Exploratory syntheses and structural characterizations of three organic–inorganic hybrid polyoxomolybdate frameworks linked by M(II)-L_n units (M = Ni, Co, Zn; L = 2,2′-biimidazole)

Abstract

Three new polyoxomolybdate compounds, {[Ni(H₂biim)₂(H₂O)](Mo₃O₁₀)} _n (1), [Co(H₂biim)₂(Hbiim)]₂(H₂Mo₈O₂₆)](H₂O)₄ (2), and {[Zn(H₂biim)₂(H₂O)][Mo₈O₂₈(MoO₂(H₂biim)₂)₂](H₄biim) (3) (H₂biim, 2,2′-biimidazole), were designed and synthesized under hydrothermal conditions. X-ray diffraction analysis reveals that 1 is a snake-shaped chain consisting of asymmetric blocks of {Mo₃O₁₀}, in which the ratio of the octahedra {MoO₆} and square pyramids {MoO₅} is 1 : 2. Compounds 2 and 3 exhibit different structures, although similar synthetic environments (including pH, temperature, and reaction time) were employed. In 2, the cluster of H₂Mo₈ is decorated by two fragments of Co(H₂biim)₂(Hbiim)⁺ via the organic bridge of Hbiim⁻. Compound 3 consists of one γ-Mo₈ , capped by two fragments of {MoO₂(H₂biim)₂)₂}²⁺ via terminal oxygens.

Keywords:

• Polyoxomolybdate
• 2,2′-Biimidazole
• Nickel(II)
• Cobalt(II)
• Zinc(II)

Acknowledgments

Financial support from the Natural Science Foundation of Shandong Province (no. BR2010BQ023), Shandong Provincial Education Department (no. J09LB55), and Qilu Normal University is gratefully acknowledged.