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Calculations of J C13‐C13 and J C13‐H1 coupling constants in hydrocarbons by the maximum overlap method
Author(s) -
Maksić Z. B.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560050835
Subject(s) - coupling constant , symmetry (geometry) , coupling (piping) , chemistry , integer (computer science) , computational chemistry , molecular physics , materials science , physics , mathematics , quantum mechanics , computer science , geometry , metallurgy , programming language
Maximum overlap calculations were performed on some forty hydrocarbons with various structural groupings. The resulting hybridizations are correlated with available J C 13 ‐H 1 and J C 13 ‐C 13 coupling constants. Linear least squares fit gives the following formulas: J C 13 ‐H 1 = (10.8( s %)/(1 + S 2 CH )) ‐ 55 Hz and J C 13 ‐C 13 = (0.1 ( s %) A ( s %) B /(1 + S 2 AB )) ‐ 8.2 Hz, the standard deviations being 0.9 Hz and 1.9 Hz respectively. It is shown that the Fermi contact term and the non‐integer hybridization do account for the variations of J C 13 ‐H 1 and J C 13 ‐C 13 coupling constants in hydrocarbons. Therefore, maximum overlap method can be used for calculation of J C 1 ‐H 1 and J C 13 ‐C 13 constants in large molecules with low symmetry where more sophisticated methods are either too expensive or still not permissible.