STABLE CARBONIUM IONS .79. 1H AND 13C NUCLEAR MAGNETIC RESONANCE SPECTROSCOPIC INVESTIGATION OF HYDROXY- AND ALKOXYCARBONIUM IONS . DETERMINATION OF MAGNITUDE AND SIGN OF GEMINAL COUPLING CONSTANTS

An nmr study of 13C-enriched hydroxycarbonium ions (protonated formaldehyde) is reported. Homo-nuclear and heteronuclear double-resonance techniques were used to determine the relative signs of the geminal and vicinal coupling constants. A geminal coupling constant of +21.7 Hz was found and both vicinal coupling constants were found to be positive. Similar values of the geminal coupling constants were found in the methoxy-carbonium ion and the chloromethoxycarbonium ion. The allylic coupling constants in the alkoxycarbonium ions were also determined, the trans-allylic coupling being greater than the cis. The results are discussed in terms of comparisons with related uncharged compounds. The question of the assignment of the isomers of protonated methyl formate is also discussed. © 1969, American Chemical Society. All rights reserved.