Enhancement of the Third-Order Nonlinear Optical Properties in Open-Shell Singlet Transition-Metal Dinuclear Systems: Effects of the Group, of the Period, and of the Charge of the Metal Atom

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• 作者：Hitoshi Fukui ; Yudai Inoue ; Taishi Yamada ; Soichi Ito ; Yasuteru Shigeta ; Ryohei Kishi ; Beno卯t Champagne ; Masayoshi Nakano
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：June 7, 2012
• 年：2012
• 卷：116
• 期：22
• 页码：5501-5509
• 全文大小：576K
• 年卷期：v.116,no.22(June 7, 2012)
• ISSN：1520-5215

文摘

Metal鈥搈etal multiply bonded complexes in their singlet state have been predicted to form a novel class of 鈥溝?dominant鈥?third-order nonlinear optical compounds based on the results of dichromium(II) and dimolybdenum(II) systems (H. Fukui et al. J. Phys. Chem. Lett.2011, 2, 2063) whose second hyperpolarizabilities (纬) are enhanced by the contribution of the d蟽 electrons with an intermediate diradical character. In this study, using the spin-unrestricted coupled-cluster method with singles and doubles as well as with perturbative triples, we investigate the dependences of 纬 on the group and on the period of the transition metals as well as on their atomic charges in several open-shell singlet dimetallic systems. A significant enhancement of 纬 is observed in those dimetallic systems composed of (i) transition metals with a small group number, (ii) transition metals with a large periodic number, and (iii) transition metals with a small positive charge. From the decomposition of the 纬 values into the contributions of d蟽, d蟺, and d未 electrons, the 纬 enhancements are shown to originate from the d蟽 contribution, because it corresponds to the intermediate diradical character region. Furthermore, the amplitude of d蟽 contribution turns out to be related to the size of the d_z² atomic orbital of the transition metal, which accounts for the dependence of 纬 on the group, on the period, and on the charge of the metal atoms. These dependences provide a guideline for an effective molecular design of highly efficient third-order nonlinear optical (NLO) systems based on the metal鈥搈etal bonded systems.