Novel substituent effect on 77Se NMR chemical shifts caused by 4c-6e versus 2c-4e and 3c-4e in naphthalene peri positions:: Spectroscopic and theoretical study
Novel substituent effect on 77Se NMR chemical shifts caused by 4c-6e versus 2c-4e and 3c-4e in naphthalene peri positions:: Spectroscopic and theoretical study
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DOI：
10.1021/jo9903860
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发表时间：
1999-09-03
影响因子：
3.6
通讯作者：
Nakanishi, W
中科院分区：
文献类型：
--
作者：
Hayashi, S;Nakanishi, W
1 - [8 - (对 - YC₆H₄Se)C₁₀H₆]SeSe[C₁₀H₆(SeC₆H₄Y - 对) - 8'] - 1'（1：Y = H，OMe，Me，Cl，Br，COOEt和NO₂）的δ(⁸Se)值与1 - (MeSe) - 8 - (对 - YC₆H₄Se)C₁₀H₆（2）的δ(⁸Se)值有良好的相关性。虽然2中δ(¹Se)值与δ(⁸Se)值有良好的相关性，正比例常数为0.252（正相关），但1的类似相关性给出的负比例常数为 - 0.282（负相关）。为了阐明1中负相关以及2中正相关相关的机制，在B3LYP和/或HF水平上，使用6 - 311 + G(2d,p)基组，对p - YC₆H₄(A)SeH --- (B)SeH - (B)SeH --- H(A)SeC₆H₄Y - p（3：1的Se₄ 4c - 6e模型）以及p - YC₆H₄(A)SeH --- (B)SeH₂（4和5：2的Se₂ π型2c - 4e和(A)Se --- (B)Se - H 3c - 4e模型）进行了包含Se核的GIAO磁屏蔽张量（σ(Se)）的从头算分子轨道计算。3中取代基对原子电荷和δ(Se)值影响的特征性质分别被证明为Y(δ⁻) ⇌ Y(δ⁻)和Y(δ⁻) ⇌ Y(δ⁻)（Y = 吸电子基），5中为Y(δ⁻) ⇌ Y(δ⁻)（此处最后一个Y(δ⁻)后可能内容不完整）
delta((8)Se) values for 1-[8-(p-YC(6)H(4)Se)C(10)H(6)]SeSe[C(10)H(6)(SeC(6)H(4)Y-p)-8']-1' (1: Y = H, OMe, Me, Cl, Br COOEt, and NO(2)) showed a good correlation with those of 1-(MeSe)-8-(p-YC(6)H(4)Se)C(10)H(6) (2). While the delta((1)Se) values correlated well with delta((8)Se) in 2 with a positive proportionality constant of 0.252 (regular correlation), a similar correlation for 1 gave a negative proportionality constant of -0.282 (inverse correlation). To clarify the mechanism associated with the inverse correlation in 1, together with the regular correlation in 2, ab initio MO calculations, containing the GIAO magnetic shielding tensor for the Se nucleus (sigma(Se)), were performed on p-YC(6)H(4)(A)SeH---(B)SeH-(B)SeH---H(A)SeC(6)H(4)Y-p (3: model of Se(4) 4c-6e for 1) and on p-YC(6)H(4)(A)SeH---(B)SeH(2) (4 and 5: models of Se(2) pi type 2c-4e and (A)Se---(B)Se-H 3c-4e for 2, respectively) with the 6-311+G(2d,p) basis sets at B3LYP and/or HF levels. The characteristic nature of the substituent effects on atomic charges and delta(Se) values in 3 is demonstrated to be Y(delta-) Y(delta-) and Y(delta-) Y(delta-), respectively, (Y = electron-withdrawing) and in 5 is Y(delta-)