One-dimensional manganese(II) complex with only end-to-end azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged manganese(II) complex of formula [Mn(L)₂(N₃)](ClO₄) 1 has been synthesized and characterized crystallographically and magnetically, where L is the bidentate Schiff base obtained from the condensation of pyridine-2-carbaldehyde with 4-methoxyl aniline. Complex 1 is of one-dimensional chain structure with single end-to-end azido bridges. Magnetic analysis reveals that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J = −6.60 cm⁻¹.     

Synthesis,crystal structure and magnetic characterization of a dinuclear Mn(II) complex with double end-on azide ligands

A new dinuclear manganese(II) complex [MnL(N₃)₂]₂ · 2CH₃OH 1 has been synthesized and characterized crystallographically and magnetically. L is a tridentate Schiff base ligand which is derived from the reaction of pyridine-2-carbaldehyde and 2-aminoethylbenzimidazole. In the complex 1, each Mn(II) ion is coordinated by one L, one terminal azide ligand and symmetrical double end-on bridging azide ligands. The intermolecular hydrogen bonds extend the structure into a two-dimensional layer. Magnetic determination of 1 indicates that ferromagnetic exchange interaction between the two manganese(II) ions exist in this complex through the double end-on azide bridges.     

A new two-dimensional manganese(II) coordination polymer with alternating double end-on and single end-to-end azido bridges: Crystal structure and magnetic properties

A new azido-bridged Mn(II) coordination polymer, [MnL(N₃)₂]n (1) (L = (E)-3-(dimethylamino)-1-(pyridin-2-yl)prop-2-en-1-one), has been synthesized and characterized by elemental analysis, IR, single crystal X-ray diffraction and magnetic measurement. X-ray analysis shows that complex 1 is a 2D network with (6, 3) layers, in which double end-on (EO) azido-bridged dimers are linked by single end-to-end (EE) azido bridges. Magnetic susceptibilities of 1 were measured under a magnetic field of 2 KOe applied over the temperature range 300–1.8 K. The analysis of magnetic data indicates that the EO- and EE-azido bridges mediate the ferromagnetic and antiferromagnetic exchange interactions, respectively, with the antiferromagnetic coupling between Mn(II) ions dominating the magnetic properties of 1.     

A new NiCuCu Ni complex containing doubly end-on azido bridged dicopper(II) and macrocyclic nickel(II) complex ancillary ligands: Synthesis, structure and magnetism

[Cu₂(NiL)₂(N₃)₄] was synthesized by combining “complex as ligand” approach and “pure bridging ligand” approach (H₂L = dimethyl 5,6,7,8,15,16-hexahydro-15-methyl-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate). The two Cu^II ions are bridged by two end-on azido ligands. ππ and oxamido–carbonyl interactions link the molecules into 1D supramolecular chains. Ferromagnetic interactions exist between the two Cu^II ions.     

Spin-canting in a 1D chain Mn(II) complex with alternating double end-on and double end-to-end azido bridging ligands

A new one-dimensional (1D) azido-bridged manganese(II) complex, [Mn(dpq)(N₃)₂]_n [dpq = dipyrido-(3,2-d:2′,3′-f)-quinoxaline] (1), was synthesized and characterized. Crystal structure study reveals that 1 contains a 1D manganese(II) chain bridged by alternating double end-to-end (EE) and double end-on (EO) azido ligands. The strong interchain π–π stacking interaction extends the structure into a 2D supramolecular array. The analysis of magnetic data indicates that the EO- and EE-azido bridges mediate the ferromagnetic and antiferromagnetic interactions, respectively. Interestingly, complex 1 exhibits a weak ferromagnetic property below 6 K probably due to spin canting.     

Dinuclear copper(II) complex with tetrathiafulvalene-based bis-acetylacetonate ligands

Deprotection of the cyanoethyl groups with 2 equivalents of the strong base (CsOH) and subsequent reaction with the electrophilic 3-chloro-2,4-pentanedione afford the bis(acetylacetone)tetrathiafulvalenes, trans- and cis-acac₂. The formation of the dinuclear rectangle-shaped complex [Cu₂(cis-acac₂)₂ 2DMF 2H₂O] (1), demonstrates the chelating ability of the interesting TTF-acetylacetonate ligand. Cyclic voltammetry experiments have evidenced the two one-electron steps to the radical cation and dication species of the new ligand, and the two quasi-reversible two-electron oxidation processes of complex 1.     

Alkoxo- and carboxylato-bridged hexanuclear copper(II) complex: Synthesis,structure and magnetic properties

Reaction of copper(II) nitrate trihydrate with N,N-dimethylethanolamine (dmea) and pivalic acid in methanol led to the hexanuclear copper(II) complex Cu₆(η¹:μ₂-C₄H₁₀NO)₄(η¹:η¹:μ₂-C₅H₉O₂)₄(η¹:μ₁-C₅H₉O₂)₂(μ₃-OH)₂ (1). The crystal structure of 1 indicates that hexametallic centers are bridged by the μ₃-alkoxo, dmea oxygens, and the μ₂-dicarboxylato oxygen atoms of pivalate ions. Furthermore, in the asymmetric unit, three types of copper ions have been found labeled as Cu₁, Cu₂ and Cu₃. The Cu₂ takes a distorted octahedral shape, whereas Cu₁ and Cu₃ adopt square pyramidal geometries. The complex 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J = − 82.6 to − 25.8 cm^− 1) and weak antiferromagnetic couplings between the dimers (J = − 10.9 and 0.8 cm^− 1).     

Homoleptic manganese(II)–azide layer: Synthesis,structural characterization and magnetic properties

A host–guest compound {(MV)[Mn(N₃)₄]}_n (1), where MV²⁺ (methylviologen dication) is generated in situ through the decarboxylation of 4,4′-dipyridinio-N,N′-diacetate, has been synthesized and characterized by X-ray crystallography and magnetic measurements. This is the first homoleptic two-dimensional Mn–azide compound, which contains single μ_1,3-azide bridged Mn(II) square layers with the organic MV²⁺ cations intercalated between the inorganic layers. Magnetic studies show antiferromagnetic interactions between adjacent metal ions (J = ?4.4 cm^?1), and the symmetric feature of the structure precludes the possibility of spin canting in this compound.     

Synthesis,crystal structure and DNA-binding studies of a Ru(II) complex containing two main ligands

A new Ru(II)-polypyridyl complex, [Ru(L)(dppz)₂](PF₆)₄ (L = 5,5′-di(1-(trimethylammonio)methyl)-2,2′-dipyridyl cation; dppz = dipyrido[3,2-a:2′,3′-c]phenazine]), has been synthesized and structurally characterized. The binding of this complex with calf thymus DNA (CT-DNA) has been investigated by spectroscopic and viscosity measurement. Results indicate that the complex binds to CT-DNA via an intercalative mode. Moreover, the complex reveals a highly efficient DNA cleavage activity upon irradiation at 365 nm, during which supercoiled pBR322 DNA was converted to nicked DNA.     

A novel water soluble octaazamacrocyclic dinuclear copper(II) complex with tetra-pendant arms: Crystal structure and SOD activity

A novel water-soluble octaazamacrocyclic dinuclear copper(II) complex with tetra-pendant arms, [Cu₂L] Cl₂? 5H₂O, was synthesized by [2+2] condensation between 2, 6-diformyl-4-chlorophenol and N, N, N', N'-tetrakis(2'-aminoethyl)-1, 2-diaminopropane in the presence of Cu(OAc)₂·H₂O. Single-crystal X-ray structural analysis reveals that every copper(II) adopts a trigonal bipyramid coordination configuration. Macrocyclic units are joined together by strong π–π stacking interaction with centroid–centroid distance of 3.658 Å. Water pentamers with O–O distances of 2.099–2.841 Å are observed in the complex. The activity of superoxide dismutase of the complex has been investigated by the nitro blue tetrazolium method.     

Copper(II) complex derived from axial chiral heterocyclic spiro ligand: Crystal structure,characterization and SOD activity

A new Cu(II) coordination polymer (1) constructed from an axially chiral heterocyclic spiro ligand, 2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-dicarboxylic acid (H₂L) and 1,3-bis(4-pyridyl)propane (bpp), has been prepared and characterized by single-crystal X-ray diffraction analysis, infrared spectra (IR), elemental analysis, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Structural analysis shows that 1 features a 2D undulated layer of rhombic meshes with (4, 4) topology. Interestingly, a 1D wave-like water tape formed by the cyclic centrosymmetric chairlike octamer water clusters (H₂O)₈ are observed between the 2D sheets. Furthermore, the experimental data and computational studies of superoxide dismutase (SOD) activity of H₂L and 1 were investigated.     

Synthesis, structure and magnetic properties of a novel lead(II) complex containing nitronyl nitroxide radicals

The lead(II) complex with nitronyl nitroxide, [Pb(NIT2Py)₂(NO₃)₂] [NIT2Py = 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the lead(II) ion is coordinated with two bidentate nitronyl nitroxide and two nitrate anions. The lead(II) ion shows seven-coordinate geometry. Magnetic susceptibility data for the title complex has been measured in the range 5–300 K. There are antiferromagnetic interaction between the coordinated nitronyl nitroxides (J = −19.35 cm⁻¹) and intermolecular ferromagnetic interactions. Thus, we observe the sixth periodic IVA group metal element Pb(II) ion providing an effective pathway for the magnetic exchange interaction between nitronyl nitroxide radicals.     

Palladium (II) and platinum (II) complexes containing organometallic thiosemicarbazone ligands: Synthesis,characterization, X-ray structures and antitubercular evaluation

A new series of palladium (II) and platinum (II) complexes containing ferrocenyl and cyrhetrenyl thiosemicarbazone ligands were synthesized and characterized. The two-step reaction of the organometallic thiosemicarbazones with i) K₂MCl₄ and ii) PPh₃ and their subsequent recrystallization from CH₂Cl₂/hexane yielded the binuclear complexes [Mˋ{ML_n(η⁵-C₅H₄)C(H)NNC(S)NHR}–(Cl)(PPh₃)] (M′Pd, Pt; ML_nRe(CO)₃, FeCp; RH, CH₃). The structures of the products were inferred from elemental analyses and IR, ¹H and ³¹P NMR spectroscopies. The molecular structures of 2b and 3d were confirmed by single crystal X-ray analysis. All complexes were screened in vitro against Mycobacterium tuberculosis and exhibited only moderate activity in the low micromolar range.     

Polycarbonateurethane films containing complex of copper(II) catalyzed generation of nitric oxide

Nitric oxide (NO) is a well known potent antiplatelet agent, and its continuous release will effectively prevent the adhesion of platelets on artificial blood vessel walls. In this paper, polycarbonateurethane (PCU) with lipophilic Cu(II)‐complex (Cu(II)‐DTTCT) blending films were prepared and used as catalyst to generate NO from nitrite. The mechanical properties of PCU films blended with Cu(II)‐DTTCT were characterized by tensile strength measurement. The tensile stress and Young's modulus of PCU films blending with Cu(II)‐DTTCT increased, however, the elongation at break decreased compared with corresponding PCU films. The NO generation was investigated in vitro in the presence of NaNO₂ and ascorbic acid in PBS (pH = 7.4) at 37°C. The flux of NO generation was quantitatively measured by Griess assay. NO flux and velocity increased with the increase of NaNO₂ concentration, the concentration of ascorbic acid in PBS and the amount of Cu(II) in the films. The loss of Cu(II) from blending film surfaces was found during the in vitro NO generation experiments, which resulted in the decrease of NO flux in the second run. The PCU film could catalyze continually generation of NO for two days, which will provide a promising approach that enable endogenous NO generation on the surface of the medical devices. The generation of biologically active level of NO at the blood/polymer interface can reduce the risk of thrombosis on the implants. Polycarbonateurethane films with NO generation function may be used as high thromboresistant blood contacting materials or coating. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A dinuclear nickel(II) complex bridged by tricyanomethanide: structure and magnetic properties

Complexation of Ni^II ion with triethylenetetramine (teta) and potassium tricyanomethanide KC(CN)₃ yielded a new binuclear complex, [(teta)Ni(C(CN)₃)₂Ni(teta)](ClO₄)₂ (1), where two nickel(II) centres are held together by two tricyanomethanide bridges. The dinuclear units are aggregated into ladders; four of them being identified inside the unit cell. The effective magnetic moment on the cooling exhibits a slight gradual increase until 25 K; below this limit a strong, abrupt ferromagnetic interaction culminating at 16 K appears.     

Synthesis,structure and catalytic activities for hydrogen transfer reaction of the carbonyl ruthenium(II) complex containing polypyridine and phosphine ligands

The synthesis and characterization of new ruthenium(II) carbonyl complexes containing polypyridine and triphenylphosphine ligands is reported. Crystallographic information obtained for the trans-PPh₃-[Ru(biq)(PPh₃)₂(CO)]Cl₂ complex (biq = 2,2’-biquinoline) reveals five-coordination on the metal. The complexes were studied as catalysts in hydrogen transfer reactions in basic solution. Turnover frequencies in the 2250-817 h^-1 range were determined in 1 hour of reaction with a substrate/catalysts ratio of 830.     

Synthesis and X-ray structural characterization of square-pyramidal copper(II) complex with aminoguanidine derivative

Aminoguanidine and its derivatives have shown antiglycation activity and are effective antioxidants. Complexes with ligands derived from aminoguanidine are relevant to both medicinal and bioinorganic chemistry. In this article, we describe the synthesis and characterization of a new mononuclear complex of copper(II) with a chelating ligand derived from aminoguanidine. Single crystals of the resulting complex were obtained by recrystallization from isopropanol. The molecular structure of the complex was obtained by X-ray diffraction which shows a distorted square pyramidal geometry, where copper(II) is coordinated to four nitrogen atoms (base of the pyramid) and to one chlorine atom (pyramid peak). The spectroscopic behavior (FT-IR and UV–vis) of both the complex and the ligand were examined.     

One-dimensional inorganic framework consisting of the sandwich-type germanomolybdate and the copper complex linker: Synthesis,crystal structure,and magnetic property

A new heteropolymolybdate, (Him)₈Na₇H₇[Cu(im)₄(CuGeMo₉O₃₃)₂][(CuGeMo₉O₃₃)₂]·41H₂O (1) (im = imidazole), was synthesized and structurally characterized by elemental analysis, IR spectra, UV electronic spectroscopy and X-ray diffraction. Compound 1 exhibits a one-dimensional chain-like framework [Cu(im)₄(CuGeMo₉O₃₃)₂]^10? with isolated [(CuGeMo₉O₃₃)₂]^12? units residing among the chains, which is first observed in sandwich-type germanomolybdate system. Electrocatalytic experiments show that compound 1 exhibits good electrocatalytic activity for nitrite reduction. The magnetic investigation indicates the existence of antiferromagnetic interactions for 1.     

Crystal and molecular structure of copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine)

Copper(II)(pyridine-2,6-dicarboxylato)(2,6-dimethanolpyridine) has been prepared and studied by the single crystal X-ray diffraction methods at 293(2) K. The compound crystallises in an orthorhombic system, space group Pbcn with a=8.196(2), b=13.124(3), c=25.612(5) Å, and Z=8 (R=0.0374 for 3175 independent reflections with I>2σ(I)). Crystal structure analysis revealed that the copper(II) atom is surrounded by two non-equivalent terdentate ligands making up an ‘all-trans’ elongated octahedral arrangement. In consequence of Jahn–Teller distortion, considerable differences are found between the ligands for the pyridine-2,6-dicarboxylate anion with the values Cu–N 1.892(3), Cu–O 2.033(2) and 2.063(2) Å, while for the 2,6-dimethanolpyridine ligand the values are 1.943(3), 2.341(3) and 2.433(2) Å. There is a relationship between the Cu–L bond distances and the five-membered metallocyclic rings (O–Cu–N). The data are compared and discussed with those found in familiar CuL₂ compounds with the CuO₄N₂ chromophore. Based on the molecular structure, the electronic, IR and EPR spectra are discussed.     

Crystal structures of palladium(II) and copper(II) complexes of meso-phenyl tripyrrinone

Meso-phenyl tripyrrinone (2), which is derived directly from N-confused porphyrin by Cu(II)-assisted oxygenolysis, can serve as a metal coordination ligand using three nitrogens and one oxygen in the core. The crystal structures of Pd(II) and Cu(II) complexes show the similar square-planar N₃O-coordination but the mode of oligomeric chains formed in the crystals by π–π stacking interaction is different: zig–zag for Cu(II) and straight for Pd(II) complex.