Salt forms of sulfadiazine with alkali metal and organic cations

The structures of four salt forms of sulfadiazine (SDH) with alkali metal cations are presented. Three contain the deprotonated SD anion. These are the discrete complex [Li(SD)(OH2)2], (I), and the coordination polymers [Na(SD)]n, (II), and [K(SD)(OH2)2]n, (III). The Na complex (II) is a three-dimensional coordination polymer whilst the K complex (III) has two crystallographically independent [K(SD)(OH2)2] units per asymmetric unit, Z′ = 2, and gives a two dimensional coordination polymer whose layers propagate parallel to the crystallographic ab plane. The different bonding modes of the SD anion in these three complexes is discussed. Structure (IV) contains protonated SDH2 cations and the Orange G (OG), C16H10N2O7S2, dianion in a structure with formula [SDH2]2[Na(OG)(OH2)4]2·3H2O. The [Na(OG)(OH2)4]2 dimers have antiparallel naphthol ring structures joined through two Na centres that bond to the hydrazone anions through the O atoms of the ketone and sulfonate substituents. The structures of the salts formed on reaction of SDH with 2-aminopyridine and ethanolamine are also presented as [C5H7N2][SD], (V), and [HOCH2CH2NH3][SD]·H2O, (VI), respectively. Structure (V) features a heterodimeric R2 2(8) hydrogen bond motif between the cation and the anion whilst structure (VI) has a tetrameric core of two cations linked by a central R2 2(10) hydrogen bonded motif which supports two anions linked to this core by R3 3(8) motifs.