Authors:Katalin Mészáros Szécsényi, V. Leovac, R. Petković, Ž. Jaćimović, and G. Pokol
The deaquation of two isostructural compounds of general formula [M(HL)2(H2O)2](NO3)2 (M=Co, Ni, HL=3,5-dimethyl-1H-pyrazole-1-carboxamidine) is discussed in the view of their crystal and molecular structure. The compounds contain the same
number and type of hydrogen bonds of the adjacent nitrate ions, only in the opposite orientation. On the basis of their deaquation
pattern such a small difference may be detected, i.e., methods of thermal analysis are sensitive enough to show very small
Authors:I. Oja Açik, J. Madarász, M. Krunks, K. Tõnsuaadu, D. Janke, G. Pokol, and L. Niinistö
Thermal decomposition of precursor xerogels for TiO2,
obtained by gelling of acetylacetonate-modified titanium(IV) tetraisopropoxide
(prepared at Ti-alkoxide:acetylacetone molar ratios of 1:1 (Ti-1) and 1:2
(Ti-2)) in boiling 2-methoxyethanol, was monitored by simultaneous TG/DTA/EGA-MS
and EGA-FTIR measurements. Thermal degradation processes of Ti-1 and Ti-2
in the temperature range of 30–700C consist of six mass loss steps,
the total mass loss being 46.3% and 54.4%, respectively. EGA by FTIR and MS
revealed release of H2O below 120C; followed by
evolution of acetone and acetic acid between approximately 100 and 320C,
and that of CO2 up to 560C. Acetylacetone is evolved
to a significant extent from sample Ti-2 at 120–200C.
Authors:K. Mészáros Szécsényi, V. Leovac, Ž. Jaćimović, V. Češljević, A. Kovács, and G. Pokol
The synthesis of copper(II) chloride complexes with 3,5-dimethylpyrazole, 1-carboxamidine-3,5-dimethylpyrazole, 5-amino-4-carboxamide-1-phenylpyrazole
and 4-acetyl-3-amino-5-methylpyrazole is described. The compounds are characterized by elemental analysis, FT-IR spectroscopy,
thermal methods, magnetic moment and molar conductivity measurements. Thermal decomposition of the dichloro-(3,5-dimethylpyrazole)-copper(II)
complex results in an unstable intermediate with a stochiometric composition. The decomposition of the other compounds is
Authors:K. Mészáros-Szécsényi, J. Päiväsaari, M. Putkonen, L. Niinistö, and G. Pokol
The coupling of a quadrupole mass spectrometer (QMS) via a heated capillary to a commercial thermogravimetric analyser is described. The amu and temperature ranges available were up to 1000 amu and 1500°C, respectively. The system was evaluated with test compounds, yielding gaseous species in the m/z range of 17-80, and then used for the study of thermal behaviour of scandium dipivaloyl methanate or Sc(thd)3 which is discussed in detail. Sc(thd)2 appears as the major Sc-containing species with m/z=411 in the gas phase at 200-300°C.
Authors:K. Mészáros-Szécsényi, E. Ivegeš, V. Leovac, A. Kovács, G. Pokol, and Ž. Jaćimović
Complexes represented by the general formula [MCl2L2] (M(II)=Zn, Mn, Co) and complexes of [Cu3Cl6L4] and CuSO4L24H2O, CoSO4L23H2O, [ZnSO4L3] where L stands for 3-amino-5-methylpyrazole were prepared. The complexes were characterized by elemental analysis, FT-IR
spectroscopy, thermal (TG, DTG, DSC and EGA) methods and molar conductivity measurements. Except for the Zn-complexes, the
magnetic susceptibilities were also determined.
Thermal decomposition of the sulphato complexes of copper(II) and cobalt(II) and the chloro complexes of cobalt(II) and manganese(II)
resulted in well-defined intermediates. On the basis of the IR spectra and elemental analysis data of the intermediates a
decomposition scheme is proposed.
Authors:V. Leovac, E. Ivegeš, K. Szécsényi, K. Tomor, G. Pokol, and S. Gal
Solvate complexes of UO22+ andN(1), N(4)-bis(salicylidene)-S-methylisothiosemicarbazone, (H2Me-L1), of general formula [UO2(Me-L1)S] (S= H2O, MeOH, EtOH, Py, DMF and DMSO) were synthesized. The methanolic UO22+” adducts of N(1)-benzoylisopropylidene-N(4)-salicylidene-S-alkylisothiosemicarbazone, (H2R-L2,R=Me, Prn) of general formula [UO2(R-L2)· MeOH], were also prepared. Thermal decomposition of the complexes was investigated in air and argon. The complexes decompose
to α-U3O8 in air, while in argon the decomposition is not completed up to 1000 K. The temperature and the mechanism of decomposition
of the complexes are a function of the solvent belonging to the inner coordination sphere.