Thermal decomposition of lanthanide(III) complexes of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand

The thermal decomposition of lanthanide complexes, with a general formula: [LnL(NO₃)₂](NO₃), where Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, and Er; and L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand, was studied by thermogravimetric (TG) and derivative thermogravimetric (DTG) techniques. The TG and DTG data indicated that all complexes are thermostable up to 398 K. The thermal decomposition of all Ln(III) complexes was a two-stage process and the final residues were Ln₂O₃ (Ln = La, Nd, Sm, Gd, Dy, Er), Tb₄O₇, and Pr₆ O₁₁. The activation energies of thermal decomposition of the complexes were calculated from analysis of the TG-DTG curves using the Kissinger, Friedman, and Flynn-Well-Ozawa methods.     

Synthesis and properties of some chromium(III) β-diketonate complexes

Summary Equimolar quantities of CrCl₃ · 3THF and-diketones, -dkH, react to yield CrCl₂(-dk) · 2THF and CrCl₂(-dk) · THF complexes in coordinating and noncoordinating solvents respectively. For 1 : 2 and 1 : 3 molar ratios of reactants, derivatives of general formulae CrCl(-dk)₂ and Cr(-dk)₃ (where-dkH = acerylacetrrnc, benzoylacetonc and dibenzoylmethane) have been isolated. All complexes have been characterized by elemental analysis, molecular weights and by i.r. spectra.     

Thermal behavior of some new isatin complexes

The complexes of the type SnCl₄(HL)·EtOH and SnCl₂L₂ (HL ¹ : the Schiff base resulted in 1:1 condensation of isatin and aniline; HL ² : the Schiff base resulted in 1:1 condensation of isatin and p-toluidine) have been synthesized and characterized. The thermal analysis of the new ligands and complexes has evidenced the thermal intervals of stability and also the thermal effects that accompany them. The Schiff bases thermal transformations consist in phase transitions, C_arom–N bond cleavage and thermolysis processes. The different nature of the complexes generates their different thermal behaviour. The complexes lead in three steps to SnO₂ and in all cases the Schiff bases degradation generates a pyrrolidone-coordinated derivative. As for the SnCl₄(HL)·EtOH complexes, the SnCl₄ formed during the last step is involved in two competitive processes, one consists in their volatilisation while the other one leads to SnO₂. As result the SnO₂ residue is smaller than the theoretically expected.     

Synthesis of (1,3-adamantylene)bis-1,3-dicarbonyl compounds

Reactions of 1,3-dihydroxyadamantane with 1,3-dicarbonyl compounds in the presence of 5 mol % of In(OTf)₃ afforded a series of (1,3-adamantylene)bis-1,3-dicarbonyl compounds in yields of 25–83%.     

The development of polar discotic metallomesogens Vanadyl 1,3-diketonate complexes

Abstract

The dependence of mesomorphism of 1,3-diketonate vanadium-oxo (vanadyl) complexes on the number of side chains was investigated. These complexes have a large dipole normal to the disc plane and are under investigation in an effort to generate discotic phases with polar order. Relatively complex phase behaviour is observed when the vanadyl 1,3-diketonate complexes are appended with four phenyl groups with two octyloxy or decyloxy side chains each for a total of eight side chains. These complexities are most likely related to the order/disorder associated with the polar vanadyl group. Vanadyl 1,3-diketonate complexes with four side chains were prepared by replacement of two of the phenyl groups with methyl or trifluoromethyl groups, and these complexes displayed only crystal phases. Complexes with two trialkyloxy phenyls and two dialkyloxy phenyls were synthesized and found to display a very stable D_hd phase. The presence of additional alkyloxy groups was found also to promote a linear chain structure, (i.e. ??V?O??V?O??), in the crystal phase.     

The development of polar discotic metallomesogens Vanadyl 1,3-diketonate complexes

The dependence of mesomorphism of 1,3-diketonate vanadium-oxo (vanadyl) complexes on the number of side chains was investigated. These complexes have a large dipole normal to the disc plane and are under investigation in an effort to generate discotic phases with polar order. Relatively complex phase behaviour is observed when the vanadyl 1,3-diketonate complexes are appended with four phenyl groups with two octyloxy or decyloxy side chains each for a total of eight side chains. These complexities are most likely related to the order/disorder associated with the polar vanadyl group. Vanadyl 1,3-diketonate complexes with four side chains were prepared by replacement of two of the phenyl groups with methyl or trifluoromethyl groups, and these complexes displayed only crystal phases. Complexes with two trialkyloxy phenyls and two dialkyloxy phenyls were synthesized and found to display a very stable D_hd phase. The presence of additional alkyloxy groups was found also to promote a linear chain structure, (i.e. --V=O--V=O--), in the crystal phase.     

Thermal behavior of poly(thiocarbonylthio-1,3-phenylene)

The thermal behavior of poly(thiocarbonylthio-1,2-phenylene) (PTCTP) was investigated from the points of view of both thermal transitions and the reactions which occur on heating at high temperature. In order better to understand the latter, S,S-diphenyldithiocarbonate (DPDTC) was synthesized and its degradation studied.For the thermal transitions it was found that, compared with the analogous poly(1,3-phenylenecarbonate) (PPC), T_g did not change, whereas there was a decrease in T_m.The degradation proceeds through different reaction pathways: the first step seems to be the breaking of the S-carbonyl bond followed by the evolution of CO mainly and, to a lesser extent, of COS. The other reaction products are mainly disulfide and sulfide moieties.     

Luminescent characteristics of some mesogenic tris(β-diketonate) europium(III) complexes with Lewis bases

Luminescent properties of liquid-crystalline tris(β-diketonate) europium(III) complexes with Lewis bases (substituted 2,2′-bipyridine and 1,10-phenantroline) are investigated. Absolute and relative quantum yields and lifetimes are determined. Absorption, excitation, and emission spectra of the complexes are investigated.     

Thermal behavior of some new triazole derivative complexes

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

Thermal investigations of some chromium(IV) complexes

The thermal decompositions of 15 solid products of reactions of chromyl chloride and chromyl acetate with alkylaromatics were studied by means of a derivatograph in argon and air atmospheres. In the case of the chromyl chloride complexes, 2Cr^IVO₂Cl₂ · HR (HR= =hydrocarbon molecule), the formation of Cr₂O₃Cl₂ was observed as a labile intermediate in the inert atmosphere, while in air the abrupt decomposition of the complexes leads to Cr₂O₃ as a residue. The decompositions of monochromium(IV) hydroxoacetate and dichromium(IV) hydroxoacetate proceed through the intermediate Cr₂O₃(CO₃) both in argon and in air atmospheres. Characteristic temperatures are discussed and the activation energiesE _a of the particular steps of thermal decompositions were calculated in all cases.

---

Zusammenfassung Die thermische Zersetzung von 15 festen Produkten der Reaktionen von Chromylchlorid und Chromylacetat mit Alkylaromaten wurde mittels eines Derivatographen in Argon- und Luftatmosphäre untersucht. Im Falle der Chromylchloridkomplexe 2 Cr^IVO₂Cl₂ · HR (HR=Kohlenwasserstoffmolekül) wurde in inerter Atmosphäre die Bildung von Cr₂O₃Cl₂ als instabiles Zwischenprodukt beobachtet, während in Luft die abrupte Zersetzung der Komplexe zu Cr₂O₃ als Rückstand führt. Die Zersetzung des Monochrom(IV)-hydroxyacetats und des Dichrom(IV)-hydroxyacetats verläuft sowohl in Argon- als auch in Luftatmosphäre über das Zwischenprodukt Cr₂O₃(CO₃). Die charakteristischen Temperaturen werden diskutiert und in allen Fällen wurden die AktivierungsenergienE _a der einzelnen Zersetzungsschritte berechnet.

---

15 . 2 Cr^IVO₂Cl₂ · HR e HR , Cr₂O₃Cl₂, — Cr₂O₃ . - (IV) Cr₂O₃(CO₃). E _a) .

---

---

The authors express their grateful thanks to Mr. L. Huss for careful measurements.     

Structural and near-IR photophysical studies on ternary lanthanide complexes containing poly(pyrazolyl)borate and 1,3-diketonate ligands

The ligands tris[3-(2-pyridyl)pyrazol-1-yl]hydroborate (L1, potentially hexadentate) and bis[3-(2-pyridyl)pyrazol-1-yl]dihydroborate (L2, potentially tetradentate) have been used to prepare ternary lanthanide complexes in which the remaining ligands are dibenzoylmethane anions (dbm). [Eu(L1)(dbm)2] is eight-coordinate, with L1 acting only as a tetradentate chelate (with one potentially bidentate arm pendant) and two bidentate dbm ligands. [Nd(L1)(dbm)2] was also prepared but on recrystallization some of it rearranged to [Nd(L1)2][Nd(dbm)4], which contains a twelve-coordinate [Nd(L1)2]+ cation (two interleaved hexadentate podand ligands) and the eight-coordinate anion [Nd(dbm)4]- which, uniquely amongst eight-coordinate complexes having four diketonate ligands, has a square prismatic structure with near-perfect O8 cubic coordination. Formation of this sterically unfavourable geometry is assumed to arise from favourable packing with the pseudo-spherical cation. The isostructural series of complexes [Ln(L2)(dbm)2](Ln = Pr, Nd, Eu, Gd, Tb, Er, Yb) was also prepared and all members structurally characterised; again the metal ions are eight-coordinate, from one tetradentate ligand L2 and two bidentate dbm ligands. Photophysical studies on the complexes with Ln = Pr, Nd, Er, and Yb were carried out; all show the near-IR luminescence characteristic of these metal ions, with longer lifetimes in CD3OD than in CH3OH. For [Yb(L2)(dbm)2], two species with different luminescence lifetimes were observed in CH3OH solution, corresponding to species with zero or one coordinated solvent molecules, in slow exchange on the luminescence timescale. For [Nd(L2)(dbm)2] a single average solvation number of 0.7 was observed in MeOH. For [Pr(L2)(dbm)2] a range of emission lines in the visible and NIR regions was detected; time-resolved measurements show a particularly high susceptibility to quenching by solvent CH and OH oscillators.     

Thermal studies on some complexes of Pd(II)

The formulae suggested for a series of complexes of Pd(II) with various amino acids have been verified by thermal methods using a derivatograph. A correlation of the obtained kinetic parameters with the structures suggested by electronic and IR spectra of the substances has been attempted.

---

Zusammenfassung Es wurden Formeln für eine Serie von Komplexverbindungen des Pd(II) mit verschiedenen Aminosäuren vorgeschlagen und thermogravimetrisch bewiesen. Die Übereinstimmung zwischen den erhaltenen kinetischen Parametern und den durch ERS und Infrarotspektroskopie angedeuteten Strukturen wurde geprüft.

---

Résumé On a vérifié par thermogravimétrie des formules brutes proposées pour les combinaisons complexes du Pd(II) avec divers acides aminés. On a examiné la correlation entre les paramètres cynétiques obtenus et les structures déduites des spectres IR et electroniques.

---

ë , Pd(II) . , , .

     

IR spectroscopic studies of some uranyl tetrachloride complexes

The IR spectra of dipotassium, dirubidium and diammonium uranyl tetrachloride hydrates (K₂UO₂Cl₄·3H₂O, Rb₂UO₂Cl₄·H₂O, (NH₄)₂UO₂Cl₄·4H₂O) have been measured in the region from 4000 down to 30 cm⁻¹. A normal coordinate analysis of the (UO₂Cl₄)²⁻ ion apart from the K⁺, Rb⁺ and NH₄⁺ ions has been made using Wilson's FG matrix method. The force constants associated with the UO and UCl bonds have been obtained on the basis of both the force models of modified Urey-Bradley and valence force fields. An effort has been directed towards the understanding of the uranyl bond weakening with coordination of the ligands. It has been suggested that this bond weakening is caused by charge transfer from the ligands to the uranium atom.     

Thermal behaviour of some nickel(II)-morpholine complexes

The preparation of Ni(CN)₂1.5M (M=morpholine) and the thermal study of this and NiBr₂3M, Nil₂4M and Ni(NCS)₂4M are described. The thermal treatment of these compounds leads to the isolation of Ni(CN)₂M, Ni(CN)₂0.5M, NiBr₂2M, Nil₂3M, Nil₂1.5M, Ni(NCS)₂2M and Ni(NCS)₂M. With the exception of NiBr₂2M and Ni(NCS)₂2M, all intermediate species are reported here for the first time. Magnetic and spectral studies have been carried out to determine the mode of coordination and stereochemistry of the complexes. The thermal study includes the determination of stability, apparent activation energy and reaction orders, and reaction enthalpies.

---

Zusammenfassung Die Darstellung von Ni(CN)₂1.5M (M=Morpholin) wird beschrieben. Das thermische Verhalten dieser Verbindung und von NiBr₂3M, Nil₂4M und Ni(NCS)₂4M wird untersucht. Durch thermische Behandlung dieser Verbindungen werden Ni(CN)₂M, Ni(CN)₂0.5M, NiBr₂2M, Nil₂3M, Nil₂1.5M, Ni(NCS)₂2M und Ni(NCS)₂M erhalten. Mit Ausnahme von NiBr₂2M und Ni(NCS)₂2M handelt es sich dabei um bisher noch nicht beschriebene Zwischenprodukte. Es wurden magnetische und spektrometrische Untersuchungen ausgeführt, um die Art der Koordinaten und die Stereochemie dieser Komplexe zu ermitteln. Die thermische Untersuchung erstreckt sich auf die Bestimmung der Stabilität, der scheinbaren Aktivierungsenergie und der Reaktionsordnungen sowie der Reaktionsenthalpien.

---

Ni(CN)₂1.5M (M=), NiBr₂3M, Nil₂4M, Ni(NCS)₂4M. Ni(CN)₂M, Ni(CN)₂0.5M, NiBr₂2M, Nil₂3M, Nil₂1.5M, Ni(NCS)₂2M, Ni(NCS)₂M. NiBr₂2M Ni(NCS)₂2M, . , . , , .

     

Structural investigations of copper(II) complexes containing unsymmetrical β-diketonate and monothio-β-diketonate ligands

The crystal structures of the complexes Cu(txhd)₂ and Cu(S-tmhd)₂ (where txhd is the anion of 2,2,6-trimethylheptane-3,5-dione and S-tmhd is the anion of 5-mercapto-2,2,6,6-tetramethyl-4-hepten-3-one) were determined. In the solid state, both complexes are square planar. In each case, only one geometrical isomer (trans or cis) was observed in the crystals; arguments are presented that both isomers are present in bulk samples of Cu(txhd)₂, while from electronic considerations, the monothio-β-diketonate ligands probably have cis geometry in Cu(S-tmhd)₂. Calculations of molecular volumes for structurally similar Cu[t-BuC(O)CHC(O)R]₂ complexes showed that there is a slight decrease in packing efficiency as the steric bulk of R increases. More importantly, strong ring-stacking interactions, such as those found for Cu(acac)₂ are not observed, or are greatly attenuated, in complexes with bulkier peripheral substituents. [Cu(txhd)(μ₃-OEt)]₄, an impurity that co-sublimed with Cu(txhd)₂, was isolated in low yield. The tetrameric structure, which is isomorphous with known [Cu(tmhd)(μ₃-OEt)]₄ (where tmhd is the anion of 2,2,6,6-tetramethylheptane-3,5-dione), has a cubane-like core.     

Thermal decomposition of bis-(DL-valinato)copper(II) and bis-(DL-methioninato)copper(II)

A kinetic study of the thermal decomposition of the complexes bis-(DL-valinato)copper(II) and bis-(DL-methioninato)copper(II) was carried out using thermogravimetry in a dynamic regime, following the theoretical model of Satava and including the equation used by Johnson and Gallagher:1/1––1=kt. Kinetic parameters were calculated and are compared with those obtained previously for the complex bis-(L-tryptophanato)copper(II). The sequence of thermal stability found is: Cu(DL-Val)₂22.

---

Zusammenfassung Die thermische Zersetzung der Komplexe Bis-(DL-valinato)kupfer(II) und Bis-(DL-methioninato)kupfer(II) wurde thermogravimetrisch im dynamischen Regime untersucht, indem von dem theoretischen Modell von atava Gebrauch gemacht und die von Johnson und Gallagher benutzte Gleichung 1/1-–1=kt einbezogen wurde. Kinetische Parameter wurden berechnet und mit den kürzlich für den Komplex Bis-(L-tryptophanato)kupfer(II) erhaltenen parametern verglichen. Die Stabilität der Komplexe nimmt in folgender Reihenfolge zu: Cu(DL-Val)₂22.

---

-(-)- -(L-) (II) , -: 1/1– –1=kt. -(L-) (II). Cu(DL-Val)₂22.

---

---

Presented at the 1985 World Conference on Thermal Analysis, Bad Hofgastein, Austria.     

Structure and chromotropic properties of mono- and binuclear mixed-ligand nickel(II) complexes containing 1,3-diketonate and polyamine ligands

Abstract  

Mixed-ligand Ni^II complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky ligands on the coordination distances and spectral properties are discussed.