Generation and Study of the Reactivity of α-Ammonium Distonic Radical Cations in Solution

Crystal structures of three newN-halomethylated quaternary ammonium salts

“…A cation-interaction between aromatic and ammonium ions is known to play an important role in many biological systems (Ma & Dougherty, 1997;Dougherty, 2013;Sussman et al, 1991;Chen et al, 2011). Part of our research interest is focused not only in understanding the reactive nature of alpha ammonium distonic radical cations which are generated from N-halomethylated quaternary ammonium salts (Ríos et al, 1996;Ríos, Bartberger et al, 1997), but also in trying to understand how these salts behave against Leishmania parasites (Ríos-Vá squez et al, 2015). The recognition of the occurrence of some supramolecular interactions in these salts may lead to a better understanding of the likely novel biological binding sites, and therefore to new suggestions about biocatalytic mechanisms.…”

“…These features clearly rule out an intramolecular cation-interaction for this molecule in the solid state. However, in studies of distonic radical cation (Ríos et al 1996;Yates et al, 1986), evidence is presented that the active conformation of the alkylamino side chain is oriented Table 1 Hydrogen-bond geometry (Å , ) for (I).…”

(Bromomethyl)trimethylammonium tetrafluoroborate

“…They are precursors to alpha distonic radical cations (i.e. species with separate radical and charged sites) (Yates et al, 1984;Rios et al, 1996). Distonic radical cations are important central intermediates in dissociation reactions of many ionized molecules and have been produced from certain X-and -ray irradiated amino acids (Budzinski & Box, 1971;Minegishi, 1977).…”

“…Distonic radical cations are important central intermediates in dissociation reactions of many ionized molecules and have been produced from certain X-and -ray irradiated amino acids (Budzinski & Box, 1971;Minegishi, 1977). These species have been studied extensively in the gas phase (Stirk & Kenttamaa, 1991;Stirk et al, 1992;Chyall & Kenttamaa, 1994) and to a smaller extent in the solution phase (Rios et al, 1996). Studies of the species continue, with the expectation of gaining a better understanding of the biological consequences of ionizing irradiation.…”

“…Distances from the anion to the N atom and to the CH 2 Br C atom are of interest with respect to potential crowding at the site of subsequent radical generation. Studies have shown that the trimethylammoniomethylene radical [(CH 3 ) 3 N + CH 2 ] readily performs hydrogen-abstraction reactions but reluctantly performs intermolecular alkene addition (Rios et al, 1996) This is especially peculiar as intramolecular alkene additions of analogous alkenyl-substituted ammonio distonic radicals [CH 2 CH(CH 2 ) n (CH 3 ) 2 N + CH 2 ] occur very readily. The shortest NÁ Á ÁB distances are 4.567 (3) Å to B at (1 À x, 1 À y, 2 À z), 4.584 (3) Å at (x, y, z), and 5.203 (3) Å at (x + 1, y, z).…”