Insights into the Mechanistic Role of Diphenylphosphine Selenide, Diphenylphosphine, and Primary Amines in the Formation of CdSe Monomers

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• 作者：Ting Qi ; Hua-Qing Yang ; Dennis M. Whitfield ; Kui Yu ; Chang-Wei Hu
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：120
• 期：6
• 页码：918-931
• 全文大小：878K
• ISSN：1520-5215

文摘

The formation mechanism of CdSe monomers from the reaction of cadmium oleate (Cd(OA)₂) and SePPh₂H in the presence of HPPh₂ and RNH₂ was studied systematically at the M06//B3LYP/6-31++G(d,p),SDD level in 1-octadecene solution. Herein, SePPh₂H, HPPh₂, and RNH₂ act as hydrogen/proton donors with a decreased capacity, leading to the release of oleic acid (RCOOH). The longer the radius of the coordinated atom is, the larger the size of the cyclic transition state is, which lowers the activation strain and the Gibbs free energy of activation for the release of RCOOH. From the resulting RCOOCdSe–PPh₂, for the formation of Ph₂P–CdSe–PPh₂ (G), SePPh₂H acts as a catalyst, in which the turnover frequency determining transition state (TDTS) is characteristic of the Se–P bond cleavage. For the formation of RHN–CdSe–PPh₂ (H), SePPh₂H also serves as a catalyst, in which the TDTS is representative of the N–H bond cleavage. For the formation of Ph₂PSe–CdSe–NHR (I), HPPh₂ behaves as a catalyst, in which the TDTS is typical of the Se–P and N–H bond cleavage. The rate constants increase as k_I < k_H < k_G, which is in good agreement with our previous experimental observations reported. The present study brings insight into the use of additives such as HPPh₂ and RNH₂ to synthesize colloidal quantum dots.