SYNTHESIS AND STRUCTURE OF BINUCLEAR GERMANIUM(IV)-THULIUM(III) COMPLEX WITH 1,3-DIAMINO-2-PROPANOLTETRAACETIC ACID

Abstract

New heteronuclear Germanium(IV)‑ Thulium (III) complex with 1,3‑diamino‑2‑propanoltetraacetic acid (H5hpdta) was synthesized for the first time. Comparative analysis of IR‑spectrum of complex and ligand proved the absence of free COOH‑groups in the structure of compound – there are no ν(СООН) absorption bands in the IR‑spectra of complex. The significant shift of the ν(С‑N) absorption band (about 45 cm-1), ν(СН) (about 5 cm-1) and presence of ν(Ge‑N) and ν(Tm‑N) bands evidences that protonized nitrogen atoms form coordination bonds with metals. Two pairs of νas(СОО) and νs(СОО) absorption bands of carboxylate ions together with stretching vibrations of Ge‑O and Tm‑O bonds confirm their coordination to metals. There are also presented νas(Ge‑O‑Tm), νs(Ge‑O‑Tm), δ(OH) and δ(Ge‑OH) absorption bands in the IR‑spectrum of complex that indicates the bridging nature of deprotonated hydroxy and hydroxyl group of ligand and also hydrolyzed form of germanium in the structure of compound. During thermal decomposition of the complex in the temperature range of 90‑150 °С as a result of the endothermic effect, two molecules of crystallization water are removed into the gas phase. The further endoeffects at around 150‑220° C are seen with the removal of three coordinated water molecules. The oxidative destruction of the complexes is accompanied by the three exoeffects in temperature range 220‑800 °С. The products of final thermal destruction at 1000°C are GeO2 and Tm2O3. According to the X‑Ray diffraction data of complex [Ge(ОН)(μ‑hpdta)(μ‑OH) Tm(H2O)3]*2H2O, the six‑coordinated atom of Germany and octa‑coordinated atom of Thulium are bound by the bridging oxygen atom of hydroxyl group and hydroxyl-anion. Thecoordination polyhedron of Ge(1) atom is a distorted octahedron formed by three O atoms of deprotonated carboxyl and hydroxyl groups, the nitrogen atom of the hpdta5– and two O atoms of two hydroxyl-anions. The coordination polyhedron of octa-coordinated atom of Thulium is formed by of the O atoms of deprotonated carboxyl, deprotonated hydroxyl groups of the hpdta5–, the bridging oxygen atom of hydroxyl‑anion, three O atoms of coordinated water molecules and one N‑atom of the hpdta5–.