Synthesis,crystal structure,spectroscopy and magnetism of a trinuclear nickel(II) complex with 3,5-pyrazoledicarboxylic acid as bridge ligands

A new complex of [Ni₃(dcp)₂(H₂O)₁₀] (1) (H₃dcp = 3,5-pyrazoledicarboxylic acid) has been synthesized from H₃dcp and Ni(NO₃)₂·6H₂O by hydrothermal reaction. Complex 1 has the discrete trinuclear structure. Three Ni(II) ions are bridged by two dcp³⁻ ligands, with 10 coordinated water molecules as terminal ligands. The molecules of [Ni₃(dcp)₂(H₂O)₁₀] extend into three-dimensional supramolecular architectures by intermolecular O–H···O hydrogen bonds as well as π-π stacking interactions. Magnetic susceptibility measurement shows that a weak antiferromagnetic interaction is operative between nickel(II) ions and an excellent simulation of the experimental data gives D = 5.27 cm⁻¹, J = −2.19 cm⁻¹ and g = 2.05.     

Synthesis and crystal structure of an unexpected anionic trinuclear cobalt(III) complex with ferrocenyl-containing tridentate ONO donor Schiff base ligands

The tridentate ONO-donor Schiff base ligand derived from the condensation of 1-ferrocenyl-1,3-butanedione and 2-aminophenol, generated in situ and treated further with potassium tert-butoxide, reacted in THF with Co(NO₃)₂·6H₂O in the presence of pyridine to afford the ionic complex [{(η⁵-C₅H₅)Fe(η⁵-C₅H₄)-C(O)CH=C(CH₃)N-C₆H₄-2-O}₂Co(III)]^-[K(HOCH₂CH₃)₂]⁺ (1, 50% yield). Compound 1 was characterized by elemental analysis, FT-IR, and multidimensional ¹H and ¹³C NMR spectroscopy. Single-crystal X-ray diffraction reveals that the two metalloligands are meridionally coordinated to a Co(III) ion that adopts a slightly distorted octahedral geometry. The doubly solvated potassium counter-ion is asymmetrically positioned with respect to the two metalloligands. Such an arrangement allows the observation by ¹H NMR of restricted rotation of the ferrocenyl units and the splitting of both carbonyl and imine carbons, thus suggesting that the structure observed in the solid state is retained in solution. Complex 1 exhibits in its cyclic voltammetry curve two anodic reversible waves attributed to the oxidation of Co(III)-phenolates into Co(III)-phenoxyl radical and that of the ferrocenyl fragment into its ferrocenium counterpart.     

Synthesis,crystal structure and characterization of manganese(III) complex containing a tetradentate Schiff base

N,N′-bis((2-hydroxyphenyl)(phenyl)methylidene)propane-1,2-diaminato-N,N′,O,O′)-(nitrato-O)-manganese(III) methanol solvate ([Mn(C₂₉H₂₄N₂O₂)(NO₃)CH₃OH]) was synthesized and characterized by FTIR, UV–Vis, TG–FTIR, TG/DSC, molar conductivity, magnetic moment measurement and single crystal X-ray analysis. In the structure, the Mn(III) ion adopts a distorted octahedral geometry with two nitrogen and two oxygen atoms from the Schiff base ligand in the equatorial plane, and the nitrate ion and methanol molecule in the axial position. The effects of organic solvents of various polarities on the UV–Vis spectra of the ligand and complex were investigated. The manganese(III) complex is easily dissolved in organic polar aprotic solvents and has moderate solubility in organic polar protic solvents.     

Synthesis,characterization, electrochemical and crystal structure investigation of bis(2-((2-aminoethylimino)methyl)-6-methoxyphenolato) cobalt(III)

The mononuclear cobalt(III) complex [Co(L)₂]Cl ·?H₂O (1) (where L is H₂N(CH₂)₂N=CC₆H₃(OMe)(O^?)) has been prepared and characterized by IR, UV-Vis spectroscopy, conductivity measurements, elemental analysis, TGA, cyclic voltammetry and an X-ray structure determination. The cobalt(III) coordination sphere in [Co(L)2] is cis-CoN₄O₂ with the NNO ligands. Electrochemical studies of 1 using cyclic voltammetry indicate an irreversible cathodic peak (E _pc, ca ?0.60 V) corresponding to reduction of cobalt(III) to cobalt(II).     

Synthesis,crystal structure,and magnetic properties of a linear trinuclear Cu(II) complex

A new linear trinuclear Cu(II) complex, [Cu₃(NTA)₂(4,4′-bpt)₄(H₂O)₂]?·?10H₂O (H₃NTA?=?nitrilotriacetic acid, 4,4′-bpt?=?4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole) (1), was obtained from evaporation of an aqueous solution containing Cu(NO₃)₂?·?6H₂O, 4,4′-bpt, nitrilotriacetic acid (H₃NTA), and NaOH. 1 was characterized using single-crystal X-ray diffraction, IR, and elemental analysis. In the trimer, the three linear copper ions are bridged by two NTA carboxylate groups in a syn–anti conformation and connected by 4,4′-bpt to produce a 1-D array. Temperature-dependent magnetic susceptibilities reveal the presence of weak antiferromagnetic exchange between metal centers.     

Synthesis,crystal structure and magnetic properties of a dinuclear manganese(III) tetradentate Schiff-base complex

A dinuclear manganese(III) tetradentate Schiff-base complex, [Mn₂(salophen)₂(4,4′-bipy)₃](BPh₄)₂ (1) (salophen = N,N′-o-phenylene-bis(salicylideneaminato)), has been synthesized and structurally characterized. Compound 1 crystallized in the triclinic, P 1 space group, a = 13.431(4), b = 13.791(4), c = 13.886(4) Å, α = 73.599(5)°, β = 80.410(6)°, γ = 71.241(5)°, V = 2328.3(12) ų. Complex 1 contains two Mn(salophen) moieties bridged by 4,4′-bipy to form a dinuclear unit, with two terminal 4,4′-bipy ligands. Variable temperature magnetic susceptibility (2–300 K) shows very weak ferromagnetic interactions between the Mn(III) ions.     

Synthesis, crystal structure and DFT analysis of a new trinuclear complex of copper

The new trinuclear complex [Cu₂(μ-L)₂CuCl₂] has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray spectroscopy, where L is a dianionic tetradentate Schiff base ligand with N₂O₂ donor atoms. The molecular structure of [Cu₂(μ-L)₂CuCl₂] was determined by X-ray crystallography. In the complex, the most remarkable aspect of the trinuclear complex is that it adopts a bent structure for the three copper atoms, with a Cu1Cu3Cu2 intramolecular angle of approximately 90.62(2)°. All three copper atoms are five coordinate, with a slightly distorted square pyramidal geometry. In the two terminals moieties, the basal plane of the square pyramidal is formed by two oxygen atoms and two nitrogen atoms of the Schiff base ligand, and the apical position at the Cu atom is occupied by the bridging Cl1 anion. The Cu1Cl1Cu2 angle is 110.51(5)°. The central copper atom also has a five-coordinate, slightly distorted square pyramidal geometry, with four phenolato oxygens belonging to the Schiff base ligands from Cu(salpn) units describing the square planar base and the Cl anions being apical. The optimized structure of the complex has been studied using the B3LYP/6-31G(d)/LanL2TZf level of theory. The calculation shows that all the copper atoms are five coordinate with distorted square pyramidal structures, which is consistent with experimental data.     

A zinc(II) complex with tris(2-( N -methyl)benzimidazlylmethyl)amine and salicylate: synthesis,crystal structure,and DNA-binding

A five-coordinate zinc complex with tris(2-(N-methyl)benzimidazylmethyl)amine (Mentb) and salicylate, with composition [Zn(Mentb)(salicylate)](NO₃), was synthesized and characterized by elemental analysis, IR and UV-Vis spectral measurements. The crystal structure of the zinc complex shows that Zn(II) is bonded to tris(2-(N-methyl)benzimidazylmethyl)amine (Mentb) and a salicylate through four nitrogens and one oxygen, and the coordination geometry is best described as distorted trigonal-bipyramid. The DNA-binding of the Zn(II) complex and Mentb were investigated by spectrophotometric methods and viscosity measurements, and the results suggest that the Zn(II) complex binds to DNA via intercalation; the binding affinity of the Zn(II) complex to DNA is greater than Mentb. Additionally, Zn(II) complex exhibited potential to scavenge hydroxyl radical in vitro.     

A one-dimensional azido-bridged manganese(III) complex with bidentate Schiff base: Crystal structure and magnetic properties

The synthesis, structural characterization, and magnetic behavior of a novel one-dimensional azido-bridged manganese(III) complex of formula [Mn(L)₂N₃] (1) is reported, where HL is the bidentate Schiff base obtained from the condensation of salicylaldehyde with 4-methoxy aniline. Complex 1 crystallizes in the monoclinic system, space group P2₁/n, with a=11.743(4) Å, b=24.986(9) Å, c=13.081(5) Å, β=95.387(7)° and Z=2. The complex is of one-dimensional chain structure with single end-to-end azido bridges and the manganese(III) ion has an elongated octahedral geometry. Magnetic studies show that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J=−5.84 cm⁻¹.     

Synthesis,structures and properties of cobalt(III) and iron(III) complexes with a new triazamacrocycle, 1,4-diacetate-1,4,7-triazacyclodecane

A new bidisplaced acetate functionalized pendant arm derivative, 1,4-diacetate-1,4,7-triazacyclodecane (L) and its corresponding Co(III), Fe(III) complexes [CoLCl] (1) and [FeLCl]₂ · 3H₂O (2) were synthesized and characterized by elemental analysis, IR spectra,UV–Vis spectra, HNMR, MS, XPRD, TGA and single-crystal X-ray diffraction analysis. The crystal structure shows the metal ions in the complexes have similar coordination six-coordinate, by three nitrogens and two oxygens of the chelate ligand, and a chloride. Through calculation of the twist angle, we discover 1 forms a distorted octahedral geometry while 2 forms a distorted-prismatic geometry. In 2, there are abundant hydrogen bonds between the oxygen atoms of water and the nitrogens and oxygens of the ligand, resulting in a two-dimensional supramolecular network with a regular triatomic water cluster. The thermal gravimetric analyses of the two complexes are also given.     

Synthesis,characterization, and crystal structure of cobalt(II) complex with 2-oximino-3-thiosemicarbazone-2,3-butanedione

The reaction of cobalt(II) chloride with the tridentate ligand 2-oximino-3-thiosemicarbazone-2,3-butanedione [Hotsb (1)] leads to the formation of the novel six-coordinated complex [Co(otsb)₂]·2H₂O (2). This complex has been synthesized and characterized by X-ray crystallography, spectroscopic and cyclic voltammetric measurements. The ligand Hotsb (1) obtained by the condensation of 2,3-butanedione monoxime and thiosemicarbazide is used for the preparation of complex 2. The Hotsb (1) crystallizes into a monoclinic lattice with space group P2₁/c. The crystal structure of 2 shows a distorted mer-octahedral geometry in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the hydrazine nitrogen atoms, the azomethine nitrogen atoms, and the thiolate sulfur atoms. The cyclic voltammogram of 2 undergoes two irreversible one-electron waves corresponding to Co^II/Co^III and Co^II/Co^I processes.     

A linear trinuclear cobalt(II) complex with 4-(2-pyridine)-1,2,4-triazole: synthesis,structure and characterization

The linear trinuclear cobalt(II) complex [Co₃(pytrz)₆(H₂O)₆](NO₃)₆ (1) with pytrz = 4-(2-pyridine)-1,2,4-triazole has been prepared and characterized. It crystallizes in the rhombohedral R-3 space group with Z = 3, a = 13.955(2), b = 13.955(2), c = 28.942(9) Å, γ = 120°, V = 4881.2(18) ų. The structure of 1 comprises the cation [Co₃(pytrz)₆(H₂O)₆]⁶⁺, in which linear trinuclear Co(II) units are bridged by six L ligands and have six aqua molecules as terminal ligands. The six free nitrates link the terminal aqua ligands through N–H ··· O hydrogen bonds with C₃ symmetry. 1 was characterized by FT-IR, electronic spectra and magnetic measurements. The variable-temperature magnetic measurements reveal weak anti-ferromagnetic interactions in 1.     

A tetradentate bisoxime and its supramolecular nickel(II) cluster: synthesis,crystal structure,and spectral properties

Salen-type bisoxime 5,5′-dimethoxy-2,2′-[(ethylenedioxy)bis(nitrilomethylidyne)]diphenol (H₂L) and its trinuclear Ni(II) cluster {[(NiL)(n-BuOH)]₂(μ-OAc)₂Ni}?·?n-BuOH have been synthesized and structurally characterized. The structure of H₂L adopts an L-shape conformation where the two salicylaldoxime moieties are well separated. In the trinuclear Ni(II) cluster, two acetates coordinate to three Ni(II)'s through Ni–O–C–O–Ni bridges, four μ-phenoxos from two [NiL(n-BuOH)] units also coordinate to Ni(II), and two n-butanols coordinate to two terminal Ni(II)'s forming a distorted octahedral geometry. The Ni–O–C–O–Ni and μ-phenoxo bridges play important roles in assembling Ni(II) and the ligands. H₂L forms a rectangle-like large cave structure through O–H?···?N, C–H?···?O, and C–H?···?π hydrogen-bond interactions, whereas its trinuclear Ni(II) cluster exhibits a 3-D supramolecular network structure through intermolecular O–H?···?O, C–H?···?O, and C–H?···?π hydrogen-bond interactions.     

A new hydrogen-bonded pseudo-dimer Mn(III) Schiff base complex. The synthesis, X-ray structure and spectroscopic studies

A new hydrogen-bonded pseudo-dimer, [Mn(III)L1(CH₃CH₂OH)]₂(ClO₄) (1) (L1 = N,N′-bis(2-hydroxy-1-naphthalidenato)-1,2-diaminopropane) has been synthesized and characterized by UV–vis, IR, elemental analysis and crystal structure analysis. The single crystal X-ray diffraction reveals that the structure affords an elongated octahedral MnN₂O₄ coordination environment, geometry with the four donor atoms of the tetradentate Schiff base in the equatorial plane and with two ethanol molecule in axial positions with Mn–O = 2.265(2) and 2.266(2) Å.     

Mononuclear gallium(III) complexes based on salicylaldoximes: Synthesis,structure and spectroscopic characterization

The reactions of Ga(acac)₃ with salicylaldoxime (saoH₂) and methyl-salicylaldoxime (Me-saoH₂) in dichloromethane/hexane afforded the complexes [Ga(acac)(saoH)₂] (1) and [Ga(acac)₃][Ga(acac)(MesaoH)₂] (2), respectively, in high yields. The crystal structures of 1 and 2 have been determined by single-crystal X-ray crystallography. Both complexes are mononuclear with the Ga(III) atoms being in octahedral environments surrounded by two bidentate chelate R-saoH⁻ and one bidentate chelate acac⁻ ligands. A [Ga(acac)₃] moiety has co-crystallized along with the methylsalicylaldoximato complex. Characteristic IR as well as NMR data are discussed in terms of the nature of bonding in the structures of the two complexes. ¹H and ¹³C NMR data in CDCl₃ indicate that the salicylaldoximato complexes isomerize in solution.     

Synthesis,structure, spectroscopic,and DNA binding properties of Co(III) and Ni(II) complexes with ((E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile)

Two new complexes, [Co(L)₂]Cl·(MeOH)₂ (1) and [Ni(L)₂]₄·EtOH (2) (L?=?(E)-2-(amino((pyridin-2-ylmethylene)amino)methylene)maleonitrile), were synthesized and characterized by X-ray crystallography, IR, UV, and fluorescence spectroscopy. According to X-ray crystallographic studies, each metal was six-coordinate with six nitrogens from two ligands. Both complexes form two-dimensional supramolecular networks via hydrogen bonding and π–π interactions. Ultraviolet and visible spectra showed that absorptions arise from π–π ^?, MLCT, and d–d electron transitions. Fluorescence spectroscopy revealed moderate intercalative binding of these two complexes with EB–DNA, with apparent binding constant (K _app) values of 9.14?×?10⁵ and 3.20?×?10^5?M^?1 for Co(III) and Ni(II) complexes, respectively. UV–visible absorption spectra showed that the absorption of DNA at 260?nm was quenched for 2 but quenched then improved for 1 with addition of complexes, tentatively attributed to the effect of the combined intercalative binding and electrostatic interaction for 1.     

A Co(III) complex with a tridentate amine-imine-oxime ligand from 1,2,3,4-tetrahydroquinazoline: synthesis,crystal structure,spectroscopic and thermal characterization

A cobalt(III) complex [Co(L)₂]Cl · PPO · H₂O (1) (HL = 1-(2-aminobenzylimino)-1-phenyl-propan-2-one oxime, PPO = 1-phenyl-1,2-propanedione-2-oxime) has been synthesized and characterized by elemental analyses, spectral, thermal, magnetic and molar conductance measurements and single crystal X-ray diffraction. It crystallizes in the monoclinic crystal system, space group P2₁/c. Complex 1 consists of one uncoordinated water, one 1-phenyl-1,2-propanedione-2-oxime molecule, one bis[1-(2-aminobenzylimino)-1-phenyl-propan-2-one oxime]cobalt(III) cation and one uncoordinated chloride. The coordination geometry around Co is slightly distorted octahedral, completed with six nitrogens of two L^? ligands. The oxime moieties have E configurations. In the crystal structure, intramolecular O–H···Cl and N–H···O and intermolecular N–H···O, O–H···Cl and N–H···Cl hydrogen bonds link the molecules into chains parallel to the c axis; hydrogen-bonded PPO molecules fill the spaces between the chains and stabilization of the structure.     

Synthesis,crystal structure and magnetic properties of a new macrocyclic trinuclear CuII-CuII-CuII complex

A new oxamido-bridged trinuclear copper(II) complex [(CuL)₂Cu](ClO₄)₂·0.5H₂O (L?=?the dianion of 2,3-dioxo-5,6,14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene) has been synthesized by self-assembly and characterized. X-ray diffraction analysis reveals that the title complex is monoclinic, space group P2₁, with a?=?16.213(5), b?=?9.811(3), c?=?18.802(6)?Å, β?=?96.790(5)°. The central copper(II) ion lies in a distorted octahedral environment. Terminal coppers have square pyramidal coordination geometry. Magnetic measurements show there is strong antiferromagnetic interaction between the central and the terminal Cu(II) ions.     

A V-shaped ligand bis(N-methylbenzimidazol-2-ylmethyl) benzylamine with its cobalt(II) complex: synthesis,crystal structure,DNA-binding properties,and antioxidant activity

A V-shaped ligand bis(N-methylbenzimidazol-2-ylmethyl)benzylamine (bmbb) and its cobalt complex, [Co(bmbb)₂](pic)₂ (pic?=?picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray revealed that the coordination sphere around Co(II) is distorted octahedral with an N₆ ligand set from two tridentate bmbb. The DNA-binding properties of bmbb and the Co(II) complex were investigated by spectrophotometric and viscosity measurements. The results suggest that bmbb and Co(II) complex both bind to DNA via intercalation, and the Co(II) complex binds to DNA more strongly than bmbb. The Co(II) complex also exhibited potential antioxidant properties in vitro studies.