Thermal properties of solid nickel(II) coordination compounds

The paper deals with the chemical and physical factors influencing the thermal octahedral square planar changes of nickel(II) complexes in the solid phase. The relationship between these transformations and the tetragonal distortion of the octahedral ligand field is discussed. Depending on the coordination of the ligands, these transformations can be divided into two groups: octahedral monomer square planar monomer, and octahedral polymer square planar monomer changes. Attention is directed only to octahedral and square planat Ni(II) complexes (square planar complexes with chromophores [NiN₄], [NiN₂O₂] and [NiO₄]), which can be isolated in the solid state before and after heating. The possibility of such a configurational change seems to be dependent upon the thermal stabilities of the initial and final complexes, the electronic and steric properties of the ligands, the complexing ability of the central atom, and particularly the equatorial-axial interactions of the ligands via the central atom.

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Zusammenfassung Vorliegende Arbeit befasst sich mit den chemischen und physikalischen Faktoren, die den thermischen Übergang oktaedrisch-rechteckig planar der Festkörperphase von Nickel(II) komplexen beeinflussen. Es werden die Beziehungen zwischen dieser Transformation und der tetragonalen Verzerrung oktaedrischer Ligandenfelder besprochen. Entsprechend der Koordinierung der Liganden können diese Transformationen in zwei Gruppen eingeteilt werden: monomer oktaedrisch-monomer rechteckig planar sowie polymer oktaedrisch-monomer rechteckig planare. Hier werden nur solche oktaedrische und rechteckig planare Ni(II)komplexe (rechteckig planare Komplexe mit (NiN₄)-, (NiN₂O₂)- und (NiO₄)-Chromophoren) betrachtet, die sowohl vor als auch nach dem Erhitzen in fester Form isoliert werden können. Die Möglichkeit solcher Konfigurationsübergange scheint von der thermischen Stabilität der Ausgangs- und Produktekomplexe, von elektronischen und sterischen Eigenschaften der Liganden, von der Komplexbildungsstärke des Zentralatomes und hauptsächlich von den äquatorial-axialen Wechselwirkungen der Liganden gegenüber dem Zentralatom abzuhängen.

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, . . , : . - ( [NiN₄], [NiN₂O₂] [NiO₂]), . , , , , , — .

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Part A: J. Thermal Anal., 16 (1979) 213.     

Cobalt(II), nickel(II) and zinc(II) coordination compounds derived from aromatic amines

The structural and spectroscopic characterization of coordination compounds of four aromatic amines derived from benzimidazole, 2-aminobenzimidazole (L1), 1-(S-methylcarbodithioate)-2-aminobenzimidazole (L2), 2-(2-aminophenyl)-1H-benzimidazole (L3) and 6,6-dimethyl-5H-benzimidazolyl[1,2-c]quinazoline (L4) are reported. Cobalt(II) [Co(L1)₂(CH₃COO)₂] (1) and nickel(II) [Ni(L1)₂(CH₃COO)₂] (2) acetate coordination compounds of L1 are discussed. The synthesis and the X-ray crystal structure of the new 1-(S-methylcarbodithioate)-2-aminobenzimidazole (L2) is informed, together with its cobalt(II) [Co(L2)₂Cl₂] (3), [Co(L2)₂Br₂] (4) and zinc(II) [Co(L2)₂Cl₂] (5), [Zn(L2)₂Br₂] (6) coordination compounds. In these compounds the imidazolic nitrogen is coordinated to the metal center, while the ArNH₂ and the S-methylcarbodithioate groups do not participate as coordination sites. A co-crystal of L1 and L2 is analyzed. Structural analyses of the coordination compounds of L3 showed that this ligand behaves as a bidentate ligand through the aniline and the imidazole groups forming six membered rings in the cobalt(II) [Co(L3)Cl₂] (7) and zinc(II) [Zn(L3)Cl₂] (8) compounds, as well as the nickel(II) nitrate [Ni(L3)₂(H₂O)₂](NO₃)₂ (9). The quinazoline L4 was produced by insertion of one acetone molecule and water elimination in L3, its X-ray crystal diffraction analysis, as well as that of its zinc(II) coordination compound [Zn(L4)₂Cl₂] (10), are discussed.     

Thermal studies on addition compounds of bis(ethylxathato)nickel(II)

Ni(xanthate)₂, a diamagnetic square planar complex forms 1:1 six-coordinated high-spin paramagnetic adducts with dinitrogen donors in different organic solvents. The thermal studies of these compounds show the loss of trapped solvent(ether) followed by the loss of the addendum leaving behind the parent xanthate complex. In the compounds with 1:3 ratio of Ni(xanthate): dinitrogen donors, the xan^? acts as an anion. The different steps of thermal decomposition in the compounds, Ni(phen)₃xan₂ and Ni(bipy)₃xan₂, can be explained on the basis of the conformational rigidity of the ligands. For the parent compound Ni(xan)₂, its 1:1 and 1:3 adducts as well as the thermal decomposition products (residues) have been analysed by chemical and physical methods. New intermediate complexes with the composition, Ni(phen)₂xan₂, Ni(bipy)S₂ and Ni(bipy)S have been obtained from the decomposition process, leading finally to NiO. The kinetic parameters were calculated using five different methods to check the applicability of these standard methods towards the elucidation of the decomposition mechanism.     

Thermal and structural properties of coordination compounds of 2-mercapto-1-methylimidazole with palladium(II) and platinum(II)

Complexes of 2-mercapto-1-methylimidazole (TMZ) with Pd^II and Pt^II of the general formula M(TMZ)_nX₂ (whereM=Pd, Pt andX=Cl, Br, I or SO₄ andn=2 or 4) were obtained. The thermal stabilities of the compounds were estimated by derivatographic measurements and lattice constants were estimated from their X-ray powder diffraction patterns.     

Coordination compounds of biological interest: Thermal properties of some compounds of saccharin (o-benzoic sulphimide) with nickel(II) and zinc(II)

The thermal properties of nickel(II) and zinc(II) complexes of saccharin (sacc) (o-benzoic sulphimide) have been studied and compared both with those of cobalt(II) and copper(II) previously studied and with those of ternary complexes of nickel(II) and zinc(II) having both saccharin and pyridine as ligands. The thermal behaviour is discussed in terms of the interaction between metal and ligands, interaction studied by IR spectroscopy, and by reflectance spectroscopy.The classical thermal stability scale Co(II) > Ni(II) > Cu(II) > Zn(II) is always obtained.     

Thiocyanate bond mode determination on solid manganese(II) mixed ligand coordination compounds

Synthesized and in solid state characterized compounds correspond to the following types [Mn(NCS)₂L_mL'_n] · x D, [Mn(NCS)₂L_y]_z, and [MnX₂(CH₃SCN)(CH₃OH)] · x D (L=CH₃OH or O-donors; L=CH₃SCN or N-donors; D=solvent molecules; x=0, 1 or 2; m=0, 1 or 2; n=1, 2 or 3; y=0, 1, 2, 3 or 4; z2; X=Cl or Br). Derivatographic investigations confirm the formation of intermediates, especially for L=H₂O the existence of thermic stable partially dehydrated (hydrate poor) species (y=1/2 or 1/3) and -NCS-bonding with different ligating atoms. Solid state FT-IR analysis were carried out for band shapes, measurements of the integrated intensity, and correlations between located absorption maxima for v(CN), v(CS), (NCS), v(MnN), and v(MnS) and the thiocyanate bond mode.     

Thermal Investigation of 1,2-propanediamine complexes of nickel(II) in the solid phase

Thermal studies have been carried out on [NiL₃]X₂·n H₂O, whereL=1,2-propanediamine;X=Cl^–, Br^–, SCN^–, 1/2SO ₄ ^2– and 1/2 SeO ₄ ^2– ; andn= 2, 1.5 and 0. [Ni₂L₅(NCS)₂](SCN)₂ and [NiL₂SO₄] have been synthesized pyrolytically in the solid-state from their mother diamine complexes. The deaquation behaviour of [NiL₃]SO₄·2 H₂O appears interesting, and its monohydrate undergoes a solid-state reaction (88–102°) without mass loss, showing an exothermic peak at 95 °C (H=– 5.1 kJ mole^–1).

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Zusammenfassung Thermische Untersuchungen wurden an [NiL₃]X₂,n H₂O ausgeführt, wobeiL-1,2-Propandiamin;X=Cl^–, Br^–, SCN^–, 1/2 SO ₄ ^2– und 1/2 SeO ₄ ^2– ;n=2, 1.5 und 0. [Ni₂Ls(NCS)₂](SCN)₂ und [NiL₂SO₄] wurden ausgehend von den entsprechenden Diaminkomplexen pyrolytisch im festen Zustand synthetisiert. Das Dehydratisierungsverhalten von [NiL₃]SO₄·2 H₂O scheint interessant zu sein, und beim entsprechenden Monohydrat wird eine ohne Massenverlust verlaufende Festkörperreaktion (88–102°) beobachtet, die sich durch einen exothermen Peak bei 95 °C (H=– 5.1 kJ mol^–1) zu erkennen gibt.

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[N³L₃]₂· n₂O, L=1,2-,=l^–, Br^–, SCN^–, 1/2 SO ₄ ^2- , 1/2SeO ₄ ^2- , an=2, 1.5 0. [Ni₂L₅(NCS)₂](SCN)₂ [NiL₂SO₄] . [N³L₃]S₄·2 ₂ , 88–102° , 95 ° =– 5.1 ·^–1.

     

Nickel(II) and cobalt(II) coordination compounds of dichloroguanidinopyrimidines

Summary New coordination compounds of Ni^II and Co^II with dichloropyrimidinoguanidine (L) have been obtained and characterized by physico-chemical and spectroscopic methods. The complexes have the general formulae: [ML₃](ClO₄)₂, [ML₂(SO₄)], [ML₂(NCS)₂], (M = Ni or Co), [NiL₂(ClO₄)₂] and [CoL₂](ClO₄)₂. The ligands are bonded to the metal ion via one nitrogen atom from the pyrimidine heterocyclic ring and one from the guanidine group.     

Heterogeneous reactions of solid nickel(II) complexes

The influence of different modes of preparation on the stoichiometry of thermal decomposition of isothiocyanatonickel(II) complexes with ammonia was studied. It was found that the complex Ni(NCS)₂(NH₃)₄ (I) prepared by heterogeneous reaction undergoes decomposition in two steps (–2 NH₃, –2 NH₃), while for complex II, of the same composition but prepared by homogeneous reaction from solution, the decomposition proceeds in three steps (–1 NH₃, –1 NH₃, –2NH₃). Electronic and infrared absorption spectra were used for the study of the spectral properties of the starting complex. It was found that the different stoichiometries of thermal decompositions of complexes I and II do not cause differences in the bonding strength of the ammonia molecules (chemical factor); this effect is rather brought about by physical factors such as different imperfections of the crystal lattice.

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Zusammenfassung Der Einfluß der Herstellung auf die Stöchiometrie der thermischen Zersetzung von Amin-Komplexen des Isothiocyanatonickels wurde studiert. Der Zerfall des Komplexes Ni(NCS)₂(NH₃)₄ (I), hergestellt durch heterogene Reaktion, verlief in zwei Etappen (–2 NH₃, –2 NH₃). Beim selben Komplex (II), hergestellt durch homogene Reaktion in Lösung, wurden jedoch drei Etappen beobachtet (–1 NH₃, –1 NH₃, –2 NH₃). Die Eigenschaften des Ausgangsproduktes wurden durch Elektronen- und IR-Spektroskopie untersucht. Das unterschiedliche thermische Verhalten ist nicht auf eine verschiedene Bindungsstärke der NH₃ Moleküle, sondern auf physikalische Ursachen, wie z. B. Unregelmässigkeiten im Kristallgitter zurückzuführen.

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Résumé On a étudié l'influence des diverses méthodes de préparation sur la stoechiométrie de la réaction de décomposition thermique des complexes de l'isothiocyanate de nickel(II) avec l'ammoniac. On a établi que le complexe Ni(SCN)₂(NH₃)₄, (I), préparé rar réaction hétérogène, subit une décomposition en deux étapes (–2NH₃, –2NH₃), tandis que le complexe (II), de même composition, mais préparé par réaction homogène, à partir de solutions, se décompose en trois étapes (–1NH₃,–1NH₃, –2NH₃). Les propriétés spectrales du complexe initial ont été étudiées par absorption électronique et infrarouge. On a trouvé que les différences de stoechiométrie des réactions de décomposition thermique des complexes (I) et (II) n'apportaient pas de différences entre les énergies de liaison des molécules d'ammoniac (facteur chimique). C'est plutôt à des facteurs physiques, comme les différentes imperfections du réseau cristallin, que cet effet serait dû.

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(II) . , Ni(NCS)₂(NH₃)₄ (I), , (–2NH₃,–2NH₃). , II , , (–1 NH₃,–1 NH₃ –2NH₃). . , I II ( ), , .

     

Mass-spectrometric investigation of coordination compounds of nickel(II) with radical anions of S-alkyl-1-phenylisothiosemicarbazides

The electron-impact mass spectra of coordination compounds of nickel(II) with the general formula NiL₂, in which the radical anions [C₆H₅N -N-C(SR)=NR¹]^–, where R=CH₃ and R=H(I), R=CD₃ and R=H(II), R=C₂H₅ and R=H(III), and R=CH₃ and R=C₆H₅(IV), serve as the ligands, have been studied. In the mass spectra of compounds I–IV the peaks of the molecular ions have the highest intensity among the organometallic fragments. The initial stage of the fragmentation of [M]^+. is associated with the formation of the rearrangement ions [NiL + H]⁺, [NiL + C₆H₅]⁺, and [NiL + SR]⁺, ions, whose appearance becomes understood, if it is taken into account that the removal of one ligand is accompanied by the impairing of spins and the mass spectra of compounds I–IV is the presence of lines for the [NiL]⁺ ion in them. The dissociative ionization of compounds I–IV is strongly reminiscent of the behavior of ordinary complexes of metals with ligands of the nonradical type. The fragmentation scheme of the molecular ions under the effects of electron impact has been presented and discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 368–371, May–June, 1990.     

Complexes of cobalt(II), nickel(II) and copper(II) with the benzenedicarboxylic acids. Thermal properties

The thermal properties of the complexes of phthalic, isophthalic and terephthalic acid with cobalt(II), nickel(II) and copper(II) are determined by thermogravimetry (TG), differential thermogravimetry (DTG) and differential scanning calorimetry (DSC).The thermal stability of the anhydrous compounds gives, for the metal ions, a sequence Co > Ni > Cu.The thermal stability series as a function of the ligand for each metal is terephthalate > isophthalate > phthalate.     

Complexes of nickel(II), copper(II) and zinc(II) with the aminobenzenemonocarboxylic acids: Thermal properties

The thermal properties of the complexes of ortho-, meta- and para-amino- benzenemonocarboxylic acids with nickel(II), copper(II), and zinc(II) are determined by TG and DTA. The activation energy values for the first decomposition step of the anhydrous compounds are also calculated. The thermal data are then examined and correlated with the structure of the compounds.     

Thermal properties of cobalt(II), nickel(II) and copper(II) glycinates and iminodiacetates. Critical comparison

The thermal properties of the Co(II), Ni(II) and Cu(II) complexes of iminodiacetic acid (H₂IDA) and of glycine were determined using TG, DTG and DSC techniques. The thermal properties of the two series were compared and discussed in terms of IR spectra, ΔH, ΔG and ΔS for the formation of the complexes in aqueous solutions, as well as the thermal data.     

Thermal investigations of nickel–zinc ferrites formation from malate coordination compounds

Nickel–zinc ferrites have been synthesized via thermal decomposition of polynuclear coordination compounds containing as ligand the anion of malic acid, namely (NH₄)[Fe₂NixZn_1–x(C₄H₄O₅)(OH)₃]·nH₂O (x =0.25, 0.5 and 0.75, n=3 and 5). A comparison between the thermal behaviour of the studied polynuclear coordination compounds is inferred. Fe₂NixZn_1–xO₄ (n=0.25, 0.5 and 0.75) ferrites with mean particle sizes of 65–85 Å and free from other phases are formed after a heating treatment of only one hour at 500°C.     

Thermal square planar-to-octahedral transformation of nickel(II) complexes containing butanediamines in a solid phase

Thermal reactions of the nickel(II) complexes, [Ni(m-bn or i-bn)₂]X₂ and [Ni(H₂O)₂(dl-bn)₂]X₂·n H₂O, where m-bn, i-bn, and dl-bn are meso-2,3-butanediamine, 2-methyl-1,2-propanediamine, and dl-2,3-butanediamine, respectively, X is Cl^?, Br^?, I^?, NO^?₃, or ClO^?₄, and n is 2 for bromide, and 0 for the others, were investigated in a solid phase before and after heating using thermal analyses (TG and DSC) and spectral and magnetic measurements. In the case of the chloride and bromide, the square planar bis(dl-bn) complexes obtained by dehydration of the respective diaqua complexes were transformed to the octahedral diacido bis(dl-bn) complexes upon further heating. The same structural transformation was observed in the thermal reactions of [Ni(m-bn)₂](NO₃)₂ and [Ni(i-bn)₂]Cl₂. It was summarily recognized that such square planar-to-octahedral transformation was favored in the order dl-bn > i-bn > m-bn complexes in the respective halides, and it was a reversible thermochromism from yellow to blue. The changes in enthalpy of the reactions were endothermic and fell in the range of about 10–20 kJ mole^?1. The possibility of such configurational change seems to be dependent mainly upon the ionic radius of the X anion, the orientation of two C-substituted methyl groups on butanediamines in the formation of the complexes, and the thermal stability of the complexes themselves.     

Novel coordination compounds of nickel(II) and copper(II) with N,Nprime-diphenylthiooxamide; formation of complexed metalhexacyanoferrate(II) gelatin-immobilized matrix systems

A novel route to complexes of NiII and CuII with N,Nprime-diphenylthiooxamide, namely complexing in a NiII or CuII hexacyanoferrate(II) gelatin-immobilized matrix in contact with an aqueous solution of the N,Nprime-diphenylthiooxamide, has been studied. Under these specific conditions, in the NiII system, four different coordination compounds are formed, three of which are insoluble in H2O; in the CuII system, only one insoluble complex is formed. When complexation is carried out in solution or the solid phase, formation of only one complex is observed in each of systems studied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Copper(II) coordination compounds with ferulic acid

The first two molecular structures of the ferulic acid (3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid, C₁₀H₁₀O₄) coordination compounds are presented, namely, [Cu₂(C₁₀H₉O₄)₄(CH₃CN)₂] 1 and [Cu₂(C₁₀H₉O₄)₄(C₆H₆N₂O)₂]·4CH₃CN (C₆H₆N₂O = nicotinamide) 2. Both compounds were synthesised from the starting mixture of Cu₂O and CuCl upon copper oxidation in the acetonitrile solution. The single-crystal X-ray diffraction analysis of 1 and 2 reveals the binuclear structure of the ‘paddle–wheel’ type for both complexes. 1 and 2 are unstable outside mother liquid due to loosely bound acetonitrile molecules. The final products of decomposition are [Cu₂(C₁₀H₉O₄)₄] 1a and [Cu₂(C₁₀H₉O₄)₄(C₆H₆N₂O)₂] 2a, which were characterized by several physico-chemical methods. The triplet X-band EPR spectra of 1a and 2a, showing signals B_Z1  15 mT, B₂  460 mT and B_Z2  580 mT, are in agreement with the expected data for the binuclear tetracarboxylate units, found in the structures of the parent complexes 1 and 2. Together with the room temperature magnetic susceptibility data, μ_eff/B.M. 1.40 (1a), 1.48 (2a), the EPR spectra analysis confirm the antiferromagnetic interaction in 1a and 2a. This is suggesting preservation and stability of the paddle–wheel structures in 1a and 2a.