Synthesis and Thermal Decomposition of Cobalt(II) bis (Tartrato) Cobaltate(II) Trihydrate

The paper describes the synthesis and characterization of cobalt(II) bis (tartrato) cobaltate(II) trihydrate Co[Co[C₄O₆H₄)₂]·3H₂O. The complex was characterized on the basis of elemental analysis, infrared, electronic, e.s.r. spectra and X-ray powder diffraction studies. The thermal decomposition of the complex led to a mixture of Co₂O₃and Co₃O₄in air at about 400°C, whereas in nitrogen it was decomposed to a mixture of CoO and C at about 384°C. A tentative reaction mechanism is suggested for the thermal decomposition of the complex in air and nitrogen. This revised version was published online in July 2006 with corrections to the Cover Date.     

Orotic acid complexes of Co(II), Ni(II), Zn(II) and Cd(II) with imidazole

The [Co(HOr)(H₂O)₂(im)₂] (1), [Ni(HOr)(H₂O)₂(im)₂] (2), [Zn(H₂O)₂(im)₄](H₂Or)₂ (3) and [Cd(HOr)(H₂O)(im)₃] (4) complexes (H₃Or: orotic acid, im: imidazole) were synthesized and characterized by elemental analysis, magnetic and conductance measurements, UV-vis and IR spectra. The thermal behaviour of the complexes was also studied by simultaneous thermal analysis techniques (TG, DTG and DTA). The orotate ligand (HOr²⁻) coordinated to the Co(II), Ni(II) and Cd(II) ions are chelated to the deprotonated pyrimidine nitrogen (N₍₃₎) and the carboxylate oxygen, while do not coordinate to the Zn(II) ion is present as a counter-ion (H₂Or⁻). The first thermal decomposition process of all the complexes is endothermic deaquation. This stage is followed by partially (or completely) decomposition of the imidazole and orotate ligands. In the later stage, the remained organic residue exothermically burns. On the basis of the first DTG_max, the thermal stability of the complexes follows order: 2, 176°C>1, 162°C>4, 155°C>3, 117°C in static air atmosphere. The final decomposition products which identified by IR spectroscopy were the corresponding metal oxides.     

One-dimensional coordination polymers of Co(II) and Cd(II)-squarate with 2-methylimidazole and 4(5)-methylimidazole ligands

Two new mixed-ligand coordination polymers, {[Co(μ_1,3-sq)(H₂O)₂(2-Meim)₂]·2(2-Meim)}_n (1) and [Cd(μ_1,3-sq)(H₂O)₂(4(5)-Meim)₂]_n (2), (sq = squarate, 2-Meim = 2-methylimidazole, 4(5)-Meim = 5-methylimidazole) have been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV–Vis) and thermal analyses are also reported. The Co(II) and Cd(II) ions are distorted octahedrally coordinated by four oxygen atoms of two O¹–O³-bridging squarate ligands and two trans-aqua ligands, and by two nitrogen atoms of the trans-imidazole (2-Meim or 4(5)-Meim) ligands. The structures of 1 and 2 consist of one-dimensional chains of μ-1,3-squarato bridged metal(II) complex units. These chains are held together by hydrogen bonding interactions, forming three-dimensional framework.     

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     

Crystal Structure and Characterization of Pd(II) Bis(diiso‐propyldithiocarbamate) Complex

The crystal and molecular structure of [Pd(iPr₂dtc)₂] (dtc = dithiocarbamate) have been determined by X‐ray crystallography. The unit cell of the crystal structure consists of two discrete monomelic molecules of [Pd(iPr₂dtc)₂]. The Pd(II) ion has an square‐planar geometry. The electronic and IR spectral data are in agreement with the X‐ray structure. The TG data indicate slight degradation of a few percent.     

Hg(II) and Cd(II) complexes with mixed donor macrocyclic thioethers: The oxophobicity of mercury(II)

A series of Hg(II) and Cd(II) homoleptic complexes with mixed donor (O,S and N,S) macrocycles is reported. The macrocyclic oxa thiacrowns 9S2O (1-oxa-4,7-dithiacyclononane) and 18S4O2 (1,10-dioxa-4,7,13,16-tetrathiacyclooctadecane) bind to Hg(II) to form distorted tetrahedral S4 geometries without coordination of the oxygen atoms. In contrast, the two macrocycles coordinate to Cd(II) through all ligand donors to form S4O2 environments. We also report the structure of bis(9N2S (1,4-diaza-7-thiacyclononane))cadmium(II), [Cd(9N2S)₂]²⁺ which shows octahedral coordination in a trans N4S2 environment. Furthermore, two new homoleptic Cd(II) complexes with the related hexadentate macrocycles 18N6 (1,4,7,10,13,16-hexaazacyclooctadecane) and 18S6 (1,4,7,10,13,16-hexathiayclooctadecane) are described. Among the Cd(II) complexes, we highlight a trend in ¹¹³Cd NMR that shows progressive upfield chemical shifts as secondary amine donors replace thioether S donors.     

Complexes of Mn(II), Co(II), Ni(II) and Cu(II) with 4,4'-bipyridine and dichloroacetates

New mixed-ligand complexes with empirical formulae M(4-bpy)L₂·1.5H₂O (M(II)=Mn, Co), Ni(4-bpy)₂L₂ and Cu(4-bpy) L₂·H₂O (where: 4-bpy=4,4'-bipyridine, L=CC L2HCOO^-) have been isolated in pure state. The complexes have been characterized by elemental analysis, ir spectroscopy, conductivity (in methanol, dimethylformamide and dimethylsulfoxide solutions) and magnetic and x-ray diffraction measurements. The Mn(II) and Co(II) complexes are isostructural. The way of metal-ligand coordinations discussed. the ir spectra suggest that the carboxylate groups are bonded with metal(II) in the same way (Ni, Cu) or in different way (Mn, Co). The solubility in water is in the order of 19.40·10^-3÷1.88·10^-3ł mol dm^-3ł. During heating the hydrate complexes lose all water in one step. The anhydrous complexes decompose to oxides via several intermediate compounds. A coupled TG-MS system was used to analyse the principal volatile products of obtained complexes. The principal volatile products of thermal decomposition of complexes in air are: H₂O₂ ⁺, CO₂ ⁺, HCl⁺, Cl₂ ⁺, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Neutral Nickel(II) and Copper(II) Tetraazamacrocyclic Complexes as Molecular Rods Attached to Gold Electrodes

New dithiolated derivatives of neutral Cu^II and Ni^II tetraazamacrocyclic complexes have been synthesized and characterized by spectroscopic and diffractional methods. These rod‐shaped molecules were assembled in monocomponent and mixed monolayers on gold electrodes. In the mixed monolayers, the active molecules were embedded in a hexanethiol matrix. The dithiolated complexes are oriented perpendicularly to the electrode, and reveal faster kinetics of electron transfer than those assembled in a single‐component monolayer. They appear as protrusions, which are easily addressed by using the STM method. In the presence of a suitable electron acceptor in the solution, the donor properties of the anchored Cu complex were weakened, which revealed donor–acceptor interactions with the monolayer. The peak position in the voltammogram indicates a stronger interaction of the solution‐based acceptor with the reduced Cu^II form than with the Cu^III complex. This suggests the possibility of switching the association on or off by applying an appropriate potential.     

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.     

Heteroleptic platinum(II) and palladium(II) complexes with thiacrown and diimine ligands

We wish to report the synthesis, crystal structures, spectroscopic and electrochemical properties of several new Pt(II) heteroleptic complexes containing the thiacrown, 9S3 (1,4,7-trithiacyclononane) with a series of substituted phenanthroline ligands and related diimine systems. These five ligands are 5,6-dimethyl-1,10-phenanthroline(5,6-Me₂-phen), 4,7-dimethyl-1,10-phenanthroline(4,7-Me₂-phen), 4,7-diphenyl-1,10-phenanthroline(4,7-Ph₂-phen), 2,2′-bipyrimidine(bpm), and pyrazino[2,3-f]quinoxaline or 1,4,5,8-tetraazaphenanthrene(tap). All complexes have the general formula [Pt(9S3)(N₂)](PF₆)₂ (N₂ = diimine ligand) and form similar structures in which the Pt(II) center is surrounded by a cis arrangement of the two N donors from the diimine chelate and two sulfur atoms from the 9S3 ligand. The third 9S3 sulfur in each structure forms a longer interaction with the platinum resulting in an elongated square pyramidal structure, and this distance is sensitive to the identity of the diimine ligand. In addition, we report the synthesis, structural, electrochemical, and spectroscopic properties of related Pd(II) 9S3 complex with tap. The ¹⁹⁵Pt NMR chemical shifts for the six Pt(II) complexes show a value near −3290 ppm, consistent with a cis-PtS₂N₂ coordination sphere although more electron-withdrawing ligands such as tap show resonances shifted by almost 100 ppm downfield. The physicochemical properties of the complexes generally follow the electron-donating or withdrawing properties of the phenanthroline substituents.     

Complex formation of polyethyleneimine with copper(II), nickel(II), and cobalt(II) ions

An influence of the structure of a globule of polyethyleneimine on the complex formation of one with the copper(II), nickel(II), and cobalt(II) ions is described. A change of the coordination number from the pH of solution for complexes of ethylenediamine, diethylenetriamine, and polyethyleneimine with metal ions was found. The fraction of monomer links, bound with metal ions, depends on the volume of the globule of macromolecule as well as the condition of the proceeding reaction. The reaction of complex formation is controlled by the diffusion of metal ions into the polymer globule in solution. The effective equilibrium constants of complex formation were found. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 914–922, 2002; DOI 10.1002/pola.10157     

Complexation Equilibria of Zn(II), Pb(II) and Cd(II) with Reduced Glutathione (GSH) and Biologically Important Zwitterionic Buffers

The interaction of zinc(II), lead(II), and cadmium(II) with Glutathione (S‐L‐glutamyl‐Lcysteinylglycine) as primary ligand and zwitterionic buffers (N‐[2‐Hydroxyethyl]piperazine‐N′‐[2‐ethanesulfonic acid]) (HEPES) and (N‐Hydroxyethyl]piperazine‐N′‐[2‐hydroxy‐propanesulfonic acid]) (HEPPSO) as secondary ligands were studied by potentiometric‐pH titration in 1:1:1 ratio at 25.0 °C and I = 0.1 mol.dm^?3 (KNO₃). The formation constants of different normal and protonated binary and ternary complex species were calculated. Formation constants for the monohydroxy, and dihydroxy complexes for the binary systems M(II) + HEPES and M(II) + HEPPSO have been evaluated. The distribution curves for the various complex species as a function of pH were constructed.     

Trans‐bis(saccharinato)cadmium(II) Complexes with 2‐Pyridylethanol: Synthesis,Crystal Structures,Spectral and Thermal Characterization of [Cd(sac)2(pyet)2] and [Cd(sac)2(H2O)(dmso)(pyet)]

Two trans saccharinate (sac) complexes of cadmium(II) with 2‐pyridylethanol (pyet) were synthesized and characterized by elemental analyses, FT—IR spectroscopy, thermal analysis and single crystal X‐ray diffractometry. The [Cd(sac)₂(pyet)₂] ( 1 ) and [Cd(sac)₂(H₂O)(dmso)(pyet)] ( 2 ) complexes crystallize in the monoclinic (P2₁/c) and orthorhombic [P2₁2₁2₁] crystal systems, respectively. The sac ligands in both complexes are N‐coordinated and located in trans positions, while the pyet molecules act as a bidentate N‐ and O‐donor ligand forming two six‐membered chelate rings. Thermal decomposition of the complexes in air results in elimination of aqua, dmso and pyet ligands, respectively, forming cadmium saccharinate as a stable intermediate, which also decomposes at higher temperatures to give cadmium oxide.     

Solid-phase thermal decomposition of polynuclear nickel(II) and cobalt(II) complexes

Solid-phase thermal decomposition of polynuclear Ni^II and Co^II pivalate complexes was studied by differential scanning calorimetry and thermogravimetry. The decomposition of the polynuclear (from bi-to hexanuclear) Co^II carboxylate complexes is accompanied by aggregation to form a volatile octanuclear complex. Thermolysis of the polynuclear NiII carboxylates results in their destructure, and the phase composition of the decomposition products is determined by the nature of coordinated ligands. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 250—260, February, 2006.     

Characterization and thermal studies of nano‐synthesized Mn(II), Co(II), Ni(II) and Cu(II) complexes with adipohydrazone ligand as new promising antimicrobial and antitumor agents

New seven complexes of N₁,N₆‐bis((2‐hydroxynaphthalin‐1‐yl)methinyl))adipohydrazone (H₂L) with MnCl₂•4H₂O, CoCl₂•6H₂O, NiCl₂•6H₂O, CuCl₂•2H₂O, Cu(NO₃)₂•3H₂O, CuSO₄•5H₂O, and Cu(OAc)₂•2H₂O have been prepared and characterized by the aid of elemental and thermal analyses, spectra (FT‐IR, ¹H NMR, MS, UV‐Vis, ESR, X‐ray powder diffraction), molar conductance and magnetic moment measurements. The XRD results unambiguously confirmed the nano‐sized particles of the complexes. The results showed that H₂L behaves as dibasic tetra‐dentate ligand towards the metal ions of interest. The low molar conductance values revealed the non‐electrolytic nature for the chelates. The magnetic moment data, UV‐Vis and ESR spectra denoted the formation of octahedral geometries for Mn(II) and Ni(II) complexes, whereas Co(II), Cu(II) complexes exhibited tetrahedral arrangement. The activation parameters for the thermal decomposition stages were calculated from TGA curves using Coats‐Redfern and Horowitz–Metzger methods. The obtained data were confirmed by 3‐D molecular modeling of the ligand and some complexes. The investigated compounds were screened for their antimicrobial activities against different types of organisms and antitumor activities towards human liver Carcinoma (HEPG2) cell to access their potential chemotherapeutic use. The free ligand (H₂L) exhibited a weak inhibition of cell viability with IC₅₀ of 11.80 μg/ml, complexes 4 , 6 and 7 showed a moderate activity with IC₅₀ of 5.56, 7.71 and 5.67 μg/ml, whereas complexes 1 , 2 , 3 , and 5 displayed a strong anticancer activity with IC₅₀ of 4.65, 3.97, 3.30 and 4.84 μg/ml, compared with IC₅₀ value of 4.73 μg/ml for the doxorubicin (standard cytotoxin drug).     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

Preparations,IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)₂Pd(CN)₄] (1) and [Cd(hydet-en)₂Pd(CN)₄] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H?···?O, N–H?···?N and O–H?···?N, thereby forming a three-dimensional network.     

Synthesis and anticancer activity of chalcogenide derivatives and platinum(II) and palladium(II) complexes derived from a polar ferrocene phosphanyl–carboxamide

The polar phosphanyl‐carboxamide, 1′‐(diphenylphosphanyl)‐1‐[N‐(2‐hydroxyethyl)carbamoyl]ferrocene ( 1 ), reacts readily with hydrogen peroxide and elemental sulfur to give the corresponding phosphane‐oxide and phosphane‐sulfide, respectively, and with platinum(II) and palladium(II) precursors to afford various bis(phosphane) complexes [MCl₂( 1 ‐κP)₂] (M = trans‐Pd, trans‐Pt and cis‐Pt). The anticancer activity of the compounds was evaluated in vitro with the complexes showing moderate cytotoxicities towards human ovarian cancer cells. Moreover, the biological activity was found to be strongly influenced by the stereochemistry, with trans‐[PtCl₂( 1 ‐κP)₂] being an order of magnitude more active than the corresponding cis isomer. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and Structural Characterization of Cadmium(II) and Mercury(II) Complexes Derived from 3‐Aminoquinoline

Two novel metal complexes derived from interactions of Cd²⁺ and Hg²⁺ ions with 3‐aminoquinoline in the molar ratio 1 : 2 are reported. The synthesized and isolated metal complexes were characterized by UV/VIS, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI‐MS spectroscopic studies, and elemental analyses. FT‐IR and NMR studies confirmed that the NH₂ group remains uncoordinated in both synthesized complexes. The molecular structure of the Cd^II complex was additionally determined by X‐ray single‐crystal analysis. The Cd complex crystallizes in the triclinic centrosymmetric P$\bar 1$ space group. Moreover, the Cd^II complex exists as neutral discrete molecule and was found to show tetrahedral geometry.     

Rhodium(III), palladium(II) and platinum(II) complexes of Bis(o-aminobenzenesulfonyl)ethylenediamine

New complexes of the formulae K₃[RhL ₃]·2 H₂O, [PdL]·H₂O and [M(LH₂)Cl₂] [whereM = Pd, Pt andLH₂ = bis(o-aminobenzenesulfonyl)ethylenediamine] have been prepared and characterized by conductivity measurements, thermogravimetric analysis, X-ray powder patterns and IR, Ligand Field and¹H-NMR spectroscopy.

---

Rhodium(III), Palladium(II)- und Platin(II)-Komplexe mit Bis(o-aminobenzolosulfonyl)ethylendiamin (Kurze Mitteilung)

Zusammenfassung Neue Komplexe der allgemeinen Formeln K₃[RhL ₃]·2H₂O, [PdL]·H₂O und [M(LH₂)Cl₂] mitM = Pd, Pt undLH₂ = Bis(o-aminobenzolosulfonyl)ethylendiamin wurden dargestellt und mit Konduktionsmessungen, thermogravimetrischen Analysen, Röntgenstrukturanalysen, IR, Ligandfeld- und¹H-NMR-Spektroskopie charakterisiert.