Structure of 5-methylcytosine hydrochloride

Abstract

C₅H₈N₃O⁺ Cl^- M_r= 161·6, monoclinic, P2₁/c, a=6·431 (1), b= 16·132(2), c= 7.030(1)Å,β =97·33(1)°, V=723·29Å, Z=4, D_x =1·48, D_m = 1·49 Mg m^-3,λ(Cu Ka) = 1·5418 Å,μ= 0·423 mm-', F(OOO) = 336, T= 295 K, R = 0·042 for 1146 observed reflections with 1> 30(1). The cytosine base is protonated at N(3). The crystal Structure is st abillzed by hydrogen bonds of the type N(3)-H···Cl and direct electrostatic interactions between Cl and atoms of the base. Molecules related by the c-glide Arc nearly parallel (angular deviation ⋍17°) and are separated by approximately 3·S Å. A comparison' of the stacking interactions observed in the present structure and in related molecules seggests that 5-methylation or the cytosine base generally results in reduced ring overlap.