一系列d8配合物1,3[(dz2)(pz)]激发态和金属间相互作用的理论研究

采用MP2和CIS方法分别优化trans-M₂(CN)₄(PH₂CH₂PH₂)₂] M＝Pt (1), Pd (2)和Ni (3)]和trans-M(CN)₂(PH₃)₂] M＝Pt (4), Pd (5)和Ni (6)]的基态和^1,3(d_z2)(p_z)]激发态结构. CIS计算显示1的激发态Pt-Pt距离相对基态变短, 而2和3的金属间距离却增长. TD-DFT方法合理地预测了1～6发射能, 如: 1在CH₂Cl₂溶液中分别拥有348和404 nm的荧光和磷光发射, 与实验的386和448 nm相对应. 在1～3的激发态中, d⁸-d⁸相互作用依次递减, 相应的发射跃迁能增加; 与单核配合物4～6相比, 金属间相互作用使得双核Pt配合物的发射波长红移, 而对双核Pd和Ni配合物影响很小.

Theoretical Studies on 1,3[(dz2)(pz)] Excited States and Metal-Metal Interaction of a Series of d8 Complexes

The structures of trans-M₂(CN)₄(PH₂CH₂PH₂)₂] M＝Pt (1), Pd (2) and Ni (3)] and trans- M(CN)₂(PH₃)₂] M＝Pt (4), Pd (5) and Ni (6)] in the ground and ^1,3(d_z2)(p_z)] excited states were optimized by the MP2 and CIS methods, respectively. The CIS calculations revealed that upon excitation the Pt-Pt distance of 1 shortens but those of 2 and 3 lengthened. Ex-perimental emissions were well reproduced by the TD-DFT calculations. For example, the fluores-cent/phosphorescent emissions of 1 were predicted to take place at 356/417 nm in the solid state and at 348/404 nm in the CH₂Cl₂ solution, agreeing with experimental 388/450 and 386/448 nm, respectively. It is shown that the metal-metal interaction decreases on going from 1 to 3 in their excited states, leading to the increase of the σ(p_z)→σ* (d_z2) emission energy along the series complexes. With respect to analogous mononu-clear d⁸ complexes (4～6), the d⁸-d⁸ interaction results in a large red shift of emission wavelength for the binuclear Pt(II) complex but slightly affects those of the binuclear Pd(II) and Ni(II) complexes.