Final Thermolysis Product Research Articles

STUDY OF THE THERMAL PROPERTIES OF SILVER(I) COORDINATION COMPOUNDS WITH 1,2,4-TRIAZOLES

In this work, using the differential thermal method, the thermal properties of silver (I) complexes with 1,2,4-triazole (1,2,4-triazolethiol) were studied. Based on the studies carried out, intermediate and final products of thermolysis of these complexes were determined, reactions of their thermal decomposition, thermal dehydration processes, and the sequential removal of acid and organic ligands from their composition were proposed. It was revealed that the onset of dehydration temperature depends on the nature of the resulting complex and the method of addition of the water molecule.

Double pseudo-polymeric complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: preparation, structural organization, and thermal behavior (low-temperature reduction and crystallization of gold)

The capability of thallium(I) alkylenedithiocarbamates to bind gold(III) from solutions in 2 M HCl was studied. Double complexes of [Au{S2CN(CH2)5}2][TlCl4] and [Au{S2CN(CH2)6}2][TlCl4] were preparatively isolated as individual forms of gold(III) binding into the solid phase. In the crystalline state, the ionic structural units of the complexes are combined together due to the secondary Au···S, Tl···S and S···Cl bonds that results in complicated supramolecular architectures. Thermal behavior of compounds was studied using the simultaneous thermal analysis technique; both reduced elemental gold and thallium(I) chloride were identified as the final thermolysis products.

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.

Nickel(II) complexes with 2-Hfur and N-donors: The magnetic effects of the structural variations, thermal properties and antimycobacterial activity against Mycolicibacterium smegmatis

New complexes of nickel(II) with 2-furoic acid (2-Hfur) and different N-donor ligands of the composition [Ni(fur)2(phen)(H2O)2]·H2O (1) (phen = 1,10-phenantroline), [Ni(fur)2(2,2′-bpy)] (2, 2,2′-bpy = 2,2′-bipyridine), [Ni(fur)2(4,4′-bpy)(CH3OH)2]n (3, 4,4′-bpy = 4,4′-bipyridine), [Ni(fur)2(pz)4]·2MeCN (4) (pz = pyrazole) have been synthesized. The structure of the compounds was established by single crystal X-ray diffraction analysis. Complexes 1, 2, and 4 are mononuclear, complex 3 is a 1D coordination polymer. The DC magnetic susceptibility data measured for 2 and 3 are indicative of antiferromagnetic exchange interactions between the metal centers, which proved to be negligibly weak in 2 and more pronounced in 3. A quantum-chemical analysis of intermolecular (for 2) and intra- and interchain (for 3) magnetic exchange pathways confirms these findings, revealing the presence of magnetic chains formed by a network of very weak intermolecular antiferromagnetic exchange interactions in the crystal of 2 and a strengthening of antiferromagnetic exchange coupling in the polymeric chains of 3. Thermal behavior of 1 and 2 was studied by simultaneous thermal analysis (STA). According to PXRD data, the final thermolysis product of complex 2 is metal Ni nanocrystals (d = 14.7(3) nm). Analysis of the results of biological activity of 1–4in vitro against Mycolicibacterium smegmatis showed a low sensitivity of the mycobacterial wall to Ni2+ cations.

Crystal Structures, Hirshfeld Surfaces, and Thermal Study of Isostructural Polymeric Ladders of La(III) and Sm(III) Coordination Compounds with 4,4'-Bipyridine and Dibromoacetates.

Two novel mixed ligand complexes with general formula [M2(4,4′-bpy)1.5(CBr2HCOO)6(H2O)2]n (where 4,4′-bpy = 4,4′-bipyridine) were synthesized. Thermal analysis was used to describe a solid intermediate and final products of thermolysis. A coupled TG-MS system was used to monitor principal volatile fragments evolved during pyrolysis. Crystal structures of the complexes were determined. Cationic dinuclear M2 (M(III) = La, Sm) coordination cores were obtained. Both crystal structures are isostructural. Single crystal X-ray diffraction analysis revealed that investigated structures of 1D coordination polymers assembled in ladder-like systems. The central atom replacement resulted in unit cell identity parameter П = 0.0091. Additionally, the isostructurality of the reported La(III) and Sm(III) complexes was revealed using Hirshfeld Surface analysis supported by Enrichment Ratio calculations.

New Heterometallic Co(III) Pivalate Complexes with 1,3-(CH2)3(NH2)2

The reactions of the complex [Co(DAP)2(Piv)2] · Piv (Ia), where Piv is the pivalate anion, DAP is 1,3-diaminopropane, with Cd(II) and Li(I) pivalates afford heterometallic compounds, molecular complex [CdCo(DAP)2(Piv)5] (I) and polymeric complex [LiCo(DAP)2(Piv)4]n (II) (CIF files CCDC nos. 1908223 and 1908224, respectively). According to X-ray photoelectron spectroscopy, the electronic structure of cobalt ions in complexes Ia and I corresponds to low-spin Co(III) surrounded by strong-field ligands. The thermal destruction of I and II, studied by synchronous thermal analysis, includes stages of desorption of solvate molecules, destruction of the 1,3-diaminopropane molecule with nitrogen evolution, and degradation of carboxylate anions. The final product of thermolysis of I is the complex oxide CdCoO2.

Oxalato complexes of Pd(II) with Co(II) and Ni(II) as single-source precursors for bimetallic nanoalloys

The single-source precursors of noble–ignoble nanoalloys are of a great interest since they can be used in many areas such as optical, biomedical, catalysis, magnetic and chemosensors. The new water-soluble double complex salts (DCSs) with aqua and oxalato ligands, [M(H2O)6][Pd(Ox)2]·nH2O (M = Co2+, Ni2+; n = 2, 4; Ox = C2O 4 2− ), were obtained, structurally characterized (single-crystal XRD) and used as precursors for M–Pd nanoalloys. Complexes, intermediate and final thermolysis products were studied by simultaneous thermogravimetric analysis combined with mass spectrometry, powder XRD, in situ synchrotron powder XRD, IR and X-ray photoelectron spectroscopy. Decomposition in different atmospheres leads to formation of bimetallic solid solution M0.5Pd0.5 (He, H2) or a mixture of metal oxides (O2). The catalysts M–Pd/TiO2 (1% Pd) were prepared by the decomposition of DCSs deposited onto titania via wetness impregnation. The H2-made Ni-containing samples showed a high photocatalytic activity in CO oxidation reaction.

Особенности термолиза малеатов Cu и La

Salts of carboxylic acids are widely used in organic synthesis, in the preparation of catalysts and nanocomposites of metals in the carbon matrix by thermolysis of maleates, acrylates or acetylenedicarboxylates of these metals; however, the studies of the thermal destruction process of such compounds are fragmentary. The processes of multi-stage decomposition of Cu and La maleates in an inert atmosphere were studied by the method of simultaneous thermal analysis with the analysis of the composition of evolved gases. Reaction mechanisms have been suggested that correspond to the gaseous products and the final solid decomposition product determined during the thermal steps of mass loss. The formation of nano-dispersed copper oxides and lanthanum oxocarbonate included in the porous carbon matrix has been shown. The results of thermal analysis have allowed us to identify common features of the maleate thermolysis. First, the decomposition of maleate ion or maleic acid is always accompanied by the formation, along with water and carbon dioxide, of two products containing a double or triple C–C bond: acrylic acid and acetylene in approximately equal amounts. Second, the presence of multiple bonds in the molecules of the initial substances and in the molecules of the gaseous products of thermolysis leads to their polymerization and further to formation of the carbon residue. The amount of this residue is the highest in the case of decomposition of lanthanum maleate and the lowest in the case of copper maleate. Third, the thermolysis of metal maleate results in a matrix consisting of a carbon polymer with particles of metals (Cu) or metal oxides / carbonates in the form of nanodispersed crystals evenly distributed in this matrix. With the use of electron microscopy the morphology and particle size of the products of the thermolysis of La and Cu maleates were determined. The thermolysis products are composites of spherical La 2 O 2 (CO 3 ) particles (2–5 µm in diameter) and Cu 2 O, CuO, Cu (10–500 nm in diameter), evenly distributed in the carbon matrix. The analysis of the thermolysis mechanism on the basis of the data on the magnitude of mass loss at each stage, thermal effects, as well as on the composition of gaseous products and on the phase composition of the final solid products of thermolysis allowed us to suggest a consistent initial formula of La and Cu maleates.

Tri- and tetranuclear heteropivalate complexes with core {Fe2NixO} (x = 1, 2): Synthesis, structure, magnetic and thermal properties

The reactions of complex [Fe2Ni(O)(Piv)6(Et2O)(H2O)2] (1) with 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy) gave the following new coordination compounds: the trinuclear complex [Fe2Ni(O)(Piv)6(phen)H2O]·(C2H5)2O (2), the tetranuclear ones [Fe2Ni2(OH)2(Piv)8(phen)2] (3) and [Fe2Ni2(OH)2(Piv)8(bpy)2] (4), depending on the crystallization conditions. According to single crystal X-ray diffraction data, all the compounds have molecular structures. The Mössbauer spectra of 1–3 correspond to high-spin Fe3+ ions in an octahedral environment consisting of oxygen atoms. The DC magnetic susceptibility studies and quantum-chemical analysis of intra- and intermolecular J pathways using broken-symmetry density functional theory (DFT) showed that all exchange interactions in tri- (1, 2) and tetranuclear (3) complexes are antiferromagnetic. The exchange coupling is weaker in 3 due to the lower ability of the bridging OH-groups to mediate superexchange. Thermal destruction processes have been studied for 2 and 3. The final products of thermolysis are the mixed oxide NiFe2O4.

Synthesis of BaSnO3/SnO2 Nanocomposites as Heterogeneous Additive for Composite Solid Electrolytes

Method of differential thermal analysis was used to study the thermolysis of a mixture of barium oxalate hydrate and α-SnO2·H2O, produced by precipitation from hydrochloric solutions. The methods of X-ray diffraction analysis, electron microscopy, and low-temperature nitrogen adsorption were used to examine the reaction products formed at various heating temperatures and determine their phase composition. The nanocomposite BaSnO3/SnO2 is the final product of thermolysis and subsequent heating to 950°C. The nanocomposite was used as a heterogeneous oxide additive for obtaining a CsNO2–BaSnO3/SnO2 composite solid electrolyte. The conductivity of the composite exceeds that of the starting salt by more than order of magnitude.

The thermal behavior of double complex compounds with the cation [Cr(ur)6]3+ in a reducing atmosphere

The thermal behavior of double complex compounds (DCC) [Cr(ur)6][Co(CN)6]·4H2O (I), [Cr(ur)6][Co(C2O4)3]·3.5H2O (II), [Cr(ur)6][Fe(CN)6]·4H2O (III), [Cr(ur)6][Fe(C2O4)3]·2H2O (IV) and urea (ur) was studied (ur = urea, H2NCONH2). Thermal decomposition was carried out by the TG-MS method and method of static experiments in the reducing atmosphere at a 1-h exposure. The final thermolysis products are characterized by elemental analysis, XDR, IR spectrometry, SEM, the specific surface area (SBET) of the samples. The porous structure of the samples was determined. Cr2O3 + Co0 are formed as a result of thermal reduction of I, II, Cr2O3 + Fe0 + Fe2O3 for III, FeCr2O4 + Fe0 for IV. The replacement of CN− ligands by C2O42− ligands leads to an increase in the specific surface by a factor of ~ 2. Catalytically activity of Co-containing degradation products is demonstrated in the model catalytic decomposition of H2O2. The relationship between SBET and the obtained values of the rate constants of the reaction is not observed. Fe-containing samples are not catalytically active.

Synthesis, structure and properties of Ni(II) coordination polymer based on α,α-dimethyl substituted zoledronate

The reaction of α,α-dimethyl substituted derivative of zoledronic acid with Ni(II) afforded 1D coordination polymer, Ni3(HL)2(H2O)6·6H2O (1). The title compound possess crystallographically and spectroscopically distinct Ni1 and Ni2 centers characterized by tetragonality distortion parameter T = 0.97 and 1.04, respectively, and is isomorphous with recently reported Co3(HL)2(H2O)6·6H2O complexes based on α,α-dimethyl and cyclopropyl substituted zoledronate derivatives.Detailed analysis of thermal stability of 1 revealed that partly dehydrated [Ni3(HL)2(H2O)3] still retains its architecture and structural integrity of coordinated ligands. Exploring supramolecular interactions that build up the crystal of 1 and related Co(II) complexes allowed a conclusion that distinct dehydration pathways observed for each compound may be correlated with subtle differences in 3D crystals packing. Ni2(P2O7) salt was identified as the major final product of thermolysis of 1.The magnetic properties of 1 analyzed in term of a spin-1 Heisenberg Ni2Ni1Ni2 trimer chains model revealed antiferromagnetic Ni1⋯Ni2 interactions within the trimers (J1 = −7.32 cm−1) and ferromagnetic Ni2⋯Ni2 intertrimers coupling (ΘW = 1.72 K). Furthermore, different values of the axial zfs D parameters and the g-factors were assigned to the Ni1 and Ni2 centers.

Double complex salts [Au(En)2][Ir(NO2)6] • nH2O (n = 0, 2), [Au(En)2][Ir(NO2)6] x [Rh(NO2)6]1–x • nH2O (x = 0.25, 0.5, 0.75): Synthesis, structure, thermal properties

The double complex salts [Au(En)2][Ir(NO2)6] • 2H2O (I) and [Au(En)2][Ir(NO2)6] (II) and solid solutions [Au(En)2][Ir(NO2)6]x[Rh(NO2)6]1–x • nH2O, where x = 0.25, 0.5, 0.75, were prepared and characterized by powder X-ray diffraction, IR spectroscopy, elemental analysis, and DTA. The crystal structures were determined by X-ray diffraction. The thermal behavior of compounds under reducing atmosphere was studied. The final products of thermolysis were found to be two-phase mixtures consisting of nano-sized pure gold particles (~55 nm) and particles of Au–Ir–Rh solid solutions (~3 nm).

Gold(III)–iron(III) heteropolynuclear complexes ([Au{S2CNR2}2][FeCl4]) n (R = C4H9, iso-C4H9): Chemisorption synthesis, supramolecular self-organization, and thermal behavior

The reactions of iron(III) dibutyl and di-iso-butyl dithiocarbamates [Fe(S2CNR2)3] (R = C4H9, iso-C4H9) with anions [AuCl4]– in 2 M HCl are studied. The result of heterogeneous reactions of gold(III) chemisorption binding from a solution is the formation of gold(III)–iron(III) heteropolynuclear complexes of the ionic type. The crystal and supramolecular structures of polymer complexes ([Au{S2CN(C4H9)2}2][FeCl4]) n (I) and ([Au{S2CN(iso-C4H9)2}2][FeCl4]) n (II) are determined by X-ray diffraction analysis (CIF files CCDC 1407704 (I) and 1407802 (II)). The structure of complex I contains two centrosymmetrical structurally nonequivalent complex cations [AuS{2CN(C4H9)2}2]+ (A and B) and complex anion [FeCl4]–. Structure II is formed by three isomeric complex cations [Au{S2CN(iso-C4H9)2}2]+ (А, В, and С) and two anions [FeCl4]– related as conformers. The isomeric cations are involved in the formation of linear (…А…В…) n (in I) or zigzag (…А…В…А…С…) n (in II) polymer chains due to pairs of weak secondary interactions Au···S. The thermal behavior of the complexes is studied by simultaneous thermal analysis. Thermal destruction includes the thermolysis of the dithiocarbamate moiety of the complexes and anions [FeCl4]– with the reduction of gold(III), release of FeCl3, and partial formation of Fe2O3. The final thermolysis products are metallic gold and Fe2O3.

Synthesis, crystal structures, and characterization of double complex salts [Au(en)2][Rh(NO2)6]·2H2O and [Au(en)2][Rh(NO2)6

Double complex salts of rhodium(III) and gold(III) of the composition [Au(en)2][Rh(NO2)6]·2H2O (1) and [Au(en)2][Rh(NO2)6] (2) have been prepared. Crystal structures of the compounds have been determined by single crystal X-ray diffraction. The compounds have been characterized by PXRD, IR, far-IR, CHN and DTA.The complexes have a layered structures. The presence of water in 1 makes the structure of the hydrated DCS less dense as compared to the anhydrous one. The environment of the cation and the anion in the two structures is the same, oxygen atoms of the nitro groups are involved in hydrogen bonds N–H⋯O, N⋯O distances being approximately the same. The structures of 1 and 2 are notable in having shortened contacts between the gold atoms and the oxygen atoms of the nitro groups of the neighboring complex anions. The thermal behavior of the complexes in a hydrogen atmosphere was investigated. The final product of thermolysis prepared at the temperature 600°С is a two-phase mixture of pure metallic gold and the solid solution Rh0.93Au0.07.

Binuclear and polynuclear cymantrenecarboxylate complexes of heavy lanthanides

New binuclear cymantrenecarboxylate complexes of rare-earth metals, [Ln2(μ-O,η2-O2CCym)2(μ2-O,O′-O2CCym)2(η2-O2CCym)2(DMSO)4] (Ln = Tb (I), Dy (II); Cym = (η5-C5H4)Mn(CO)3) and [Ln2(μ2-O,O′-O2CCym)4(η2-NO3)2(DMSO)4] (Ln = Tb (III), Dy (IV)), are synthesized and characterized by X-ray diffraction analysis. The carboxylate clusters containing the Mn2+ ion, which is formed due to the destruction of the cymantrenenecarboxylate anion, [Tb4(μ3-OH)4(μ2-O,O′-O2CCym)6(H2O)3(THF)4][MnCl4] · 4CH2Cl2 · 6THF (V) with the cubane-like structure, and [Er2Mn(μ2-O2CCym)6(η2-O2CCym)2((MeO)3PO)4] · 2MePh (VI) with linear structure, are also obtained. The magnetism of complexes I, II, V, and VI is studied in a direct magnetic field. The magnetic properties of complexes II and VI are studied in direct and alternating magnetic fields. Complex II exhibits the properties of a single-molecule magnet. The thermal decomposition of complexes I–IV is studied by differential scanning calorimetry and thermogravimetric analysis. According to the X-ray diffraction analysis data, the final thermolysis products of complexes III and IV in air are multiferroics LnMn2O5.

Chemisorption of gold(III) from solutions using thallium(I) diisobutyldithiocarbamate: Supramolecular structure and thermal behavior of the polymeric gold(III)-thallium(III) complex ([Au{S2CN(iso-C4H9)2}2][TlCl4]) n

Chemisorption of gold(III) from 2 M HCl using thallium(I) diisobutyldithiocarbamate via an ion exchange/redox process gives a polymeric gold(III)-thallium(III) complex of the formula ([Au{S2CN(iso-C4H9)2}2][TlCl4])n (I). Its supramolecular structure determined by X-ray diffraction (CIF file CCDC no. 1009388) comprises three structurally nonequivalent complex cations [Au{S2CN(iso-C4H9)2{2]+ (A, B, and C) and two nonequivalent [TlCl4]−-anions, both the cations and the anions being conformers. The isomeric cations are united through pairs of relatively weak secondary nonvalent Au⋯S contacts into zigzag polymer chains (⋯A⋯B⋯C⋯B⋯)n, with alternating nonequivalent [TlCl4]− anions on both sides. The thermal behavior of complex I was studied by simultaneous thermal analysis. The TG curve shows two steps of its weight loss. The first step involves thermal decomposition of the dithiocarbamate portion of the complex and [TlCl4]− with reduction of gold(III) to metallic gold and release of TlCl. The second step is due to evaporation of TlCl. The final thermolysis product of complex I is reduced metallic gold.

Gold(III) ionic complexes [Au{S2CN(C2H5)2}2]Cl and ([Au{S2CN(C2H5)2}2][AuCl4]) n : Synthesis, supramolecular self-assembly, polymorphism, and thermal behavior

A heterogeneous reaction between freshly precipitated oxovanadium(IV) diethyldithiocarbamate [VO{S2CN(C2H5)2}2] and a solution of AuCl3 in 2 M HCl has been shown to yield two ionic gold(III) compounds: the water-soluble ionic complex [Au{S2CN(C2H5)2}2]Cl (I) and the coordination polymer ([Au{S2CN(C2H5)2}2][AuCl4])n (II), which was preparatively separated from the precipitate phase. The molecular and crystal structures of the synthesized complexes have been established by X-ray diffraction. The crucial role in the supramolecular self-assembly of the compounds obtained belongs to C-H⋯Cl hydrogen bonds (in I) and Au⋯S and Au⋯Cl secondary interactions (in II). Polymeric complex II has been found to be able to form two polymorphs, which differ from each other by the building mode of cation-anion polymeric chains. The study of the thermal behavior of the synthesized complexes by simultaneous thermal analysis in an argon atmosphere has allowed us to recognize conditions for the recovery of bound gold. In both cases, reduced metallic gold is the only final thermolysis product.

Investigation into the Palladium‐Europium Acetate Reductive Decomposition with Synchrotron Radiation‐Based X‐ray Diffraction and X‐ray Absorption Spectroscopy

AbstractThe reductive decomposition of the complex Pd2Eu2(μ,η2‐OOCMe)2(μ‐OOCMe)8(H2O)2·(HOOCMe)2upon heating from room temperature to 500 °C in a hydrogen atmosphere was investigated by in situ synchrotron radiation‐based X‐ray absorption fine structure spectroscopy (XAFS) including observations of X‐ray near‐edge structure (XANES) and extended absorption fine structure (EXAFS) at Pd K‐ and Eu L3‐edges and synchrotron X‐ray diffraction (XRD). The Pd‐Eu2O3nanocomposite was found to be the final thermolysis product. The decomposition proceeds via series of intermediate crystalline phases, including europium(II) and (III) anhydrous acetates and EuO(CH3COO) oxidoacetate. Surprisingly, the major fraction of europium occurs in the reduced form Eu2+within a limited temperature range of 200–300 °C. Presumably, the reversible Eu3+↔Eu2+redox‐process is associated with the stability of nanocrystalline palladium hydride, which acts as a stronger reducing agent as compared to molecular hydrogen.

New binuclear ferrocenecarboxylates of rare-earth metals as precursors for ferrites: Syntheses, structures, and solid-phase thermolysis

New ferrocenecarboxylates of rare-earth metals, [Ln2(μ-O,η2-OOCFc)2(μ2-O,O′-OOCFc)2(η2-NO3)2(DMSO)4] (Ln = Gd (I), Tb (II), and Y (III)) and [Gd2(μ-O,η2-OOCFc)2(η2-OOCFc)4(DMSO)2(H2O)2] · 2DMSO · 2CH2Cl2 (IV), are synthesized and characterized by X-ray diffraction analysis. Unlike all earlier known ferrocenecarboxylates of rare-earth metals, in isostructural compounds I–III the Ln atoms are linked by four bridging carboxyl residues, two of which are chelate-bridging (the coordination number of Ln is 9). Binuclear structure IV is formed by two chelate-bridging carboxylate ligands (the coordination number of Gd is 9). Weak antiferromagnetic and weak ferromagnetic interactions between the Gd atoms are observed in complexes I and IV, respectively. The thermal decomposition of the synthesized compounds is studied by differential scanning calorimetry and thermogravimetry. According to the X-ray diffraction data, the final thermolysis products of the complexes in air are garnets Ln3Fe5O12.