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arXiv physics/0212010physics.chem-ph
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六氨钴绝热自交换理论

Theory of adiabatic Hexaamminecobalt-Self-Exchange

R. G. Endres, M. X. LaBute, D. L. Cox

摘要:

我们用第一性原理密度泛函理论方法,半经典Marcus理论和已知的电荷转移参数重新研究了热诱导Co(NH_3)_6^{2+/3+} [Co(II/III)]氧化还原反应.我们证实了一个先前提出的机制,涉及Co(II)的激发态(^2E_g)在过渡态区域变得低于基态(^4T_1g)。这大大降低了过渡态势垒约6.9千卡/摩尔,并导致自旋允许和绝热电子交换过程。我们的计算结果与以前的实验结果相一致,即Co(III)的自旋激发能(^3T_1g)和Co(II)的光学吸收峰(^2E_g)在实验上没有发现.我们的速率是6 × 10^{-3} 1/Ms的数量级,因此比以前通过实验确定的快2个数量级。

英文摘要:

We have reexamined the thermally induced Co(NH_3)_6^{2+/3+} [Co(II/III)] redox reaction using the first principles density-functional-theory method, semiclassical Marcus theory, and known charge transfer parameters. We confirm a previously suggested mechanism involving excited state (^2E_g) of Co(II) which becomes lower than the ground state (^4T_1g) in the transition state region. This lowers the transition state barrier considerably by about 6.9 kcal/mol and leads to a spin-allowed and adiabatic electron exchange process. Our calculations are consistent with previous experimental results regarding the spin-excitation energy (^3T_1g) of Co(III), and the fact that an optical absorption peak (^2E_g) of the Co(II) species could not be found experimentally. Our rate is of order 6 10^{-3} 1/Ms and hence 2 orders of magnitude faster than determined previously by experiments.

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