Nitrogen-14 nuclear quadrupole resonance study of the guanidinium ion

Numerous ionic compounds containing the guanidinium ion have been investigated by means of nitrogen-14 nuclear quadrupole resonance techniques. The nitrogen resonance spectrum of the amino groups of the quanidinium ions yielded, with a few exceptions, an average e 2qQ/h = 3553.6 kHz and an average asymmetry parameter η = 0.39493. The Townes-Dailey theory is employed in interpreting the quadrupole coupling data to yield the electronic populations of the bonds. In two cases (guanidinium acetate and guanidinium carbonate) large deviations from the average quadrupole coupling parameters were observed. These deviations are interpreted, by means of a modified Townes-Dailey theory, to indicate that hydrogen bonds are formed between the guanidinium ions and the anions.