Study on the thermal behavior of the complexes of the type [PdX2(tdmPz)] (X = Cl−, Br−, I−, SCN−) (original) (raw)
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Thermal decomposition of palladium(II) pyrazolyl complexes. Part I
Journal of Analytical and Applied Pyrolysis, 2004
Thermal behavior of pyrazolyl complexes [PdCl 2 (HPz) 2 ] (1), [PdCl 2 (HdmPz) 2 ] (2), [Pd(SCN) 2 (HPz) 2 ] (3), [Pd(SCN) 2 (HdmPz) 2 ] (4), [Pd(N 3 ) 2 (HdmPz) 2 ] (5), [Pd(PzNHCO) 2 ] (6) and [Pd(dmPzNHCO) 2 ] (7) (HPz=pyrazole, HdmPz=3,5-dimethylpyrazole) has been studied by TG and DTA. In general, the thermal stability of [PdX 2 (HL) 2 ] (HL=HPz, HdmPz) compounds varies in the following order: HdmPz>HPz as well, according to the trends X=Cl ->SCN ->NNN -. Except for 5, the [PdX 2 (HL) 2 ] complexes showed higher thermal stability than the 6 and 7 chelates. No stable intermediates were isolated during the thermal decompositions because of the overlapping degradation processes. The final products of the thermal decompositions were identified as metallic palladium by X-ray powder diffraction.
Journal of Thermal Analysis and Calorimetry, 2014
The Schiff base bis(4-ethylbenzyl) p-phenylenediimine, 4-eb-p-phen (1), and six new dimeric Pd(II) complexes of the type [Pd(l-X)(4-eb-p-phen)] 2 {X = Cl (2), Br (3), I (4), N 3 (5), NCO (6), SCN (7)} have been synthesized and characterized by elemental analysis, IR spectroscopy, and 1 H and 13 C{ 1 H}-NMR experiments. The thermal behavior of the complexes 2-7 has been investigated by means of thermogravimetry and differential thermal analysis. From the final decomposition temperatures, the thermal stability of the complexes can be ordered in the following sequence: 3 [ 4 [ 7 [ 2 & 5 [ 6. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction (XRD).
Thermal study of cyclopalladated complexes of the type [Pd 2 (dmba) 2 X 2 (bpe
Journal of Thermal Analysis and Calorimetry, 2005
The synthesis, characterization and thermal analysis of the novel cyclometallated compounds [Pd2(dmba)2Cl2(μ-bpe)] (1), [Pd2(dmba)2(N3)2(μ-bpe)] (2), [Pd2(dmba)2(NCO)2(μ-bpe)] (3), [Pd2(dmba)2(SCN)2(μ-bpe)] (4), [Pd2(dmba)2(NO3)2(μ-bpe)] (5) (bpe=trans-1,2-bis(4-pyridyl)ethylene; dmba=N,N-dimethylbenzylamine) are described. The thermal stability of [Pd2(dmba)2X2(μ-bpe)] complexes varies in the sequence 1>4>3>2>5. The final residues of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.
Thermal decomposition of palladium(II) pyrazolyl complexes; Part II
Journal of Thermal Analysis and Calorimetry, 2005
In this work the synthesis and determination of kinetic parameters of thermal decomposition of the complexes Gd(thd)3phen and Gd(thd)3bipy (where thd=2,2,6,6-tetramethyl-3,5-heptanodione; phen=1,10-phenantroline and bipy=2,2-dipyridine) by non-isothermal thermogravimetry is reported. The kinetic parameters of activation energy, reaction order and frequency factor were obtained from the thermogravimetric data by non-isothermal integral methods proposed by Coats-Redfern and Madhusudanan, as well as by approximation methods proposed by Horowitz-Metzger and Van Krevelen. The kinetic model that best described the thermal decomposition reaction for the two complexes was R1 indicating that the mechanism is controlled by one-dimensional phase-boundary (zero order) and is defined by the function g(&agr;)=1-(1-&agr;). Based on the values of activation energy obtained by Coats-Redfern method, the following order in the thermal stability was noticed: Gd(thd)3phen<Gd(thd)3bipy.
Thermochimica Acta, 1996
1,4-Morpholine (morph), 1,4-thioxane (thiox), 1,4-dithiane (dith), N-methylmorpholine (Mmorph) and N,N'-dimethylpiperazine (DMP) complexes of palladium(II) were synthesized. Thermal investigations have been carried out and the stereochemical changes which occurred during thermal decomposition studied. The complexes were found to have the compositions: [Pd(morph)2Cl2], [Pd(thiox)2Cl2], [Pd(dith)2Cl2], [Pd(Mmorph)zC12].2H20, and [Pd(DMP)2C12]. The characterization and the configurational and conformational changes were studied using elemental and thermal analyses and IR spectral data. All the complexes were found to have square planar structures. Thermodynamic parameters such as activation energy E*, and enthalpy change AH were evaluated for the dehydration and decomposition reactions of the complexes using standard methods. The stability of the complexes with respect to activation energy was compared and interpreted in terms of steric and inductive effects.
Journal of Thermal Analysis and Calorimetry
This work describes the synthesis, characterization, and the thermal behavior investigation of four palladium(II) complexes with general formulae [PdX2(mba)2], in which mba = N-methylbenzylamine and X = OAc− (1), Cl− (2), Br− (3) or I− (4). The complexes were characterized by elemental analysis, infrared vibrational spectroscopy, and 1H nuclear magnetic resonance. The stoichiometry of the complexes was established by means of elemental analysis and thermogravimetry (TG). TG/DTA curves showed that the thermodecomposition of the four complexes occurred in 3–4 steps, leading to metallic palladium as final residue. The palladium content found in all curves was in agreement with the mass percentages calculated for the complexes. The following thermal stability sequence was found: 3 > 2 > 4 > 1. The geometry optimization of 1, 2, 3, and 4, calculated using the DFT/B3LYP method, yielded a slightly distorted square planar environment around the Pd(II) ion made by two anionic groups and two nitrogen atoms from the mba ligand (N1 and N2), in a trans-relationship.
Studies on the Thermal Behavior of Polynuclear Palladium(II) Compounds Containing Pyrazolato Ligands
Brazilian Journal of Thermal Analysis, 2019
The synthesis, spectroscopic characterization and thermal behavior of the pyrazolate-bridged palladium complexes [Pd3(µ-N3)(µ-Pz)5]n (1), [Pd3(µ-N3)(µ-mPz)5]n (2), [Pd3(µ-N3)(µ-IPz)5]n (3), [Pd6(µ-N3)2(µ-Pz)5(µ-mPz)5]n (4), [Pd6(µ-N3)2(µ-Pz)5(µ-dmPz)5]n (5) and [Pd6(µ-N3)2(µ-Pz)5(µ-IPz)5]n (6) {pyrazolate (Pz-), 4-methylpyrazolate (mPz-), 3,5-dimethylpyrazolate (dmPz-), 4-iodopyrazolate (IPz-)} have been described in this work. The thermal decomposition of the compounds occurs in four or five stages and the final decomposition residues were identified as metallic palladium using X-ray powder diffraction method. TG studies showed that the introduction of substituted pyrazolato groups in the composition of the polynuclear compounds affect significantly their thermal stability. It can be concluded that the presence of pyrazolato ligands containing methyl or iodine groups at the 4 position has a crucial effect on the thermal stability of the polynuclear compounds described in this work.
Journal of Thermal Analysis and Calorimetry, 2018
This study describes the synthesis, characterization and thermal behavior study of the Schiff base N,N 0-bis(3,4dimethoxybenzaldehyde)ethane-1,2-diamine (C.1) and four new compounds of palladium(II) N,N-chelate coordination, with the general formula [Pd(X 1)(X 2)(3,4dm-1,2am)] where 3,4dm-1,2am=N,N 0-bis(3,4-dimethoxybenzaldehyde)ethane-1,2-diamine, X 1 = X 2 = Cl-(C.2), X 1 = X 2 = Cland Br-(C.3), X 1 = X 2 = N 3-(C.4) and X 1 = X 2 = NCO-(C.5). The compounds were characterized by elemental analysis, infrared vibrational spectroscopy (IR) and nuclear magnetic resonance (NMR) 1 H and 13 C. The TG/DTA curves showed that the thermal decomposition of the C2-C.5 complexes occurred in steps that involve the removal of both inorganic and organic ligand, and palladium oxidation steps forming palladium(II) oxide followed by the reduction of PdO into Pd(0), this being the constituent of the residual mass observed at the end of the TG curves, which have values consistent with the expected ones. The formed compounds can be ordered according to thermal stability considering the initial decomposition temperature (C.5 > C.2 [ C.3 > C.4).
Thermochemical parameters of dimethyl and di-iso-propyl dithiocarbamate complexes of palladium(II)
Journal of Thermal Analysis and Calorimetry, 2000
The standard molar enthalpy of formation of crystalline dialkyldithiocarbamate chelates, [Pd(S 2 CNR 2 ) 2 ], with R=CH 3 and i-C 3 H 7 , was determined through reaction-solution calorimetry in 1,2-dichloroethane, at 298 K. Using the standard molar enthalpies of formation of the gaseous chelates, the homolytic (526±18 and 666±10) and heterolytic (2693±18 and 2957±10 kJ mol -1 ) mean enthalpies of palladium-sulphur bond dissociation were calculated.