Methyl anion formal charge

Form C for the acid, however, contains two adjacent atoms having positive formal charges whereas form C for the anion does not. If we consider structures containing adjacent atoms of like charge as inadmissible, then covalent azides should have but two forms as compared with three for ionic azides. While such a correlation may be far fetched, azide behavior is predicted correctly. Azides of the alkali and alkaline-earth metals (ionic azides) decompose at much higher temperatures than do azides of the heavy metals or hydrazoie acid itself (which are predominately covalent). Similarly, simple organic azides such as methyl azide, CH3N3, for which only two admissible forms may be drawn tend to be less stable than acid... 

Equation (4.94) can be used to predict quantitatively the effect of heteroatoms in different positions in a given system. One can, for example, predict from the distribution of formal charge in the a-naphthylmethyl anion (21) that heteroatoms should have a greater effect in the ring carrying the exo-cyclic group. Thus the methyl groups in 1-methylisoquinoline (22) and... 

As the methylene protons of the cycloproparenes are formally benzylic, the compounds should be at least as acidic as the corresponding methyl arenes. Simple extended Huckel calculations concur and predict some stabilization of 6 from charge delocalization the cycloproparenyl anion (6) is expected to be accessible. Indeed, treatment of 1 with butyl-lithium at -78 °C provides an organolithium that has been characterized by NMR and shown to be monomeric in solution. Both the H NMR (H(d 1.91, H(2/s) 5.83, H(3/4) 6.13 ppm, respectively) and NMR (C(,) 31.3, C(,a/5a) 149.0, 99.1, C(3/4) 120.4 ppm, respec-... 

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