Thiocarbonyl compounds thermodynamics

As mentioned above (see Scheme 1), three main directions of the decomposition of intermediates that formed are possible when phosphorus and arsenic ylides react with compounds bearing C=X bonds 5,6,19,63,64,88 (i) elimination of R3E15=X to form olefins (Wittig type reaction) (ii) retro-Wittig type decomposition and (iii) elimination of R3E15 and formation of three-membered cycles (Corey-Chaykovsky type reaction). According to the data of Erker and coworkers,12,13,51 under kinetic control, the reaction of phosphorus ylides with thiocarbonyl compounds also affords phosphines and thiiranes, whose further transformations lead to olefins and R3PS under thermodynamic control. 

As indicated earlier, quantum-mechanical methods, particularly molecular orbital (MO) treatments, are tools used to explore essentially all fields of thiocarbonyl chemistry. Hence, we shall first review the current status and scope of this methodology with respect to a number of important topics. This shall be followed by a survey of the experimental and theoretical data available on the thermodynamics, structure and selected aspects of the reactivity of these compounds. 

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