1,3,5-triamino-1,3,5-trideoxy-cis-inositol, a ligand with a remarkable versatility for metal ions. 10. Surface complexation of [Nb6O19](8-) with Ni-II: solvothermal synthesis and X-ray structural characterization of two novel heterometallic Ni-Nb-pol

摘要

Solvothermal reaction of NiCl2, Nb(OEt)(5) and 1,3,5-triamino-1,3,5-trideoxy-cis-inositoI (taci) in a 1:1:1 ratio under alkaline conditions (NaOH) resulted in the formation of two new Nb-Ni heteropolyoxometalate complexes. [Ni(taCi)(2)](2){trans[Nb6O19][Ni(taci)](2)).26H(2)O (1) and [Na(H2O)(6)](2) {cis-[H2Nb6O19][Ni(taci)](2)}.18H(2)O (2), were characterized by single crystal X-ray analysis. In both compounds, two [Ni(taCi)](2+) entities are each bonded to three Nb-O-Nb bridges of a central Nb6O19 unit, resulting in the formation of an approximately C-3v symmetric NiN3O3 coordination geometry. The mononuclear analogue [Ni(taCi)(H2O)(3)](2+) was crystallized as the sulfate and structurally characterized for comparison. The two isolated anions {trans [Nb6O19][Ni(taci)](2) (4-) and {cis-[H2Nb6O19][Ni(taci)](2)}(2-) have approximate D-3d and C-2v symmetry, respectively. Compound 2 crystallized, however, in the cubic space group Pn (3) over barm (No. 224) with the two Ni centers equally distributed over four symmetry equivalent sites. In this structure, the [Na(H2O)(6)](+) cations and the {cis-[H2Nb6O19][Ni(taci)](2)}(2-) anions represent linearly and tetrahedrally connecting building blocks in a hydrogen bonded supramolecular architecture which can be described in terms of two independent but interpenetrating diamond-type nets. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 53]