Copper(II), zinc(II) and cobalt(II, III) coordination compounds with tartaric acid anion as ligand were synthesized. These are:
(1) {[Cu2(C4H4O6)2(H2O)2](H2O)4}n
(2) {[Zn2(C4H4O6)2(H2O)2](H2O)3}n
(3) {[Co2(C4H4O6)2(H2O)2](H2O)3}n
(4) Cu2(C4H4O6)(C4H5O6)2(NH3)5(H2O)5
(5) Zn(C4H5O6)2(NH3)4(H2O)
(6) Co2(C4H4O6)(C4H5O6)2(NH3)2,5(H2O)
(7) (CH6N3)[Co2(C4H3O6)2(H2O)2](CH5N3)2(H2O)4
As starting compounds copper(II), zinc(II) and cobalt(II) salts were used. Syntheses were performed at room and at elevated temperature with continuous stirring. Distilled water and acetonitrile were used as solvents.
The compounds 1, 2, and 3 were already described, however different procedures were applied for them. X-ray powder diffractograms confirmed an identity of these compounds to our samples. These findings are in agreement also with the elemental CHN analysis results.
For the compounds 4, 5 and 6 no appropriate match within CSD database were found, thus their structural formulae were determined via the elemental CHN analysis results. X-ray powder difractograms of the compounds 4 and 6 are very similar, therefore an isostructurality is suggested for them. Single crystals were gained during the synthesis of the compound 7 suitable for the structural analysis. This enabled us to determine the dinuclear structure for this compound revealing cobalt ions in different oxidation states, namely 2+ in 3+.
An obvious difference of the electronic spectra of the cobalt compounds is clearly related to this, as the compound 7 reveals more bands than very similar spectra of Co(II) only compounds 3 and 6.
Low value of the magnetic measurements for the compounds 4, 6 and 7 is in agreement with their dinuclearity.
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