Thermoanalytical and IR-spectral Investigation of Mg(II) Complexes with Heterocyclic Ligands

Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the complexes Mg(pc)(na)₃⋅3H₂O (I), Mg(pc)(py)₂⋅2H₂O (II),Mg(pc)(pic)₂⋅2H₂O (III) and Mg(pc)(caf)₂⋅4H₂O (IV), where pc=2,6- pyridinedicarboxylate, na=nicotinamide,py=pyridine, pic=γ-picoline and caf=caffeine. The thermal decomposition of these compounds is multi-stage processes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of destruction of these complexes are suggested. Heating of these compounds first resulted in a release of water molecules. In complexes I, II and IV the loss of the molecular ligands (na, py and caf) occur (on the TG curves) in one step (-2na, -2py and -2caf) and in complex III in two steps (-pic, -pic). The final product of the thermal decomposition was MgO. The thermalstability of the complexes can be ordered in the sequence: IV<I<III<II. Nicotinamide, pyridine, γ-picoline and caffeine were co-ordinated to Mg(II) through the N atom of the respective heterocyclic ring. IR data suggested a unidentate co-ordination of carboxylates to Mg(II) in complexes I–IV. This revised version was published online in July 2006 with corrections to the Cover Date.     

New Complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3,3-dimethylglutaric Acid

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)3,3-dimethylglutarates were investigated and their quantitative composition, solubility in water at 293 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with general formula MC₇H₁₀O₄⋅nH₂O (n=0−2) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes of Mn(II),Co(II), Ni(II) and Cu(II) are dehydrated in one step and next all the anhydrous complexes decompose to oxides directly (Mn, Co, Zn) or with intermediate formation free metal (Ni,Cu) or oxocarbonates (Cd). The carboxylate groups in the complexes studied are bidentate. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II)attain values 5.62, 5.25, 2.91 and 1.41 M.B., respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal Behaviour of the N-donor Adducts of Metal Saccharinates. II. 1,10-phenanthroline saccharinato complexes of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II)

Adducts of Co(II), Ni(II), Cu(II), Zn(II) and Pb(II) saccharinates with 1,10-phenathroline were synthesized and their thermoanalytical (TG, DTG and DTA) curves in the 20–1000°C temperature interval and static air atmosphere were recorded. The complexes are best represented as M(C₁₂H₈N₂)_x(C₇H₄NO₃S)₂⋅yH₂O (x=2, 2, 2, 2 and 1; y=1, 1, 2, 1 and 2 for M=Co, Ni, Cu, Zn and Pb, respectively). The decomposition of the compounds regularly started with dehydration, followed by loss of the phenanthroline ligand(s). The structures of the Cu and Pb complexes are notably different from other compounds. FTIR spectra of the title compounds in the region of the OH, CO and SO₂ stretching vibrations were also studied. The pronounced similarity of the spectra of Co, Ni and Zn adducts indicates possible isomorphism among them. This revised version was published online in July 2006 with corrections to the Cover Date.     

Syntheses and spectrothermal studies of triethanolamine complexes of Co(II), Ni(II), Cu(II) and Cd(II) squarates

The triethanolamine complexes, [M(tea)₂]sq·nH₂O, (n=2 for Co(II), n=0 for Ni(II), Cu(II) and n=1 for Cd(II), tea=triethanolamine, sq²⁻=squarate), have been synthesized and characterized by elemental analyses, magnetic susceptibility and conductivity measurements, UV-Vis and IR spectra, and thermal analyses techniques (TG, DTG and DTA). The Co(II), Ni(II) and Cu(II) complexes possess octahedral geometry, while the Cd(II) complex is monocapped trigonal prismatic geometry. Dianionic squarate behaves as a counter ion in the complexes. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) release of the tea ligands and (iii) burning of organic residue. On the basis of the first DTG_max of the decomposition, the thermal stability of the anhydrous complexes follows the order: Ni(II), 289°C>Co(II), 230°C>Cu(II), 226°C>Cu(II), 170°C in static air atmosphere. The final decomposition products — the respective metal oxides — were identified by FTIR spectroscopy.     

Thermal and Other Properties of New 4,4'-bipyridine-trichloroacetato Complexes of Mn(II), Ni(II) and Zn(II)

New mixed-ligand complexes of general formulae Mn(4-bpy)(CCl₃COO)₂⋅H₂O, Ni(4-bpy)₂(CCl³COO)₂⋅2H²O and Zn(4-bpy)₂(CCl₃COO)₂⋅2H²O (where 4-bpy=4,4’-bipyridine) were obtained and characterized. The IR spectra, conductivity measurements and other physical properties of these compounds were discussed. The central atoms M(II) form coordinate bonds with title ligands. The thermal behaviour of the synthesized complexes was studied in air. During heating the complexes decompose via different intermediate products to Mn₃O₄, NiO and ZnO; partial volatilization of ZnCl₂was observed. A coupled TG-MS system was used to the analysis of the principal volatile thermal decomposition products of Mn(II) and Ni(II) complexes. The principal volatile mass fragments correspond to: H₂O⁺, OH⁺, CO⁺ ₂, HCl⁺, Cl⁺ ₂, CCl⁺ and other. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spectroscopic,Magnetic and Thermal Investigations on Cu(II), Mn(II), Co(II) and Fe(III) Complexes with Glutamyl Nitroanilide

New complexes CuL₂×2H₂O, CoL₂×3H₂O, MnL₂×2H₂O and FeL₃×2H₂O, L=γ-L -glutamyl-5-(p-nitroanilide), were synthesized and characterized by their spectral, magnetic and thermal properties. The thermal stabilities of the synthesized complexes were examined in the temperature range 20–500°C. In all these complexes γ-L -glutamyl-5-(p -nitroanilide) acts as a bidentate ligand, its coordination involving the carbonyl oxygen and the nitrogen atom of the second amino group. The local structure around the Cu(II) ion is pseudotetrahedral. In the Co(II), Mn(II) and Fe(III) complexes, the metal ions are in the high-spin form, with octahedral stereochemistry. This revised version was published online in August 2006 with corrections to the Cover Date.     

Complexes of Co(II), Ni(II), and Cu(II) chlorides and bromides with tetrazol-1-yl-tris(hydroxymethyl)methane: Synthesis and structure

The reactions of Co(II), Ni(II), and Cu(II) chlorides and bromides and their metallic powders with tetrazol-1-yl-tris(hydroxymethyl)methane (L) afforded new complexes ML₂Hal₂ · mH₂O(M = Co(II) or Ni(II), Hal = Cl⁻; M = Cu(II), Hal = Cl⁻ or Br⁻, m = 0; and M = Co(II) or Ni(II), Hal = Br⁻, m = 2), MLnCl₂ (M = Co(II) or Ni(II), n = 2 or 4; M = Cu(II), n = 2), and MLnBr₂ · mH₂O (M = Ni(II), n = 2, m = 2; M = Cu(II), n = 2, m = 0). The compositions and structures of the synthesized complexes were determined by elemental analysis, IR spectroscopy (50–4000 cm⁻¹), and X-ray diffraction analysis. The introduction of a bulky substituent into position 1 of the tetrazole cycle was shown to exert almost no effect on the coordination mode but affected the composition and structure of the complexes.     

Spectral and Thermal Studies of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Complexes with 3-methylglutaric Acid

Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methylglutarates were prepared as solids with general formula MC₆ H₈ O₄ ×n H₂ O, where n =0–8. Their solubilities in water at 293 K were determined (7.0×10⁻² −4.2×10⁻³ mol dm⁻³ ). The IR spectra were recorded and thermal decomposition in air was investigated. The IR spectra suggest that the carboxylate groups are mono- or bidentate. During heating the hydrated complexes lose some water molecules in one (Mn, Co, Ni, Cu) or two steps (Cd) and then mono- (Cu) or dihydrates (Mn, Co, Ni) decompose to oxides directly (Mn, Cu, Co) or with intermediate formation of free metals (Co, Ni). Anhydrous Zn(II) complex decomposes directly to the oxide ZnO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectrothermal studies on Co(II), Ni(II), Cu(II) and Zn(II) salicylato (1,10-phenanthroline) complexes

The cobalt, nickel, copper and zinc atoms in bis(1,10-phenanthroline)bis(salicylato-O)metal(II) monomeric octahedral complexes [M(Hsal)₂(phen)₂]·nH₂O, (M: Co(II), n=1; Cu(II), n=1.5 and Ni(II), Zn(II), n=2) are coordinated by the salicylato monoanion (Hsal) through the carboxyl oxygen in a monodentate fashion and by the 1,10-phenanthroline (phen) molecule through the two amine nitrogen atoms in a bidentate chelating manner. On the basis of the DTG_max, the thermal stability of the hydrated complexes follows order: Ni(II) (149°C)>Co(II) (134°C)>Zn(II) (132°C)>Cu(II) (68°C) in static air atmosphere. In the second stage, the pyrolysis of the anhydrous complexes takes place. The third stage of decomposition is associated with a strong exothermic oxidation process (DTA curves: 410, 453, 500 and 450°C for the Co(II), Ni(II), Cu(II) and Zn(II) complexes, respectively). The final decomposition products, namely CoO, NiO, CuO and ZnO, were identified by IR spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of Copper(II), nickel(II), cobalt(II) and palladium(II) complexes of vicinal oxime-imine ligands; induced chelate isomerism in the same molecule of the nickel(II) complex

Summary Metal complexes of the title ligands were characterized in order to determine the factors influencing the stability of chelate isomerism in the same molecule. The ligands were prepared by 1:1 condensation of isonitrosoacetylacetone (Hiso) with eithero-aminophenol (H₂ isoaph),p-aminophenol (H₂ isopph), or aniline (Hisoanil). The following complexes have been synthesized: [(isoaph)Cu]₄, (Hisoaph)₂Co, (Hisopph)₂ M·nH₂O (M=Ni(II), n=2;M=Pd(II), n=0;M=Co(II), n=2), [(isopph) Cu·H₂O]₂, and (isoanil)₂ M (M=Ni(II), Cu(II), Co(II), or Pd(II)). Both chelate rings in these metal complexes are five-membered. Transimination of one –C=N–C₆H₅ group to –C=NH in (isoanil)₂Ni produced a six-membered chelate ring in (isoim)Ni(isoanil). The induced chelate isomerism is ascribed to intermolecular hydrogen bonding of the imino-hydrogen and the basic nitrogen of the same six-membered chelate ring of an adjacent square planar molecule. Other types of hydrogen bondings with the oximato oxygen (intra- or intermolecular) favour the formation of five-membered chelate rings. Analytical, spectroscopic, and magnetic moment data are in accordance with the suggested formulations.Part of the Ph.D. thesis of Sana M. Imam     

Spectrothermal studies of 1,10-phenanthroline complexes of Co(II), NI(II), Cu(II) and Cd(II) orotates

The 1,10-phenanthroline (phen) complexes of Co(II), Ni(II), Cu(II) and Cd(II) orotates were synthesized and characterized by elemental analysis, magnetic susceptibility, spectral methods (UV-vis and FTIR) and thermal analysis techniques (TG, DTG and DTA). The Co(II), Ni(II), Cu(II) and Cd(II) ions in diaquabis(1,10-phenanthroline)metal(II) diorotate octahedral complexes [M(H₂O)₂(phen)₂](H₂Or)₂·nH₂O (M=Co(II), n=2.25; Ni(II), n=3; Cu(II) and Cd(II), n=2) are coordinated by two aqua ligands and two moles of phen molecules as chelating ligands through their two nitrogen atoms. The monoanionic orotate behaves as a counter ion in the complexes. On the basis of the first DTG_max, the thermal stability of the hydrated complexes follows the order: Cd(II), 68°C 68°C     

Thermal Decomposition of Cu(II) Complexes with 2-Chloro- and 2,6-Dichlorobenzoic Acid and Imidazole

The reaction products of Cu(II) 2-chlorobenzoate and the imidazole (1), and of Cu(II) 2,6-dichlorobenzoate and the imidazole (2) formulated as CuL’₂⋅2imd⋅2H₂O and CuL”₂⋅2imd⋅2H₂O (L’=C₇H₄ClO₂ ⁻, L”=C₇H₃Cl₂O₂ ⁻, imd=imidazole), were prepared and characterized by means of spectroscopic measurements and thermochemical properties. The blue (1) and green (2) complexes were obtained as solids with a 1:2:2 molar ratio of metal to carboxylate ligand to imidazole. When heated at a heating rate of 10 K min⁻¹ the hydrated complexes, (1) and (2), lose some of the crystallization water molecules and then decompose to gaseous products. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spectral,thermal and magnetic investigations of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates

Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH₃C₆H₃(CO₂)₂]·nH₂o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

Coordination compounds of Co(II), Ni(II) and Cu(II) with capric acid hydrazide

The reaction of aquo-ethanolic solutions of Co(II), Ni(II) and Cu(II) salts and ethanolic solution of capric acid hydrazide (L) yielded paramagnetic, high-spin bis- and tris(ligand) chelate complexes. The tris(ligand) complexes, [ML ₃]X ₂·nH₂O [M=Co(II), Ni(II);X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ], have an octahedral structure formed on account of the bidentate (NO) coordination of three neutral hydrazide molecules. In the bis(ligand) complexes,ML ₂(NCS)₂ [M=Co(II), Ni(II)] and CuL ₂ X ₂·nH₂O (X=NO ₃ ^– , ClO ₄ ^– and 1/2SO ₄ ^2– ), the oxoanions and NCS^– take also part in coordination. The complexes have been characterized by elemental analysis, IR spectra, magnetic measurements, molar conductivity and TG analysis.

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Caprinsäurehydrazid-Komplexe von Co(II), Ni(II) und Cu(II)

Zusammenfassung Durch die Reaktion von wäßrig-ethanolischen Lösungen von Co(II)-, Ni(II)-und Cu(II)-Salzen mit einer ethanolischen Lösung von Caprinsäurehydrazid (L) wurden paramagnetische high-spin Bis- und Tris-Ligand-Chelatkomplexe erhalten. Tris-Ligand-Komplexe des Typs [ML ₃ X ₂·nH₂O [M=Co(II), Ni(II);X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ], die eine oktaedrische Struktur besitzen, entstehen durch die Koordination von drei neutralen zweizähnigen (NO)-Hydrazidmolekülen. Bei den Bis-Ligand-KomplexenML ₂(NCS)₂ [M=Co(II), Ni(II)], sowie bei den Bis-Ligand-Komplexen CuL ₂ X ₂·nH₂O (X=NO ₃ ^– , ClO ₄ ^– , 1/2SO ₄ ^2– ) nehmen bei der Koordination außer Hydrazid auch die Säurereste teil. Die Komplexe wurden durch Elementaranalyse, IR-Spektren, magnetische Messungen, molare Leitfähigkeit und TG-Analysen charakterisiert.

     

Characterization and TG-MS studies of lactato and bipyridine-lactato complexes of Co(II) and Ni(II)

Two lactates and four new mixed ligand complexes with formulae Co(lact)₂·2H₂O, Ni(lact)₂·3H₂O, Co(4-bpy)(lact)₂, Co(2,4'-bpy)₂(lact)₂, Ni(4-bpy)(lact)₂·2H₂O and Ni(2,4'-bpy)₂(lact)₂ (where 4-bpy=4,4'-bipyridine, 2,4'-bpy=2,4'-bipyridine, lact=CH₃CH(OH)COO^-) were isolated and investigated. The thermal behaviour of compounds was studied by thermal analysis (TG, DTG, DTA). In the case of hydrated complexes thermal decomposition starts with the release of water molecules. The compounds decompose at high temperature to metal(II) oxides in air. A coupled TG-MS system was used to analyse the principal volatile products of thermolysis and fragmentation processes of obtained complexes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and Structural Studies on Homo-and Heterobinuclear Complexes of Cu(II), Ni(II) and Co(II) with Arylideneanthranilic Acid Schiff Bases

Homo and heterobinuclear complexes of arylidene- anthranilic acids with Cu(II), Ni(II) and Co(II) are prepared and characterised by chemical analysis, spectral and X-ray diffraction techniques as well as conductivity measurements. Two types of homo-binuclear complexes are formed. The first has the formula M₂L₂Cl₂(H₂O)_n where M=Cu(II), Ni(II) and Co(II), L = p-hydroxybenzylideneanthranilic acid (hba), p-dimethylaminobenzylideneanthranilic acid (daba) and p-nitrobenzylideneanthranilic acid(nba) and n = 0–3. The second type has the formula M₂LCl₃(H₂O)_n in which M is the same as in the first type, L = benzylideneanthranilic acid (ba), (daba) (in cases of Cu(II) and Ni(II)); and n = 1–5. Heterobinuclear complexes having the formula (MLCl₂H₂O) MCl₂(H₂O)_n are isolated by reaction of Cu(II) binary chelates with Ni(II) and/or Co(II) chlorides. These are also characterized and their structures are elucidated.     

Complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 4-chloro-2-methoxybenzoic acid anion

The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ were obtained as polycrystalline solids with general formula M(C₈H₆ClO₃)₂·nH₂O and colours typical for M(II) ions (Mn – slightly pink, Co – pink, Ni – slightly green, Cu – turquoise and Zn – white). The results of elemental, thermal and spectral analyses suggest that compounds of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate. The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) heated in air to 1273 K are dehydrated in one step in the range of 323–411 K and form anhydrous salts which next in the range of 433–1212 K are decomposed to the following oxides: Mn₃O₄, CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are CuO and Cu. The solubility value in water at 293 K for all complexes is in the order of 10^–3 mol dm^–3. The plots of χ_M vs. temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) follow the Curie–Weiss law. The magnetic moment values of Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺ ions in these complexes were determined in the range of 76−303 K and they change from: 5.88–6.04 μ_B for Mn(C₈H₆ClO₃)₂·4H₂O, 3.96–4.75 μ_B for Co(C₈H₆ClO₃)₂·5H₂O, 2.32–3.02 μ_B for Ni(C₈H₆ClO₃)₂·5H₂O and 1.77–1.94 μ_B for Cu(C₈H₆ClO₃)₂·4H₂O.     

Manganese(II), cobalt(II) and nickel(II) complexes with 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one,pseudohalides and some bidentate N-donor ligands

Some mixed ligand complexes of the type [M(L)(en or phen)(X)₂]; where M = Mn(II), Co(II) or Ni(II); L = 2-phenyl-3-(benzylamino)-1,2-dihydroquinazolin-4(3H)-one; en = ethylenediamine, phen = 1,10-phenanthroline; X = N₃ ⁻ or NCS⁻ have been prepared. All the complexes were characterized by physico-chemical, spectroscopic and thermal studies. On the basis of electronic spectra and magnetic susceptibility measurements, an octahedral geometry has been proposed for all the complexes. The phen complexes are thermally more stable than the en complexes. The electrochemical behavior of the Ni(II) complexes showed that the complexes of phen are reduced at more positive potential compared to the corresponding en complexes.     

Synthesis and characterization of new metal(II) complexes with formates and some nitrogen donor ligands

New mixed-ligands complexes with empirical formulae: M(2,4′-bpy)₂L₂·H₂O (M(II)Zn, Cd), Zn(2-bpy)₃L₂·4H₂O, Cd(2-bpy)₂L₂·3H₂O, M(phen)L₂·2H₂O (where M(II)=Mn, Ni, Zn, Cd; 2,4′-bpy=2,4′-bipyridine, 2-bpy=2,2′-bipyridine, phen=1,10-phenanthroline, L=HCOO⁻) were prepared in pure solid state. They were characterized by chemical, thermal and X-ray powder diffraction analysis, IR spectroscopy, molar conductance in MeOH, DMF and DMSO. Examinations of OCO⁻ absorption bands suggest versatile coordination behaviour of obtained complexes. The 2,4′-bpy acts as monodentate ligand; 2-bpy and phen as chelating ligands. Thermal studies were performed in static air atmosphere. When the temperature raised the dehydration processes started. The final decomposition products, namely MO (Ni, Zn, Cd) and Mn₃O₄, were identified by X-ray diffraction.     

Novel heteroligand complexes of Co(II), Cu(II), Ni(II) and Mn(II) formed by 2,2′-dipyridyl or 1,10-phenanthroline and phosphortriamide ligands: Synthesis and structure

This paper presents examples of mixed-ligand Co(II), Cu(II), Ni(II) and Mn(II) complexes, with a distorted octahedral coordination geometry, with 2,2′-dipyridyl or 1,10-phenanthroline and phosphortriamide ligands. The complexes of the general type ML₂·Lig (where M = Co(II), Cu(II), Ni(II), Mn(II); L⁻ = {Cl₃C(O)NP(O)R₂}⁻ (R = NHBz, NHCH₂CHCH₂, NEt₂); Lig = 2,2′-dipyridyl or 1,10-phenanthroline) were synthesised and characterised by means of X-ray diffraction, IR and UV–Vis spectroscopy. The phosphortriamide ligands are coordinated via oxygen atoms of phosphoryl and carbonyl groups involved in six-membered metal cycles. The additional ligands 2,2′-dipyridyl or 1,10-phenanthroline are coordinated to the central atom, forming five-membered cycles.