Final Decomposition Products Research Articles

Thermoanalytical study of precursors for In2S3 thin films deposited by spray pyrolysis

Abstract Thermal decomposition of precursors for In2S3 thin films obtained by drying aqueous solutions of InCl3 and SC(NH2)2 at the In:S molar ratios of 1:3 (1) and 1:6 (2) was monitored by simultaneous TG/DTA/EGA-FTIR measurements in the dynamic 80%Ar + 20%O2 atmosphere. XRD and FTIR were used to identify the dried precursors and products of the thermal decomposition. The precursors 1 and 2 are complex compounds, while in 2 free SC(NH2)2 is also present. The thermal degradation of 1 and 2 in the temperature range of 30–900 °C consists of four mass loss steps, the total mass loss being 89.1 and 78.5%, respectively. According to XRD, In2S3 is formed below 300 °C, crystalline In2.24(NCN)3 is detected only in 1 above 520 °C and In2O3 is the final decomposition product at 900 °C. The gaseous species evolved include CS2, NH3, H2NCN, HNCS, which upon oxidation yield also COS, SO2, HCN and CO2.

Bismuth(III) Bis(N,N-diethyldithiocarbamato)alkylene Dithiophosphates: FAB+ Mass, Thermal Decomposition, and SEM Studies

FAB+ mass, thermal decomposition, and scanning electron microscopy (SEM) studies have been carried out on the complexes [Bi{(C2H5)2NCS2}2{S2 POC (CH3)2C(CH3)2O}] and [Bi{(C2H5)2NCS2}2{S2{POCH2C(C2H5)2CH2O}]. The structural composition, thermal properties, and microstructures of the complexes have been determined. FAB+ mass spectrometry coupled to thermal analysis allowed characterization of the structure, composition, and thermal properties of the complexes. In the FAB+ mass spectra, the base peak indicates a strong chelating tendency of dithiocarbamates as compared to the alkylene dithiophosphates, while the weak molecular ion peak indicates pyrolytic decomposition of the complex. Thermal studies indicate the formation of metal sulfide as a final decomposition product. In addition, SEM studies of the complexes show different types of topography and morphology of the complexes. Images obtained at various magnifications show the different texture of the complexes.GRAPHICAL ABSTRACT

Thermal decomposition and antimicrobial activity of zinc(II) 2-bromobenzoates with organic ligands

New zinc(II) 2-bromobenzoate complex compounds with general formula Zn(2-BrC6H4COO)2·nL·xH2O (where L = urea, nicotinamide, N-methylnicotinamide, N,N-diethylnicotinamide, isonicotinamide, phenazone n = 0–2, x = 0–2) were prepared and characterized by elemental analysis, IR spectroscopy and thermal analysis. The thermal decomposition of hydrated compounds started with dehydration process. During the thermal decomposition organic ligand, carbon dioxide and bis(2-bromophenyl)ketone were evolved. The solid intermediates and volatile products of thermal decomposition were proved by IR spectroscopy and mass spectrometry. The final solid product of the thermal decomposition heated up to 1073 K was zinc oxide. Antimicrobial activity of the prepared compounds was tested against various strains of bacteria, yeasts and filamentous fungi (E. coli, S. aureus, C. albicans, R. oryzae, A. alternate and M. gypseum). It was found that the selected bacteria were more sensitive to the studied zinc(II) complex compounds than the yeast and the filamentous fungi.

Thermal behaviour of some new complexes with bismacrocyclic ligands as potential biological active species

Abstract Novel complexes of type [M2LCl4]·nH2O ((1) M:Ni, n = 5; (2) M:Cu, n = 0 and (3) M:Zn, n = 2; L: ligand resulted from 1,2-phenylenediamine, 3,6-diazaoctane-1,8-diamine and formaldehyde template condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. Processes as water or hydrochloric acid elimination as well as oxidative degradation of the organic ligand were observed. Complexes display a different thermal behaviour as result of dissimilar chemical interaction of metal ions with chloride anions. The final product of decomposition was metal(II) oxide as powder X-ray diffraction indicated.

Thermal study of mononuclear Pd(II) complexes of the type [Pd(X)2(Rtu)(PPh3)] (X = Cl, SCN; Rtu = N-methylthiourea, N-phenylthiourea)

The synthesis, spectroscopic characterization, and thermal analysis of the compounds [Pd(X)2(mtu)(PPh3)] (X = Cl− (1), SCN− (2); mtu = N-methylthiourea; PPh3 = triphenylphosphine) and [Pd(X)2(phtu)(PPh3)] (X = Cl− (3), SCN− (4); phtu = N-phenylthiourea) are described. The thermal decomposition of the compounds occurs in two, three, or four stages and the final decomposition products were identified as Pd0 by X-ray powder diffraction. The thermal stability order of the complexes is 4 > 3>2 > 1.

Thermal behaviour of new Cu(II) complexes with Schiff bases functionalised with 1,3,5-triazine moieties as potential antibacterial agents

Abstract New complexes of type [Cu(L1)2(OH2)]·4H2O (1), [Cu(L2)(OH2)]·0.5H2O (2) and [Cu3(L3)2(OH2)3]·0.5H2O (3) were synthesized by [1 + 1], [1 + 2] and [1 + 3], respectively, template condensation of 2,4,6-triamino-1,3,5-triazine and salicylic aldehyde in the presence of copper(II). The features of complexes have been established from microanalytical, IR and UV–Vis data. The thermal analyses have evidenced the thermal intervals of stability and also the accompanying thermodynamic effects. Processes as water elimination and oxidative degradation of the organic ligands were observed. After water elimination, complexes revealed a similar thermal behaviour. The final product of decomposition was copper(II) oxide as powder X-ray diffraction indicated.

Effect of alkali metal ion and hydrogen bonds on thermal stability of M[VO(O 2) 2bpy]· nH 2O (M = Li +–Rb +) and Cs[VO(O 2) 2bpy]·H 2O 2 complexes

The compounds M[VO(O 2) 2bpy]· nH 2O (M = Li +–Rb +) and Cs[VO(O 2) 2bpy]·H 2O 2 were characterized by thermogravimetry (TG). In the course of TG experiments, performed from 25 up to 550 °C, three main stages of decomposition were observed: (i) dehydration, (ii) releasing of the oxygen molecules and (iii) decomposition of bpy. The final product of decomposition is MVO 3, with small amounts of paramagnetic vanadium(IV) species. Volatile products were detected on-line using mass spectrometer. Mechanism of the decomposition is discussed on the basis of crystal structures of complexes. The main role is played by hydrogen bonds involving peroxo ligands and polarising power of alkali metal ions.

Guanidinium Formate Decomposition on the (101) TiO2-Anatase Surface: Combined Minimum Energy Reaction Pathway Calculations and Temperature-Programmed Decomposition Experiments

Local minima, saddle points, and connecting intrinsic reaction paths for the decomposition of guanidinium formate (GuFo) on a (101) TiO2-anatase surface and in the gas phase have been studied on the basis of density functional theory (DFT) energy surfaces. We are aware of only one preceding electronic structure theory study of reaction barriers at a slab surface model. The formation of ammonia and carbon dioxide as final products of the GuFo decomposition is proposed to proceed in three principal stages: first, the decomposition of GuFo to guanidine and formic acid, then the hydrolysis or decomposition of guanidine to ammonia and carbon dioxide via urea and isocyanic acid intermediates, and, in parallel to the latter, the decomposition of formic acid to water and carbon monoxide or to hydrogen and carbon dioxide. The moment in which water enters the decomposition of guanidine is crucial and determines its course. Temperature-programmed decomposition experiments propose a decomposition of guanidine to urea...

A simple synthesis and characterization of binary Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and its final decomposition product CoFeP 4O 12

This paper reports the synthesis of binary Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O by a simple, rapid and cost-effective method using CoCO 3–Fe(c)–H 3PO 4 system in water–acetone media at ambient temperature. Thermal transformation of the synthesized powder was investigated by TG/DTG/DTA and DSC techniques, which indicate that its final decomposed product was a binary cobalt iron cyclotetraphosphate CoFeP 4O 12. The FTIR and XRD results of the synthesized Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and the decomposed CoFeP 4O 12 indicate the pure monoclinic phases with space group P2 1/n and C2/c, respectively. The morphologies of Co 0.5Fe 0.5(H 2PO 4) 2·2H 2O and CoFeP 4O 12 powders appear non-uniform particle shapes and high agglomerates, which are different from the cases of the single compounds M(H 2PO 4) 2·2H 2O and M 2P 4O 12 (where M = Co, Fe). The magnetic properties of the studied compounds are superparamagnetic behaviors, which are important for specific applications. The physical properties of the studied powders are comparable with those reported in our previous study, affected by medium and condition of preparation method.

Low-dimensional compounds containing cyanido groups. XXI. Crystal structure, spectroscopic, thermal and magnetic properties of two polymorphous modifications of [Cu(men)2Pt(CN)4]n complex (men = N-methyl-1,2-diaminoethane)

Violet (1) and blue (2) polymorphous modifications of [Cu(men)2Pt(CN)4]n (men=N-methyl-1,2-diaminoethane) have been prepared and investigated by IR and UV–vis spectroscopy, thermal analysis, measurement of magnetic data and X-ray structural analysis. Both modifications are formed by similar but differently packed zigzag chains, which consist of [Cu(men)2]2+ moieties bridged by two trans arranged cyanido groups of [Pt(CN)4]2− units. The Cu(II) atoms in both structures are hexacoordinated by four nitrogen atoms in the equatorial plane from two molecules of bidentate men ligands with the average Cu–N(Me) and Cu–N(H2) bond lengths of 2.046(8) and 2.008(8)Å, respectively, and by two nitrogen atoms from bridging cyanido groups in the axial positions at average distance of 2.50(7)Å. Broad nearly symmetric bands observed in the UV–vis spectra of 1 and 2 of 2B1g→2Eg transitions are consistent with a deformed octahedral coordination of the CuN6 chromophoric groups. One and two ν(CN) absorption bands observed in the IR spectra of 1 and 2, respectively, are in agreement with different local symmetries of [Pt(CN)4]2− units and different Cu–N(cyanido) bond lengths in these polymorphs and are subject of discussion on the spectral–structural correlations in 1D compounds. The complexes are stable up to 238°C when their two-stage thermal decompositions start and ending up with a mixture of CuO and metallic Pt as the most probable final thermal decomposition products. The temperature dependence of the magnetic susceptibility suggests the presence of aweak antiferromagnetic exchange coupling between Cu(II) atoms in 1, J/hc=−0.17cm−1 and in 2, J/hc=−1.3cm−1.

Preparation, thermal decomposition, and crystal structure of Zn(II) 2-chlorobenzoate complex with nicotinamide

A new Zn(II) 2-chlorobenzoate complex, [Zn(2-ClC6H4COO)2(nad)2] (nad = nicotinamide), was synthesized and characterized by elemental analysis, infrared (IR) spectroscopy, mass spectrometry, thermal analysis, and X-ray structure determination. The mechanism of thermal decomposition of the complex was studied by TG/DTG, DTA, IR spectroscopy, and mass spectrometry. The thermal decomposition is characterized as a two-step process. Zinc oxide was found as the final product of the thermal decomposition performed up to 900°C. Mass spectrometry was used to determine the volatiles released during thermal decomposition. The IR spectrum indicates that carboxylate is coordinated to zinc in monodentate coordination. [Zn(2-ClC6H4COO)2(nad)2] crystallizes in the monoclinic system, space group Pn, a = 10.376(2) Å, b = 10.100(1) Å, c = 12.604(1) Å, β = 100.79(1)°. The zinc is tetrahedrally coordinated by two nitrogens of nicotinamide and two oxygens of 2-chlorobenzoate.

A novel polymorph of gadolinium tetrahydroborate produced by mechanical milling

Gadolinium tetrahydroborate produced by mechanochemical processing of LiBH 4–3GdCl 3 mixture exhibits a structural transformation at 484 K. The high-temperature structure has a type cubic structure Gd(BH 4) 3 ( a = 11.418 Å), which is isostructural with the one recently reported for Ce(BH 4) 3. This new phase remains upon heating up to 503 K. Combination of thermal hydrogen desorption, DSC, PXRD and FTIR allows to determine that the thermal decomposition of high-temperature structure Gd(BH 4) 3 starts above 503 K and leads to 3.1 wt% of hydrogen release obtaining mainly GdH 2 as final decomposition product.

Preparation, Crystal Structures and Thermal Decomposition of Ba2(EDTA) and Ba2(EDTA)·2.5H2O

AbstractThe barium ethylenediaminetetraacetato (EDTA) complexes, Ba2(EDTA) and Ba2(EDTA)·2.5H2O, were hydrothermally synthesized and characterized by single‐crystal X‐ray structure determination. Ba2(EDTA) (monoclinic, P21/c, (No.14), a = 9.7651(10) Å, b = 8.0870(6) Å, c = 10.3313(11) Å, β = 118.024(4)°, V = 720.20(12) Å3, Z = 2) exhibits a layered arrangement of coordination polyhedra around barium whereas in the crystal structure of Ba2(EDTA)·2.5H2O (tetragonal, P4nc, (No.104), a = 19.7126(7) Å, c = 8.9813(4) Å, V = 3490.0(2) Å3, Z = 8) a completely different three dimensional framework containing wide channels is formed. Thermoanalytical investigations reveal a reversible dehydration behavior for Ba2(EDTA)·2.5H2O. The anhydrous form was characterized by PXRD (tP, a = b = 19.226(10) Å, c = 8.986(3) Å, V = 3335.4(3) Å3) and is assumed to be closely related to the crystal structure of the hydrated starting material. The final decomposition product of both compounds after heating in air up to 1000 °C was found to consist of pure BaCO3.

Pathways of Amino Acid Transformation and Decomposition in Saturated Subcritical Water Conditions

The reactions of amino acids under subcritical water conditions were investigated. All reactions were carried out under a pressure value corresponds to the saturated vapor pressure of water at the employed reaction temperature (hereafter called the saturated subcritical water condition). The reaction temperatures were in the range of 503-563 K. As reactants, seventeen different amino acids were investigated including, glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tyrosine, serine, threonine, cysteine, proline, lysine, histidine, arginine, aspartic, and glutamic. The obtained data revealed that the major decomposition pathway were the deamination and decarboxylation. It was found that glycine, alanine, valine, and proline were synthesized as intermediate decomposition products of other amino acids. Glutamic acid is the only amino acid that decomposed through lactamization process to pyroglutamic acid. Based on the experimental data a general decomposition pathway of all tested amino acids was developed by considering that the decomposition reactions extended to produce final decomposition products, carbon monoxide, water, and ammonia.

Thermal properties of Ca(II) and Cd(II) complexes of pyridinedicarboxylates

The thermal behavior of [Ca(H2O)3(2,3-pydcH)2] n (I), [Cd(H2O)3(2,3-pydc)] n (II), and [Cd(H2O)6][Cd(2,3-pydcH)3]2 (III) complexes with pyridine-2,3-dicarboxylic acid was monitored by TG, DTG, and DSC analysis, where 2,3-pydcH—mono deprotonated pyridine-2,3-dicarboxylic acid and 2,3-pydc—doubly deprotonated dicarboxylate anion. Thermal decomposition of these compounds go through one or two dehydratation stages, followed by the loss of organic matter. The final decomposition products are found to be the corresponding metal oxides. The possible scheme of destruction of the complexes have been used to reveal the relationships between stability and molecular structure.

Carboxylate clusters with the M4O4 cubane-like core: pivalate cocrystal containing CoII and NiII

Joint thermolysis of the dinuclear pivalate complexes M2(μ-H2O)(μ-Piv)2(Piv)2(HPiv)4 (M = Co (1) and Ni (2), Piv- is the pivalate anion), in decane at 174 °C at the reactant ratio 1: 1 followed by treatment of the dry thermolysis product with methanol afforded crystals of a new cocrystallization product of the molecules containing the heterometallic cubane-like core M4(Co,Ni)O4. According to the X-ray diffraction data and the results of magnetic measurements, inductively coupled plasma atomic emission spectrometry (ICP-AES), and investigations of the solid-state thermal decomposition products, the isolated cocrystallization product has the general formula [Co1.6Ni2.4(μ3-OMe)4(μ2-Piv)2(pg2 -Piv)2(MeOH)4] ·4MeOH (3·4MeOH). Thermolysis of the crystals of the solvate 3·4MeOH is a destructive process accompanied by the intramolecular redox reaction. A mixture of metallic Ni and cobalt oxide (CoO) are the final solid decomposition products of 3 · 4MeOH in an argon atmosphere, whereas a mixture of the phases NiO, Co3O4, and NiCo2O4 is formed in air.

Thermal Polymorphism and Decomposition of Y(BH4)3

The structure and thermal decomposition of Y(BH(4))(3) is studied by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), (11)B MAS NMR spectroscopy, and thermal analysis (thermogravimetric analysis/differential scanning calorimetry). The samples were prepared via a metathesis reaction between LiBH(4) and YCl(3) in different molar ratios mediated by ball milling. A new high temperature polymorph of Y(BH(4))(3), denoted beta-Y(BH(4))(3), is discovered besides the Y(BH(4))(3) polymorph previously reported, denoted alpha-Y(BH(4))(3). beta-Y(BH(4))(3) has a cubic crystal structure and crystallizes with the space group symmetry Pm3m and a bisected a-axis, a = 5.4547(8) A, as compared to alpha-Y(BH(4))(3), a = 10.7445(4) A (Pa3). Beta-Y(BH(4))(3) crystallizes with a regular ReO(3)-type structure, hence the Y(3+) cations form cubes with BH(4)(-) anions located on the edges. This arrangement is a regular variant of the distorted Y(3+) cube observed in alpha-Y(BH(4))(3), which is similar to the high pressure phase of ReO(3). The new phase, beta-Y(BH(4))(3) is formed in small amounts during ball milling; however, larger amounts are formed under moderate hydrogen pressure via a phase transition from alpha- to beta-Y(BH(4))(3), at approximately 180 degrees C. Upon further heating, beta-Y(BH(4))(3) decomposes at approximately 190 degrees C to YH(3), which transforms to YH(2) at 270 degrees C. An unidentified compound is observed in the temperature range 215-280 degrees C, which may be a new Y-B-H containing decomposition product. The final decomposition product is YB(4). These results show that boron remains in the solid phase when Y(BH(4))(3) decomposes in a hydrogen atmosphere and that Y(BH(4))(3) may store hydrogen reversibly.

Influence of Mg deficiency on crystal structure and superconducting properties inMgB2single crystals

The effects of high-temperature vacuum-annealing induced Mg deficiency in MgB2 single crystals grown under high pressure were investigated. As the annealing temperature was increased from 800 to 975 C, the average Mg content in the MgB2 crystals systematically decreased, while Tc remains essentially unchanged and the superconducting transition slightly broadens from 0.55 K to 1.3 K. The reduction of the superconducting volume fraction was noticeable already after annealing at 875 C. Samples annealed at 975 C are partially decomposed and the Mg site occupancy is decreased to 0.92 from 0.98 in as-grown crystals. Annealing at 1000 C completely destroys superconductivity. X-ray diffraction analysis revealed that the main final product of decomposition is polycrystalline MgB4 and thus the decomposition reaction of MgB2 can be described as 2MgB2(s) = MgB4(s) + Mg(g). First-principles calculations of the Mg1-x(VMg)xB2 electronic structure, within the supercell approach, show a small downshift of the Fermi level. Holes induced by the vacancies go to both sigma and pi bands. These small modifications are not expected to influence Tc, in agreement with observations. The significant reduction of the superconducting volume fraction without noticeable Tc reduction indicates the coexistence, within the same crystal, of superconductive and non-superconductive electronic phases, associated with regions rich and poor in Mg vacancies.

Thermal Decomposition of Ferric Oxalate Tetrahydrate in Oxidative and Inert Atmospheres: The Role of Ferrous Oxalate as an Intermediate

AbstractThe thermal decomposition of ferric oxalate tetrahydrate Fe2(C2O4)3·4H2O was studied in dynamic oxidative and inert atmospheres by using a simultaneous thermogravimetric (TG) and differential scanning calorimetric (DSC) analytical device equipped with an evolved gas analyzer (EGA). Solid‐state decomposition products formed during the decomposition were analyzed by 57Fe Mössbauer spectroscopy, in situ and ex situ X‐ray powder diffraction, and magnetic measurements. In the dynamic inert atmosphere, we observed the formation of a tiny amount of superparamagnetic iron oxide (most likely Fe3O4) together with a majority of ferrous oxalate (FeC2O4) and remains of undecomposed Fe2(C2O4)3 after the first decomposition step, which finished at 210 °C. The astonishing presence of the oxidic phase at such low temperatures is a highly probable side effect of the main reduction action of the electrons on the FeIII cations in the ferric oxalate structure, thus resulting in the creation of intermediate FeC2O4. The final product of decomposition of the FeC2O4 intermediate in a dynamic inert atmosphere is a mixture of wüstite (FexO), α‐iron (α‐Fe), and magnetite (Fe3O4). Their proportion accurately reflects actual disproportionation/synproportionation/redisproportionation processes likely encouraged by the preserved size and morphology of the initial ferric oxalate crystals and that are dependent on temperature. In the oxidative atmosphere, the decomposition proceeds in the three overlapped stages that include dehydration, the astonishing reductive formation of FeC2O4 as an intermediate, and final decarboxylation to hematite (α‐Fe2O3). The principal effect of the experimental conditions on the amount of intermediate formation of FeC2O4 in the oxidative atmosphere is also discussed and evaluated from the isothermal experiments carried out at 180 °C.

Preparation, spectral, thermal, and biological properties of zinc(II) 4-chloro- and 5-chlorosalicylate complexes with methyl 3-pyridylcarbamate and phenazone

AbstractNew zinc(II) 4-chloro- and 5-chlorosalicylate complex compounds of the general formula ((4- or 5-Cl)C6H3(2-OH)COO)2Zn · Ln (where L = methyl 3-pyridylcarbamate, phenazone; n = 2, 4) were prepared and characterized by elemental analysis, thermal analysis (TG/DTG, DTA), and IR spectroscopy. During thermal decomposition, mpc, phen, chlorosalicylic acid, chlorophenol, carbon dioxide, and carbon monoxide were released. Volatile products of the thermal decomposition were confirmed by mass spectrometry. The final solid product of the thermal decomposition up to 700°C was zinc oxide or metallic zinc. Antimicrobial activity of the compounds prepared was tested against various strains of bacteria, yeasts and filamentous fungi. The highest antimicrobial effect was determined against the G+ bacteria S. aureus.