Proximity effects on (1)J(CH) couplings are studied from a theoretical point of view in the following systems: CH4/FH (A) and H2O/HCN (B) which form dimers by hydrogen-bond interactions. (1)J(CH) couplings for different intermolecular distances are calculated for the C-H bond facing the atom bearing lone pairs. While in the former system, this coupling is increased owing to the proximity to the F atom; in the latter this coupling is decreased owing to the proximity to the O atom. These opposite trends are accompanied by slight shortening and lengthening, respectively, of the corresponding C-H bond lengths. As part of this work, measurements of (1)J(CH) couplings in 9-(1,3-dioxolan-2-yl)-1,2,3,4-tetrafluorotriptycene (I) and 1-formyl-2-hydroxy-8-fluoronaphthalene (II) and (1)J(NH) in o-fluorobenzamide (III), showing proximity effects as those described above are carried out. These results suggest that (1)J(XH) couplings are adequate probes to distinguish two different types of X-H...Y hydrogen bonds.
Proximity effects on nuclear spin--spin coupling constants. 1. (CH) couplings in the vicinity of an atom bearing a lone pair / C., Vizioli; M. C., RUIZ DE AZUA; C. G., Giribet; R. H., Contreras; L., Turi; J. J., Dannenberg; I. D., Rae; J. A., Weigold; M., Malagoli; M., Malagoli; Lazzeretti, Paolo. - In: THE JOURNAL OF PHYSICAL CHEMISTRY. - ISSN 0022-3654. - STAMPA. - 98:36(1994), pp. 8858-8861. [10.1021/j100087a007]
Proximity effects on nuclear spin--spin coupling constants. 1. (CH) couplings in the vicinity of an atom bearing a lone pair
LAZZERETTI, Paolo
1994
Abstract
Proximity effects on (1)J(CH) couplings are studied from a theoretical point of view in the following systems: CH4/FH (A) and H2O/HCN (B) which form dimers by hydrogen-bond interactions. (1)J(CH) couplings for different intermolecular distances are calculated for the C-H bond facing the atom bearing lone pairs. While in the former system, this coupling is increased owing to the proximity to the F atom; in the latter this coupling is decreased owing to the proximity to the O atom. These opposite trends are accompanied by slight shortening and lengthening, respectively, of the corresponding C-H bond lengths. As part of this work, measurements of (1)J(CH) couplings in 9-(1,3-dioxolan-2-yl)-1,2,3,4-tetrafluorotriptycene (I) and 1-formyl-2-hydroxy-8-fluoronaphthalene (II) and (1)J(NH) in o-fluorobenzamide (III), showing proximity effects as those described above are carried out. These results suggest that (1)J(XH) couplings are adequate probes to distinguish two different types of X-H...Y hydrogen bonds.
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