ISSN:
0749-1581
Keywords:
Polychloroazanaphthalenes
;
Multiple substituent chemical shifts
;
MSCS
;
NIMS
;
13C predictions
;
Molecular orbital charge calculations
;
CNDO/2 calculations
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Three methods, two empirical and one semi-empirical, for predicting 13C chemical shifts in six poly-chloroheterocyclics are considered. It was found that the semi-empirical correlations with CNDO/2 calculated charges, although useful, could not be used in isolation from the other two methods. Of these, the MSCS (multiple substituent chemical shifts) method could be used to predict all eighteen carbon shifts in perchloroquinoline and perchloroisoquinoline, whilst the NIMS method (hypothetical nitrogen insertion method) was limited to the carbons in the heterocyclic ring. In brief, it was found that the MSCS method was the most accurate (less than ± 1 ppm) for predicting chemical shifts, intrinsically compensating for some of the errors arising from mutual atom-atom interactions.New 13C data are reported for heptachloroquinoline, a mixture of two polychloroquinolines, hepta-chloroisoquinoline and two, separable, new polychloroisoquinolines.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260270906
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