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用密度泛函理论(DFT)方法,在B3LYP和混合基组(C,H原子用6-31 G*;Co,N,O用6-31 1+G(2d,p))水平上,对含轴向配体的三种Co(Ⅲ)席夫碱配合物[Co(MeO-salen)(国m)_2]~+、[Co(MeO-salen)(2-Melm)_2]~+和[Co(MeO-salen)(Melm)_2]~+(lm=咪唑,Melm=1-甲基咪唑,2-Melm=2-甲基咪唑,MeO-salenH2=salen型席夫碱,即(R,R)-N,N’-双(5-甲氧基亚水杨基)-1,2-二亚胺基环己烷)在二氯甲烷溶液中的基态结构进行了优化,并用含时密度泛函理论(TDDFT)方法,在相同泛函和基组水平上计算了其激发能、振子强度和旋转强度.这些计算中均用极化连续介质模型(PCM)考虑了溶剂效应.计算的电子圆二色(ECD)谱与实验谱吻合较好.通过对有关跃迁性质的分析,对实验电子圆二色光谱进行了解析与指认.结果表明,长波区的第一个园二色(CD)吸收带主要是由π→d荷移跃迁(LMCT)引起的,而不是通常认为的d→d跃迁.轴向配体的加入对配合物前两个CD吸收带的符号没有影响,但会影响带形和强度.手性salen配合物的绝对构型为λ(RR)时,第一个CD吸收带为正,第二个为负.这些结论对于深入理解该类配合物的电子结构和手征光学性质具有重要的科学意义.
The density functional theory (DFT) method was used to study the effect of B3LYP on the level of 6-31 1 + G (2d, p) for B3LYP and mixed base groups (6-31 G * for C and H atoms; Three Co (Ⅲ) Schiff Base Complexes Containing Axial Ligands [Co (MeO-salen) (m) _2] ~ +, [Co (MeO-salen) (2-Melm) _2] [Co (MeO-salen) (Melm) 2] + lm = imidazole, Melm = 1-methylimidazole, 2-Melm = 2-methylimidazole, MeO-salenH2 = , R) -N, N’-bis (5-methoxy salicylidene) -1,2-diimidocyclohexane) in dichloromethane solution was optimized, Density functional theory (TDDFT) method was used to calculate the excitation energy, oscillator strength and rotational strength at the same functional and group level, and the solvent effect was taken into account in all calculations using a polarized continuous-medium model (PCM) The electronic circular dichroism (ECD) spectrum is in good agreement with the experimental one, and the experimental electronic circular dichroism spectrum is analyzed and identified through the analysis of the transition properties.The results show that the first circular dichroism (CD) ) Absorption band is mainly caused by π → d charge transition (LMCT) instead of the usual d → d transition. The addition of axial ligand has an effect on the sign of the first two CD absorption bands No effect, but will affect the band shape and intensity.When the absolute configuration of the chiral salen complex is λ (RR), the first CD absorption band is positive and the second is negative.These conclusions for the further understanding of this class The electronic structure and chiral optical properties of complexes have important scientific significance.