Vìsnik Odesʹkogo Nacìonalʹnogo Unìversitetu: Hìmìâ (May 2018)
SYNTHESIS, STRUCTURE AND THERMAL PROPERTIES OF GERMANIUM(IV), TIN(IV) COMPLEXES WITH RS-MANDELIC ACID
Abstract
Germanium(IV) and tin(IV) coordination compounds [Ge(Mand)2(H2O)2]∙2H2O (1), (H3O) [Ge(OH)(Mand)2] (2), [Sn(Mand)(HMand)2] 5Н2О (3) were synthesized for the first time with the RS-mandelic acid. Thermogravimetric analysis of 1-3 shows, that compounds are crystalohydrates. Thermal destruction of 1 and 2 is gradational. In the thermal interval 80-160°С an endothermic effect with the maximum at 140°С and weight loss, which corresponds to two molecules of crystalline water, is observed. At 160-220°С two more water molecules are deleted from the inner sphere of the complex. On the thermogram of 2 in the thermal interval 140-240°С the first endoeffect with the weight loss of two water molecules, that are bonded more fixedly, then crystalline ones, is observed. In contrast with 1 and 2, during the heating of 3 in the thermal interval of 80-170°С, an endothermic effect, which is followed by elimination of 5 crystalline water molecules, is observed. Disappearing of ν(С=О) = 1716 сm-1 absorption band and presence of νas(СОО–) = 1690 сm-1 in 1 (pic. 2.4 б), νas(СОО–) = 1688 сm-1, νs(СОО–) = 1323 сm-1 in 2 and νas(СОО–) = 1654 сm-1, νs(СОО–) =1322 сm-1 in 3 shows the presence of bonding between carboxyl group and germanium (tin) in 1-3. The bonding between hydroxyl group and metals is confirmed by presence of ν(С-О) absorption band at 1064 сm-1. Herewith in the spectra of complexes 1 and 2 deformation vibrations С-ОН are absent, and in spectrum of 3 they are presented at 1494 сm-1. The bonding is also confirmed by presence of valence vibrations bands of the Ge-O bond equal 744 сm-1 in 1 and 737 сm-1 in 2, and in the spectrum of 3 by presence of ν(Sn-О) = 567 сm-1. In the spectrum of 2 the clear absorption band at 834 сm-1, which corresponds to the deformation vibrations of Ge-O-H-group, is found. Consequently, germanium is presented in the compound in the hydrolyzed form. The schemes of structures are presented.
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