Lone-Pair Orientation Effect of an -Oxygen Atom on 1JCC NMR Spin-Spin Coupling Constants in o-Su
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- 作者：Oscar E. Taurian ; Rubé ; n H. Contreras ; Dora G. De Kowalewski ; Jorge E. Pé ; rez ; Clá ; udio F. Tormena
- 刊名：Journal of Chemical Theory and Computation
- 出版年：2007
- 出版时间：July 2007
- 年：2007
- 卷：3
- 期：4
- 页码：1284 - 1294
- 全文大小：115K
- 年卷期：v.3,no.4(July 2007)
- ISSN：1549-9626
文摘
The well-known N lone-pair orientation effect on <SUP>1JCC spin-spin coupling constants(SSCCs) in oximes and their derivatives was used to study how negative hyperconjugativeinteractions of type LP1(O) 
*CC depend on ortho interactions involving the OH group. Thisstudy demanded the following analyses: (i) a qualitative estimation of how 1JCC SSCCs areaffected by hyperconjugative interactions, (ii) a study of similar stereochemical effects to thosein oximes, but in 1JC1C2 and 1JC1C6 in a series of 2-substituted phenols, and (iii) a quantitativeestimation, with the natural bond order approach, of some key electron delocalization interactions.A few unexpected results are quoted. LP1(O) *CC interactions are affected by proximityinteractions as follows: (a) they are enhanced by hydrogen bonds transferring charge into the(O-H)* antibonding orbital; (b) they are enhanced by proximity interactions of type LP1(O)···H-C; (c) they are inhibited by interactions of type LP(O1)···H-O. Consequences of theseobservations are discussed.
*CC depend on ortho interactions involving the OH group. Thisstudy demanded the following analyses: (i) a qualitative estimation of how 1JCC SSCCs areaffected by hyperconjugative interactions, (ii) a study of similar stereochemical effects to thosein oximes, but in 1JC1C2 and 1JC1C6 in a series of 2-substituted phenols, and (iii) a quantitativeestimation, with the natural bond order approach, of some key electron delocalization interactions.A few unexpected results are quoted. LP1(O) *CC interactions are affected by proximityinteractions as follows: (a) they are enhanced by hydrogen bonds transferring charge into the(O-H)* antibonding orbital; (b) they are enhanced by proximity interactions of type LP1(O)···H-C; (c) they are inhibited by interactions of type LP(O1)···H-O. Consequences of theseobservations are discussed.