Thermal Decomposition Of Complexes Research Articles

Kinetic Modeling of Mass Loss during Carbonization of Sodium Carboxymethyl Cellulose (CMC) Aerogels

The carbonization of sodium carboxymethyl cellulose (CMC) aerogels involves complex thermal decomposition processes leading to the formation of carbonaceous residues. Understanding the kinetics of mass loss during carbonization is vital for optimizing the production of CMC carbon aerogels with desired properties. In this study, a mathematical model is presented that describes the kinetics of mass loss during the carbonization process of CMC aerogels. This model considers the temperature and concentration dependence of CMC decomposition reactions and is validated against experimental data obtained at various conditions. The proposed kinetic model elucidates the underlying mechanisms governing mass loss during carbonization, offering valuable insights for the design and optimization of CMC carbon aerogels across diverse applications. Furthermore, the analysis of the experimental data reveals variations in both the reaction order and the rate constant for different concentrations of CMC aerogels, indicating distinct kinetic behavior. These findings contribute to a deeper understanding of the carbonization process and pave the way for tailored synthesis approaches to meet specific application requirements.

NiO nanoparticles by thermal decomposition of complex and evaluation of the structural, morphological, and optical properties

An efficient method for the synthesis of metal oxide nanoparticles (NPs) involves the solid-state thermal decomposition of precursor complexes. This study reports on the preparation of nanocrystalline nickel oxide (NiO) through a solid-state thermal decomposition of nickel(II) bis(N-methyl-N-paramethoxyphenyl dithiocarbamate) in a furnace. The novel Ni(II) complex was characterized using various analytical techniques. The single-crystal X-ray structure of the new nickel dithiocarbamate complex, C18H20N2NiO2S4, was determined and it showed a square-planar nickel coordination environment. The CH⋯S intramolecular hydrogen bond in this complex contributes to the planarity of the Nickel coordination environment. The complex underwent thermal decomposition in the air at about 750 °C for varying times of 90, 120, 150, and 180 min, resulting in the production of the oxide. Subsequently, the study explored how varying calcination times influenced the structural, morphological, and optical characteristics of the formed NiO nanoparticles. Face-centered cubic (FCC) structure of NiO NPs was confirmed whose crystallite size increased with an increase in the dwelling time of calcination and has been attributed to the possible coalescence of smaller crystallites to form larger ones. The confirmation of the face-centered cubic (FCC) structure of NiO nanoparticles was established, with the crystallite size observed to increase alongside longer calcination periods. This phenomenon has been linked to the potential amalgamation of smaller crystallites into larger ones. The optical energy bandgap decreased from 4.35 to 3.40 eV with an increase in the calcination time due to the increase in crystallite size occasioned by a longer reaction time from 90 to 180 min. These NPs will be useful as photocatalysts due to their high crystallinity and the capability to absorb within the visible region of the solar spectrum.

EXO-LIGAND COMPLEXES OF DIETHYLENTRIAMINE-PENTAACETATOGERMANATIC(IV) ACID

The synthesis of complexes based on diethylenetriaminepenta-acetategermanate(IV) acid and a number of exo-ligands was carried out. Their composition, thermal stability, method of coordination of diethylenetriaminepentaacetic acid (H5Dtpa) and protonation of exo-ligands (isoniazid Ind, diphenylguanidine Dphg, piracetam Pam, imidazole Im, cytosine Ctz, 1,10-phenanthroline Phen, 2,2´-bipyridine Bipy), were established. The structural scheme and molecular formula of the obtained compounds were proposed (HL)[Ge(OH)(HDtpa)]·nH2O, де L = Ind, n = 0 (1), Dphg, n = 8 (2), Pam, n = 4 (3), Im, n = 2 (4), Ctz, n = 2 (5), Phen, n = 5 (6), Bipy, n = 4 (7). Based on the elemental analysis of the synthesis products 1–7, it was determined that they exhibit a molar ratio of Ge:N = 1:6 (1, 2, 5), Ge:N = 1:5 (3, 4, 6, 7), therefore, Ge:Dtpa:Ind (Dphg, Pam, Im, Ctz, Phen, Bipy) = 1:1:1. The thermal decomposition of complexes 2–7 begins with an endothermic effect in the temperature range of 80–180 °C, during which a certain amount of crystallization water molecules is removed. The relatively high temperature of its removal is due to the formation of a broad system of intermolecular and intramolecular hydrogen bonds, which is characteristic of various metal complexonates. Thus, in the new compounds, the structure of the octahedral polyhedron of Germanium remains the same as in the original complex acid: the Ge atom is coordinated by two Nitrogen atoms and three Oxygen atoms of three Dtpa acetate groups. The coordination number of Germanium is complemented to 6 by the hydroxo-ligand. All carboxyl groups of the ligand are deprotonated, as evidenced by the presence of bands νas(COO⁻) at 1630–1690 cm⁻¹ and νs(COO⁻) at 1380–1420 cm⁻¹. The presence of Ge-N and Ge-O bonds in the synthesized complexes is confirmed by the bands of valence vibrations of these bonds in the range of 640–650 cm⁻¹ and 590–620 cm⁻¹, respectively. Particularly noteworthy is the band of deformation vibrations of the Ge-O-N group at 810–820 cm⁻¹. In complexes 1–7, a splitting of bands in the 3000 cm⁻¹ region (valence vibrations of the C-H bond) is observed, indicating that all nitrogen atoms in their molecules are coordinated or protonated. The obtained compounds are of interest as promising agents for biomedical applications.

The supramolecular hybrid inorganic–organic l-argininato-based copper(II) materials – preparation, structural, spectroscopic and thermal properties

Synthesis and characterization of the single crystal of new ternary copper(II) complexes containing l−arginine of formulae {[Cu(μ−O,O’−NO3)(l−Arg)(bpy)]NO3}n (1) and [CuCl(l−Arg)(bpy)]Cl·3H2O (2) (l−Arg =l−arginine; bpy=2,2′−bipyridine) with one−dimensional polymeric and monomeric nature, respectively, were the initial goal of the present study. Complete crystal and molecular structures figuration were achieved by powder and single crystal X−ray diffraction supported by Hirshfeld surface analysis, spectroscopic (FT−IR, FT−Raman, X− and Q−bands EPR, NIR−Vis−UV) methods as well as thermal analysis. In 1, the infinite 1D coordination chains are formed by the NO3– ions linking [Cu(l−Arg)(bpy)]2+ units. In 2, the self−assembled [Cu(l-Arg)(bpy)Cl]+ dimers are linked into 1D zig-zag chains. The intermolecular interactions in both crystals were explored by using Hirshfeld surface and 2D fingerprint plots analysis. The Q−band spectra displayed the anisotropic signals allowing to determine the g|| parameters. The thermal decomposition of complexes 1 and 2 occur by the formation of “creatine−proline” as a product of l−Arg decomposition.

A New Approach to the Synthesis of Nanocrystalline Cobalt Boride in the Course of the Thermal Decomposition of Cobalt Complexes [Co(DMF)6]2+ with Boron Cluster Anions

In the course of the study, nanocrystalline cobalt monoboride was prepared by thermal decomposition of precursors [Co(DMF)6][An], where [An] = [B12H12]2- (1), [trans-B20H18]2- (2) or [B10Cl10]2- (3) in an argon atmosphere. Three new salt-like compounds 1-3 were prepared when Co(NO3)2 was allowed to react with (Et3NH)2[An]. Compound 1 is new; the structures of compounds 2 and 3 have been previously reported. Samples 1-3 were annealed at 900 °C in argon to form samples 1a-3a, which were characterized by single crystal XRD for 1 and powder XRD for 1-3. Powder XRD on the products showed the formation of BN and CoB for 1a in a 1:1 ratio; 2a gave a higher CoB:BN ratio but an overall decreased crystallinity. For 3a, only CoB was found. IR spectra of samples 1a-3a as well as X-ray spectral fluorescence analysis for 3a confirmed these results. The nanoparticular character of the decomposition products 1a-3a was shown using TEM; quite small particle sizes of about 10-15 nm and a quite normal size distribution were found for 1a and 2a, while the decomposition of 3 gave large particles with 200-350 nm and a broad distribution.

Study of the thermal behavior, evolved gas analysis and temperature diffraction patterns of new light lanthanide complexes with niflumic acid

Seven new complexes of niflumic acid with light lanthanide ions (La-Gd except Pm) were obtained in solid state. With the application of chemical, elemental and thermal analysis, the minimal formulas of the complexes were established, which were different despite the fact that the syntheses of the complexes were carried out under the same conditions. The complex with La(III) ions is mononuclear and its stoichiometry is represented by the formula La(nif)3∙2.5 H2O. The remaining complexes are binuclear and their stoichiometry is expressed by the formula Ln2(nif)4(OH)2∙nH2O (where: Ln is Ce or Pr, n is equal to 4 or 5, respectively) or Ln2(nif)3(OH)3∙4 H2O (where: Ln = Nd, Sm, Eu or Gd). On the basis of the FTIR spectra, it was stated that the carboxylate groups of the ligand can coordinate metal ions in a bidentate chelating or tridentate chelating-bridging mode. XRPD analysis of the obtained compounds showed that they are amorphous. Based on the TG/DTG–DSC analysis, it was shown that the thermal decomposition of the complexes is a multistage process, depending on the metal ion and the used atmosphere. It was found that the stability of the dehydrated compounds in air atmosphere increases in the order: La < Pr < Nd < Sm < Gd = Eu < Ce, while in nitrogen atmosphere, the stability of these complexes is as follows: La < Nd < Ce = Pr < Eu < Sm < Gd. Using coupled TG-FTIR-MS techniques, the decomposition pathways of the synthesized compounds were examined and the gaseous products released during thermal oxidation and pyrolysis of the complexes were identified. The EGA analysis showed that the gaseous products contained mainly H2O, CO2, COF2, fragments from the partial decomposition of the organic ligands (both in air and nitrogen atmosphere), NO (in air) and CO (in N2). Moreover, based on the temperature diffraction patterns, it was found that the thermal degradation of most of the studied complexes, both in air and nitrogen atmosphere, did not end at 1000 °C. It has been experimentally proven that during thermal decomposition of niflumic acid complex with Nd(III) ions in an oxidizing atmosphere at approximately 440 °C NdF3 is formed as one of a solid intermediate product. At the temperature of 570 °C, the tetragonal form of this compound appears additionally in the solid residue. At 800 °C, the solid residue is a mixture of Nd2O3 and NdOF, while the final product obtained at 1000 °C is Nd2O3 and NdOF. Under pyrolysis conditions, only at a temperature of 800 °C it was possible to identify solid intermediate products and in the case of the niflumic acid complex with Nd(III) ions complex it was a mixture of NdOF and NdF3. NOF has been identified as one of the solid products of thermal degradation.

Citric Acid Recovery and Methanol Production from a Waste Food Fruit Sample by Thermal Decomposition of a Reusable Zinc Citrate Complex

Citric acid (CA) is an important organic acid that is produced on a large scale by the fermentation process. The CA recovery in fermentation technology requires a large amount of CaSO4 as waste and involves a multi-step complex process. Similarly, the production of methanol by the conventional route requires harsh reaction conditions. Therefore, in the present investigation, zinc metal was extracted as zinc oxide from the used alkaline battery material and subsequently employed for CA recovery and methanol production in a more economical way. The phase formation and surface area of the metal oxides (Fe2O3, MnO2, TiO2, and ZnO) were confirmed by the X-ray diffraction and sorption analysis. In the series of materials used in this study, the ZnO exclusively reacted with CA in the waste fruit sample to produce the zinc citrate complex. The maximum uptake of CA was found to be 68% (933.3 mg/g) on ZnO material after 10 min of contact time, which is much higher uptake in the series of the studied materials. Furthermore, the upgrading strategy was developed to produce methanol by the dry distillation method from the recovered zinc citrate complex. The decomposed gaseous products (CH3OH, CO2, and ethylene) were confirmed by thermogravimetric analysis–mass spectrometry (TGA-MS) probe analysis. At first, a loss in mass of about 23% was seen between 100 and 300 °C on the zinc citrate complex’s surface owing to the dehydration reaction of CA-containing hydroxyl groups. The decarboxylation process of the citrate molecule resulted in the second mass loss. During the decarboxylation reaction, the three-carboxylate anion readily breaks down into zinc oxide and CO2 at higher temperatures, as seen by the significant amount of CO2 production. Based on the TGA-MS analysis, we strongly suggest that the ketonization reaction does not occur between the ketones. The proposed green technology enables the use and recycling of electronic and food waste into value-added raw materials for the production of fine chemicals.

The Unconventional Cadmium Borosulfates Cd[B2O(SO4)3] and Cd4[B2O(SO4)6

AbstractBorosulfates are an expanding class of silicate‐analogous materials. We report the syntheses and crystal structures of two unconventional cadmium borosulfates. Cd[B2O(SO4)3] crystallises in a new structure type in space group Pnma (no. 62, a=896.92(8), b=1152.0(1), c=872.75(8) pm, 1380 refl., 94 ref. param., wR2=0.112). Cd4[B2O(SO4)6] adapts the α‐Mg4[B2O(SO4)6]‐type structure with space group P (no. 147, a=822.22(4), c=797.88(5) pm, 1810 refl., 58 ref. param., wR2=0.078). Together with simultaneously elsewhere reported conventional phyllosilicate‐analogous Cd[B2(SO4)4], there are now in total three cadmium borosulfates with differing dimensionality of their anions, i. e. 0D, 1D and 2D. These results highlight the special position of cadmium in the periodic table and the ambiguity of its behaviour as main group or transition metal when comparing to other analogous or related borosulfates. The [B2O(SO4)3]2− and [B2O(SO4)6]8− anions are known from other main group and transition metal borosulfates. However, Cd2+ is the first cation for which borosulfates comprising both anions are reported for the same cation. Moreover, the optical and thermal properties of both compounds are reported using IR and UV‐Vis spectroscopy as well as thermogravimetry. Both unconventional borosulfates were prepared by the thermal decomposition of the conventional borosulfate Cd[B2(SO4)4] pursueing our studies on the complex thermal decomposition behaviour of such borosulfates.

Single crystal structure features of a new synthesized heteronuclear Mn/Cu complex, a precursor for heterogeneous catalytic conversion of CO

A unique hetero-nuclear complex formulated as [Cu(pydc)2Mn(H2O)5].2H2O (1) where pydc2− = pyridine-2,6-dicarboxylato has been synthesized through a facile and environment-friendly ultrasonic reaction. Complex 1 was characterized by various techniques, including single-crystal X-ray diffraction (SC-XRD). X-ray crystallographic analysis reveals that the parallelepiped green crystals of complex 1 have a monoclinic structure with space group P21/c. The CuII and MnII centers have distorted square bipyramid geometry, while extensive H-bonding interactions help to produce a three-dimensional network. The bimetallic Cu-Mn/Al2O3 catalyst was prepared by thermal decomposition of [Cu(pydc)2Mn(H2O)5].2H2O/Al2O3. Also, a reference catalyst formulated as Cu-Mn/Al2O3 was prepared via the impregnation conventional method. Characterization of catalysts was carried out using inductively coupled plasma mass spectrometry (ICP-MS), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) surface area. The performance of the catalysts was evaluated for CO conversion in the low-temperature water-gas shift (LT-WGS) reaction in the temperature range of 160–240 °C. A comparison of the WGS performance of these catalysts points out the potential application of inorganic complex in LT-WGS reaction. The catalyst constructed by thermal decomposition of complex 1 shows higher activity than the reference catalyst prepared by the impregnation conventional method.

Numerical simulation of complex thermal decomposition processes in pyrolysis furnace for recycling solid waste Mg(NO3)2.2H2O

This study aims to reveal the complex thermal decomposition processes in a pilot-scale pyrolysis furnace for recycling solid waste Mg(NO3)2.2H2O produced in nitric acid leaching process of laterite nickel ore, by using CFD method. Specifically, an integrated mathematical model combining the gas-particle flow and the thermal decomposition reaction as well as the heat, mass transfer between gas and particle was developed based on the Euler-Lagrange method. And then, the developed model was used to study the flow characteristics of the gas and particle and the thermal decomposition processes for Mg(NO3)2.2H2O in the pyrolysis furnace. Furthermore, the effect of operating parameters (gas inlet temperature, mass flow rate and particle size of Mg(NO3)2.2H2O) on the performance of pyrolysis furnace (decomposition rate of Mg(NO3)2.2H2O) was studied. The results show that the developed model is reasonable. Increasing gas inlet temperature, decreasing mass flow rate and particle size of Mg(NO3)2.2H2O can effectively promote the decomposition rate of Mg(NO3)2.2H2O. Under the conditions of gas inlet temperature 1123 K, mass flow rate of Mg(NO3)2.2H2O 200 kg/h, and average particle size of Mg(NO3)2.2H2O 75 µm, the dehydration reaction mainly occurs in the furnace height of 11–8 m, while the denitration reaction mainly occurs in the furnace height of 10.5–1 m. The total decomposition rate of Mg(NO3)2.2H2O is 99.75%.

Mononuclear Transition Metal Cymantrenecarboxylates as Precursors for Spinel-Type Manganites.

Novel mononuclear cymantrenecarboxylate complexes of transition metals, [Co(H2O)6](CymCO2)2·4H2O (Cym = (η5-C5H4)Mn(CO)3) (1), [Ni(H2O)6](CymCO2)2·4H2O (2), [Zn(H2O)6](CymCO2)2·4H2O (3), [Co(CymCO2)2(imz)2] (imz = imidazole, 4), [Co(CymCO2)2(bpy)2]·2PhMe (bpy = 2,2′-bipyridyl, 5), [Ni(CymCO2)(bpy)2(H2O)][CymCO2]·0.5MePh·2H2O (6), [Cu(CymCO2)2(imz)2] (7), and [Cu(CymCO2)2(bpy)(H2O)] (8), were obtained and characterized by single-crystal X-ray analysis. Complexes 1–3 are isostructural. Magnetism of the Co complexes 1, 4, and 5 was studied; it was shown that they exhibit the properties of field-induced single-molecule magnets with magnetization reversal barriers (ΔE/kB) of 44, 13, and 10 K, respectively. Thermal decomposition of complexes 1–8 was studied by means of DSC and TGA methods. The final products of thermolysis of 1–6 in air, according to powder XRD data, are the pure spinel phases MMn2O4; for the cases of copper complexes, the mixtures of CuMn2O4 and CuO were found in the products.

N,N′-Diarylformamidine Dithiocarbamate Ag(I) Cluster and Coordination Polymer

An Ag(I)formamidine cluster Ag6L16 (1) and an Ag(I)formamidine coordination polymer Ag7(L2)2 2 (L1 = N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate and L2 = N,N′-mesityl formamidine dithiocarbamate) have been synthesized from the reactions of L1 and L2 with AgNO3 respectively. The complexes were characterized using spectroscopic and analytical methods, including single-crystal X-ray diffraction. In the structure of 1, a six vertex distorted square bi-pyramidal octahedron is formed from an Ag6 core. The N,N′-bis(2,6-disopropylphenyl) formamidine dithiocarbamate ligands stabilize this core through two main –CS2 bridging modes giving a propeller like structure. In the structure of 2, each of the two Ag(I) centers are bridged by two N,N′-mesityl formamidine dithiocarbamate ligands forming 8-member Ag2(CS2)2 metallacycles with an inversion center in the middle of the Ag—Ag argentophilic bond. The metallacycles are connected through Ag—S bonds forming ribbons in the crystallographic a-axis. The Ag(I) centers are coordinated to two N,N′-mesitylformamidine dithiocarbamates through the dithiocarbamate S atoms. The thermal decomposition of complexes 1 and 2 had similar thermograms with one major weight loss activity and the formation of elemental silver particles thereafter.

Synthesis and thermal properties of the heterometallic nickel–ruthenium complex: a potential precursor for catalytically active nanosized Ni–Ru alloy

Thermal decomposition of the novel heterometallic complex [RuNO(NO2)4OHNi(En)2] results in a single-phase metastable solid solution Ni0.5Ru0.5. The catalytic activity of the prepared nanoalloy in the CO methanation reaction was demonstrated.

SYNTHESIS AND STRUCTURE OF HETEROMETALLIC – MIXED-LIGAND Ge(IV) – 3d-METAL COMPLEXES WITH GALLIC ACID AND 1,10-PHENANTHROLINE

Authors have developed optimal conditions and synthetic methods in water-organic solutions for ten heterometallic – mixed-ligand complexes of germanium(IV) and 3d-metals with gallic acid (Н2Gal) and 1,10-phenanthroline (phen), their composition and structure [M(phen)3][Ge(H2O)(HGal)2]∙nH2O (M = Mn (1), Co (2), Ni (3), Zn(5)); [CuCl(phen)2]2[Ge(H2O)(HGal)2]∙2H2O (4). Comparative analysis of their IR-spectra and spectra gallic acid and 1,10-phenanthroline with involvement diffuse reflection spectra allowed to establish coordination sphere of germanium and 3-metals. IR-spectra of complexes 1-5 are similar, therefore coordination of ligands in them is the same. Comparatively to the IR-spectrum of gallic acid, there are absent valence absorption bands of free carboxylic groups while two bands of asymmetric and symmetric oscillation of C-O groups in carboxylate ions CОО- appear in the spectra of complexes. Deformation bands d(Сarom-О-Н) are shifted to the low-frequency region for 50-40 cm-1, which indicates deprotonation and binding to the complexing agent of OH-groups from gallic acid. Appearance of deformation bands d(H2О) at 1625 сm-1 is characteristic for the coordination water in composition of complexes. Presence of coordination and crystalline water as well as unbonded OH-group are confirmed with the band n(Ge-О) at 620 сm-1. Thermal decomposition of mixed-metal complexes starts with an endothermic effect in the temperature range 80-160°С where elimination of certain number of water molecules takes place: two – for 1 and 4, three – for 2 and 5, four – for 3. On the thermogravigrams of all compounds one more endoeffect in the temperature range 160-220°С is presented, where removal of one coordination water molecule happens. It was established, that coordination polyhedron of germanium was formed by five oxygen atoms of deprotonated hydroxyl groups from two molecules of gallic acid and one water molecule in all compounds. Second ligand – 1,10-phenanthroline is coordinated to 3d-metal through heterocyclic nitrogen atoms with formation of cations with different composition [M(phen)3]2+ (M = Mn, Co, Ni, Zn) та [CuCl(phen)2]+.

Ethanol Oxidation at Pt Nanoparticles Supported on Titanium Modified by Thermal Decomposition of Tin and Ruthenium Acetylacetonate Complexes

Sn and Ru oxides prepared by thermal decomposition of metal acetylacetonate (acac) complexes on Ti have a substantial support effect on platinum catalyzed oxidation of ethanol. Sn and Ru oxides and mixed Sn–Ru oxides (Ru-doped SnO2) deposited onto Ti foils were drop coated with preformed Pt nanoparticles. Cyclic voltammetry in H2SO4(aq) showed a strong synergistic effect between Ru and Sn oxide for ethanol oxidation, with a 2:1 ratio of Ru(acac)3 to Sn(acac)2 in the oxide precursor solution producing the most active catalyst. X-ray photoelectron spectroscopy revealed a significant transfer of electron density from the Ru-doped SnO2 to the Pt nanoparticles (electronic/ligand effect), and increased Pt oxide formation. Both of these effects can promote the oxidation of adsorbed CO, while the electronic effect also influences the adsorption strength of ethanol. The variation of the balance of these effects with the level of Ru doping is a plausible explanation for the dependence the ethanol oxidation activity on the composition of the oxide layer.

Facile Synthesis of CuO and Ag Nanoparticles by Thermal Decomposition of Novel Schiff Base Complexes

Facile Synthesis of CuO and Ag Nanoparticles by Thermal Decomposition of Novel Schiff Base Complexes

Chemical Vapour Deposition of CdS Thin Films at Low Temperatures from Cadmium Ethyl Xanthate

Thin films of nanometer sized cadmium sulfide were directly prepared by aerosol-assisted chemical vapor deposition (AA-CVD) method, cadmium ethyl xanthate complex was used as precursor material at 225 oC, 250 oC and 275 oC. The thermal decomposition of complex was characterized by thermal analysis, (thermogravimetric analysis (TGA) and a differential scanning calorimetry (DSC)). The prepared CdS thin films have been characterized by XRD and SEM- EDX analysis. TGA curves ensured that the rapid decomposition of [Cd(S2COEt)2] gives a CdS in single step between 150 oC and 200 oC. XRD patterns confirmed that the CdS particles crystalized as a hexagonal crystallographic phase at low temperatures. The grain size of particles increased with increasing the preparation temperatures from 225 oC to 275 oC,. The spherical CdS nanoparticals were observed in SEM analysis.

The power of model-fitting kinetic analysis applied to complex thermal decomposition of explosives: reconciling the kinetics of bicyclo-HMX thermolysis in solid state and solution

Thermal decomposition of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (Bicyclo-HMX) both in solid state and in solution has been studied with a set of thermal analysis methods. Differential scanning calorimetry data obtained at several heating rates were analyzed using the model-fitting kinetic technique using the free open-source THINKS thermokinetic software. The kinetic parameters for a noncatalytic stage of thermolysis in solution are found to be Ea = 168.7 ± 1.4 kJ mol−1, log (A, s−1) = 15.7 ± 0.2, to prove the activation energy agrees with the theoretical prediction of the barrier for N–NO2 bond rupture in BC-HMX molecule. Thermal decomposition of solid BC-HMX is a complex process, typical for explosives. A formal three-step kinetic scheme is proposed, which explains the numerous experimental findings (thermal behavior at various confinement degree, morphology changes under heating) and the previous literature results as well. The first step of the process obeys a third-order nucleation-growth model with the Ea = 186.6 ± 1.2 kJ mol−1 and log (A, s−1) = 16.7 ± 0.3. Overall, the power of the model-fitting kinetic analysis is demonstrated and the extension of the proposed methodology to other energetic materials with complex decomposition patterns is suggested.

Synthesis, Characterization, Crystal Structure, and Hirshfeld Surface Analysis of Zinc, Cadmium, and Mercury Diphosphine Complexes; Precursors for Oxide Nanoparticles

In this article, complexes of Zinc(II), Cadmium(II), and Mercury(II) with Xantphos were synthesized and the molecular structure of two new complexes of [Cd(Xantphos)I2] and [Hg(Xantphos)I2] was determined by single-crystal X-ray crystallography. The hirshfeld surface analyses showed different types of intermolecular interactions in these diphosphines complexes. Moreover, the thermal decomposition of complexes was investigated using the thermogravimetric analysis, which approved the calcination of complexes had led to the formation of corresponding metal oxide nanoparticles. The crystallinity and morphology of final metal oxide nanoparticles characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and IR spectroscopy.

Synthesis, Characterization, Crystal Structure, and Hirshfeld Surface Analysis of Zinc, Cadmium, and Mercury Diphosphine Complexes; Precursors for Metal Oxide Nanoparticles

In this article, complexes of Zinc (II), Cadmium (II), and Mercury (II) with xantphos were synthesized and the molecular structure of two new complexes of [Cd(xantphos)I2] and [Hg(xantphos)I2] was determined by single-crystal X-ray crystallography. The hirshfeld surface analyses showed different types of intermolecular interactions in these diphosphines complexes. Moreover, the thermal decomposition of complexes was investigated using the thermogravimetric analysis, which approved the calcination of complexes had led to the formation of corresponding metal oxide nanoparticles. The crystallinity and morphology of final metal oxide nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and IR spectroscopy.