Department of Material Science and Chemistry, Faculty of Systems Engineering, Wakayama University, 930 Sakaedani, Wakayama 640-8510, Japan.
Bioinorg Chem Appl. 2009;2009:381925. doi: 10.1155/2009/381925. Epub 2009 Aug 6.
Nuclear couplings for the Se-Se bonds, (1)J(Se, Se), are analyzed on the basis of the molecular orbital (MO) theory. The values are calculated by employing the triple zeta basis sets of the Slater type at the DFT level. (1)J(Se, Se) are calculated modeled by MeSeSeMe (1a), which shows the typical torsional angular dependence on varphi(C(Me)SeSeC(Me)). The dependence explains well the observed (1)J(obsd) (Se, Se) of small values (<or= 64 Hz) for RSeSeR' (1) (simple derivatives of 1a) and large values (330-380 Hz) observed for 4-substituted naphto[1,8-c, d]-1,2-diselenoles (2) which correspond to symperiplanar diselenides. (1)J (Se, Se: 2) becomes larger as the electron density on Se increases. The paramagnetic spin-orbit terms contribute predominantly. The contributions are evaluated separately from each MO (psi(i)) and each psi(i) --> psi(a) transition, where psi(i) and psi(a) are occupied and unoccupied MO's, respectively. The separate evaluation enables us to recognize and visualize the origin and the mechanism of the couplings.
基于分子轨道（MO）理论分析了 Se-Se 键的核偶合常数 (1)J(Se, Se)。采用 DFT 水平的 Slater 型三重 zeta 基组计算了这些值。通过 MeSeSeMe（1a）对 (1)J(Se, Se)进行建模，其显示出典型的扭转角依赖关系，取决于 varphi(C(Me)SeSeC(Me))。这种依赖性很好地解释了观察到的 RSeSeR'（1）（1a 的简单衍生物）中较小的 (1)J(obsd)（Se, Se）（<或= 64 Hz）和 4-取代的萘并[1,8-c, d]-1,2-二硒唑（2）中观察到的较大值（330-380 Hz），这对应于对称平面的二硒化物。(1)J（Se, Se：2）随着 Se 上的电子密度增加而增大。顺磁自旋轨道项贡献占主导地位。贡献分别从每个 MO（psi(i)）和每个 psi(i) --> psi(a)跃迁进行评估，其中 psi(i)和 psi(a)分别为占据和未占据的 MO。单独评估使我们能够识别和可视化偶合的起源和机制。
