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Silicon NMR

PHYSICAL PROPERTIES
 

Isotope
Natural 
Abundance
(%)
Nuclear
Spin
(I)
Magnetogyric
ratio
(107*rad/T*s)
Quadruple 
moment
(1028*Q/m2)
Resonance
frequency
(MHz)
at 11.744T
(500 MHz for 1H)
Relative 
sensitivity
(1H=1.00)
Absolute 
sensitivity
(1H=1.00)
29Si
4.6832
1/2
-5.3190
0
99.325
7.84*10-3
3.69*10-4
 
 The other naturally ocurring isotopes (28Si (92.21%) and 30Si (3.09%)) have spin I=0.
APPLICATION FIELDS
Organosilicon compounds (silicates, zeolites ...)
Solid-state NMR applications
NMR REFERENCES
 The standard internal reference is Me4Si (TMS) (absolute frequency of 19.867187 MHz with respect to 100.00 MHz of TMS). Other references can be used as, for instance, [(CH3)3Si]4C (3.6ppm), [(CH3)3Si]2O (7.22ppm) or [(CH3)2SiO]4 (-19.86ppm). Also see IUPAC recommendations for reporting the NMR chemical shits of all nuclei relative to the 1H resonance of TMS (02JMR323-156).
NMR PARAMETERS
  •  29Si chemical shifts cover a range between -580/+270 ppm. However, the majority of silicon compounds resonate in the -200/+50 ppm interval.
  • X-29Si coupling constants where X=1H, 13C, 19F, 31P, and 29Si are readily measured.
    • NMR EXPERIMENTS
  •  1H-decoupled vs 1H-coupled 29Si NMR spectra. Due to the negative magnetic moment, NOE can lead to null signals. If protons are present, 29Si {1H} INEPT or DEPT experiments can successfully  be applied with highly improved sensitivity.
  • 1D 1H-29Si HMQC ( 96MRC945 ) experiment.
  • 2D 1H-29Si correlations using the HETCOR ( 85MRC10 ), HMQC ( 94MRC326 , 95JMRB300-106 ), and HSQC ( 95JMRA119-115 ) pulse sequences.
  • 2D 29Si-29Si INEPT-COSY experiment ( 84JACS29 , 93MRC623 , 82JACS4716 ).
  • 2D z-filtered HETCOR to measure J(29Si-X) coupling constants ( 92JMR338-99 , 92MRC950 ).
  • 2D 13C-29Si INEPT-HMQC experiment ( 93JMRA329-101 ).
  • 3D 1H/13C/29Si experiment ( 99JACS273 and 02ORG3250 ) to be applied on carbosilane dendrimers and mixture of organosilane compounds.
    • BIBLIOGRAPHY
    Monographic reviews can be found in 96ENC4386 , 00ENC2031 and B96GIE1.
    Revision work: B79HAR309.

    81JACS1577

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