X-ray crystal structure and properties of the [Mo(CN)2O(acetam)] · 2.5H2O complex

The X-ray crystal structure and properties of the [Mo(CN)₂O(acetam)] · 2.5H₂O {acetam = N-[1-(pyridin-2-yl)-ethylidene]diethanetriamine} complex are described. The complex was prepared by the in situ reaction of [Mo(CN)₄O(H₂O)]^2–, 2-acetylpyridine and diethylenetriamine in aqueous solution. The complex is seven coordinated. The Mo atom having a distorted pentagonal bipyramid arrangement with a tetradentate 'half-unit' Schiff base and oxygen ligand in a plane. The properties of the salt, i.r., u.v.–vis. spectra and cyclic voltammetry measurements are described and compared with those of [Mo(CN)₂O(diaceen)] · H₂O {diaceen = N,N-bis[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine) having the same coordination number for the metal.     

Syntheses,characterization and catalytic activity of peroxo tantalum polyoxotungstates

Peroxo-tantalum and tantalum mono-substituted tungstosilicates with the Keggin structure, K₅[-SiW₁₁Ta(O₂) O₃₉]18H₂O (1) and K₅[-SiW₁₁TaO₄₀]14H₂O (2) respectively, and peroxo-tantalum and tantalum mono-substituted tungstophosphates with the Wells–Dawson structure K₇[₂-P₂W₁₇Ta(O₂)O₆₁]16H₂O (3) and K₇[₂-P₂W₁₇TaO₆₂]14H₂O (4), respectively, were prepared by stereoselective synthesis and characterized by elemental analysis, i.r. and u.v. spectroscopy, XPS, ³¹P and ¹⁸³W n.m.r. spectroscopy, and polarography, as well as cyclic voltammetry. The presence of a peroxo group in the complexes (1) and (3) was supported by observation of an i.r. band due to the —O—O— bond at 881 cm^–1, the charge transfer bands of (²—O₂)Ta at ca. 316 and 389 nm, the O_1s binding energy at 532.0 eV and a new irreversible reduction polarographic wave at E_1/2 0.1 V, assigned to the reduction of peroxo group and which enhances the oxidant properties of the heteropoly anions. There are six lines for complex (1) and nine lines for complex (3) in the ¹⁸³W n.m.r. spectra, showing that the complex (1) has a mono-substituted Keggin structure and complex (3) has a mono-substituted ₂-Wells–Dawson structure. The catalytic activities of the complexes with respect to epoxidation of maleic acid with H₂O₂ as oxidant were examined and the best result, 83.5% yield, was obtained for [(C₄H₉)₄N]₅[-SiW₁₁Ta(O)₂O₃₉]·18H₂O.     

Crystal structure of [Cu4(pytp)2(SO4)2(H2O)10](SO4)2 · 4H2O. A tetranuclear copper(II) complex with a new asymmetric ligand,pytp*, as a bridge

A new asymmetric bridge ligand, pytp, was prepared and characterized systematically by f.t.i.r., u.v.–vis., ¹H-n.m.r. and by FAB-MS spectroscopy. A tetranuclear Cu^II complex [Cu₄(pytp)₂(SO₄)₂(H₂O)₁₀](SO₄)₂·4H₂O (1) was prepared and characterized by elemental analysis and u.v.–vis. spectroscopy. A crystal structure analysis indicates that there are two different coordination spheres in (1) and that two of the copper centers are bridged by two ₂-SO₄ entities, creating a most unusual sulphate bridge.     

Synthesis,Crystal Structure and Spectroscopic Studies of a Supramolecular Compound [Cu(IDA)(phen)(H2O)]·4H2O Built from π–π Interactions and Hydrogen Bonds

The stoichiometric reaction of (MeCOO)₂Cu, iminodiacetic acid (H₂IDA) and 1,10-phenanthroline (phen) in H₂O yields the novel complex [Cu(IDA)(phen)(H₂O)]·4H₂O (1). An X-ray structural determination shows that the dimer was formed by diverse hydrogen bonding and – interactions, and that each metal Cu^II center is six-coordinate, exhibiting an octahedral coordination. The complex was also characterized by t.g.a., FT–IR and u.v.–vis. spectroscopy and the electrochemical behavior of (1) was also studied. Its electronic spectra have been calculated by the CIS method.     

Two new ternary vanadyl(IV) complexes containing ATP

Summary Two new ternary VO²⁺ complexes, [VO H₂ATP-dipy]·6H₂O (dipy: , dipyridyl)and [VO H₂ATP-ophen] ·6H₂O (ophen:o-phenanthroline), were prepared and characterized by chemical analyses, x-ray diffractometry, u.v./vis. and i.r. spectroscopy. Both complexes are probably polymeric, with the terminal PO₃-moieties of H₂ATP acting as bridging ligands.     

Coordination compounds of nickel with trithiocyanuric acid. Part IV. Structure of [Ni(pmdien)(ttcH)] (pmdien = N,N,N′,N′,N′′-pentamethyldiethylenetriamine,ttcH3 = trithiocyanuric acid)

Ni^II mixed-ligand complexes of compositions [Ni(pmdien)(ttcH)] (1), [Ni(baphen)₂(ttcH)] · 4H₂O (2), [Ni-(dpa)(ttcH)(H₂O)] (3), [Ni(cyclam)(ttcH)] · 2H₂O (4), [Ni(hexaa)](ttcH) (5) and [Ni(hexab)(ttcH)] · 2H₂O (6), (baphen = 4,7-diphenyl-1,10-phenanthroline, dpa = 2,2-dipyridylamine, cyclam = 1,4,8,11-tetraazacyclotetradecane, hexaa = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]-octadecane, hexab = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) have been prepared and characterized by means of i.r., u.v.–vis. spectroscopies and magnetochemical measurements. The redox properties of the complexes were studied by cyclic voltammetry. The crystal and molecular structure of [Ni(pmdien)(ttcH)] was determined. The nickel atom is penta-coordinated by three N atoms of pmdien, and by S and N atoms of trithiocyanurate(2–) anion.     

Two-Dimensional Supramolecular from the Self-Assembly of Dissymmetrical Oxamidato-Bridged Heterometallic Trinuclear Building Blocks: Synthesis, Crystal Structure, and Magnetic Properties

Two heterometallic trinuclear complexes {[Cu(oxbp)]₂Co(H₂O)₂}1.5DMF0.5H₂O (complex 1) and {[Cu(oxbm)]₂Co(H₂O)₂}2DMF (complex 2) were obtained from the self-organization of two new dissymmetrical oxamidato-bridged copper(II) building blocks [Cu(oxbp)]^– and [Cu(oxbm)]^–[H₃oxbp=N-benzoato-N'-(3-aminopropyl)oxamido, H₃oxbm=N-benzoato-N'-(2-amino-2-methylethyl)oxamido, DMF=dimethylformamide]. The crystal structure of complex 1 has been determined. Complex 1 crystallize in triclinic system, space group P-1, a=8.0609(16) Å, b=10.661(2) Å, c=22.279(5) Å, =85.32(3), =86.64(3), =70.90(3), and Z=1. The crystal structure of complex 1 consists of neutral trinuclear complex units, and hydrogen bond involved DMF and water molecules. Through the hydrogen bonds, weak coordination and CuCu weak interactions, complex 1 features a 2-D supramolecular structure. Magnetic susceptibility measurements (5–100 K) indicate that the central Co(II) and terminal copper metal ions are antiferromagnetically coupled with J=–28.09 and J=–29.70 cm^–1 for complex 1 and 2, respectively.     

Spectroscopic and voltammetric studies of the cobalt (II) complex of Morin bound to calf thymus DNA

Absorption and emission spectra, viscometric and electrochemical studies have been carried out on the interaction of Morin (2, 3, 4, 5, 7-pentahydroxyflavone) and its Co complex, CoL₂·3H₂O[L = Morin (2-OH group deprotonated)], with calf thymus DNA. In the presence of DNA, the complex exhibits a hypochromism in the u.v.–vis. spectra and a large enhancement in emission spectra suggests that the complex binds to DNA via a weak partial intercalation, revealed by competitive experiments, viscosity and by electrochemical studies. The binding constant is ca. 2 × 10³ M^–1 at 20 °C. Both ZnL₂·3H₂O and CoL₂·3H₂O complexes have the same molecular structure, ZnL₂·3H₂O shows the spectral characteristics and electrochemical behaviour which agrees with observations for other intercalators in the presence and absence of DNA, whereas the CoL₂·3H₂O complex shows different spectral characteristics and electrochemical behaviour to that of ZnL₂·3H₂O, which suggests that the mode and affinity of the complex CoL₂·3H₂O binding to DNA are different from that of ZnL₂·3H₂O. Both ZnL₂·3H₂O and CoL₂·3H₂O complexes exhibited different antitumour activity. So the binding mode and affinity of complexes to DNA may play an important role in determining the antitumour activity.     

The study of new zinc(II) aliphatic carboxylate complex compounds by methods of thermal analysis

Four new complex compounds were prepared by the reaction of zinc bromobutyrate and organic ligands. The general formula of the synthetized complex compounds are (2-Brbut)₂ZnL and (4-Brbut)₂ZnL₂nH₂O (but=butyrate, L=theobromine (tbr), theophylline (tph), methyl-3-pyridyl carbamate (mpc), n=0-1). The compounds were characterized by chemical analysis and IR spectroscopy. The thermal behaviour of the zinc(II) complexes was studied by thermal analysis. Thermal decomposition in the case of hydrated compounds starts with the release of water molecules. Then molecules of organic ligands and the bromobutyrate anion are released and decomposed. CH₃CH₂CH=O, CO, CH₂=CHCH=O, CH₂O and ZnBr₂ were found as gaseous products of thermal decomposition during heating up to 700°C. IR, mass spectroscopy, X-ray powder diffraction and chemical analysis were used for the determination of solid and gaseous intermediates and products of the thermal decomposition.This revised version was published online in November 2005 with corrections to the Cover Date.     

Cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin

A new series of hexacoordinate cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin HL having formulae [LM(OAc)(H₂O)₂] · nH₂O (M = Co^II, Cu^II and Ni^II), [LMCl(H₂O)₂] · nH₂O (M = Co^II and Ni^II), [LCuCl(H₂O)]₂ · 2H₂O, [LCu(H₂O)₃](ClO₄) and [LCu(HSO₄)(H₂O)₂] were isolated and characterized by elemental analyses, molar conductivities and magnetic susceptibilities, and by i.r., electronic and e.s.r. spectral measurements, as well as by thermal (t.g. and d.t.g.) analyses. The i.r. spectra indicate that the ligand HL behaves as a monobasic tridentate towards the three divalent metal ions via an azo-N, carboxylate-O and thiohydantoin-O atom. The magnetic moments and electronic spectral data suggest an octahedral geometry for Co^II complexes, distorted octahedral geometry for both Ni^II and Cu^II complexes with a dimeric structure for [LCuCl(H₂O)]₂ · 2H₂O through bridged chloro ligands. The X-band e.s.r. spectra reveal an axial symmetry for the copper(II) complexes with unsymmetrical M_s = ± 1 signal and G-parameter less than four for the dimeric [LCuCl(H₂O)]₂ · 2H₂O. The thermogravimetry (t.g. and d.t.g.) of some complexes were studied; the order and kinetic parameters of their thermal degradation were determined by applying Coats–Redfern method and discussed.     

Synthesis,crystal structure and properties of a manganese(III) Schiff-base complex: [{Mn(vanen)(Him)(H2O)}{Mn(vanen)(Him)2}](ClO4)2 · 4H2O(H2vanen = N,N′-bis(methoxysalicylidene)-1,2-diaminoethane)

A novel manganese(III) complex, [{Mn(vanen)(Him)(H₂O)}(Mn(vanen)(Him)}](ClO₄)₂ · 4H2O [H₂vanen = N,N-bis(methoxysalicylidene)-1,2-diaminoethane], has been synthesized and characterized by elemental analysis, i.r. spectroscopy, t.g.a. and by an X-ray single crystal study. The complex consists of two sets of cations: [Mn(vanen)(Him)(H₂O)]⁺ (A) and [Mn(vanen)(Him)₂]⁺ (B), each of which has six-coordinate geometry, significantly elongated due to the Jahn-Teller distortion at the d⁴ manganese(III) center. The presence of lattice and coordinate water molecules are also confirmed by the t.g. study and the i.r. spectra.     

Manganese(II) complexes with edta-type ligands. The molecular structure of aquo-dihydrogen(1,2-propanediamine-N,N,N′,N′-tetraacetate)manganese(II) trihydrate, [Mn(H21,2-pdta)(H2O)] · 3H2O

New manganese(II) complexes with ethylenediamine-N,N,N,N-tetra-3-propionate (edtp) and 1,2-propanediamine-N,N,N,N-tetraacetate (1,2-pdta) were prepared and characterized by elemental analysis, i.r. spectroscopy and magnetic measurements. The structure of [Mn(H₂1,2-pdta)(H₂O] · 3H₂O was determined by the single crystal X-ray diffraction technique. The complex crystallizes in the space group P2₁/n(#14) of the monoclinic crystal system with unit cell parameters a = 10.993(2) Å, b = 14.092(2) Å, c = 11.753(1) Å, = 96.302(9)⁰, V = 1809.7(3) ų, Z = 4 and R = 0.051. The complex contains seven-coordinated Mn^II ion with H₂1,2-pdta ion acting as hexadentate ligand and one water molecule.     

DNA-binding and cleavage studies of a dinuclear copper(II) complex with a 26-membered hexaazamacrocycle

The complex, [Cu₂LCl₂]Cl₂ · 3H₂O, where L = the macrocyclic ligand bis-p-xylylBISDIEN Schiff base, has been prepared and characterized by elemental analysis, i.r. and mass spectra. The binding of the complex with calf thymus DNA has been investigated using absorption spectroscopy, cyclic voltammetry, fluorescence spectroscopy and viscosity measurements. The results suggest that the complex can bind to CT DNA by intercalation via the aromatic ring on the macrocycle into the base pairs of DNA. The complex exhibits efficient nuclease activity.     

Disordered Crystal Structure of the 1:3 Solvated Molecular Ionic Complex of 1,10-Diaza-18-crown-6 with (+)-Tartaric Acid

The disordered crystal structure of the 1:3 solvated molecular ionic complex of 1,10-diaza-18-crown-6 with (+)-tartaric acid [C₁₂H₂₈N₂O₄]²⁺·2C₄H₅O ₆ ^- ·C₄H₆O₆·1.5CH₃OH·1.7H₂O (I) was investigated by XRD analysis. Crystals I are monoclinic: space group P2 ₁, a = 9.662(2), b = 13.618(5), c = 14.316(3) , = 93.97(2)°, Z = 2. Structure I was solved by direct methods and refined by the full-matrix least-squares procedure anisotropically to R = 0.081 for all 3539 unique measured reflections (CAD-4 automatic diffractometer, CuK ). In structure I, the solvated methanol and water molecules are disordered on many sites. The DA18C6 dication is also disordered and has two different asymmetric conformations. The two tartrate anions lie on different sides of the cavity of the DA18C6 dication, whose two NH ₂ ⁺ groups each forms two H-bonds of N–H...O type with each of the tartrate anions. The (+)-tartaric acid molecule and the solvated molecules are not involved in the H-bonds with the DA18C6 dication. The molecular ionic complex I exists in crystal as a complex infinite three-dimensional supramolecular structure.     

Dinuclear complexes of cobalt(II) with N,N′-substituted dithioxamides derived from α-aminoacids

Summary The coordination behaviour of N,N-bis(1-carboxymethyl)dithioxamide (GLYDTO), N,N-bis(1-carboxyethyl)dithioxamide (ALADTO), N,N-bis(1-carboxy-2-methylpropyl) dithioxamide (VALDTO) and N,N-bis(1-carboxy-3-methylbutyl)dithioxamide (LEUDTO) has been investigated by isolating and characterizing the dinuclear, neutral cobalt(II) complexes, [Co₂(L-4H)(H₂O)₂] (L = GLYDTO, ALADTO, VALDTO or LEUDTO) and [Co₂(L-4H)(H₂O)₆] (L = ALADTO or VALDTO). All ligands were characterized by mass, i.r., and ¹H- and ¹³C-n.m.r. spectroscopy. The complexes possess distorted octahedral structures as revealed by the magnetic and electronic (diffuse reflectance) spectral data. The i.r. data indicate that the ligands are bis-tridentate, bis-dianions coordinated to each metal ion through the carboxylate oxygen, deprotonated thioamide nitrogen and thiocarbonyl sulphur atoms.     

N-Ferrocenylcarbonyl-N′-benzoylhydrazine and its transition metal(II) complexes

Summary A new ferrocene derivative, N-ferrocenylcarbonyl-N-benzoylhydrazine (H₂FB) and its transition metal complexes, [M(FB)]₂·H₂O (M = Mn^II, Co^II, Cu^II, Zn^II, Cd^II or Hg^II) and M(HFB)₂·nH₂O (M = Mn^II or Cd^II) were prepared by reacting H₂FB with the metal(II) acetates and characterized by elemental analyses, i.r. and u.v. spectroscopy and t.g.a. H₂FB appears to act as a tetradentate ligand, coordinating to the metal through the nitrogen enolic oxygen atoms.     

Crystal structure and properties of H3[PMo12O40] · 3C2H6O

The title compound H₃[PMo₁₂O₄₀]· 3C₂H₆O was prepared and characterized by X-ray crystallography, its i.r. spectrum, cyclic voltammetry and e.s.r. spectra. The anion of the title compound is a Keggin-type heteropoly structure based upon a central PO₄ tetrahedron surrounded by 12 MoO₆ octahedra arranged in four groups of three edge-shared octahedra Mo₃O₁₃. Weak hydrogen bonds exist between the organic solvent molecules and the heteropoly anion. The catalytic activity of the title compound was determined by the synthesis of butyl acetate. The conversion of n-BuOH reached 93.3% and the yield of MeCO₂Bu-n was 92.0% when the ratio of MeCO₂H to n-BuOH, catalyst amount, reaction time, reaction temperature were 2:1, 0.24% of the reactants (50 mg), 2.0 h and 115 120 °C, respectively.     

Structural versatility and electrochemical properties of four copper(II) complexes based on 1<Emphasis Type="Italic">H</Emphasis>-indazole-3-carboxylic acid

Copper (Cu)(II) complexes were synthesized by Ind-3-COOH combined with N-containing auxiliary ligands via a combinatorial strategy involving hydrothermal and solvent-evaporation method. The synthesized complexes had the following formulas: [Cu(Ind-3-COO)₂] (1), [Cu(PHEN)(Ind-3-COO)]₂·2H₂O (2), [Cu₂(DPP)(Ind-3-COO)₂(H₂O)]·H₂O, (3) and [Cu(BPY)(Ind-3-COO)₂]·4H₂O (4). Meanwhile, the symbol abbreviations were listed as follows: Ind-3-COOH = 1H-indazole-3-carboxylic acid, 1,3-bis(4-pyridyl)propane (DPP), 1,10-phenanthroline (PHEN) and 4,4′-bipyridine (BPY). The crystalline structure and spectroscopy of each complex were characterized by single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy and powder X-ray diffraction. The redox reactions in the complexes were then investigated by performing cyclic voltammetry under nitrogen conditions at room temperature. Two pairs of distinctive irreversible reduction potentials were identified, which could be attributed to the processes of Cu(II)–Cu(I) and Cu(I)–Cu(0).     

E.s.r. studies on acylhydrazine and hydrazone copper(II) sulfate complexes

Summary Cu^II complexes of the [CuL₂(SO₄)]·nH₂O and [CuL(SO₄)(H₂O)₂]·nH₂O type, where L = benzoylhydrazine (PhCONHNH₂; BH) or iso-propanone benzoylhydrazone (PhCONHN:CMe₂; IBH), L= iso-nicotinoylhydrazine (NC₅H₄CONHNH₂; INH) or isopropanone iso-nicotinoylhydrazone (NC₅H₄CONHN: CMe₂; IINH); n = 0–2, were prepared and characterized by elemental analyses, molar conductances, and electronic, e.s.r. and i.r. spectral measurements. The electronic and e.s.r. spectra suggest a tetragonally distorted octahedral geometry in the solid state as well as in DMSO solution. The e.s.r. data also reveal an axial symmetry for most of the complexes in the solid state and in DMSO solution at 300 and 77 K, while the complex of IBH is isotropic at 300 K. The M_s = 2 transition observed for this complex suggests that it is a dimer. BH and INH bond to Cu^II through the C-O and NH₂ groups, whereas IBH and IINH bond through C-O and C-N groups.