| Popis: |
In this work, the new coordination compounds of Nd(III) and Er (III) with b-diketonate ligands containing an unsaturated substituent at the a-position of the chelate ring (dimethylheptendione and dimethyloctendione) were synthesized. The composition and structure of the synthesized compounds were studied using physicochemical methods of analysis such as the elemental, NMR, IR and electron spectroscopy and thermogravimetric analysis. Using IR spectroscopy, it was established that ligands are bidentate-cyclically coordinated to metals. The results of thermogravimetric analysis indicate that the complexes are nonvolatile and decompose to oxides of the corresponding metals, and their coordination sphere is supplemented with water molecules. From the shape and position of the bands in the electronic absorption spectra and diffuse reflection spectra, it was determined that for the complexes Ln (b-dik)3.nH2O (Ln =Nd, Er, b-dik = dmhpd, dmod, n = 2-3) the tetragonal symmetry of the nearest coordination environment; coordination polyhedron is a square antiprism. When comparing the diffuse reflectance spectra of dimethylheptendionate and dimethyloktendionate complexes among themselves and with the previously studied complexes with methacrylacetophenone, it was noted that the shape of the spectra and the spectral splitting of the bands for the corresponding metals are not significantly different. This allows to conclude, that the coordination environment of the studied b-diketonate compounds is close.Based on the band shifts in the electronic spectra, the covalence parameters of the Ln–O bond and the oscillator strength were calculated, from which it was also shown that the nature of the substituent affects the covalence parameters, but does not affect the symmetry and structure of the coordination polyhedron. Based on the studies conducted, the monomeric structure of the synthesized complexes was definitely confirmed. Accordingly, they can be used in further work as monomers in polymerization reactions and the preparation of precursors of luminescent materials. |
