Spectral,thermal and magnetic investigations of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH₃C₆H₃(CO₂)₂]·nH₂o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition of scandium(III) o-nitrobenzoate,o-chlorobenzoate,o-methylbenzoate,o-hydroxybenzoate and o-aminobenzoate in air atmosphere

The conditions of thermal decomposition of scandium o-nitrobenzoate, o-chlorobenzoate, o-methylbenzoate, o-hydroxybenzoate and o-aminobenzoate were studied. On heating, the carboxylates decompose in two steps, only scandium anthranilate decomposes in one step. The hydrated complexes first lose water of crystallization and then are transformed to Sc₂O₃. The dehydration of the complexes is an endothermic process and the decomposition of anhydrous complexes is strongly exothermic. Scandium o-nitrobenzoate decomposes explosively.     

Thermal decompositions of scandium(III) 2,4-dinitrobenzoate, 3,5-dinitrobenzoate, 2,4-dichlorobenzoate and 3,4-diaminobenzoate in air atmosphere

The thermal decompositions of scandium 2,4-dinitrobenzoate, 3,5-dinitrobenzoate, 2,4-dichlorobenzoate and 3,4-diaminobenzoate were studied. On heating, the carboxylates decompose in two steps. The hydrated complexes first lose crystallization water and are transformed to Sc₂O₃. The dehydration of the complexes is accompanied by an endothermic effect and decomposition of the anhydrous or monohydrate complezes by strong exothermic effects. Scandium 2,4-dinitrobenzoate and 3,5-dinitrobenzoate decompose explosively.     

Thermal decomposition of scandium(III) benzenetricarboxylates in air and nitrogen atmospheres

The conditions of thermal decomposition of scandium(III) hemimellitate, trimellitate and trimezinate in air and nitrogen atmospheres have been studied. On heating, the benzene-tricarboxylates of Sc(III) decompose in two stages. First, the hydrated complexes lose crystallization water; heating in air finally yields Sc₂O₃, and heating in a nitrogen atmosphere Sc₂O₃ and C. The dehydration of the complexes is associated with strong endothermic effects. The decomposition of benzenetricarboxylates in air is accompanied by an exothermic effect and in nitrogen by an endothermic effect. The activation energies of the dehydration and decomposition reactions have been calculated for the Sc(III) benzenetricarboxylates.     

Spectral and thermal studies of Y(III) and heavy lanthanide 4-chlorophthalates

Summary Complexes of heavy lanthanide(III) (Gd-Lu) and Y(III) with 4-chlorophthalic acid were prepared and their IR spectra, solubility in water at 295 K and thermal decomposition were investigated. When heated the complexes with general formula Ln₂[ClC₆H₃(CO₂)₂]₃·nH₂O where n=6 for Tb, Dy(III), n=4 for Gd, Ho and Er(III), n=2 for Tm-Lu(III) and n=3 for Y(III) decompose to the oxides Ln₂O₃, Tb₄O₇ with intermediate formation of oxochlorides LnOCl.     

Spectral and thermal studies of light lanthanide 4-chlorophthalates

Conditions for the preparation of light lanthanide 4-chlorophthalates were investigated and their composition, solubility in water at 295 K, IR spectra and thermal decomposition were determined. 4-Chlorophthalates of La–Nd(III) were prepared as complexes with general formula NaLn[ClC₆H₃(CO₂)₂]₂, whereas compounds of Sm and Eu have general formula Ln₂[ClC₆H₃(CO₂)₂]₃·6H₂O. During heating all complexes decompose to oxides with intermediate formation of oxochlorides. The carboxylate groups in the complexes studied are bidentate bridging (Sm, Eu) or bidentate chelating and bridging (La–Nd).     

Thermal decomposition of scandium(III) 2-chloro-, 30chloro, 4-chloro- and 2,4-dichlorobenzoates in an air atmosphere

The conditions of thermal decomposition of hydrated scandium(III) chlorobenzoates were studied. On heating, the carboxylates decompose in many steps. The hydrated complexes first lose water of crystallization in one or two steps and then anhydrous compounds are transformed to Sc₂O₃ with formation of Sc₂O(CO₃)₂ intermediate. The dehydration of the complexes is accompanied by an endothermic effect and the decomposition of anhydrous complexes by strong endothermic effects. The anhydrous complexes are melted at 255–300°C.     

Thermal decompositions of scandium(III) m-nitrobenzoate,m-chlorobenzoate,m-hydroxybenzoate and m-aminobenzoate in air atmosphere

The conditions of thermal decomposition of scandium(III) m-nitrobenzoate, m-chlorobenzoate, m-hydroxybenzoate and m-aminobenzoate were studied. On heating, most of these carboxylates decompose in two steps; only scandium(III) 3-aminobenzoate decomposes in one step. The hydrated complexes first lose crystallization water and are then transformed to Sc₂O₃. The hydration of the complexes is accompanied by an endothermic effect, and the decomposition of the anhydrous complexes by a strong exothermic effect. Scandium(III) 3-nitrobenzoate decomposes explosively.     

Spectroscopic and Thermal Studies of Rare Earth Element 4-Methylphthalates

Complexes of lanthanide(III) (La-Lu) and Y(III) with 4-methylphthalic acid were prepared and their IR spectra, solubility in water at 295 K and thermal decomposition were investigated. Rare earth complexes were obtained as solids with a 2:3 ratio of metal to organic ligand. COO^– groups in the prepared complexes act as bidentate chelating and bidentate bridging. During heating they are dehydrated in one (La-Tm) or twosteps (Yb, Lu and Y) and then decompose to the oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇. This revised version was published online in July 2006 with corrections to the Cover Date.