Thermal behaviour of mixed long-chain alkylammonium tetrachlorozincates

Mixed crystals of composition (n-C_mH_2m+1NH₃)_2xm(n-C_nH_2n+1 · NH₃)_2?2xm ZnCl₄ (m= 12; n=14, 16, 18) are formed upon annealing mechanical mixtures of layer compounds (n-C_nH_2n+1NH₃)₂ZnCl₄, through solid state diffusion of the n-alkylammonium cations. From a common high temperature monophasic modification, in which the polymethylenic chains are conformationally molten, different modifications are obtained on cooling [depending on the (n ? m) value] in which chain crystallinity is developed. The structure of such modifications is speculated on the grounds of DSC and preliminary X-ray diffractometric and IR data, and compared with that of similar previously characterized systems.     

Interaction of long chain alkylammonium cations with reduced charge montmorillonite

Reduced charge montmorillonites (RCM) were prepared using lithium thermal treatment. The sorption of octylammonium (OA), dodecylammonium (DDA) and hexadecylammonium ions (HDA) on differently charged samples were studied. The amounts of DDA and HDA sorbed on each RCM exceed the cation exchange capacity (CEC) but that of OA exceeds only the CEC of samples with the lowest CEC. The sorption is affected not only by the layer charge but also by the formation of collapsed interlayer spaces in the lowest charged montmorillonites. X-ray measurements confirmed the decrease of the layer charge after lithium thermal treatment and the layer charge heterogeneity in RCMs.     

On the thermal behaviour of palladium (II) macrocyclic polycatenars

Polycatenar saturated macrocycles 1,10-bis[3,4,5-tris(4-dodecyloxy)benzoy1]-1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3b) and 1,10-bis[3,4-bis(4-dodecyloxy)benzoy1] -1,10-diaza-4,7,13,16-tetrathiacyclo-octadecane (3d) reacted with [Pd(MeCN)₄][BF₄]₂ led to the cationic complexes [4b][BF₄]₂ and [4d][BF₄]₂, respectively. Complexes [4b][BF₄]₂ and [4d][BF₄]₂ showed smectic mesomorphism on heating as confirmed by small angle X-ray diffraction. A concurrent, irreversible structural change of the complex cations was observed and a tentative explanation is suggested.     

Phase diagrams of binary systems of alkylammonium tetrachlorometallates(II)

The phase diagrams of four binary systems (C₁₀H₂₁NH₃)₂CoCl₄?(C₁₆H₃₃NH₃)₂CoCl₄, (C₁₂H₂₅NH₃)₂CoCl₄?(C₁₆H₃₃NH₃)₂CoCl₄, (C₁₀H₂₁NH₃)₂ZnCl₄?(C₁₆H₃₃NH₃)₂ZnCl₄ and (C₁₂H₂₅NH₃)₂ZnCl₄?(C₁₆H₃₃NH₃)₂ZnCl₄ were investigated by means of DSC. These six compounds and their binary mixtures can retain energies between 74 and 115 J/g during solid-state transformations at temperatures between 70 and 105°C, and they are therefore being considered for potential use in solar energy systems.     

Extraction kinetics and ultrafiltration removal of Nickel (II) by long chain alkoxypicolinic acids in cationic and mixed micelles

Micellar particles can solubilize lipophilic extractants similarly to the organic phase in classical biphasic extraction. This analogy is used here to investigate the kinetics of complex formation between Ni²⁺ ions and long chain 5-alkoxypicolinic acids (C_n-PIC, withn=12, 15, 18) solubilized in different types of micelles, namely cetyl trimethylammonium bromide (CTAB), hexaethyleneglycol-dodecylether (C₁₂EO₆) and CTAB/C₁₂EO₆ mixed micelles. In the case of CTAB micelles, the interaction between the carboxylic function of the extractant and the polar head of surfactant molecules was expected to decrease the rate of complex formation so as to make possible kinetic separation of mixtures of metal ions. The observed rate constants for complex formation at pH 4.5 or 7.0 are indeed much smaller in CTAB micelles than in C₁₂EO₆ or mixed micelles, but they still remain too high for the previous purpose, although the influence of the surfactant concentration demonstrates, as expected, a much stronger partitioning in the case of CTAB in comparison to C₁₂EO₆. On the other hand, it is shown that, once complex formation has occurred the removal of Ni²⁺ ions can be achieved using ultrafiltration. The yield of extraction increases withn, with the mole fraction of C₁₂EO₆, and with the ligand to metal ratio.Institut Nancéien de Chimie Moléculaire (I.N.C.M.)     

The thermal behaviour of some Co(II) complex combinations with schiff bases

In order to evidence the ligand influence on the thermal stability for Co(II) complex combinations, we have synthesized five complex combinations of this metal with Schiff bases obtained by condensation of ethylenediamine with acetylacetone and benzoylacetone; phenylenediamine with benzoylacetone and also anthranilic acid with benzaldehyde. This revised version was published online in July 2006 with corrections to the Cover Date.     

Unique spin transition and wide thermal hysteresis loop for a cobalt(II) compound with long alkyl chain

The cobalt(II) compounds with long alkyl chains, [Co(C12-terpy)(2)](BF(4))(2)·EtOH·0.5H(2)O(1·EtOH·0.5H(2)O) and [Co(C12-terpy)(2)](BF(4))(2) (1) was synthesized and characterized. The compound 1·EtOH·0.5H(2)O exhibits a "re-entrant spin crossover". The compound 1 exhibits the reentrant spin crossover and multi phase transitions with a wide thermal hysteresis loop.     

Selectivity of mechanochemical chain scission in mixed palladium(II) and platinum(II) coordination polymers

The selectivity of ultrasound induced chain scission was studied in reversible polymers with coordinative bonds (Pd-P and Pt-P) of different strengths in series.     

Iron(II) spin crossover complexes with branched long alkyl chain

The bzimpy iron(II) complexes, 1-3, containing branched long alkyl chains were synthesized and characterized in detail. The temperature-dependant magnetic susceptibility of 1 showed gradual spin crossover behavior from low spin to high spin state, while 2 retained only low spin state in the same condition. Interestingly, 3 displayed an abrupt spin transition in temperature range from T_1/2↑ = 236 K to T_1/2↓ = 230 K with the thermal hysteresis loop about 6 K. The differential scanning calorimetric analysis of 3 revealed two species of liquid crystal phase transitions at 236 K and 351 K, respectively.     

Synthesis and thermal behaviour of morpholine complexes with cobalt (II) and manganese (II) thiocyanates

The 1 4 complexes of cobalt (II) and manganese (II) thiocyanates with morpholine (Morph), [M(NCS)₂(Morph)₄] (M=Co, Mn), were prepared and studied by means of thermogravimetry, derivative thermogravimetry and differential scanning calorimetry. By thermal treatment of the above compounds, the 12 and 11 complexes, [M(NCS)₂(Morph)₂] (M=Co, Mn; n=1, 2), were formed. Magnetic data, infrared and electronic spectra and molar conductance values for the compounds are reported. All the complexes contain N-bonded morpholine and the 14 complexes are suggested to have a monomericcis pseudooctahedral structure with N-bonded thiocyanate, whereas the 12 and 11 complexes are considered to have a six-coordinated polymeric configuration involving bridging NCS groups.

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Zusammenfassung Mittels. Thermogravimetrie, Derivativthermogravimetrie und Differential-Scanning-Kalorimetrie wurden die zuvor dargestellten 14 Komplexe von Kobalt(II)- und Mangan(II)thiozyanaten mit Morpholin (morph) [M(NCS)₂(morph)₄] mit M=Co, Mn untersucht. Durch Erhitzen obiger Verbindungen entstehen die 12- bzw. 11-Komplexe [M(NCS)₂(morph)_n] mit M=Co, Mn undn=1, 2. Magnetisierungsdaten, Infrarot- und Elektronenspektren sowie die molare Leitfähigkeit der Verbindungen wurden ermittelt bzw. angegeben. Alle Komplexe enthalten N-gebundenes Morpholin. Die 14 Komplexe besitzen eine monomere cis-pseudooktaedrische Struktur mit N-gebundenem Thiozyanat, während die 12- und 11-Komplexe eine hexakoordinierte polymere Struktur mit NCS-Gruppenbrücken zu besitzen scheinen.

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, (.) [(S)₂(.)₄]. [ (S)₂(.) _n ], =1 2. , , . . 14 ( : ) - N- . 121 11 - , .

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The authors express their thanks to Dirección Regional de Universidad e Investigación de la Comunidad Autónoma de Murcia for providing financial assistance.     

四氯合金属(II)酸烷铵在280-500K间的热力学性质和相变 I:四氯合锰(II)酸n-十二烷铵

在280-500K的温度范围内用自动绝热量计测定了(n-C12HxNH3)2MnCl4的热容.发现了两个固-固相变,固ID→固II和固I→固II.前者的相变温度、相变焓和相变熵分别为330.6±0.1K,47.78±0.29kJ.mol^-^1和144.5±0.9J.K^-^1.mol^_^1,后者的对应相变热参数分别为334.5±0.1K,5.96±0.05kJ.mol^-^1和17.82±0.15J.K^-^1.mol^-^1.报道了该物质每隔10K的热力学性质.     

Synthesis and thermal behaviour of a series of pentacyanoligandferrate(II) complexes

[M_mFe(CN)₅L·xH₂O] (M = Mn, Fe, Co, Ni, Cu; L = pyridine or pyrazine derivative) have been synthesized, and their UV-vis and IR spectral characteristics are reported. Thermolysis of the solids leads to water release, ligand release and/or decomposition, redox interaction between Fe³⁺ (or Cu²⁺) with CN⁻ or L, and redox interaction between M²⁺ (or Cu⁺) and CN⁻, yielding elemental metal and metal carbides.     

Mesophase behaviour and thermal stability of octa-alkoxy substituted phthalocyaninatocobalt (II) complexes

Cobalt (II) phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions were prepared. The alkoxy chain length was varied between n-butyloxy (C₄H₉O) and n-octadecyloxy (C₁₈H₃₇O). Studies by polarizing optical microscopy and high temperature X-ray diffraction revealed that all the complexes are liquid crystalline and that they exhibit a hexagonal columnar mesophase (Col_h). Transition enthalpies were determined by differential scanning calorimetry. The clearing point could only be observed for compounds with a chain length longer than C₁₃H₂₇O. Both the melting and clearing points decrease with increasing chain length. The transition temperatures of these discotic metallomesogens are higher than those of the corresponding metal-free phthalocyanines, but are comparable with those of the corresponding copper (II) compounds. The thermal decomposition of the compounds was studied by thermogravimetry.     

Mesophase behaviour and thermal stability of octa-alkoxy substituted phthalocyaninatocobalt (II) complexes

Cobalt (II) phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions were prepared. The alkoxy chain length was varied between n-butyloxy (C₄H₉O) and n-octadecyloxy (C₁₈H₃₇O). Studies by polarizing optical microscopy and high temperature X-ray diffraction revealed that all the complexes are liquid crystalline and that they exhibit a hexagonal columnar mesophase (Col_h). Transition enthalpies were determined by differential scanning calorimetry. The clearing point could only be observed for compounds with a chain length longer than C₁₃H₂₇O. Both the melting and clearing points decrease with increasing chain length. The transition temperatures of these discotic metallomesogens are higher than those of the corresponding metal-free phthalocyanines, but are comparable with those of the corresponding copper (II) compounds. The thermal decomposition of the compounds was studied by thermogravimetry.     

The synthesis, structural features and thermal behaviour of thiophene-containing dithiocarboxylate complexes of zinc(II)

The complexes [Zn₂(S₂CTR)₄] (T = 2,5-disubstituted thiophene, R = C₄H₉ (1), C₆H₁₃ (2), C₈H₁₇ (3), C₁₂H₂₅ (4) and C₁₆H₃₃ (5)) have been synthesized and their structural features investigated. Compared to the analogous dithiobenzoate complexes, the crystal structure determination of 2 revealed that the thiophene induces a “step-rod” chain pattern instead of the linear, rodlike structure found for the corresponding dithiobenzoates. Complexes 1–5 did not display mesophases under thermal conditions, but an irregular melting pattern was observed for 3 and 4.     

Similarities and differences of thermal behaviour of 2-hydroxymethylbenzimidazole complexes with Zn(II) and Cd(II) ions

For a comparison of structural data and thermal behaviour of Zn(II) and Cd(II) complexes with biologically important ligand, 2-hydroxymethylbenzimidazole (L) the complex of the formula [ZnL₃](NO₃)₂L_0.67L′_0.33 was prepared and characterized by elemental analysis, infrared (IR) spectra, single-crystal X-ray diffraction and thermal analysis (where L′ = 2-carbaldehydebenzimidazole). IR and X-ray studies have confirmed a bidentate fashion of coordination of the 2-hydroxymethylbenzimidazole to Zn(II) ion (through the nitrogen atom of heteroaromatic ring and oxygen atom of hydroxymethyl group). The zinc ion is hexacoordinated and the shape of polyhedron can be described as pseudo-octahedron (N₃O₃ chromophore type). The decomposition process of studied Zn(II) and Cd(II) benzimidazole complexes in the air atmosphere proceeds in three or four main stages and traces structures of complexes. On the basis of the first DTG_max of the decompositions the thermal stability of the complexes follows the order: [CdL₃](NO₃)₂LEtOH_0.25 < [CdL₂(NO₃)₂] < [ZnL₃](NO₃)₂L_0.67L′_0.33. As the final solid products of thermal decomposition suitable metal oxides are formed.     

四氯合金属(II)酸正烷铵在280-500K间的热力学性质和相变 II: 四氯合锌(II)酸正十二烷铵

研究了四氯合锌(II)酸正十二烷铵(C12H25NH3)2ZnCl4(1)]在280-500K间的热力学性质和相变热参数. 据报导(RNH3)MX4型化合物在300-380K间有相变焓很大的固-固相变, 是很有开发前景的固-固相变低温储能材料, 本文为(1)的应用提供了精确的热数据.     

The thermal properties of cobalt(II), nickel(II) and copper(II) iminodiacetates

The thermal properties of the Cu(II), Ni(II) and Co(II) complexes of iminodiacetic acid (H₂IMDA) were determined using TG, DTG and DSC techniques. The complexes, of general formula, MIMDA-2H₂O evolved water of hydration from 50 to 150°C which was followed by the decomposition of the anhydrous complex in the 250 to 400°C temperature range. The thermal stability, as determined by procedural decomposition temperatures, was: Ni(II) >Co(II) >Cu(II). The thermal stability is discussed in terms of IR spectra, ΔH, and ΔS, as well as thermal data.     

An angular overlap model treatment of mixed valence Pt(II)-Pt(IV) haloamine chain complexes

Summary A recently proposed extension of the angular overlap model (AOM) is applied to the linear chain compounds [Pt^II(AA)₂·Pt^IV X ₂(AA)₂] ⁴⁺ withX=Cl, Br, I;AA = ethylenediamine, 1,2- and 1,3-diaminopropane, and to Wolffram's red and Reihlen's green salt. The energy band structures are calculated from AOM parameters which are derived from d-d spectra of isolated Pt(II) and Pt(IV) complexes reported in the literature. Assignments of absorption edges and other peaks in the crystal spectra as well as spectral shifts due to changes in the geometric structure are discussed. Since the AOM energy expressions are given in analytical form, the procedure supplies various advantages over the extended Hückel theory which currently has been adapted for treating chain structures.

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Behandlung von gemischt-wertigen Pt(II)-Pt(IV)-Ketten-Komplexverbindungen mit dem Angular Overlap-Modell

Zusammenfassung Eine kürzlich vorgeschlagene Erweiterung des Angular Overlap -Modells (AOM) wird auf die linearen Kettenverbindungen [Pt^II(AA)₂·Pt^IV X ₂(AA)₂] ⁴⁺ mitX=Cl, Br, I;AA = Ethylendiamin, 1,2- und 1,3-Diaminopropan sowie auf Wolfframs Rot-und Reihlens Grün-Salz angewandt. Die Energiebänder werden von AOM-Parametern berechnet, die aus d-d-Spektren isolierter Pt(II)- und Pt(IV)-Komplexe gewonnen wurden, welche in der Literatur zu finden sind. Diskutiert werden Zuordnungen zu Absorptionskanten und anderen Maxima in den Kristallspektren ebenso wie spektrale Verschiebungen aufgrund von Änderungen in der geometrischen Struktur. Da die AOM-Energieausdrücke in analytischer Form vorliegen, hat dieses Verfahren diverse Vorteile im Vergleich zur Extended Hückel-Theorie, die kürzlich ebenfalls so erweitert wurde, daß damit Kettenstrukturen behandelt werden können.