Structures of five salt forms of disulfonated monoazo dyes

The structures of five s-block metal salt forms of three disulfonated monoazo dyes are presented. These are [Na2L1(OH2)4]n (I), [CaL1(OH2)4]n (II), [NaL2(OH2)2]n.2nH2O (III), [Mg(OH2)6][L2]2·8H2O (IV) and [BaL3(OH2)4]n.2nH2O (V) where L1 = azobenzene-3,3′-disulfonate, L2 = 4-aminodiazeniumylbenzene-3,4′-disulfonate
and L3 = 4-amino-2-methyl-5-methoxyazobenzene-2′,4′-disulfonate. Structure (III) is that obtained on crystallizing the commercial dyestuff Acid Yellow 9 [74543–21-8]. The Mg species is a solvent-separated ion-pair structure and the others are all coordination polymers with bonds from metal to sulfonate groups. (I) is a three-dimensional coordination polymer, (V) is a two-dimensional coordination polymer and both (II) and (III) are one-dimensional coordination polymers. The coordination behaviour of the azo ligands and the water ligands, the dimensionality of the coordination polymers and the overall packing motifs of these five structures are contrasted to those of monosulfonate monoazo congers. It is found that (I) and (II) adopt similar structural types to those of monosulfonate species but that the other three structures do not.