系列二亚胺羰基Mn配合物光谱的密度泛函研究  

DFT Study on Spectra of Mn-Carbonyl Molecular Complexes

作　　者：慈成刚 臧杰超 李明飞[1] CI Cheng-gang;ZANG Jie-chao;LI Ming-fei(Key Laboratory of Computational Catalytic Chemistry of Guizhou Province,Qiannan Normal University for Nationalities,Duyun 558000,China)

机构地区：[1]黔南民族师范学院贵州省计算催化化学重点实验室,贵州都匀558000

出　　处：《光谱学与光谱分析》2023年第5期1434-1441,共8页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(22163007);贵州省科技厅项目(黔科合基础[2020]1Y050);黔南民族师范学院项目(qnsyk201601)资助。

摘　　要：CO_(2)还原始终是能源和环境领域的重要挑战。二亚胺羰基Mn配合物价格低廉,稳定性好,可调变性强,成为近年来光催化还原CO_(2)的热门催化剂。紫外-可见光谱和红外光谱研究有助于调控CO_(2)光还原催化剂性能。基于密度泛函理论(DFT)和含时密度泛函理论(TD-DFT),对系列二亚胺羰基锰配合物[Mn(bpy)(CO)_(3)Br],(简写为1),[Mn(phen)(CO)_(3)Br],(简写为2),[Mn(phen-dione)(CO)_(3)Br],(简写为3),[Mn(phen-dione)(CO)_(3)CH_(3)CN]^(+),(简写为4)(bpy=2,2′-bipyridine,phen=1,10-phenan-throline,phen-dione=phenanthroline-5, 6-dione)的紫外-可见光谱和红外光谱进行研究。基于TD-DFT方法,采用多种泛函,对紫外-可见光谱进行模拟。结果显示1和2主要有两个最大吸收峰,分别位于371 nm (1), 408 nm (1)和361 nm (2), 414 nm (2),其电子跃迁类型均为由金属Mn中心基团向二亚胺配体的电荷转移(MLCT)跃迁。而3和4均具有三个吸收峰,分别位于290 nm (3), 337 nm (3), 431 nm (3)和294 nm (4), 319 nm (4), 371 nm (4)。其中,除了4的294 nm吸收峰对应了二亚胺配体内部的π—π*跃迁,3和4的其余吸收峰均为MLCT跃迁。伴随着二亚胺配体电负性的增强,吸收峰向可见光区移动(红移),而因Mn中心配体电负性的增强,导致吸收峰向紫外光区移动(蓝移)。一旦电子从Mn中心基团转移至二亚胺配体,Mn中心基团成为缺电子中心,有利于外界电子进入。因Mn中心基团的轨道主要由金属Mn和配体的σ*反键轨道组成,有利于Mn中心基团配体Br-/CH_(3)CN解离,形成活性中间体。红外光谱计算结果显示1, 2, 3和4的特征振动峰主要分为两类:金属Mn中心的C=O键伸缩振动(1, 2, 3和4的1 920~2 020 cm^(-1))和二亚胺羰基的C=O键伸缩振动(3的1 690 cm^(-1)和4的1 694 cm^(-1))。伴随着二亚胺羰基配体和Mn中心配体电负性的增强,1到4的特征峰波数略微增加。计算的分子结构,紫外-可见光谱和红外光谱与实验结果符合很好,能�The reduction of CO_(2) is still a challenge in energy sources and the environmental field.Diamine coordinated manganese tricarbonylcatalysts containing diamine ligands,as inexpensive molecule based inorganic materials,become a potentially interesting catalyst in the photoreduction of CO_(2).The ultraviolet-visible(UV-Vis)and infrared(IR)spectra are beneficial to the modulation of catalysts for the photoreduction of CO_(2).TheUV-Vis and IR spectra of a series of diamine coordinated manganese tricarbonyl catalysts,[Mn(bpy)(CO)_(3)Br],(1),[Mn(phen)(CO)_(3)Br](2),[Mn(phen-dione)(CO)_(3)Br](3),[Mn(phen-dione)(CO)_(3)CH_(3)CN]^(+)(4)(bpy=2,2′-bipyridine,phen=1,10-phenan-throline,phen-dione=phenanthroline-5,6-dione)has been investigated using Density Functional Theory(DFT)and Time-Dependent Density Functional Theory(TD-DFT)calculations.The UV-Vis spectrawere obtained using several TD-DFT calculations.The simulated UV-Vis spectra of 1 and 2 all show two peaks centered at 371 nm(1),408 nm(1)and 361 nm(2),414 nm(2),respectively.Absorption peaks of 1 and 2 arise from a metal-to-ligand charge transfer(MLCT)transition.The simulated UV-Vis spectra of 3 and 4 show three absorption peaks centered around 290 nm(3),337 nm(3),431 nm(3)and 294 nm(4),319 nm(4),371 nm(4),respectively.Herein,except for the peak of 294 nm(4)generated by the ligand-to-ligandπ—π*transition,the remain absorption peaks of 3 and 4 all arise from MLCT absorption.The increased electronegativity of diamine ligands is responsible for shifting absorption peak from the UV region to the visible region(red).The increased electronegativity of the Mn-centeredligand is responsible for shifting absorption peak from the visible region to the UV region(blue).Once an electron is transferred from the Mn-centered unit to the diamine ligands,the Mn center will become anelectron-deficient unit.Herein,the Mn-centeredunit contributes from theσantibonding orbital between the Mn atom and ligand in the MLCT states.Thus,when the populated excited MLCT states are hit,the rele

关 键 词：二亚胺羰基锰配合物 紫外-可见光谱 红外光谱 前线分子轨道 密度泛函理论 

分 类 号：O657.3[理学—分析化学]