Ab initio calculation of ^<29>Si NMR chemical shifts for the clusters of Si(OH)_4, Si(OH)_5^- and Si(OH)_6^<-2>

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Author(s)

    • KANZAKI Masami
    • Department of Mechanical Sciences Tokyo, Institute of Technology

Abstract

In order to identify five-coordinated Si(Si<SUP>v</SUP>) species in crystalline and amorphous silicates by NMR spectroscopy, <SUP>29</SUP>Si NMR chemical shifts for the clusters of Si(CH<SUB>3</SUB>)<SUB>4</SUB> (TMS), Si(OH)<SUB>4</SUB>, Si(OH)<SUB>5</SUB><SUP>−</SUP> and Si(OH)<SUB>6</SUB><SUP>−2</SUP> were calculated using ab initio molecular orbital theory. The calculated shifts relative to TMS cluster were −71.7 and −179.0 ppm for Si(OH)<SUB>4</SUB> and Si(OH)<SUB>6</SUB><SUP>−2</SUP>, respectively, and are in good agreement with observed shifts. The calculated shift for Si(OH)<SUB>5</SUB><SUP>−</SUP> was −127.4 ppm, falls just between the shifts of Si(OH)<SUB>4</SUB> and Si(OH)<SUB>6</SUB><SUP>−2</SUP>. The chemical shift for Si<SUP>v</SUP> species in polymerized silicates is expected to appear at about −150 ppm, if the effect of polymerization is considered. Present calculation thus supports the assignment of −150 ppm peak as Si<SUP>v</SUP> species, which has been found in the alkali-silicate glasses quenched from high pressures.

Journal

  • Mineralogical Journal

    Mineralogical Journal 18(1), 1-8, 1996-01-01

    Japan Association of Mineralogical Sciences

References:  19

Cited by:  1

Codes

  • NII Article ID (NAID)
    10008772579
  • NII NACSIS-CAT ID (NCID)
    AA00739590
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    05442540
  • Data Source
    CJP  CJPref  J-STAGE 
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