Triphenylmethyl tetramethylammonium

In an attempt to demonstrate the existence of pentavalent nitrogen, Schlenk and Holtz studied the reaction of triphenylmethyl sodium with tetramethylammonium chloride (52). The highly colored material was strongly conducting in polar solvents and could be identified as a salt, the stability of which is due to the resonance stabilization of the triphenyl-methide anion. In the absence of such stabilizing substituent effects (53), as with n-butyl or another alkyllithium reagent, a metalation of the tetramethylammonium cation occurs, which leads to type I products (18) ... 

More conclusive results were obtained by Schlenk and Holz as much as twenty years later. In reactions of tetramethylammonium chloride with triphenylmethyl-sodium4) and, later, benzylsodium 5), bright red compounds were formed which according to elemental analyses did contain five organic groups per nitrogen atom. Although the formulation of these compounds, e.g. 

Contrary to the resonance stabilized triphenylmethyl-4), benzyl-5) and fluorenyl-anions 8, phenyllithium did not leave the tetramethylammonium ion unaffected. Instead, it removed a proton to form trimethylammonium-methylide (<5) 19), the prototype of that interesting class of zwitter-ionic compounds for which Wittig coined the name ylides 20). 

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