Three coordination compounds with 5-sulfosalicylic acid (H3L) and isonicotinamide (C6H6N2O) were synthesized. These compounds are blue-green copper(II) 1, pink cobalt(II) 2 and white zinc(II) compound 3. The structures of copper and zinc compound have already been determined as polymeric {[Cu(HL)(C6H6N2O)(H2O)2]·2H2O}n, and monomeric Zn(HL)(C6H6N2O)2(H2O)2]·2H2O. Powder diffractograms and CHN elemental analyses of the isolated compounds corroborate with the known structures. No known structure for the compound 2 with cobalt was found, so its powder diffractogram cannot be compared with the known structure. Due to a similarity of the CHN analysis of 2, with the proposed formulae of Co(HL)(C6H6N2O)(H2O)5, and the CHN data for the compound 1, similar structures for them are suggested. The IR spectra of all three title compounds are in accordance with a presence of all ligands written in their respective formulae. On the other hand, the electronic spectra of all three compounds differ clearly, being in agreement with three different metals and different arrangement of the ligands in their coordination spheres. The colours of the isolated compounds are consistent with the absorption of red light for Cu(II) compound, yellow-green for Co(II) compound along with an absence of the d-d bands for the Zn(II) compound.
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