N-(ω-Dimethylammonioalkyl)-N´,N´,N´´,N´´-tetramethylguanidinium-dichlorides 5a, b are obtained from the chloroformamidinium salt 2 and diamines 3a, b. Their crystal structures reveal that the guanidinium ions are associated with the chloride ions via N-H· · ·Cl hydrogen bonds. By deprotonation of 5a, b with one equivalent of sodium hydroxide, the guanidinium chlorides 4a, b are accessible, and a further deprotonation leads to the aminoguanidines 6a, b, which hydrolyze in the presence of excessive aqueous sodium hydroxide to give the aminoalkylureas 7a, b.
The salts 9a, b and 10a, b were synthesized from 4a, b and 5a, b, respectively, by anion metathesis by means of sodium tetraphenylborate. 7a reacts with dimethyl sulfate to give the waxy ammonium salt 11a, which was converted to the crystalline tetraphenylborate salt 12a. The crystal structures of all the tetraphenylborates were determined by single-crystal X-ray diffraction analysis.