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Reduction of Phosphine Oxide by Using Chlorination Reagents and Dihydrogen: DFT Mechanistic Insights
Author(s) -
Zhu Hui,
Qu ZhengWang,
Grimme Stefan
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900379
Subject(s) - chemistry , exergonic reaction , phosphine oxide , phosphonium , phosphine , borane , reagent , electrophile , inorganic chemistry , medicinal chemistry , metal , oxide , frustrated lewis pair , chloride , catalysis , lewis acids and bases , organic chemistry
Extensive DFT calculations provide detailed mechanistic insights into the metal‐free reduction of phosphine oxide Ph 3 P=O by using chlorination reagents O=CClX (X=COCl, Cl, OCCl 3 and Ph) and H 2 . Fast electrophilic attack to the P=O group oxygen atom is favored by exergonic CO 2 release to form phosphonium Ph 3 PCl + and chloride Cl − , which may slowly cleave H 2 by an unstable HPh 3 PCl complex yielding Ph 3 PH + and Cl − ions in solution. Moderate heating is required to accelerate the slow H 2 ‐activation step and to eliminate HCl to form phosphine Ph 3 P instead of Ph 3 PH + Cl − salt as the desired product. Though partially quenched by Ph 3 P (and reactant Ph 3 P=O if present), borane B(2,6‐F 2 C 6 H 3 ) 3 can be still combined with Cl − and Ph 3 P as reactive frustrated Lewis pair (FLP) catalysts.