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Salt forms of the monoazo dye Mordant Orange 1
Alan R Kennedy1, Connor MacCall1, Michael W Reid1
1Department of Pure & Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, Scotland, United Kingdom.
None:
The crystal structures of eight salt forms of the carboxylate-functionalized monoazo dye Mordant Orange 1 are presented and discussed, primarily in terms of their coordination behaviour. The relatively non-polar metals Mg and Li give the solvent-separated ion-pair structures hexaaquamagnesium bis{2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate} tetrahydrate, [Mg(H2O)6](C13H8N3O5)2·4H2O, and tetraaqualithium 2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoate dihydrate, [Li(H2O)4](C13H8N3O5)·2H2O, respectively. The alkaline earth metals Sr and Ba give isostructural catena-poly[[[(dimethylformamide)strontium(II)]-μ-aqua-bis{μ-2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoato}] dimethylformamide disolvate] and the barium(II) analogue, {[M(C13H8N3O5)2(DMF)(H2O)]·2DMF}n (M = Sr, Ba; DMF is dimethylformamide, C3H7NO), and a crystallographic mirror plane passes through the metal centre and the DMF ligand. These are 1D coordination polymers that propagate via M-O-M bridges where the O atom is from a carboxylate group or from a water ligand. For the Na, Rb and mixed Cs/Na salt forms, namely, poly[tetra-μ-aqua-diaquabis{μ-2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoato}disodium(I)], [Na2(C13H8N3O5)2(H2O)6]n, poly[tetra-μ-aqua-bis{μ-2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoato}dirubidium(I)], [Rb2(C13H8N3O5)2(H2O)4]n, and poly[tetra-μ-aqua-diaquabis{μ-2-hydroxy-5-[(E)-(4-nitrophenyl)diazenyl]benzoato}caesium(I)sodium(I)], [NaCs(C13H8N3O5)2(H2O)6]n, the nitro substituent was found to be as competitive in its ability to bond to metal as the carboxylate group. For Na, this gave a 1D coordination polymer, where Na4 units link through the length of the azo anions and via bonds to both nitro and carboxylate groups. For both the Rb and the mixed Cs/Na salt forms, higher metal coordination numbers and more extensive bridging interactions give 3D coordination polymers.
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