Two N,N-Dimethylbiguanidium Salts Displaying Double Hydrogen Bonds to the Counter-Ions.

Abstract

The crystal structures of N,N-dimethylbiguanidium oxalate monohydrate, C 4 H 13 N 5 2+ .C 2 O 4 2- .H 2 O, (I), and N,N-dimethyl-biguanidium sulfate monohydrate, C 4 H 13 N 5 2+ .SO 4 2- .H 2 O, (II), show that both compounds contain the same N,N-dimethylbiguanidium dication. In (I), two independent oxalate ions lie about inversion centres. Strong double hydrogen bonds, with D...A distances of 2.658 (2) and 2.830 (3) A in (I), and 2.722 (3) and 2.815 (3) A in (II), are present between N atoms of the N,N-dimethylbiguanidium moieties and either the carboxylate group of the oxalate anion or the sulfate anion.