[M(L)2(NCS)2] Complexes (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II); L = Hydrazide of Diphenylphosphinylacetic Acid)

Dithiocyanates of bis(hydrazidediphenylphosphinylacetic acid) M(II), where M is Mn, Fe, Co, Ni, Cu, and Zn were synthesized. Their magnetic properties were studied. All compounds were paramagnetic monomers with pseudooctahedral stereochemistry, except for the Zn(II) complex.     

Electrochemical reduction of Fe(III), Cr(III), and Mn(III) porphyrin complexes in DMSO

The half-wave potentials are given for the electrochemical reduction of Fe(III), Cr(III), and Mn(III) porphyrin complexes. Cyclic voltamperometry was used to study the reversibility of these reactions. An effect was demonstrated for the structure of the porphyrin ligand on the half-wave potentials for the reduction of the Mn(III) complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1665–1668, July, 1991.     

The mass spectra of 1,1,1-trichloro-2,4-pentanedione and its Al(III), Cr(III), Fe(III), Mn(II), Co(II) and Cu(II) complexes

The compounds 1,1,1-trichloro-2,4-pentanedione, Cu(II)tca₂, Co(II)tca₂, Mn(II)tca₂, Al(III)tca₃, Cr(III)tca₃ and Fe(III)tca₃ (tca?1,1,1-trichloro-2,4-pentanedionato, [CCl₃COCHCOCH₃]^?) have been prepared and their mass spectra have been obtained. The mass spectral results have been compared with findings for comparable fluorinated and nonhalogenated compounds. Comparisons are made in terms of internal redox reactions and hard and soft acid base theory. Rearrangement of chloride from ligand to metal accompanied by the elimination of CO or other neutral even electron fragments emerges as an important reaction for the ions of these compounds. While the internal redox reactions characteristic of all previous β-diketonate complex mass spectra still occur, their importance appears reduced to some degree by the facility of the chlorine rearrangement.     

Cyano-bridged Mn(III)3M(III) (M(III) = Fe, Cr) complexes: synthesis, structure, and magnetic properties

Two cyano-bridged tetranuclear complexes composed of Mn(III) salen (salen = N,N'-ethylene bis(salicylideneiminate)) and hexacyanometalate(III) (M = Fe, Cr) in a stoichiometry of 3:1 have been selectively synthesized using {NH2(n-C12H25)2}3[M(III)(CN)6] (M(III) = Fe, Cr) starting materials: [{Mn(salen)(EtOH)}3{M(CN)6}] (M = Fe, 1; Cr, 2). Compounds 1 and 2 are isostructural with a T-shaped structure, in which [M(CN)6]3- assumes a meridional-tridentate building block to bind three [Mn(salen)(EtOH)]+ units. The strong frequency dependence and observation of hysteresis on the field dependence of the magnetization indicate that 1 is a single-molecule magnet.     

Studies on some salicylaldehyde Schiff base derivatives and their complexes with Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II)

The formation constants of some transition metal ions Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline (I), 2-aminopyridine (II), 4-aminopyridine (III) and 2-aminopyrimidine (IV) were determined pH-metrically in ethanolic medium (80%, v/v). The formation constants were determined for all binary complexes. The important infrared (IR) spectral bands corresponding to the active groups in the four ligands and the solid complexes under investigation were studied. The solid complexes have been synthesized and studied by thermogravimetric analysis. The thermal dehydration and decomposition of these complexes were studied kinetically using the integral method applying the Coats-Redfern equation. It was found that the thermal decomposition of the complexes follow second order kinetics. The thermodynamic parameters of the decomposition are also reported. The electronic absorption spectra of the investigated ligands were carried out to determine the pK(a) values spectrophotometrically.     

Extraction of Mn(II), Co(II), Cr(III) and Fe(III) from succinic acid medium by high molecular weight amines

The extraction behavior of Mn(II), Co(II), Cr(III) and Fe(III) has been studied in high molecular weight amines from succinic acid medium. The effect of different variables, like, type of amine, effect of pretreatment of amine with various acids, type of diluent and concentration of metal, succinate, hydrogen ions and amine, has been investigated. Extraction of Cr(III) and Fe(III) species is proposed and some binary separations achieved.     

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.     

Solid-state coordination chemistry: influences of (M(terpyridyl))(M = Fe(III), Cu(II), Ni(II)) subunits on molybdenum oxide structures

The hydrothermal reactions of Na2MoO4 x 2H2O and 2,2':6',2"-terpyridine with appropriate salts of Fe(II), Cu(II), and Zn(II) yield a variety of mixed metal oxide phases. The Cu(II) system affords the molecular cluster [Cu(terpy)MoO4].3H2O (MOXI-40 x 3H2O), as well as a one-dimensional material [Cu(terpy)Mo2O7](MOXI-41) which is constructed from (Mo4O14)4- clusters linked through (Cu(terpy))2+ units. In constrast, the Zn(II) phase of stoichiometry identical to that of MOXI-41, [Zn(terpy)Mo2O7](MOXI-42), exhibits a one-dimensional structure characterized by a (Mo2O7)n2n- chain decorated with peripheral (Zn(terpy))2+ subunits. The iron species [(Fe(terpy))2Mo4O12](MOXI-43) is also one-dimensional but exhibits [(Fe(terpy))2(MoO4)2]2+ rings linked through (MoO4)2- tetrahedra. A persistent structural motif which appears in MOXI-40, MOXI-41, and MOXI-43 is the [(M(terpy))2(MoO4)2]n cluster with a cyclic )(M2Mo2O4) core. In general, the secondary metal sites M(II, III) are effective bridging groups between molybdate subunits of varying degrees of aggregation. Furthermore, the ligands passivate the bimetallic oxide from spatial extension in two or three dimensions and provide a routine entree into low-dimensional structural types of the molybdenum oxide family of materials.     

Chemistry of substituted sulphuric acids—XVII. Complexes of V(III), Cr(III), Mn(II) and Fe(II) methylsulphates

V(III), Cr(III), Mn(II) and Fe(II) methylsulphates form stable donor-acceptor complexes with nitrogen donors. 1:1 and 1:2 complexes with bipyridyl have been prepared in respect of trivalent salts and 1:2 and 1:4 metal:base complexes have been obtained in respect of divalent metal salts with bipyridyl and pyridine respectively. Electronic spectra suggest an octahedral geometry around metal ions. IR spectra of the anhydrous metal methylsulphates have been studied and assigned. The changes in the IR spectra of the methylsulphate group in different stereochemical situations have been observed.     

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) ions: synthesis, structural characterization and biological activity studies

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO₂(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV–vis, ¹H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25 ± 1 °C and at 0.1 M KNO₃ ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO₂(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats–Redfern and Horowitz–Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H₂O)₄]·Cl₂ and [Zn(LFX)(H₂O)₄]·Cl₂ were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 μg/ml.     

Synthesis and characterization of metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Ru(III), Rh(III) and Pd(II) with derivatives of 1,3,4-thiadiazole-2,5-dithiol as new ligands

The synthesis of some new transition metal complexes with 1,3,4-thiadiazole-2,5-dithiol derivatives (L₁ and L₂) as new ligands is reported. Each complex was prepared by the reaction of the ligands with the appropriate metal salts (CrCl₃, MnCl₂·4H₂O, FeCl₃, CoCl₂·6H₂O, NiCl₂·6H₂O, CuCl₂·2H₂O, RuCl₃, RhCl₃ and PdCl₂). Elemental micro analysis (C.H.N.), UV–Visible spectroscopy, ¹H NMR, infrared (IR) spectroscopy, atomic absorption, magnetic susceptibility, continuous variation method and molar conductance techniques were used to characterize the structural formulae of these chelate complexes.     

Spectroscopic, thermal and biological studies of the coordination compounds of sulfasalazine drug: Mn(II), Hg(II), Cr(III), ZrO(II), VO(II) and Y(III) transition metal complexes

The complexations of sulfasalazine (H3Suz) with some of transition metals have been investigated. Three types of complexes, [Mn(HSuz)-2(H2O)4] x 2H2O, [M(HSuz)-2(H2O)2] x xH2O (M=Hg(II), ZrO(II) and VO(II), x=4, 8 and 6, respectively) and [M(HSuz)-2(Cl)(H2O)3] x xH2O (M=Cr(III) and Y(III), x=5 and 6, respectively) were obtained and characterized by physicochemical and spectroscopic methods. The IR spectra of the complexes suggest that the H3Suz behaves as a bidentate ligand. The thermal decomposition of the complexes as well as thermodynamic parameters (DeltaE*, DeltaH*, DeltaS* and DeltaG*) were estimated using Coats-Redfern and Horowitz-Metzger equations. In vitro antimicrobial activities of the H3Suz and the complexes were tested.     

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.     

Ethylene Oligomerization by (dppe)MCl_2 [M = Fe(II), Co(II),Ni(II)] Complexes/EAO

Transition-metal-catalyzed oligomerzation of ethylene is an important process to provide a-olefins in the C6~C20 range. In recent years, the catalytic behavior of late transition metal complexes containing bi- and tri-dentate ligands for oligomerization of ethylene to a-olefins has attracted much attention. When oligomerization of ethylene catalyzed by nickel diimine and Fe(II), Co(II) 2,6-bis(imino)pyridine catalysts, the oligomers with high average molecular weight were obtained1-5. Eth…     

Syntheses, structures, and properties of trinuclear complexes [M(bpca)(2)(M'(hfac)(2))(2)], constructed with the complexed bridging ligand [M(bpca)(2)] [M, M' = Ni(II), Mn(II); Cu(II), Mn(II); Fe(II), Mn(II); Ni(II), Fe(II); and Fe(II), Fe(II); Hbpca = Bis(2-pyridylcarbonyl)amine, Hhfac = Hexafluoroacetylacetone

Five trinuclear complexes [M(bpca)(2)(M'(hfac)(2))(2)] (where MM'(2) = NiMn(2), CuMn(2), FeMn(2), NiFe(2), and FeFe(2); Hbpca = bis(2-pyridylcarbonyl)amine; and Hhfac = hexafluoroacetylacetone) were synthesized almost quantitatively by the reaction of [M(bpca)(2)] and [M'(hfac)(2)] in 1:2 molar ratio, and their structures and magnetic properties were investigated. Three complexes, with M' = Mn, crystallize in the same space group, Pna2(1), whereas two complexes, with M' = Fe, crystallize in P4(1), and complexes within each set are isostructural to one another. In all complexes, [M(bpca)(2)] acts as a bis-bidentate bridging ligand to form a linear trinuclear complex in which three metal ions are arranged in the manner M'-M-M'. The central metal ion is in a strong ligand field created by the N(6) donor set, and hence the Fe(II) in the [Fe(bpca)(2)] moiety is in a low-spin state. The terminal metal ions (M') are surrounded by O(6) donor sets with a moderate ligand field, which leads to the high-spin configuration of Fe(II). Three metal ions in all complexes are almost collinear, and metal-metal distances are ca. 5.5 A. The magnetic behavior of NiMn(2) and NiFe(2) shows a weak ferromagnetic interaction between the central Ni(II) ion and the terminal Mn(II) or Fe(II) ions. In these complexes, sigma-spin orbitals of the central Ni(II) ion and those of terminal metal ions have different symmetry about a 2-fold rotation axis through the Ni-N(amide)-M'(terminal) atoms, and this results in orthogonality between the neighboring sigma-spin orbitals and thus ferromagnetic interactions.     

Asymmetric Schiff Base (N 2 O 3 ) Complexes as Ligands Towards Mn(II), Fe(III) and Co(II), Synthesis and Characterization

Heterobi- and tri-nuclear complexes [LMM'Cl] and [(LM) 2 M'](M=Ni or Cu and M'=Mn, Fe or Co) have been synthesised. The heteronuclear complexes were prepared by stepwise reactions using two mononuclear Ni(II) and Cu(II) complexes of the general formula [HLM]·1/2H 2 O, as ligands towards the metal ions, Mn(II), Fe(III) and Co(II). The asymmetrical pentadentate (N 2 O 3 ) Schiff-base ligands used were prepared by condensing acetoacetylphenol and ethylenediamine, molar ratio 1 1, to yield a half-unit compound which was further condensed with either salicylaldehyde or naphthaldehyde to yield the ligands H 3 L 1 and H 3 L 2 which possess two dissimilar coordination sites, an inner four-coordinate N 2 O 2 donor set and an outer three-coordinated O 2 O set. 1 H NMR and IR spectra indicate that the Ni(II) and Cu(II) ions are bonded to the inner N 2 O 2 sites of the ligands leaving their outer O 2 O sites vacant for further coordination. Different types of products were obtained according to the type of metal ion. These products differ in stoichiometry according to the type of ligand in the parent compound. Electronic spectra and magnetic moments indicate that the structures of the parent Ni(II) and Cu(II) complexes are square-planar while the geometry around Fe(III), Mn(II) and Co(II) in their products are octahedral as elucidated from IR, UV-visible, ESR, 1 H NMR, mass spectrometry and magnetic moments.     

Spectrophotometric Study of Mithramycin Complexes with Cu(II), Fe(III) and Tb(III)

Abstract

The coordination of the anticancer drug mithramycin to Tb(III), Fe(III) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions, the competitor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(II) at pH 7.5, Fe(III) at pH 3.5 and Tb(III) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species.     

Isomorphous replacement of M(II) ions in M(II)-Gd(III) dimers (M(II) = Cu(II), Mn(II), Ni(II), Co(II), Zn(II)): magnetic studies of the products

Complexes [M(II)Gd(III){pyCO(OEt)pyC(OH)(OEt)py}?](ClO?)?·EtOH [M(II) = Cu(II) (1), Mn(II) (2), Ni(II) (3), Co(II) (4) and Zn(II) (5)] crystallize in the monoclinic Cc space group and contain one hexacoordinate M(II) ion and one enneacoordinate Gd(III) ion, bridged by three {pyCO(OEt)pyC(OH)(OEt)py}? ligands. Magnetic susceptibility measurements indicate a ferromagnetic interaction for 1 and antiferromagnetic interactions for 2-4. Using the ? = -J?(Gd(III))?(M(II)) spin Hamiltonian formalism, fits to the magnetic susceptibility data yielded J values of +0.32 cm?1 for 1, -1.7 cm?1 for 2, and -0.22 cm?1 for 3. In complex 4, the orbital contributions of Co(II) precluded the determination of the magnetic coupling. The complex follows the Curie-Weiss law with θ = -2.07 K (-1.44 cm?1).