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Abstract  

This paper reports the investigation of the thermal stability of a series of new complexes with azo and azomethinic chromophores of the type [Er(HL)2(H2O)2](HO); ((B) H2L: o,o’-dihydroxy-azobenzene (A); (D) H2L: N-(2-hydroxy-1-naphthalidene)aminophenol (C); (F) H2L: N-(2-hydroxy-1-naphthalidene)anthranilic acid (E)). The complexes thermal behaviour steps were investigated and comparatively presented with those of corresponding ligand. The thermal transformations are complex processes according to TG and DTG curves including phenol elimination, oxidative condensation and thermolysis processes. The final product of complexes decomposition is Er2O3.

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Summary This paper reports the investigation of the thermal stability of two new complexes with allylacetoacetate anion, Cu(C7H9O3)2 (1) and Ni(C7H9O3)2(OH2)2 (2), respectively. The bonding and stereochemistry of the complexes have been characterized by IR, electronic and EPR spectra. The main decomposition steps were evidenced. The two complexes exhibit a different thermal behaviour. Thus, the copper complex suffers an oxidative degradation of allylacetoacetate ligand leading to copper carbonate, which is decomposed to copper oxide. The Ni(II) complex lose the water molecules first and then the organic ligand decomposition occurs. An intermediary malonaldehyde complex seems to be obtained. Complex (1) presents in vitro antimicrobial activity.

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Summary This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type M(phen)(C3H3O2)2(H2O)y ((1) M=Mn, y=0; (2) M=Ni, y=2; (3) M=Cu, y=1; (4) M=Zn, y=2; phen=phenanthroline and C3H3O2 is acrylate anion). The thermal behaviour steps were investigated. The thermal transformations are complex processes according to TG and DTG curves including dehydration, oxidative condensation of acrylate and thermolysis processes. The final products of decomposition are the most stable metal oxides.

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Abstract  

The complexes of the type SnCl4(HL)·EtOH and SnCl2L2 (HL 1 : the Schiff base resulted in 1:1 condensation of isatin and aniline; HL 2 : the Schiff base resulted in 1:1 condensation of isatin and p-toluidine) have been synthesized and characterized. The thermal analysis of the new ligands and complexes has evidenced the thermal intervals of stability and also the thermal effects that accompany them. The Schiff bases thermal transformations consist in phase transitions, Carom–N bond cleavage and thermolysis processes. The different nature of the complexes generates their different thermal behaviour. The complexes lead in three steps to SnO2 and in all cases the Schiff bases degradation generates a pyrrolidone-coordinated derivative. As for the SnCl4(HL)·EtOH complexes, the SnCl4 formed during the last step is involved in two competitive processes, one consists in their volatilisation while the other one leads to SnO2. As result the SnO2 residue is smaller than the theoretically expected.

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Abstract  

This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type M(dipy)(C3H3O2)2(H2O)y ((1) M: Mn, y=1; (2) M: Ni, y=2; (3) M: Cu, y=1; (4) M: Zn, y=2; dipy: 2,2’-dipyridine and C3H3O2 is acrylate anion). The thermal behaviour steps were investigated. The thermal transformations are complex processes according to TG and DTG curves including dehydration, oxidative condensation of acrylate and thermolysis processes. The final products of decomposition are the most stable metal oxides.

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The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [MLCln]· mH2O ((1) M:Ni, L:L(1), n=1, m=2; (2) M:Cu, L:L(2), n=1, m=2; (3) M:Ni, L:L(3), n=2, m=0; (4) M:Cu, L:L(3), n=1, m=2) are presented in this paper. The ligands L(1)-L(3) have been synthesised by template condensation of 1,2-diaminoethane with formaldehyde and 2-amino-1,3,4-thiadiazole-5-thiole or 2-acetamino-1,3,4-thiadiazole-5-sulfonamide. The bonding and stereochemistry of the complexes have been characterised by IR, electronic and magnetic studies at room temperature. The thermal behaviour provided confirmation of the complex composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands and/or the metallic ions generates a different thermal behaviour for complexes. The complexes do not show biological activity against HIV virus.

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Journal of Thermal Analysis and Calorimetry
Authors: R. Olar, M. Badea, D. Marinescu, E. Iorgulescu, and S. Stoleriu

Summary This paper deals with the first investigation concerning the thermal behaviour of Ni(II) complexes with ligands having biguanide moieties. The new complex [NiL(1)](ClO4)2·2.5H2O (1) with the Schiff base resulted in [2+1] condensation of N,N-dimethylbiguanide with pentane-2,4-dione (L(1)) and the complex [Ni2L(2)](ClO4)4 (2), with the Schiff base, L(2), resulted through the oxidative condensation of L(1) have been synthesized and characterised. The bonding and stereochemistry of the complexes have been characterized by IR and electronic spectra. The cyclic voltammograms show the characteristic waves for mononuclear and respectively binuclear Ni(II) complexes and indicate that both complexes exhibit catalytic effects on the CO2 electrochemical reduction. The thermal behaviour provided confirmation of the complexes composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands generates a different thermal behaviour for complexes.

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Abstract  

This paper reports an investigation of the thermal stabilities of the class of coordination compounds containing lanthanide ions Ln(III) (Ln=La, Sm, Eu, Dy, Er), Co(II) ions and oxalate anions C2O 4 2– . The thermal decomposition steps were identified, and in some cases the values of the non-isothermal kinetic parameters were determined.

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Summary The complexes of the type [M(HDMBG)Cl3] ((1) M:Co; (2) M:Zn;) and [M(DMBG)Cl2] ((3) M:Pd; (4) M:Pt; DMBG: N,N-dimethylbiguanide) present in vitro antimicrobial activity. The modification evidenced in IR and 1H NMR spectra (in the case of complex (2)) was correlated with the presence of N,N-dimethylbiguanide ion as unidentate, coordinated through N3 and of N,N-dimethylbiguanide as chelate, coordinated through N1 and N4 respectively. The electronic reflectance spectrum showed the d-d transition for complex (1) characteristic for the tetrahedral surrounding while the spectra for complexes (3) and (4) have the characteristic pattern for square-planar stereochemistry. The cyclic voltammetric data show the characteristic waves for mononuclear complexes of the metallic ions presented below. The thermal analysis has evidenced the thermal intervals of stability and also the thermodynamics effects that accompany them. The different nature of the ligands generates a different thermal behaviour for complexes.

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