Thermochemical mimicry

While thermochemical mimicry has been shown for ionic chlorides and cyanides, the same study showed that near-constancy vanished as the corresponding chlorides and cyanides became more covalent57. Perhaps we should not be disappointed that the cyano/chloro difference of the enthalpies of formation of RC1 and RCN, S20 (g Cl, CN R) (equation 20),... 

For the iodides, we know of no established thermochemical mimicry, although the comparative closeness of the electronegativities of carbon and iodine is suggestive. More precisely, the value for the enthalpies of zz-propyl to isopropyl iodide rearrangement, 10.0 ... 

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