Abstract
Neutron diffraction data available in the literature have been analyzed statistically to arrive at the ideal geometry for the commonly occurring groups, NH +4 , NH +3 , CH3, CH2, and CH; this has yielded optimum experimental values for the bond length and bond angle parameters. They are: N-H distance of 1.030 Å in both NH +4 and NH +3 groups, H-N-H angle of 109.47° and 108.1° respectively in NH +4 and NH +3 and 110.8° for the corresponding X-N-H angle in −NH +3 . For CH3, CH2, and CH groups the bond length C-H is 1.090 Å, while the H-C-H and X-C-H angles are respectively 108.2° and 110.5° in CH3 and 107.2° and 109.3° in CH2. The importance of using precise values of both bond lengths and bond angles for the ideal geometry when estimating theoretical second moments is emphasized.
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Contribution No. 564 from the Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Madras-600025, India.
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Jagannathan, N.R., Srinivasan, R. On the estimation of second moment for organic compounds in wide-line pmr: analysis of group geometry. Journal of Crystallographic and Spectroscopic Research 12, 25–37 (1982). https://doi.org/10.1007/BF01161097
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DOI: https://doi.org/10.1007/BF01161097