A previous post posed the question; during the transformation of one molecule to another, what is the maximum number of electron pairs that can simultaneously move either to or from any one atom-pair bond as part of the reaction? A rather artificial example (atom-swapping between three nitrosonium cations) was used to illustrate the concept, in which three electron pairs would all move from a triple bond to a region not previously containing any electrons to form new triple bonds and destroy the old. Here is a slightly more realistic example of the phenomenon, illustrated by the (narcisistic) reaction below of a bis(sulfur trifluoride) carbene. Close relatives of this molecule are actually known, with either one SF3 of the units replaced by a CF3 group or a SF5 replacing the SF3[1]
References
- B. Poetter, K. Seppelt, A. Simon, E.M. Peters, and B. Hettich, "Trifluoroethylidynesulfur trifluoride, CF3C.tplbond.SF3, and its dimer", Journal of the American Chemical Society, vol. 107, pp. 980-985, 1985. https://doi.org/10.1021/ja00290a038