S. Niizuma, Lawrence Kwan, N. Hirota
Apr 1, 1978
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0
Influential Citations
25
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Journal
Molecular Physics
Abstract
The magnetic and dynamic properties of bromo and chloro substituted benzonitriles, anisoles and anilines were studied by means of E.P.R. and zero-field odmr at 1·2–4·2 K. Single-crystal E.P.R. studies showed that the zero-field splitting parameter D of bromo substituted molecules are positive as in other aromatic molecules. It was also shown that para bromo substitution depresses the energies of the Tx and Ty sublevels preferentially. This indicates that the second-order effect of the spin-orbit mixing of the T 1 state with the 3 nπ* state is the most important in affecting the zero-field splitting. Single-crystal E.P.R. spectra of 4-bromobenzonitrile and 4-bromoanisole gave resolved hyperfine splittings at certain orientations. The analysis of the in-plane hyperfine structure of 4-bromobenzonitrile gives Azz = 16 G and Ayy = 13 G, which are considerably different from the values expected from the spin densities in benzonitrile and the 81Br hyperfine coupling of α-bromomaleic acid. The large value of Axx ...