Theoretical study on second hyperpolarizabilities of singlet diradical square planar nickel complexes involving o-semiquinonato type ligands.
Theoretical study on second hyperpolarizabilities of singlet diradical square planar nickel complexes involving o-semiquinonato type ligands.
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DOI：
10.1021/jp804400s
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
H. Fukui;R. Kishi;Takuya Minami;H. Nagai;Hideaki Takahashi;T. Kubo;K. Kamada;K. Ohta;B. Champagne;E. Botek;M. Nakano
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文献类型：
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作者：
H. Fukui;R. Kishi;Takuya Minami;H. Nagai;Hideaki Takahashi;T. Kubo;K. Kamada;K. Ohta;B. Champagne;E. Botek;M. Nakano
应用混合密度泛函理论方法研究涉及几种双齿配体[o-C6H4XY，其中X = Y = O、NH、S、Se和PH以及(X, Y) = (NH, NH2)和(S, NH2)]的方形平面镍配合物的第二超极化率(gamma)的双自由基特征依赖性。研究发现，作为供体原子的函数，这些配合物的双自由基特征在 0.0 到 0.884 之间变化，并且与 14 x 10(3) 到 819 x 10(3) au 范围内的 γ 的显着变化相关。特别是，最大的伽马值与中间双自由基特征相关，与纯烃系统获得的结构-性质关系非常一致。配体的X和Y供体基团的电负性增加，由于C=X(Y)键的双键性质增强，导致双自由基特性更大，这进一步稳定了两端苯环上的双自由基。这表明配体的供体原子的电负性成为双自由基特征的调节参数，然后成为这些配合物的伽马值的调节参数。
Hybrid density functional theory method is applied for investigating the diradical character dependence of the second hyperpolarizability (gamma) of square planar nickel complexes involving several types of bidentate ligands [o-C6H4XY, where X = Y = O, NH, S, Se, and PH as well as (X, Y) = (NH, NH2) and (S, NH2)]. It is found that, as a function of the donor atoms, the diradical character of these complexes varies from 0.0 to 0.884 and is associated with substantial variations of gamma ranging from 14 x 10(3) to 819 x 10(3) au. In particular, the largest gamma values are associated with intermediate diradical characters in good agreement with the structure-property relationship obtained for pure hydrocarbon systems. Increasing the electronegativity of the X and Y donor groups of the ligands leads to larger diradical characters as a result of the enhancement of the double bond nature of the C=X(Y) bonds, which further stabilizes the diradicals on both-end benzene rings. This demonstrates that the electronegativities of the donor atoms of the ligands become a tuning parameter of the diradical character and then of the gamma values of these complexes.