Authors:Agnieszka Czylkowska and Mirosława Markiewicz
A novel mixed-ligand complexes with empirical formulae: Dy(4-bpy)(CCl2HCOO)3 · H2O and Ln(4-bpy)1.5(CCl3COO)3 · 2H2O (where Ln(III) = Ce, Nd) were prepared and characterized by chemical and elemental analysis and IR spectroscopy, conductivity
(in methanol, dimethyloformamide and dimethylsulfoxide). Analysis of the diffractograms showed that the obtained complexes
are crystalline. Way of metal-ligand coordination discussed. The thermal properties of complexes in the solid state were studied
under non-isothermal conditions in air atmosphere. During heating the complexes decompose via intermediate products to the oxides: Ln2O3 (Nd, Dy) and CeO2. TG-MS system was used to analyse principal volatile thermal decomposition and fragmentation products evolved during pyrolysis
of Dy(4-bpy)(CCl2HCOO)3 · H2O in air.
New solid complexes of a herbicide known as dicamba (3,6-dichloro-2-methoxybenzoic acid) with Pb(II), Cd(II), Cu(II) and Hg(II)
of the general formula M(dicamba)2·xH2O (M=metal, x=0-2) and Zn2(OH)(dicamba)3·2H2O have been prepared and studied. The complexes have different crystal structures. The carboxylate groups in the lead, cadmium
and copper complexes are bidentate, chelating, symmetrical, in Hg(dicamba)2·2H2O - unidentate, and in the zinc salt - bidentate, bridging, symmetrical. The anhydrous compounds decompose in three stages,
except for the lead salt whose decomposition proceeds in four stages. The main gaseous decomposition products are CO2, CH3OH, HCl and H2O. Trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition products are oxychlorides
of metals and CuO.
Transition metal dithiocarbamate complexes, [M(S2CN(C2H5)(CH2CH2OH)] (M=Co, Ni, Cu, Zn and Cd) have been prepared and characterized by elemental analysis and infrared spectra. Thermal decomposition
of all the complexes occurs in two or three stages. The first stage in all the complexes is always fast with 65-70% mass loss.
In all cases the end product is metal oxide except in the case of cobalt complex which gives Co metal as an end product. During
decomposition of copper complex, first CuS is formed at ~300C which is converted into CuSO4 and finally CuO is formed. However, decomposition in helium atmosphere yields CuS. SEM studies of transition metal dithiocarbamates
reveal needle shape crystalline phase at room temperature and formation of metal sulphide/oxide at higher temperatures. The
activation energy varies in a large range of 33.8-188.3 kJ mol-1, being minimum for the Cu complex and maximum for the Zn complex possibly due to d10 configuration. In the case of Ni, Zn and Cd complexes the order of reaction is two suggesting bimolecular process involving
intermolecular rearrangement. However, in other cases it is a unimolecular process. Large negative values of ΔS# for all the complexes suggest that the decomposition process involves rearrangement.
Authors:Erika Szunyogová, Dagmar Mudroňová, Katarína Györyová, Radomíra Nemcová, Jana Kovářová, and Lenka Piknová-Findoráková
Spectroscopic (IR), thermoanalytical (TG/DTG, DTA) and biological methods
were applied to investigate physicochemical and biological properties of seven
zinc(II) complex compounds of the following formula Zn(HCOO)2·2H2O
(I), Zn(HCOO)2·tph (II), Zn(CH3COO)2·2H2O (III), Zn(CH3COO)2·tph
(VI), Zn(CH3CH2CH2COO)2·2H2O (VII), where tph=theophylline, phen=phenazone. The formation of various
intermediates during thermal decomposition suggests the dependence on the
length of aliphatic carboxylic chain and type of N-donor ligand (tph, phen).
The final product of the thermal decomposition was ZnO. The antimicrobial
activity of these complexes were tested against G+
and G– bacteria. Strong inhibitive effect
was observed towards E. coli, salmonellae
and Staph. aureus.
Authors:Wiesława Ferenc, Beata Bocian, and J. Sarzyński
Four new complexes of 2,3,4-trimethoxybenzoic acid
anion with manganese(II), cobalt(II), nickel(II) and copper(II) cations were
synthesized, analysed and characterized by standard chemical and physical
methods. 2,3,4-Trimethoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) are
polycrystalline compounds with colours typical for M(II) ions. The carboxylate
group in the anhydrous complexes of Mn(II), Co(II) and Ni(II) is monodentate
and in that of Cu(II) monohydrate is bidentate bridging one. The anhydrous
complexes of Mn(II), Co(II) and Ni(II) heated in air to 1273 K are stable
up to 505–517 K. Next in the range of 505–1205 K they decompose
to the following oxides: Mn3O4,
CoO, NiO. The complex of Cu(II) is stable up to 390 K, and next in the range
of 390–443 K it loses one molecule of water. The final product of its
decomposition is CuO. The solubility in water at 293 K is of the order of
10–3 mol dm–3
for the Mn(II) complex and 10–4 mol dm–3
for Co(II), Ni(II) and Cu(II) complexes. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in 2,3,4-trimethoxybenzoates experimentally determined in the range of
77–300 K change from 5.64–6.57 μB (for Mn2+),
4.73–5.17 μB (for Co2+), 3.26–3.35 μB
(for Ni2+) and 0.27–1.42 μB (for Cu2+).
2,3,4-Trimethoxybenzoates of Mn(II), Co(II) and Ni(II) follow the Curie–Weiss
law, whereas that of Cu(II) forms a dimer.
Authors:Reema Porob, Sitara Khan, S. Mojumdar, and V. Verenkar
Nickel manganese succinato-hydrazinate (NiMn2(C4H4O4)3·6N2H4),
has been synthesized for the first time by a novel precursor technique and
characterized by IR, AAS and XRD. Thermal decomposition of the compound was
studied from room temperature (rT) to 800°C
by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis
besides isothermal mass loss studies. The compound was found to decompose
autocatalytically, once ignited. TG-DSC shows two steps decomposition i.e.
dehydrazination followed by decarboxylation. The infrared spectral studies
show the N–N stretching frequency at 972 cm–1
suggesting a bidentate bridging structure of hydrazine molecule in (NiMn2(C4H4O4)3·6N2H4).
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+,
Co2+, Ni2+, Cu2+
and Zn2+ were obtained as polycrystalline solids
with general formula M(C8H6ClO3)2nH2O and colours typical for M(II) ions (Mn – slightly pink, Co –
pink, Ni – slightly green, Cu – turquoise and Zn – white).
The results of elemental, thermal and spectral analyses suggest that compounds
of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and
Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate.
The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II)
and Zn(II) heated in air to 1273 K are dehydrated in one step in the range
of 323–411 K and form anhydrous salts which next in the range of 433–1212
K are decomposed to the following oxides: Mn3O4,
CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are
CuO and Cu. The solubility value in water at 293 K for all complexes is in
the order of 10–3 mol dm–3.
The plots of χMvs.
temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II)
follow the Curie–Weiss law. The magnetic moment values of Mn2+,
Co2+, Ni2+ and Cu2+
ions in these complexes were determined in the range of 76−303 K and
they change from: 5.88–6.04 μB for Mn(C8H6ClO3)24H2O, 3.96–4.75
μB for Co(C8H6ClO3)25H2O, 2.32–3.02 μB for Ni(C8H6ClO3)25H2O and 1.77–1.94
μB for Cu(C8H6ClO3)24H2O.
Authors:Erika Szunyogová, Katarína Györyová, Daniela Hudecová, Lenka Piknová, J. Chomič, Zuzanna Vargová, and V. Zeleňák
The thermal decomposition of the complexes Zn(form)2⋅2phen
(IV), where phen=phenazone, form=formiate,
ac=acetate, prop=propionate, but=butyrate has been studied in air by TG/DTG
and DTA methods. The possible mechanism of the thermal decomposition was proposed.
The final product of thermal decomposition was ZnO. IR data show unidentate
coordination of carboxylate group to Zn(II) ion. The complexes were tested
against various strains of microorganisms and their efficiency decrease in
the sequence yeasts >bacteria>filamentous fungi.
Authors:Xue-Gang Chen, Shuang-Shuang Lv, Ping-Ping Zhang, Lu Zhang, and Ying Ye
, respectively. Fourier transform infrared (FT-IR) spectra were scanned by a NICOLET 560 ESP FT-IR spectrometer (NICOLET, USA) in the range of 4,000–400 cm −1 . The surface morphologies and chemical compositions of the samples were studied by an S-4800 scanning
Authors:Yi-Xi Zhou, Li-Xian Sun, Zhong Cao, Jian Zhang, Fen Xu, Li-Fang Song, Zi-Ming Zhao, and Yong-Jin Zou
synthesized by a one-pot solution reaction and a solvothermal method, respectively, by slightly modifying the literature recipe [ 15 , 16 ]. Their structures were characterized by powder X-ray diffraction and FT-IRspectra. Their thermal decomposition