溶液中M(H2O)26+/3+(M=V, Cr, Mn, Fe, Co)自交换电子转移体系内层重组能和活化能的理论研究

通过建立电子转移过程的活化模型和重组模型, 提出了用量子化学从头算方法研究电子转移过程内层重组能和活化能的新方法. 在UMP26/311G水平上获得了5对过渡金属水合离子体系M(H2O)26+/3+(M= V, Cr, Mn, Fe, Co)自交换反应的内层重组能和活化能, 获得了与Marcus电子转移理论相一致的结果.     

溶液中M（H2O）6^2＋／3＋（M=V,Cr,Mn,Fe,Co）自交换电子转移体系内层重组能和活

通过建立电子转移过程的活化模型和重组模型,提出了用量子化学从头算方法研究电子转移过程内层重组能和活化能的新方法。在UMP2／6－311G水平上获得了5对过渡金属水合离子体系M（H2O）6^2 /3 (M=V,Cr,Mn,Fe,Co)自交换反应的内层重组能和活化能,获得了与Marcus电子转移理论相一致的结果。     

Co(H_2O)_6~(2 /3 )体系电子转移反应动力学的理论研究

电子转移过程在化学、生命科学、材料科学等领域普遍存在,几十年来一直受到国际学术界的广泛关注,是当前化学研究的前沿课题之一[1－6].过渡金属络合物间的电子转移是一类重要的电子转移过程,其动力学行为是理论和实验研究的热点[7－12].根据过渡态理论,这类自交换反应速率可表示为ket=κeZeffexp(－ΔE/RT)(1)其中,Zeff为核频率因子,对于溶液中的双分子反应其值约为1011dm3·mol－1·s－1[11];ΔE是活化能;κe称为电子因子,对于绝热反应κe=1.显然,活化能和电子因子是影响电子转移速率的两个关键因素.根据络合物的结构特点,一…     

Co(H2O)26+/3+体系电子转移反应动力学的理论研究

电子转移过程在化学、生命科学、材料科学等领域普遍存在,几十年来一直受到国际学术界的广泛关注,是当前化学研究的前沿课题之一[1-6].过渡金属络合物间的电子转移是一类重要的电子转移过程,其动力学行为是理论和实验研究的热点[7-12].根据过渡态理论,这类自交换反应速率可表示为     

Co(H2O)62+/3+体系电子转移反应动力学的理论研究

A theoretical scheme is presented which is based on an activation model for calculating the rate of the electron- exchange reaction between transition metal complexes in aqueous solution and applies to Co(H2O)6 2+/3+ electron transfer system. The activation parameter and activation energy of the system are obtained via the activation model. The slopes of the potential energy surfaces (curves) of the reacting system at the separated reactants are calculated from the fitted potential energy curves. The coupling matrix element is determined by using the perturbation theory and numerical integral method. Theoretical rate constants are obtained for the system at both UHF/6-311G and UMP2/6-311G levels. The agreement of the theoretical results with experimetal values is excellent. This fact indicates the scheme proposed is feasible and accurate in studying the self- exchange eletron transfer reaction.     

气相双原子分子自交换电子转移过程中重组能与活化能的相关分析

基于电子转移过程中的基本特征，提出了标度电子转移过程活化能和重组能的两种精确确定方案，并利用有关实验光谱数据拟合的精确势函数对气相双原子分子自交换过程的能量指标进行了确定．分析表明势能面的非谐性修正是重要的，该方案是合理的，所得结果吻合较好，并证明了重组能与活化能并不存在简单的４倍关系．     

Theoretical Study of the Inner/sphere Reorganization Energy and Activation Energy of Self/exchange Electron Transfer Reaction for M(H2O)26+/3+ (M=V, Cr, Mn, Fe and Co) Systems

通过建立电子转移过程的活化模型和重组模型, 提出了用量子化学从头算方法研究电子转移过程内层重组能和活化能的新方法. 在UMP26/311G水平上获得了5对过渡金属水合离子体系M(H     

非桥基配体对配合物的电子转移反应的影响——Cis-[Co(en)_2Cl_2]~+和Cis-[Co(en)_2(OH)_2Cl]~(2+)与Fe(Ⅱ)间电子转移反应

在成桥活化配合物反应机理基础上,Ogarl,P.Benson等人,根据中心离子的结构和成桥基配体的性质,用配位场理论,研究报导了水中配合物间电子转移反应的动力学行为。本文,在混合溶剂中配合物间电子转移反应机理研究的基础上,探索了非桥基配体Cl~-和H_2O,对H_2O、H_2O—McOH、H_2O—DMF等溶剂中Cis-[Co(cn)_2Cl_2]~+和Cis-[Co(cn)_2(OH_2)Cl]~(2+)和Fe(Ⅱ)间电子转移反应的影响。实验发现:相同条件下,无论在     

[Fe(CN)_6]~(4-)还原trans-[Co(en)_2(ImH_)2]~(3+)的电子转移反应动力学机理

在不同的温度下，考察了六氰合铁（Ⅱ）配阴离子［Ｆｅ（ＣＮ）６］４－还原ｔｒａｎｓ－［Ｃｏ（ｅｎ）２（ＩｍＨ）２］３＋的反应动力学。结果表明，反应遵循Ｈ．Ｔａｕｂｅ所提出的外配位界电子传递机理。在２５℃，Ｉ＝０．５ｍｏｌ·Ｌ－１，ｔｒａｎｓ－［Ｃｏ（ｅｎ）２（ＩｍＨ）２］３＋／［Ｆｅ（ＣＮ）６］４－反应体系的前驱配合物离子对形成常数为Ｑ１ｐ＝９８．９ｍｏｌ－１·Ｌ，电子转换速率常数为Ｋｅｔ＝１．３×１０－４ｓ－１，电子转移过程活化焓ΔＨ≠ｅｔ和活化熵ΔＳ≠ｅｔ分别为１４１．２ｋＪ·ｍｏｌ－１、５７３．５Ｊ·ｍｏｌ－１·Ｋ－１。     

H_2O-DMF混合溶剂中[Co(N_3)(NH_3)_5]~(2 )与[Fe(H_2O)_6]~(2 )间电子转移反应

研究了H_2O-DMF馄合溶剂中[Co(N_3)(NH_3)_5]~(2 )被Fe(Ⅱ)还原的反应速度变化规律后,证实:当DMF的摩尔分数X_(DMF)<0.3时,表观速度常数K_(aDD)随着X_(DMF)增大而增大;X_(DMF)>0.3时,K_(app)随着X_(DMF)增大而减小;K_(aDD)与[H~ ]有良好线性关系。 H_2O-DMF混合溶剂中所测定的吸收光谱显示出:近紫外区溶液的吸光度随X_(DMF)增大而增大,它反映出Fe(Ⅱ)的配位圈中配体H_2O分子被DMF分子逐渐置换而形成混合配体配合物的过程。 还观察到,在H_2O-DMF混合溶剂中,Fe(Ⅱ)的电极电势与X_(DMF)的依存性:随X_(DMF)增加,Fe(Ⅱ)的电极电势下降,但X_(DMF)>0.3后,Fe(Ⅱ)的电极电势几乎为一定值。 因此,反应速度的变化,可归因于Fe(Ⅱ)配位圈中水分子的被置换和Fe(Ⅱ)电极电势的变化上。     

Theoretical study of self‐exchange electron‐transfer reactions for the M(H2O)\documentclass{article}\pagestyle{empty}\begin{document}$^{2+/3+}_{6}$\end{document} (M = V,Cr, Mn,and Fe) systems

Based on an activation model, a available scheme to calculate the rate of the electron‐transfer reaction between transition‐metal complexes in aqueous solution is presented. Ab initio technique is used to determine the electron‐transfer reactivity of the type M(H₂O)$^{2+/3+}_{6}$ of transition‐metal complexes at the UMP2/6‐311G level. The activation parameters and activation energies of the electron‐transfer systems are obtained via the activation model. An alternative determining method of the potential energy surface (curve) slope at the crossing point is given in which the inner‐sphere contribution of potential energy surface slope is expressed as the sum of two separate reactants. Theoretical self‐exchange rate constants for M(H₂O)$^{2+/3+}_{6}$ (M = V, Cr, Mn, and Fe) systems are obtained at 298 K and zero ionic strength. The calculated results of the activation energy, electronic transmission factor, and electron‐transfer rate are compared with the corresponding quasi‐experimental values as well as those obtained from other methods, and better agreements are found. The present results indicate that the scheme can adequately describe the self‐exchange reactions involved in this study. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 32–41, 2000     

Coexistence of Two Thermally Induced Intramolecular Electron Transfer Processes in a Series of Metal Complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)2] (M=Co,Fe, and Ni) bearing Non‐Innocent Catechol‐Based Ligands: A Combined Experimental and Theoretical Study

The different thermally induced intermolecular electron transfer (IET) processes that can take place in the series of complexes [M(Cat‐N‐BQ)(Cat‐N‐SQ)]/[M(Cat‐N‐BQ)₂], for which M=Co ( 2 ), Fe ( 3 ) and Ni( 4 ), and Cat‐N‐BQ and Cat‐N‐SQ denote the mononegative (Cat‐N‐BQ^?) or dinegative (Cat‐N‐SQ^2?) radical forms of the tridentate Schiff‐base ligand 3,5‐di‐tert‐butyl‐1,2‐quinone‐1‐(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)imine, have been studied by variable‐temperature UV/Vis and NMR spectroscopies. Depending on the metal ion, rather different behaviors are observed. Complex 2 has been found to be one of the few examples so far reported to exhibit the coexistence of two thermally induced electron transfer processes, ligand‐to‐metal (IET^LM) and ligand‐to‐ligand (IET^LL). IET^LL was only found to take place in complex 3 , and no IET was observed for complex 4 . Such experimental studies have been combined with ab initio wavefunction‐based CASSCF/CASPT2 calculations. Such a strategy allows one to solicit selectively the speculated orbitals and to access the ground states and excited‐spin states, as well as charge‐transfer states giving additional information on the different IET processes.