The Thermal Stability of Ciprofloxacin Complexes with Magnesium(II), Zinc(II) and Cobalt(II)

The thermal behaviour of Mg(II), Zn(II) and Co(II) compounds of ciprofloxacin was studied by thermogravimetry (TG) and differential thermal analysis (DTA) in order to determine or to confirm some structural characteristics of substances. The complexes decompose in two steps: dehydration and pyrolytic decomposition of the anhydrous complexes to form metal oxide or metal fluoride. The dehydration process of one magnesium(II) compound takes place in two steps suggesting a marked difference in the bonding of water molecules. The different bonding mode of the ciprofloxacin molecules in both magnesium compounds leads to different residues of the thermal decompositions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Zinc and Cobalt Complexes Derived from Tetradentate Tripodal Ligands with N2O2 Donorset as Model Compounds for Phosphatases

Starting from the tripodal tetradentate ligands ‐(3,5‐dibromo‐2‐hydroxybenzyl)(2‐hydroxybenzyl)(2‐pyridyl)methylamine (H₂L1), (3,5‐dibromo‐2‐hydroxybenzyl)(2‐hydroxy‐5‐nitrobenzyl)(2‐pyridyl)methylamine (H₂L2), and (3,5‐dichloro2‐hydroxybenzyl)(2‐hydroxy‐5‐nitrobenzyl)(2‐pyridyl)methylamine (H₂L3) the new isostructural dinuclear zinc compounds [Zn₂(L1)₂]·N(CH₂CH₃)₃ ( 1 ), [Zn₂(L2)₂]·2CH₃OH ( 2 ) and [Zn₂(L3)₂]·C₄H₁₀O ( 3 ) were synthesized. Due to their enzyme‐like trigonal bipyramidal N₂O₃ coordination environment of the zinc ions and the similar Zn···Zn distances the complexes can be considered to be structural models for the active sites in phospholipase C and nuclease P1. With H₂L3 also the dinuclear complex [Co₂(L2)₂(CH₃OH)]·2CH₃OH·0.5C₄H₁₀O ( 4 ) could be prepared. The new compounds were isolated and characterized by single crystal X‐ray crystallography as well as infrared spectroscopy. The cobalt compound 4 was additionally characterized by UV‐Vis spectroscopy and magnetic measurements. 1 crystallizes in the monoclinic space group P2₁/n with a = 11.2814(2), b = 28.6154(2), c = 13.1866(3) Å, β = 96.995(1)°, V = 4225.2(2) ų, Z = 4. 2 and 3 are monoclinic, space group C2/c with a = 23.084(5), b = 9.232(2), c = 21.849(4) Å, &β; = 96.83(3)°, V = 4623(2) ų, Z = 4, and a = 22.7834(3), b = 9.2463(1), c = 21.6351(3) Å, &β; = 97.592(1)°, V = 4517.7(2) ų, Z = 4, respectively. 4 crystallizes in the monoclinic space group I2/a with a = 22.4680(4), b = 20.5517(4), c = 22.8910(6) Å, &β; = 111.938(1)°, V = 9804.7(4) ų, Z = 8. 4 shows an effective magnetic moment of 6.72 μ_B at 300 K which clearly indicates the presence of two cobalt(II) high spin ions with Curie‐Weiss behaviour above 80 K. At lower temperatures a decrease of the effective magnetic moment was observed.     

Zinc(II), Cobalt(II) and Nickel(II) Complexes of 5-Substituted-1,3,4-Thiadiazoles

Zn(II), Co(II) and Ni(II) complexes with some 5-substituted-1,3,4-thiadiazoles (L₁-L₄) have been prepared and characterized by conductivity, microanalysis, thermal analysis, infrared and electronic spectra measurements. All complexes behave as 1:1 electrolyte and the ligands are coordinated as bidentate molecules. The stability constants and energy of formation are determined and discussed on the basis of the ligands structure.     

Phosphorus-Containing Heterocyclic Compounds Derived from N-Vinylpyrroles

C-phosphorylation of N-vinylpyrroles with phosphorus(III) halides is shown to occur both at position 2 of the pyrrole ring and at the vinyl group. The properties of the resulting phosphorus-containing heterocyclic compounds and bis-phosphorylated N-vinylpyrroles are reported. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 495–499, 1997     

Coordination Compounds of Cobalt(II), Nickel(II), and Zinc(II) Malonates and Phthalates with Benzohydrazide

Benzohydrazide complexes of cobalt(II), nickel(II), and zinc(II) malonates and phthalates were synthesized and characterized by chemical analysis, IR spectroscopy, diffuse reflectance spectroscopy, and thermogravimetry.     

Coordination Compounds of Cobalt(II), Nickel(II), and Zinc(II) Valerates and Benzoates with Phenylacethydrazide

Complexes of cobalt(II), nickel(II), and zinc(II) valerates and benzoates with phenylacethydrazide were synthesized. These compounds were characterized by chemical analysis, IR spectroscopy, diffuse reflection spectroscopy, and thermogravimetry.     

Synthesis and Crystal Structure of Iron(II) and Cobalt(III) Complexes with Hetarylhydrazone Derived from o-Diphenylphosphinobenzaldehyde and 1-Hydrazinophthalazine

Doklady Chemistry - Reaction of 1-phthalazinylhydrazone of o-diphenylphosphinobenzaldehyde (HL) with Fe(II) and Co(II) perchlorates has led to complexes of different composition and structure:...     

Nickel(II) and Zinc(II) Complexes with Benzoylacetaldehyde Derivatives

Russian Journal of Coordination Chemistry - Ni(II) and Zn(II) complexes, [M(Ln)A] (n = 1–3, A = NH3, Py), were prepared from the products of condensation of benzoylacetaldehyde with aromatic...     

Five-coordinate Cobalt(II), Nickel(II) and Zinc(II) Complexes Derived from 2-pyridine-2-yl-3-(pyridine-2-carboxylideneamino)-1,2-dihydroquinazolin-4(3H)-one. The Crystal Structure of the Cobalt(II) Complex

The synthesis of cobalt(II), nickel(II) and zinc(II) complexes of 2-pyridine-2-yl-3(pyridine-2-carboxylideneamino)-1,2-dihydroquinazolin-4(3H)-one is described. The ligand and metal complexes were characterized by elemental analysis, conductivity measurements, spectral (u.v.–vis., i.r., 1D n.m.r., 2D hetcor and mass) and thermal studies. The cobalt(II) complex crystallizes as pink crystals in the monoclinic crystal system, space group P21/n with a = 10.066(6) Å, b = 15.929(9) Å, c = 12.624(7) Å, α = 90.00(9)°, β = 110.850 (8)°, γ = 90.00, V = 1891.5 (18) ų and Z = 4. The geometry around the cobalt atom is distorted trigonal bipyramidal with τ = 0.83 [structural parameter, τ = (β − α)/60; where α and β are the two basal angles in a five coordinate complex].     

Carbonyl Complexes of Platinum (II) and Palladium(II) with Heterocyclic Cyclometalating Ligands

Russian Journal of General Chemistry -     

Synthesis and Characterization of Two vic-Dioximes Containing the 1,3-Dioxolane Ring and 1,4-Diaminobutane and Their Cobalt(II), Nickel(II), Copper(II) and Zinc(II) Metal Complexes

Two new vic-dioxime ligands, (E,E)-N-{4-[(1,4-dioxaspiro[4.4]non-2-ylmethyl)amino]butyl}-N-hydroxy-2-(hydroxyimino)ethanimidamide (L¹H₂) and (E,E)-N-{4-[(1,4-dioxaspiro[4.5]dec-2-ylmethyl)amino]butyl}-N-hydroxy-2-(hydroxyimino)ethanimidamide (L²H₂) containing two different heteroatoms (N,O) have been prepared from anti-chloroglyoxime, N-(1,4-dioxaspiro[4.4]non-2-ylmethyl)butane-1,4-diamine (3) and N-(1,4-dioxaspiro[4.5]dec-2-ylmethyl)butane-1,4-diamine (4). Co^II, Ni^II and Cu^II complexes of the ligands have a metal:ligand ratio of 1:2 and the ligands coordinate through the two N atoms, as do most of the vic-dioximes. However, Zn^II complexes of the ligands have a metal:ligand ratio of 1:1 and the ligands are coordinated only by the N, O atoms of the vic-dioximes. In the Co^II complexes two water molecules, and in the Zn^II complexes a chloride ion and a water molecule, are also coordinated to the metal ion. The structures of the compounds were determined by a combination of elemental analysis, magnetic moments, molar conductances, thermogravimetric analysis (t.g.a.) and spectroscopic (u.v.–vis., i.r., ¹H- and ¹³C-n.m.r.) data.     

Palladium(II) Pyridinecarboxaldimine Complexes Derived from Unsaturated Amines

Pyridinecarboxaldimines (N–N′) derived from pyridin-2-ylcarboxaldehydes and unsaturated amines add to [PdCl₂(coe)]₂ (coe = cis-cyclooctene) to give complexes of the type PdCl₂(N–N′) in moderate yields. The palladium complexes have been investigated as substrates for hydroboration reactions and as antifungal agents against Aspergillus niger, A. flavus, Candida albicans, and Saccharomyces cerevisiae.     

Synthesis and Characterization of Some New Zinc(II) Complexes Incorporating Heterocyclic Thiophosphates as a Ligand

New tetracoordinated complexes of Zn (II) have been synthesized by the reaction between zinc chloride and 3-methyl-2-benzothiazolylidenamido-thiophosphoryl dichloride (L₁), (3-methyl-2-benzothiazolylidenamido)-bis-(diethylamido)thiophosphate (L₂), 3-benzyl-2-benzothiazolylidenamido thiophosphoryl dichloride (L₃), and (3-benzyl-2-benzothiazolylidenamido)-bis-(diethyl-amido) thiophosphate (L₄) in a 1:1 ratio. The complexes have been isolated and characterized by elemental analysis, electrical conductivity, and mass and IR spectral studies. The stability constants of these complexes also have been determined in aqueous solution by spectrophotometric methods.     

Cobalt (II) Complexes with Tri- and Tetradentate Schiff Bases Derived From 2-Furyl Glyoxal and Some Amines

Coordination compounds of cobalt (II) with four new schiff bases of furyl glyoxal, 2-furyl-methyl-2′-carboxylato ketoanil (2 FMCKA), 2-furyl glyoxal ethyenediimine (2 FGED), 2-furyl giyoxal-2′-sulphonic acid anil (2 FGSAA) and 2-furyl glyoxal-2′-chloro-4-nitro anilimimine (2 FGCNA) were prepared and characterised with the help of elemental analyses, magnetic measurements, infra-red and electonic spectral data. Various ligand field parameters such as 10 Dq, B & C, F² & F⁴, f² & f⁴, h, B° etc. and transition energies ν₁;, ν₂ & ν₃, were calculated with the help of electronic spectral data. The ν(C=N) bands in the IR spectra of all the ligands are lowered in complexation indicating nitrogen coordination of the ligands. All these studies indicate that cobalt(II) ion is in a distorted octahedral environment.     

Cobalt(II), Nickel(II), and Copper(II) Complexes with Diphenylthiocarbazide

New [ML(H₂O)₂] complexes (M = Co²⁺, Ni²⁺, or Cu²⁺; H₂L = diphenylthiocarbazide) were synthesized and studied using IR and diffuse reflection electronic spectroscopy, magnetic chemistry, conductometry, and DTA. The metals were shown to coordinate L^2–through nitrogen and sulfur atoms. The complex [CuL(H₂O)₂] is a dimer.     

Water-Soluble Polymeric Complexes of Cobalt(II) and Nickel(II) with Azolate Anions

N-Unsubstituted azoles (1,2,4-triazole, 3-amino-1,2,4-triazole) and 5-R-tetrazoles (R = H, CH₃, C₂H₅, C₄H₉, CH = CH₂, C₆H₅, p-CH₃C₆H₄, NH₂) form water-soluble polymeric complexes in systems containing certain transition metal salts. The data obtained and the results of MP2/6-31G^{* *} calculations of the electronic structures of 5-R-tetrazolate anions show that the ability of azoles for formation of polymeric complexes with transition metal ions is mostly determined by the acid-base properties of azoles. The geometric structure of a polymeric chain with the Co²⁺ ion having the coordination number 6 and the 5-methyltetrazolate anion being a bridging ligand was examined at the STO-3G level. It was shown that the coordination by the 2- and 3-nitrogen atoms of the tetrazole ring is most favored by energy.     

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.