An ab initio study of 15N-11B spin-spin coupling constants for borazine and selected derivatives |
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Authors: | Del Bene Janet E Elguero José Alkorta Ibon Yañez Manuel Mó Otilia |
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Affiliation: | Department of Chemistry, Youngstown State University, Youngstown, Ohio 44555, Instituto de Química, Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain. jedelbene@ysu.edu |
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Abstract: | Ab initio equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) calculations have been performed to investigate substituent effects on coupling constants for borazine and selected substituted borazines. For molecules in which F atoms are not bonded to adjacent atoms in the ring, F substitution increases the one-bond (11)B-(15)N coupling constants involving the atom at which substitution occurs but leaves the remaining one-bond B-N coupling constants essentially unchanged. For these molecules, the magnitudes of one-bond B-N coupling constants are only slightly dependent on the number of F atoms present. Fluorine substitution at adjacent B and N atoms in the borazine ring further increases the one-bond B-N coupling constant involving the substituted atoms and has the same effect on the other one-bond coupling constants as observed for corresponding molecules in which substitution occurs at alternate sites. In contrast to the effect of F substitution, substitution of Li at either N or B decreases one-bond B-N coupling constants relative to borazine. The effects of F and Li substitution on one-bond B-N coupling constants for borazine are similar to F and Li substitution effects on (13)C-(13)C coupling constants for benzene. |
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