DIFFERENT-LIGAND COMPLEXES OF GERMANIUM(IV) WITH MANDELIC, GALLIC ACIDS AND HETEROCYCLIC AMINES
Optimal synthesis methods of germanium(IV) coordination compounds with mandelic (H2Mand), gallic (H4Gal) acids and 1,10-phenantroline (phen), 2,2′-bipyridine (bipy) in water solution were developed. Their composition was established. Thermogravimetric analysis of coordination compounds with mandelic acid 1, 2 showed that complexes are crystallohydrates. Thermal destruction of both compounds is similar: the endothermic effect with the maximum at 100 °C and 90 °C is observed in the temperature range 70-230 °C (for 1) and 80-240 °C (for 2) respectively. This effect is followed by the weight loss about 3,3% for 1 and 6,1% for 2, which corresponds to one and two water molecules. The difference in thermal destruction of 3 and 4 (with gallic acid) is absence of low-temperature endo-thermic effects. Two consequent exothermic effects in the interval 260-520 °C are observed for 3 (for 4 - one exothermic effect at 340-520 °C), during which phen and bipy molecules ware eliminated. During the X-Ray analytics there was established that 3 (CCDC 1862035; e-mail: deposit@ccdc.cam.ac.uk) is different-ligand complex with distorted octahedral polyhedron, which is formed with four oxygen atoms of two molecules of gallic acid and two nitrogen atoms of 1,10-phenantroline. In the crystal 3 molecules are bonded between each other through hydrogen bonds and form three-dimensional net. In crystal c emptiness between molecules with the volume 1084.76 Å3 (which is 33% from the total unit cell volume) is formed along the crystallographic axis. In this article it is shown that mononuclear different-ligand complexes with octahedral coordination polyhedron of germanium [Ge(Mand)2(phen)]∙2H2O (1), [Ge(Mand)2(bipy)]∙H2O (2), [Ge(H2Gal)2(phen)] (3), [Ge(H2Gal)2(bipy)] (4) were formed. Their structures were suggested.