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The conditions of thermal decomposition of La, Ce(III), Pr, Nd, Sm, Eu and Gd diglycolates have been studied. On heating, the diglycolates of Ce(III), Pr, Eu and Gd lose crystallization water and yield anhydrous salts, which are then transformed into oxides.
Abstract
The physico-chemical properties and thermal stability in air of light lanthanide 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates were compared and the influence of the position of –OCH3 substituent on their thermal stability was investigated. The complexes of these series are crystalline, hydrated or anhydrous salts with colours typical of Ln3+ ions. The carboxylate group is a bidentate, chelating ligand. The thermal stability of 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates of rare earth elements was studied in the temperature range 273–1173 K. The positions of methoxy groups in benzene ring influence the thermal properties of the complexes and their decomposition mechanism. The different thermal properties of the complexes are connected with various influence of inductive and mesomeric effects of –OCH3 substituent on the electron density in benzene ring.
Abstract
The physico-chemical properties and thermal stabilities in air of rare earth element 4-chloro-3-nitrobenzoates and 5-chloro-2-nitrobenzoates were compared and the influence of the positions of the Cl and NO2 substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated or anhydrous salts with colours typical of Ln3+. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO2 group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of Y and the lanthanides were studied in the temperature range 273-1173 K, but those of the 5-chloro-2-nitrobenzoates of these elements were studied only at 273-523 K, because they decompose explosively above 523 K. The positions of the Cl and NO2 substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO2 substituents on the electron density in the benzene ring.
Summary
Foreword to this special volume of Discrete Geometry consists primarily of articles presented at one of three consecutive meetings held in Calgary and Banff during a period in May of 2005.
Complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 4-chloro-2-methoxybenzoic acid anion
Physico-chemical properties
Abstract
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)2 nH2O 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 χM vs. 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.
Abstract
The physico-chemical properties and thermal stability in air of rare earth element 4-chloro-2-nitro- and 4-chloro-3-nitrobenzoates of the general formulae Ln(C7H3NO4Cl)3
2H2O were compared and the influence of the position of the Cl and NO2 substituents on their thermal stabilities was investigated. The complexes of both series are crystalline, hydrated salts with colours typical of Ln3+. The carboxylate group in these complexes is a bidentate, chelating ligand. The NO2 group in the chloronitro complexes does not undergo isomerization. The thermal stabilities of the 4-chloro-3-nitrobenzoates of rare earth elements were studied in the temperature range 293–1173 K, but those of 4-chloro-2-nitrobenzoates of those elements were studied only at 293–523 K because they decompose explosively above 523 K. The positions of the Cl and NO2 substituents on the benzene ring influence the thermal properties of the complexes and their decomposition mechanisms. The different thermal stabilities of the complexes are connected with various inductive and mesomeric effects of the Cl and NO2 substituents on the electron density in benzene ring.
