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Rare earth elements 1,3,5-benzenetricarboxylates were prepared as solids of the general formula Ln(C9H3O6nH2O, where n=6 for La-Dy and n=4 for Ho-Lu,Y. Their solubilities in water at 293 K are of the order 10-4-10-6 mol dm-3. The IR spectra of the complexes indicate that the carboxylate groups are bridging and bidentate chelates. Hydrated 1,3,5-benzenetricarboxylates lose water molecules during heating in one step (La-Tb), two steps (Y, Ho-Tm) or three steps (Dy, Yb, Lu). The anhydrous complexes are stable up to 573-742 K and decompose to oxides (Ce-Lu) at higher temperatures.

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Abstract  

Complexes of lanthanides(III) (La-Lu) and Y(III) with 3,4,5-trihydroxybenzoic acid (gallic acid) were obtained and their thermal decomposition, IR spectra and solubility in water have been investigated. When heated, the complexes with a general formula Ln(C7H5O5)(C7H4O5nH2O (n=2 for La-Ho and Y: n=0 for Er-Lu) lose their crystallization water and decompose to the oxides Ln2O3, CeO2, Pr6O11, and Tb4O7, except of lanthanum and neodymium complexes, which additionally form stable oxocarbonates such as Ln2O2CO3. The complexes are sparingly soluble in water (0.3·10–5–8.3·10–4 mol dm–3).

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Abstract  

Complexes of lanthanide(III) (La–Lu) and Y(III) with 1-hydroxy-2-naphthoic acid were obtained as crystalline compounds with a general formula Ln[C10H6(OH)COO]3nH2O:n=6 for La–Tm and Y, n=2 for Yb and n=0 for Lu. IR spectra of the prepared complexes were recorded, and their thermal decomposition in air were investigated. Spectroscopic data suggest that in the coordination of metal-organic ligand only oxygen atoms from the carboxylate group take part. When heated, the complexes decompose to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7 with intermediate formation of Ln(C11H7O3)(C11H6O3).

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Abstract  

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)3,3-dimethylglutarates were investigated and their quantitative composition, solubility in water at 293 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with general formula MC7H10O4nH2O (n=0−2) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes of Mn(II),Co(II), Ni(II) and Cu(II) are dehydrated in one step and next all the anhydrous complexes decompose to oxides directly (Mn, Co, Zn) or with intermediate formation free metal (Ni,Cu) or oxocarbonates (Cd). The carboxylate groups in the complexes studied are bidentate. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II)attain values 5.62, 5.25, 2.91 and 1.41 M.B., respectively.

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Abstract  

New mixed-ligand complexes of general formulae Mn(4-bpy)(CCl3COO)2⋅H2O, Ni(4-bpy)2(CCl3COO)2⋅2H2O and Zn(4-bpy)2(CCl3COO)2⋅2H2O (where 4-bpy=4,4’-bipyridine) were obtained and characterized. The IR spectra, conductivity measurements and other physical properties of these compounds were discussed. The central atoms M(II) form coordinate bonds with title ligands. The thermal behaviour of the synthesized complexes was studied in air. During heating the complexes decompose via different intermediate products to Mn3O4, NiO and ZnO; partial volatilization of ZnCl2was observed. A coupled TG-MS system was used to the analysis of the principal volatile thermal decomposition products of Mn(II) and Ni(II) complexes. The principal volatile mass fragments correspond to: H2O+, OH+, CO+ 2, HCl+, Cl+ 2, CCl+ and other.

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Journal of Thermal Analysis and Calorimetry
Authors: K. Kafarska, D. Czakis-Sulikowska, and W. Wolf

Abstract  

New metal(II) complexes with empirical formulae Co(ibup)2·4H2O, Cd(ibup)2·3H2O, Co(nap)2·H2O, Cd(nap)2·3H2O (where ibup=(CH3)2CHCH2C6H4CH(CH3COO) and nap=CH3O(C10H6)CH(CH3COO)) were isolated and investigated. The complexes were characterized by elemental analysis, molar conductance, IR spectroscopy and thermal decomposition. The thermal behavior was studied by TG, DTG, DTA methods under non-isothermal conditions in air atmosphere. The hydrated complexes lose water molecules in first step. All complexes decompose via intermediate products to corresponding metal oxides CoO and CdO. A coupled TG-MS system was used to detect the principal volatile products of thermolysis and fragmentation processes of Co(nap)2·H2O. The IR spectra of studied complexes revealed also absorption of the carboxylate group. Principal concern with the position of asymmetric, symmetric frequencies. The value of their separation allow to deduce about type of coordination these groups.

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Summary The complexes of lanthanides(III) and Y(III) with 4-hydroxy-3-methoxybenzoic acid (vanillic acid) of the formula Ln(C8H7O4)3×nH2O where n=2 for La(III), Pr(III); n=3 for Nd(III); n=4 for Sm(III); n=5 for Ce(III) and n=6 for Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), Lu(III) and Y(III) were prepared and IR spectra and X-ray diffraction patterns and their thermal decomposition were investigated. The carboxylate group in the studied complexes is a bidentate chelating or a bidentate chelating and bridging ligand. They are crystalline compounds. When heated, the complexes lose their crystallization water and decompose to the oxides Ln2O3, CeO2, Pr6O11 and Tb4O7. The intermediate decomposition products of complexes of La(III) to Lu(III) (except Ce(III)) are oxocarbonates Ln2O2CO3.

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Abstract  

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) 3-methyladipates were investigated and their qualitative composition and magnetic moments were determined. The IR spectra and powder diffraction patterns of the complexes prepared of the general formula M(C7H10O4)nH2O (n=0-11) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Co, Ni) or two steps (Mn, Zn) losing all crystallization water molecules (Co, Ni) or some water molecules (Mn, Zn) and then anhydrous (Co, Ni, Cu) or hydrated complexes (Mn, Zn) decompose directly to oxides (Mn, Co, Zn) or with intermediate formation the mixture of M+MO (Ni, Cu). The carboxylate groups are bidentate (Mn, Co, Ni, Cu) or monodentate (Zn). The complexes exist as polymers. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.48, 4.49, 2.84 and 1.45 B.M., respectively.

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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part IV. Thermal and spectral properties of 2-chloro- and 2-bromobenzoato Cu(II) complexes with nicotinamide and different bonded water molecules

Journal of Thermal Analysis and Calorimetry
Authors: E. Jóna, L’. Lajdová, M. Loduhová, S. Lendvayová, V. Pavlík, J. Moncol’, P. Lizák, and S. C. Mojumdar

Elemental analyses (C, H, and N) were carried by means of Carlo Erba 1106 Analyser. The infrared (IR) spectra were obtained on Philips analytical PU 9800 FTIR spectrometer in the range 400–4,000 cm −1 . Thermal decomposition studies were carried

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Abstract  

Several isomorphic groups of micas: Muscovite-Phengite-Muscovite-Li-Muscovite; Biotite-Zinnwaldite-Lepidolite and Biotite-Phlogopite were investigated by DTA, TG and DTG. Octehedral vacancies and the sites of octahedral cationic occupancy were determined from IR-spectra of the hydroxyls. The influence of a composition and fine structure of the micas on the shape of the thermal curves was discussed. A one to one correspondence between the isomorphic series members and individual thermal curves makes it possible to determine the chemical composition of a mica sample. The combination of thermal and IR-spectra of hydroxyl analyses permits to link the Order-Disorder data with thermal properties of mica.

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