toward an octahedron. Crystal data for 1: monoclinic space group Cc, a = 21.618(14) Å, b = 9.878(5) Å, c = 19.949(13) Å, beta = 109.51(4) degrees, V = 4015(4) Å(3), Z = 4. Crystal data for 3: triclinic space group P&onemacr;, a = 10.085(2) Å, b = 10.210(2) Å, c = 21.551(4) Å, alpha = 84.40(3) degrees, beta = 84.03(3) degrees, gamma = 60.86(3) degrees, V = 1924.9(6) Å(3), Z = 2. Crystal data for 5: triclinic space group P&onemacr;, a = 11.850(2)Å, b = 13.888(3) Å, c = 18.716(4) Å, alpha = 86.08(3) degrees, beta = 89.15(3) degrees, gamma = 83.36(3) degrees, V = 3052.3(11) Å(3), Z = 4.
authors.affiliation: Institute of Inorganic Chemistry, University of Saarland, D-66041 Saarbrücken, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Veith
authors.forename: Sanjay
authors.initials: S
authors.lastname: Mathur
authors.forename: Volker
authors.initials: V
authors.lastname: Huch