Ground and Excited State Surfaces for the Photochemical Bond Cleavage in Phenylmethylphenylphosphonium Ions

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• 作者：Sebastian Thallmair ; Benjamin P. Fingerhut ; Regina de Vivie-Riedle
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：October 17, 2013
• 年：2013
• 卷：117
• 期：41
• 页码：10626-10633
• 全文大小：392K
• 年卷期：v.117,no.41(October 17, 2013)
• ISSN：1520-5215

文摘

Photolytic bond cleavage is a well-established method to generate carbocations for organic synthesis. Changes in the leaving group have a large influence on the chemical yield. The underlying potential energy surfaces governing the initial process are mostly unknown. We provide potential energy surfaces of ground and excited states on the CASSCF/CASPT2 level of theory for the charged precursor phenylmethylphenylphosphonium ion. We present the electronic and structural changes accompanying the excitation process and the subsequent bond cleavage. Inter-ring charge-transfer processes play a crucial role in the Franck鈥揅ondon region. Beyond the Franck鈥揅ondon region, competing reaction pathways emerge connected through conical intersections. The phenylmethylphenylphosphonium ion is used as a model system for the commonly used diphenylmethyltriphenylphosphonium ion. The appropriateness of the model is tested by CC2 calculations of the excitation spectrum.