Thermal behavior of some new complexes bearing ligands with polymerisable groups

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.     

Thermal behavior of some new triazole derivative complexes

A series of new complexes with mixed ligands of the type [ML(C₃H₃O₂)₂]·nH₂O (((1) M=Mn, n=1; (2) M=Co(II), n=2; (3) M=Ni(II), n=4; (4) M=Cu(II), n=1.5; (5) M=Zn(II), n=0; L=3-amino-1,2,4-triazole and (C₃H₃O₂)=acrylate anion) were synthesized and characterised by chemical analysis and IR data. In all complexes the 3-amino-1,2,4-triazole acts as bridge while the acrylate acts as bidentate ligand except for complex (5) where it is found as unidentate. The thermal behaviour steps were investigated in nitrogen flow. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion and 3-amino-1,2,4-triazole degradation respectively. The final products of decomposition are the most stable metal oxides, except for complex (4) that leads to metallic copper.     

Thermal behavior of some new isatin complexes

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, C_arom–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.     

Thermal stability of some new complexes bearing ligands with polymerizable groups

A series of new complexes with mixed ligands of the type M(4,4’-dipy)(C₃H₃O₂)₂(H₂O)_y ((1) M=Mn, y=2; (2) M=Ni, y=2; 4,4’-dipy: 4,4’-dipyridyl and C₃H₃O₂ is acrylate anion) and respectively M₂(4,4’-dipy)(C₃H₃O₂)₄(H₂O)_y ((3) M=Cu, y=0; (4) M=Zn, y=1). The modification evidenced in IR spectra was correlated with the presence of acrylate ion as unidentate in the case of complex (1) and as bidentate for others complexes. The electronic reflectance spectra showed the d–d transition for complex (1) and (2) characteristic for the octahedral surrounding while the spectrum for complex (3) have the characteristic pattern for square-pyramidal stereochemistry. The thermal behaviour steps were investigated. The thermal transformations are complex processes according to TG and DTG curves including dehydration, acrylate ion oxidative degradation and thermolysis process of aromatic amine. The final products of decomposition are the most stable metal oxides.     

Thermal behaviour of benzenesulfenamides and of their chromium carbonyl complexes

Benzenesulfenamides with the formula R-S-N-(R)₂ (R=C₆H₅ andR=NC₄H₈O, C₇H₇ and C₆H₁₁) and their chromium carbonyl complexes were studied by means of TG and mass spectrometric methods. The thermal behaviour of the compounds the stabilities of free sulfenamides are lower than those observed for the corresponding chromium carbonyl complexes. Combined thermogravimetry — mass spectrometry results suggest that the fragmentation mechanism of the carbonyl complexes involves cleavage of the Cr-S and Cr-CO bonds while that of sulfenamide depends mainly on the dissociation rates of the NR₂ groups.This work was partially supported by the Departamento técnico de Investigation of the Universidad de Chile, Grant Q3280/9324.     

Photochemistry of macromolecular metal complexes. II. Synthesis,thermal, and photochemistry of some polypyridyl complexes of chromium (III) bound to macromolecules

Polymer coordinated chromium(III) complexes [Cr(bpy)₂(PAA)₂]⁺, 1 , [Cr(bpy)₂-(PMA)₂]⁺, 2 , [Cr(phen)₂(PAA)₂]⁺, 3 , and [Cr(phen)₂(PMA)₂]⁺, 4 , [where bpy, phen, PAA and PMA are, respectively, 2,2′-bipyridine, 1,10-phenanthroline, poly(acrylic acid), and poly(methacrylic acid)] were synthesized. The polymer–chromium(III) complexes were characterized by elemental and spectroscopic analyses. Thermal substitution reactions of these macromolecular chromium(III) complexes in basic solutions lead to the replacement of the polypyridyl ligand by hydroxide ion while in strong acidic solutions the polymer complexes precipitate out. The photochemical reactions are qualitatively similar to that of the thermal reactions and the quantum yields are dependant on the pH of the medium. Further, lower quantum yields were observed for the aquation of the polymer complexes in comparison with the monomeric chromium(III) complexes and the results are discussed in terms of the effect of the polymer environment. Flash photolysis of 1 and 3 results in the formation of transients with maxima at 480 nm for 1 and 470 nm, 580 nm for 3 . The decay of the transients were found to obey first order kinetics and the rate constants were determined. The transients were suggested to be the alkyl-chromium complexes. Flash photolysis of 2 and 4 does not produce transients which is interpreted to be due to the presence of a methyl group in the ligand which hinders the formation of the carbonchromium bond.     

Single-crystal electronic spectra of some quadrate chromium(III) complexes

Polarised electronic spectra of trans-[Cr(tmd)₂F₂](ClO₄), trans-[Cr(en)₂(dma)₂](ClO₄)₃, trans-[Cr(en)₂(dmf)Cl](ClO₄)₂ and trans-[Cr(en)₂(dmf)Br](ClO₄)₂ have been measured at 77 K (tmd = trimethylenediamine; dma = N,N-dimethylacetamide; dmf = N,N-dimethylformamide; en = ethylenediamine, pn = propylenediamine). The observed quartet bands have been given definitive quadrate assignments based on polarisation characteristics. The four-component quadrate quartet bands have been uncovered and assigned also in the unpolarised crystal spectrum of trans-[Cr(en)₂(dmf)₂](ClO₄)₃ at 77 K and the solution spectrum of trans-[Cr(en)(pn)F₂]⁺. The band maxima derived by gaussian analysis in these spectra have been fitted with the theoretical energy equations of d³ configuration in quadrate ligand fields including full configuration interaction. The ligand field parameters Dq, Dt, and Ds and the election correlation parameter, B, extracted by such a fitting, have been compared with those obtained for other similar systems earlier. The significance of the ligand field symmetry parameters and the translated angular overlap model parameters is discussed.     

Thermal stability of some new complex compounds with alylacetoacetate as ligand

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.     

Thermal stability of new complexes bearing both acrylate and aliphatic amine as ligands

This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type [M(en)(C₃H₃O₂)₂]·nH₂O ((1) M=Ni, n=2; (2) M=Cu, n=0; (3) M=Zn, n=2; en=ethylenediamine and (C₃H₃O₂)=acrylate anion). The thermal behaviour steps were investigated in a nitrogen flow. The thermal transformations are complex processes according to TG and DTA curves including dehydration, ethylenediamine elimination as well as acrylate thermolysis. The final products of decomposition are the most stable metal oxides except for complex (2) that generates metallic copper.     

Evaluating the biological potential of some new cobalt (II) complexes with acrylate and benzimidazole derivatives

This paper presents the synthesis, physico‐chemical and biological properties of four new coordination compounds with mixed ligands: acrylate ion (acr) and benzimidazole/benzimidazole derivatives with the general formula [Co(L) ₂ (acr) ₂ ]·nH ₂ O [ (1) L: benzimidazole (HBzIm), n: 0.5; (2) L: 2‐methylbenzimidazole (2‐MeBzIm), n: 0.5; (3) L: 5‐methylbenzimidazole (5‐MeBzIm), n: 0; (4) L: 5,6‐dimethylbenzimidazole (5,6‐Me₂BzIm), n: 0]. Their chemical formulae were achieved correlating the chemical analysis with mass spectrometry data, the ligands coordination modes were assigned by Fourier transform‐infrared measurements, and the trigonal bipyramidal geometry of cobalt ion in complexes was assigned by data correlation of UV–Vis‐NIR spectra and magnetic moments measurements. Single‐crystal X‐ray diffraction reveals a mononuclear structure with a pentacoordinated cobalt (II) ion, connected to two acrylato coordinated in different modes and two unidentate 5,6‐dimethylbenzimidazole ligands for compound (4) . The biological tests were performed against several microbial strains, the cytotoxicity was evaluated on HCT8 cellular lines and the cell cycle analysis was performed on HT29 cellular lines. Microbiological assays indicated that Co (II) complexes present a very good to good activity against Candida albicans 1760, Enterococcus faecium E5, Bacillus subtilis ATCC 6683 and Escherichia coli ATCC 25922. Predictive pharmacokinetic (ADME), toxicity and drug‐likeness profiles were evaluated for Co (II) complexes. Our results highlight that Co (II) complexes depicted in the present study are suitable to be used as efficient pharmacological agents.     

Thermal decomposition of chromium(III) nitrate(V) nanohydrate

Thermal decomposition of Cr(NO₃)₃·9H₂O in helium and in synthetic air was studied by means of TG, DTA, EGA and XRD analysis. The dehydration occurs together with decomposition of nitrate(V) groups. Eight distinct stages of reaction were found. Intermediate products of decomposition are hydroxy- and oxynitrates containing chromium in hexa- and trivalent states. The process carried out in helium leads to at about 260°C and in air is formed at about 200°C. The final product of decomposition (>450°C) is Cr₂O₃, both in helium and in air. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal and photochemical behaviour of Zn(II) complexes of some cephalosporins

Zn(II) complexes of some cephalosporin antibiotics namely cephalexin, cephapirin, cefamandole, cefuroxime, cefotaxime and ceftazidime were synthesised and characterized. The stoichiometrics and the mode of bonding of the complexes were deduced from their elemental analysis, IR and electronic spectroscopies. Thermal stabilities and the photochemical behaviour of the complexes were studied. The Zn(II) complex of cephalexin exhibited a high light sensitivity. The remaining Zn(II) complexes behaved similarly to their free antibiotics, upon irradiation.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal stability of some azo-derivatives and their complexes

this paper deals with the first investigation concerning the thermal stability of two 1-(2-benzothiazolyl)-3-methyl-4-azo-pyrazil-5-one derivatives and their Cu(II) coordination compounds of type ((C₄H₉)₄N)₂[Cu(L)₂]. The thermal decomposition steps were established. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermogravimetric and spectroscopic studies on La(III) and Ce(III) complexes with some thio-schiff bases

Solid complexes of five derivatives of thio-Schiff bases with La(III) and Ce(III) ions were prepared and characterized by elemental and thermogravimetric analyses. The suggested general formula of the solid complexes is [ML₂(H₂O)X]·2H₂O, whereM=trivalent lanthanide ion,L=Schiff base andX=Cl^? or ClO ₄ ^? . Information about the water of hydration, the coordinated water molecules, the coordination chemistry and the thermal stability of these complexes was obtained and is discussed. Additionally, a general scheme of thermal decomposition of the lanthanide-Schiff base complexes is proposed.     

Some new acrylate complexes as a criterion in their selection for further co-polymerization reaction

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.     

Thermal properties of complexes of lanthanides(III) and some of d-block elements with 5-chloro-2-methoxybenzoic acid

The thermal properties of 5-chloro-2-methoxybenzoates of lanthanides(III) and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) were studied in air and nitrogen atmospheres. The complexes were obtained as mono-, di-, tetra- and pentahydrates with a metal to ligand ratio of 1:3 (in the case of lanthanides(III)) and 1:2 (in the case of d-block elements). They have colours typical for Ln³⁺ and M²⁺ ions. All complexes are polycrystalline compounds. When heated they dehydrate to form anhydrous salts which next in air are decomposed to the oxides of the respective metals while in nitrogen to the mixtures of metal oxides, oxychlorides and carbon. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal and spectroscopic investigation of new binuclear Pt(II) complexes with carboxylic acids

The thermal decomposition of the binuclear Pt(II) complexes with acetate, propionate, valerate and izovalerate ligands were studied by TG and DTA techniques. The Pt(II) complex with acetic acid (PtAA) was stable up to 343.15 K, Pt(II) complex with propionic acid (PtPrA) was stable up to 323.15 K, Pt(II) complex with valeric acid (PtVA) was stable up to T=313.15 K and Pt(II) complex with isovaleric acid (PtIvA) was stable up to 408.15 K. The PtAA complex was investigated again after a year by thermogravimetric analysis. After the thermal decomposition of the Pt(II) complexes with carboxylic acids, only in the PtVA complex and PtAA complex (investigated after a year) the final residue contains only platinum, while in the rest complexes the solid residue was a mixture of platinum and platinum carbides (PtC₂, Pt₂C₃).     

Thermal decomposition of nickel(II) complexes under quasi-equilibrium conditions

The stoichiometry of thermal decomposition and the relationship between the thermal parameters (quasi-equilibrium decomposition temperaturesT _D and decomposition entalpies H _D) of NiL₄(NCS)₂ complexes (L=imidazole derivatives) were studied. It was found that changes in the experimental conditions strongly influence the decomposition stoichiometry. TheT _D and H _D can be ordered in the following sequence (according toL): imidazole<2-Me imidazole<2-Et imidazole相似文献   

Thermal decomposition of rubidium-sodium halidothiocyanatobismuthates(III)

Mono- and binuclear rubidium-sodium halidothiocyanatobismuthates(III) have been prepared. Thermal, chemical and X-ray analyses were used to establish the thermal decomposition course of these complexes. The pyrolysis occurs in three stages connected with the mass loss and exothermic effects. The decomposition temperatures of the title salts are 190–210°C.     

Synthesis, characterization and magnetism of μ-chloranilato bi-nuclear chromium (III) complexes

Five new chloranilato-bridged binuclear chromium (III) complexes have been synthesized and identified as [Cr2(CA)L4]-(ClO4)4[L denotes 5-methyl-1,10-phenanthroline (Me-phen); 2,9-dimethyl-1, 10-phenanthroline ( Me2-phen); 5-chloro-1,10-phenanthroline(Cl-phen); diaminoethane (en) or 1,3-diaminopropane (pn)], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and magnetic moment of room-temperature measurements, and IR and electronic spectral studies, it is proposed that these complexes have CA-bridged structures and consist of two chromium (III) ions, each in an octahedral environment. The complexes [Cr2(CA)(Me-phen)4](ClO4)4(1) and [Cr2(CA)(Me2-phen)4](ClO4)4(2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, , giving the exchange parameter J = -7.8 cm-1 for (1) and J= -6.5 cm*1 for (2). This result