Spin-Spin Coupling Constants for Iminoboranes RBNH, HBNR, and RBNR and Comparisons with Corresponding Isoelectronic Acetylenes RCCH and RCCR, for R = H, CH3, NH2, OH, and F
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- 作者：Janet E. Del Bene ; José ; Elguero ; Ibon Alkorta ; Manuel Yá ; ñ ; ez ; Otilia Mó
- 刊名：Journal of Chemical Theory and Computation
- 出版年：2007
- 出版时间：March 2007
- 年：2007
- 卷：3
- 期：2
- 页码：549 - 556
- 全文大小：102K
- 年卷期：v.3,no.2(March 2007)
- ISSN：1549-9626
文摘
Ab initio equation-of-motion coupled-cluster singles and doubles method calculationshave been performed on iminoboranes RBNH, HBNR, and RBNR, for R = H, CH3, NH2, OH,and F, to evaluate substituent effects on one- and two-bond 15N-11B, 11B-1H, and 15N-1Hspin-spin coupling constants. For comparison purposes, 13C-13C coupling constants wereevaluated for corresponding isoelectronic molecules RCCH and RCCR. The absolute values of1J(N-B) and 1J(C-C) increase in the series HBNR and RCCH as the 
-electron-withdrawingability of R increases. In contrast, NH2 substitution at B leads to a decrease in the absolutevalue of 1J(N-B), but OH and F substitution increase 1J(N-B). Disubstitution has dramaticallydifferent effects on coupling constants for RCCR and RBNR. In the former, 1J(C-C) more thandoubles relative to the corresponding RCCH and HCCH; in the latter, disubstitution of OH andF decreases 1J(N-B) relative to the corresponding monosubstituted derivatives, while NH2substitution increases 1J(N-B). Changes in one- and two-bond B-H and N-H coupling constantsupon substitution are similar to changes observed for 1J(N-B) in the corresponding monosubstituted derivatives RBNH and HBNR.
-electron-withdrawingability of R increases. In contrast, NH2 substitution at B leads to a decrease in the absolutevalue of 1J(N-B), but OH and F substitution increase 1J(N-B). Disubstitution has dramaticallydifferent effects on coupling constants for RCCR and RBNR. In the former, 1J(C-C) more thandoubles relative to the corresponding RCCH and HCCH; in the latter, disubstitution of OH andF decreases 1J(N-B) relative to the corresponding monosubstituted derivatives, while NH2substitution increases 1J(N-B). Changes in one- and two-bond B-H and N-H coupling constantsupon substitution are similar to changes observed for 1J(N-B) in the corresponding monosubstituted derivatives RBNH and HBNR.