Polyoxomolybdodiphosphonates: Examples incorporating ethylidenepyridines

Abhishek Banerjee, Farah S. Raad, Nina Vankova, Bassem S. Bassil, Thomas Heine, Ulrich Kortz

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Abstract

We have synthesized and structurally characterized three pyridylethylidene-functionalized diphosphonate-containing polyoxomolybdates, [{MoVIO3}2{MoV2O 4}{HO3PC(O)(CH2-3-C5NH 4)PO3}2]6- (1), [{Mo VI2O6}2{MoV 2O4}{O3PC(O)(CH2-3-C 5NH4)PO3}2]8- (2), and [{MoV2O4(H2O)}4{O 3PC(O)(CH2-3-C5NH4)PO 3}4]12- (3). Polyanions 1-3 were prepared in a one-pot reaction of the dinuclear, dicationic {MoV2O 4(H2O)6}2+ with 1-hydroxo-2-(3- pyridyl)ethylidenediphosphonate (Risedronic acid) in aqueous solution. Polyanions 1 and 2 are mixed-valent MoVI/V species with open tetranuclear and hexanuclear structures, respectively, containing two diphosphonate groups. Polyanion 3 is a cyclic octanuclear structure based on four {MoV2O4(H2O)} units and four diphosphonates. Polyanions 1 and 2 crystallized as guanidinium salts [C(NH 2)3]5H[{MoVIO3} 2{MoV2O4}{HO3PC(O) (CH2-3-C5NH4)PO3} 2]•13H2O (1a) and [C(NH2) 3]6H2[{MoVI2O 6}2{MoV2O4}{O 3PC(O)(CH2-3-C5NH4)PO 3}2]•10H2O (2a), whereas polyanion 3 crystallized as a mixed sodium-guanidinium salt, Na8[C(NH 2)3]4[{MoV2O 4(H2O)}4{O3PC(O)(CH 2-3-C5NH4)PO3}4] •8H2O (3a). The compounds were characterized in the solid state by single-crystal X-ray diffraction, IR spectroscopy, and thermogravimetric and elemental analyses. The formation of polyanions 1 and 3 is very sensitive to the pH value of the reaction solution, with exclusive formation of 1 above pH 7.4 and 3 below pH 6.6. Detailed solution studies by multinuclear NMR spectrometry were performed to study the equilibrium between these two compounds. Polyanion 2 was insoluble in all common solvents. Detailed computational studies on the solution phases of 1 and 3 indicated the stability of these polyanions in solution, in complete agreement with the experimental findings.

Original languageEnglish
Pages (from-to)11667-11675
Number of pages9
JournalInorganic Chemistry
Volume50
Issue number22
DOIs
Publication statusPublished - 2011 Nov 21

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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    Banerjee, A., Raad, F. S., Vankova, N., Bassil, B. S., Heine, T., & Kortz, U. (2011). Polyoxomolybdodiphosphonates: Examples incorporating ethylidenepyridines. Inorganic Chemistry, 50(22), 11667-11675. https://doi.org/10.1021/ic201652h