Cupric Siliconiobate. Synthesis and Solid-State Studies of a Pseudosandwich-Type Heteropolyanion

Travis M. Anderson†, Todd M. Alam†, Mark A. Rodriguez†, Joel N. Bixler†, Wenqian Xu‡, John B. Parise‡ and May Nyman*†
Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185, and Department of Chemistry and Geosciences, SUNYStony Brook, Stony Brook, New York 11794
Inorg. Chem., 2008, 47 (17), pp 7834–7839
DOI: 10.1021/ic800860q
Publication Date (Web): August 1, 2008
Copyright © 2008 American Chemical Society
†

Sandia National Laboratories.

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‡

SUNYStony Brook.

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* To whom correspondence should be addressed. E-mail: mdnyman@sandia.gov.

Abstract

Abstract Image

The Na+ and [Cu(en)2(H2O)2]2+ (en = ethylenediamine) salt of a pseudosandwich-type heteropolyniobate forms upon prolonged heating of Cu(NO3)2 and hydrated Na14[(SiOH)2Si2Nb16O54] in a mixed water−en solution. The structure [a = 14.992(2) Å, b = 25.426(4) Å, c = 30.046(4) Å, orthorhombic, Pnn2, R1 = 6.04%, based on 25869 unique reflections] consists of two [Na(SiOH)2Si2Nb16O54]13− units linked by six sodium cations, and this sandwich is charge-balanced by five [Cu(en)2(H2O)2]2+ complexes, seven protons, and three additional sodium atoms (all per a sandwich-type cluster). Diffuse-reflectance UV−vis indicates that there is a λmax at 383 nm for the CuII d−d transition and the 29Si MAS NMR spectrum has two peaks at −78.2 ppm (151 Hz) and −75.5 ppm (257 Hz) for the two pairs of symmetry-equivalent internal [SiO4]4– and external [SiO3(OH)]3− tetrahedra, respectively. Unlike tungsten-based sandwich-type complexes, the [Na(SiOH)2Si2Nb16O54]13− units are linked exclusively by Na+ instead of one or more d-electron metals.

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History

  • Published In Issue September 01, 2008
  • Article ASAPAugust 01, 2008
  • Received: May 12, 2008

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