异核Au基电荷转移配合物的结构与Au-Rh配合物取代基效应和激发态的理论研究

Theoretical Studies on the Au-based Charge-Transfer Complexes and Substituent Effects and Excited States of the Heterobimetallic Au-Rh Analogue

采用SVWN、XαVWN和MP2方法优化了Au基电荷转移配合物[AuIMI(CNH)2(PH2CH2PH2)2]2+(M=Co(1),Rh(2)和Ir(3))的基态结构。计算表明3种方法都能描述Au-M弱相互作用(Au-M距离在0.268～0.302nm范围内,伸缩振动频率在99～139cm-1,键级在0.022～0.055),其中SVWN计算的金属间距离最接近实验值。在SVWN理论级别上优化了[AuⅠRhⅠ(CNR′)2(PR2CH2PR2)2]2+(R=H,R′=Me(2a)和tBu(2b);R=Me,R′=H(2c)以及Me(2d))以及[AuⅠMⅡ(CN)2(PH2CH2PH2)2]+(M=Ni(4),Pd(5)和Pt(6))的结构,验证了取代基近似和方法选择的合理性。单激发组态相互作用优化得到了2的最低能单重和三重激发态结构,波函数分析表明电子激发使得激发态的金属间距离相对基态缩短。通过多种TD-DFT(time-depen dentdensity functional theory)和溶剂化效应模型计算,预测2的荧光和磷光发射分别在2.26～2.82和1.83～1.66eV,与实验测得的2.48和2.03eV相对应。这些发射归属为σ*[dz2(Rh)-dz2-y2(Au)]→σ[spz(Au-Rh)](金属中心:MC)、dz2(Rh)→spz(Au)(金属到金属电荷转移:MMCT)以及金属到配体电荷转移(MLCT)跃迁的混合性质。

The ground-state structures of the Au-based charge-transfer complexes, [Au^I M^I （CNH）2（PH2CH2PH2）2]^2＋ （M=Co （1）, Rh （2） and Ir （3））, were optimized using the SVWN, XαVWN and MP2 methods. It was shown that the weak Au-M interaction was reasonably described. This is evident in the calculated Au-M distances （0.268-0.302 nm）, stretching frequencies （99-139 cm^-1） and bond orders （0.022-0.055）. Among these methods, the distances calculated by the SVWN functional are closest to the reported experimental values. To confirm the substituent approximation and the choice of methods, we optimized the structures of [Au^IRh^I（CNR＇）2（PR2CH2PR2）2]^2＋ （R=H, R＇=Me （2a） and ^tBu （2b）; R=Me, R＇=H （2c） and Me （2d）） and [Au^IM^II（CN）2（PH2CH2PH2）2]^＋ （M=Ni （4）, Pd （5） and Pt （6）） at the SVWN level. The CIS （single excitation configuration interaction） calculations revealed that complex 2 features the lowest-energy metal-localized singlet and triplet excited states, along with the promotion of electrons into bonding orbitals. Associated with different TD-DFF （time-dependent density functional theory）methods and solvent-effect models, the fluorescent and phosphorescent emissions were predicted at 2,26-2.82 and 1.83-1.66 eV, respectively, in agreement with experimental values of 2.48 and 2.03 eV. We attributed these emission to the admixture of σ^＊[dz^2（Rh）-dz^2-y^2（Au）]→σ[spz（Au-Rh）] （Metal-centered, MC）, dz^2（Rh）→σ,（Au） （Metal to metal charge transfer, MMCT） and metal to ligand charge transfer （MLCT） transition characters.