ISSN:
0749-1581
Keywords:
NMR
;
14N NMR
;
11B NMR
;
borazines
;
coupling constants 1J(29Si14N),1J(14N11B)
;
coupling signs
;
14N electric field gradient
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The nuclear spin relaxation rate of the quadrupolar 14N nuclei in N,N′,N″-tris(trimethylsilyl)borazine (1) is surprisingly slow [T1(14N)=0.1 s]. This allows one to measure 1J(29Si14N) (9.6 Hz) directly from the 29Si NMR spectra and also to compare signs of coupling constants 1J(29Si14N) (〈0) and 3J(14NSiC1H) (〉0) by 2D 29Si/1H HETCOR experiments. Since the transverse relaxation time T2(14N) in 1 is governed by scalar relaxation of the second kind, the magnitude of 1J(14N11B) can be evaluated (23 ± 0.5 Hz). 11B, 14N and 29Si NMR data for N,N′-bis(trimethylsilyl)borazine (2) were also obtained, and 11B and 14N NMR spectra of the parent borazine [HBNH]3 (3), and of [HBNMe]3 (4) were remeasured. Calculation of the tensor components of the 14N electric field gradient shows that eqzz in 1 and in 2 for 14N(Si) is significantly smaller than for other borazines [HBNR]3, e.g. with R=H (3) or Me (4), in agreement with the experimental results.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260330711
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