Rhenium(IV)–copper(II) heterobimetallic complexes: Synthesis,crystal structure and magnetic properties

Two Re(IV)–Cu(II) heterometallic complexes {(CuL_α)[ReCl₄(ox)]}_n (where L_α = N-meso-5,12-Me₂-7,14-Et₂-[14]-4,11-dieneN₄), 1, and (CuL_β)[ReCl₄(ox)] (L_β = N-rac-5,12-Me₂-7,14-Et₂-[14]-4,11-dieneN₄N-rac-5,12-Me₂-7,14-Et₂-[14]-4,11-dieneN₄), 2, were synthesized. The [CuL²⁺] macrocyclic cation is coordinated from above and below by [ReCl₄(ox)]²⁻ units through the chloro-ligands and creates a chloro-bridged heterometallic Re^IV–Cu^II one-dimensional zig-zag chain. Compound 2 can be viewed as a heterobimetallic dinuclear unit, in which the Re(IV)-Cu(II) centers are linked by an oxalato bridge. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.8–300 K. Compound 1 behaves like a ferrimagnetic {Re(IV)–Cu(II)} bimetallic, one-dimensional chain with intrachain antiferromagnetic coupling. Compound 2 shows a weak antiferromagnetic interaction within the [Re(IV)–Cu(II)] unit along with a strong single-ion anisotropy, D(Re) = −63 cm⁻¹.     

One-dimensional cyanide-bridged Cr(III)–Cu(II) complexes: synthesis,crystal structures and magnetic properties

Using two trans-dicyanidechromium(III) precursors K[Cr(bpdmb)(CN)₂] (bpdmb^2? = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate), K[Cr(bpClb)-(CN)₂] (bpClb^2? = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate) and one Cu(II) complex of a 14-membered macrocycle as ancillary organic ligand as assembling segments, two one-dimensional cyanide-bridged Cr^III–Cu^II complexes {{[Cu(cyclam)][Cr(bpdmb)(CN)₂]}ClO₄} _n ·nCH₃OH·nH₂O (1) and {{[Cu(cyclam)][Cr(bpClb)(CN)₂]}ClO₄} _n ·nCH₃OH (2) (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that their similar one-dimensional cationic single-chain structures consist of alternating units of [Cu(cyclam)]²⁺ and [Cr(bpdmb)(CN)₂]^?/[Cr(bpClb)(CN)₂]^? with free ClO₄ ^? as balancing anions. Investigations of the temperature dependences of magnetic susceptibility and the field-dependent magnetization reveal that both complexes have overall ferromagnetic coupling between the neighboring Cr(III) and Cu(II) centers through the bridging cyanide groups.     

A three-dimensional highly stable cobalt(II) metal–organic framework based on terephthalic acid: synthesis, crystal structure, thermal and physical properties

A metal?Corganic framework complex, [Co(??₃?Ctp)(??₂?pyz)] _n , where H₂tp?=?1,4-benzenedicarboxylic acid (terephthalic acid) and pyz?=?pyrazine, has been synthesized under hydrothermal conditions and characterized by physico-chemical and spectroscopic methods, thermogravimetric analysis and single-crystal X-ray diffraction. Each Co(II) center is surrounded by four carboxylate oxygen atoms from three tp ligands and two nitrogen atoms from two pyrazine ligands, giving a distorted octahedral geometry. The entire framework is made up of two-dimensional sheets of dicobalt ions linked via terephthalate ligands to form rectangles. The sheets are then linked into each other via the axial pyrazine ligands, forming an interlocked 3-D network, which is finally arranged as an ABAB interconnected pattern. Photoluminescence measurements for the polymer in the solid state show an emission at 414?nm, which suggests this complex as a potential blue-light material. The electrochemical behavior of a modified carbon paste electrode prepared from the complex has been studied by cyclic voltammetry, indicating quasi-reversible redox behavior.     

Ultrasonic synthesis,crystal structure,luminescent, and magnetic properties of a new metal–organic complex based on Ce(IV)–Sr(II)

Research on Chemical Intermediates - This paper presents the sonochemical synthesis of a new hetero-metallic inorganic complex, formulated as [(Sr(OH2)5Ce(dipic)3Sr(OH2)6][Ce(dipic)3]·6H2O...     

Volatile complexes of Pd(II) with methoxy-β-iminoketones: Synthesis,properties, and crystal and molecular structure

This paper describes a procedure for the synthesis of two new volatile complexes, Pd(L¹)₂ and Pd(L²)₂, from sterically hindered methoxy-β-iminoketones, where HL¹ = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-C(CH₃)₃; HL² = C(CH₃)₂(OCH₃)-C(NH)-CH₂-C(O)-CH(CH₃)₂. Element analysis and IR spectral data are given. The results of full X-ray crystal structure analysis of the complexes are reported. The compounds have molecular structures; the crystals of the complexes have different symmetry groups and unit cell dimensions. The Pd(L¹)₂ complex molecule has a nonplanar structure; the Pd(L²)₂ complex has a cis-structure. The geometrical characteristics obtained for the coordination units are as follows: the Pd-O and Pd-N bond lengths and N-Pd-O chelate angles were estimated at 1.960 Å, 93.7° for Pd(L¹)₂, and 1.984 Å, 1.976 Å, 92.4° for Pd(L²)₂.     

Trichloro-mono- β -diketonato oxorhenium(V) complexes: synthesis,characterization and crystal structure

Oxorhenium(V) complexes of β-diketonate systems have been synthesized and isolated in pure form. The red complexes n-Bu₄N[ReO(R₁COCHCOR₂)Cl₃] (acac, R₁=R₂=CH₃; bzac, R₁=CH₃ and R₂=C₆H₅; bzbz, R₁=R₂=C₆H₅) have been characterized by elemental analyses, spectroscopic and other physico-chemical tools. One complex, n-Bu₄N[ReO(bzbz)Cl₃] (1c) has been subjected to single-crystal X-ray analysis. In the structure of the anion, the metal has a six-coordinate octahedral environment in which the bidentate β-diketone ligand is cis and trans to the terminal oxygen.     

Synthesis,crystal structure,thermal decomposition,and XPS studies of homo and heterotrinuclear Cu(II)–Cu(II)–Cu(II) and Cu(II)–Ni(II)–Cu(II) complexes obtained from salpn type ligands

In this study, a mononuclear CuL complex was prepared by the use of bis-N,N′-(salicylidene)-1, 3-propanediamine (LH₂) and Cu²⁺ ion. NiCl₂ and NiBr₂ salt were treated with this complex in dioxanewater medium and two new complexes [(CuL)₂NiCl₂(H₂O)₂] and [(CuL)₂NiBr₂(H₂O)₂)] with Cu(II)–Ni(II)–Cu(II) nucleus structure were obtained. In addition to this bis-N,N′-(2-hydroxybenzyl)-1,3-diaminopropane (L^HH₂) was prepared by the reduction of LH₂ with NaBH₄ in MeOH medium. The treatment of this reduced complex with Cu²⁺ ion resulted a complex [(CuL^H)₂CuCl₂] with a structure of Cu(II)–Cu(II)–Cu(II). The complexes prepared were characterized by the use of elemental analysis, IR spectroscopy, thermogravimetric and X-ray diffraction methods. The crystal structures of [(CuL)₂NiBr₂(H₂O)₂] (СIF file CCDC 1448402) and [(CuL^H)₂CuCl₂] (СIF file CCDC 1448401) complexes were elucidated. It was found that halogen ions are coordinated to terminal Cu²⁺ ions which are in a distorted square pyramid coordination sphere. It was determined that the central Cu(II), which joins terminal square pyramidal Cu(II), was coordinated only by the phenolic oxygens of the ligand while the central Ni(II) was coordinated by two phenolic oxygens of the organic ligand and two water molecules. These complexes were investigated by XPS and it was found that the terminal and central Cu²⁺ ions were different in Cu(II)–Cu(II)–Cu(II) complex. Also, the thermal degradation of the CuLH complex unit was observed to exothermic in contrast to the expectations.

     

Cadmium(II) complexes containing 2,2′-dimethyl-4,4′-bithiazole ligand: synthesis,characterization, and crystal structure

Mononuclear and coordination polymer compounds of 2,2′-dimethyl-4,4′-bithiazole (dm4bt) ligand have been prepared by metallation of dm4bt with Cd(NO₃)₂ · 4H₂O and CdCl₂ · H₂O. The compounds were characterized by IR, ¹H NMR, UV–Vis spectroscopy, and X-ray crystallography. The structural study of [Cd(dm4bt)₂(NO₃)₂] · H₂O (1) shows that the complex is a monomeric seven-coordinate (CdN₄O₃) cadmium(II)-bithiazole system with two bidentate dm4bt and mono and bidentate nitrates. The structure of [Cd(dm4bt)Cl₂] _n (2) is a distorted octahedral environment around the cadmium(II) (CdN₂Cl₄) forming a 1-D coordination polymer as a result of bridging by two chlorides and 2-D structure from π–π stacking interactions.     

Hydrothermal synthesis, crystal structure, and properties of two novel binuclear complexes based on Zaltoprofen and 2,2′-bipyridine ligands

Two novel binuclear metal-organic coordination complexes [M₂(Zaltoprofen)₂(Bipy)₂] [M = Cd (I), Zn (II); Zaltoprofen = 5-(1-carboxyethyl)-2-(phenylthio)phenylacetic acid, Bipy = 2,2′-bipyridine) have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR and electronic spectroscopy, powder X-ray diffraction, and fluorescent properties. Complexes I, II crystallize isomorphously in the monoclinic space group P2₁/c. Structural analysis shows that the M(II) atom of I and II is coordinated with four oxygen atoms from the carboxyl group of the Zaltoprofen together with two nitrogen atoms from the Bipy. The 3D structures of the complexes are stabilized by π-π stacking interactions.     

1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) as ligand in Cd(II) complexes: synthesis,crystal structures,and fluorescence

Hydrothermal reactions of 1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) with CdCl₂ and CdI₂ yielded three new coordination polymers, {[CdCl(2,3′-bpt)(H₂O)]·2H₂O}_n (1), {[Cd₂I₃(2,3′-H_0.5bpt)₂]}_n (2), and [CdI₃(2,3′-Hbpt)](2,3′-H₂bpt)·H₂O (3). Structural analysis reveals that 1 has a 1-D double chain structure; in 2, 2,3′-bpt bridges adjacent Cd(II) ions to form a 1-D twofold helical chain, which further connects via μ₂-I^-, giving a 2-D grid structure in the ab plane; 3 is mononuclear. These complexes are further connected through weak hydrogen bonding interactions, and/or weak π···π stacking interactions, to generate 3-D supramolecular structures. The fluorescence properties of 1 and 2 have been investigated in the solid state at room temperature.     

Syntheses,crystal structures and fluorescent properties of two 4,4′-dipyridylsulfide based zinc(II) and cadmium(II) helical complexes

Two allomeric helical coordination polymers, {[Zn(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (1) and {[Cd(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (2) (4,4′-dps = 4,4′-dipyridylsulfide, H₃SSA = 5-sulfosalicylic acid), have been synthesized by similar experimental methods and characterized by elemental analysis, single-crystal X-ray diffraction, and fluorescence spectra. Both crystallize in monoclinic system, space group P₂1/n, with a = 11.7947(13) Å, b = 13.7475(15) Å, c = 20.183(2) Å, and Z = 4 for 1 and a = 11.940(7) Å, b = 14.068(8) Å, c = 20.323(12) Å, and Z = 4 for 2. In both complexes, the metal (Zn^II for 1 and Cd^II for 2) are six-coordinate with a N₃O₃ donor set in a distorted octahedron. Half of the 4,4′-dps are μ ₂-bridging, linking adjacent metal centers and forming P₂1/n dimensional helical structures along the b-axis. Fluorescence measurements show that 1 and 2 have medium fluorescent emission at 402 and 405 nm, respectively.     

Trans hexaco-ordinate complexes of copper(II) and nickel(II) with 4(5)-hydroxymethyl-5(4)-methylimidazole—crystal structure and physico-chemical properties

Trans complexes of Cu(II) and Ni(II) with 4-hydroxymethyl-5-methylimidazole (L), of the general formula [ML₄](NO₃)₂ have been obtained. The complexes were characterized by single X-ray diffraction, elemental analysis, EPR spectroscopy, IR, FIR and Vis–NIR spectra. In these co-ordination compounds, the azole ligand has a dual nature. Two of these molecules are monodentate, co-ordinated through the ‘3’ ‘pyridynic’ nitrogen atom of the imidazole ring, while the remaining two are bidentate ligands, the oxygen atom of the CH₂OH group being another electron donor (giving CuN₄O₂ and NiN₄O₂ chromophores). The structure of both chromophores is described by a slightly distorted tetragonal bipyramid. The stability constants and structures of the Cu(II) and Ni(II) complexes with the studied ligand (4-CH₂OH5-CH₃im) in aqueous solution have been determined by potentiometric and spectrophotometric methods. The stability of the transition metal complexes of 4-CH₂OH5-CH₃im depends on the presence of the hydroxymethyl group, the oxygen atom of which interacts with the metal-ion.     

Tetra(μ3-hydroxo) bridged copper(II) tetranuclear cubane complexes: synthesis,crystal structure,and DNA binding studies

The tridentate Schiff base H₂L was synthesized by the condensation of equimolar amount of 1-amino-2-propanol and salicylaldehyde. The reaction of H₂L with an equimolar amount of Cu(CH₃COO)₂·H₂O in methanol leads to the formation of the tetranuclear Cu₄L₄, 1. However, reaction of equimolar amount of H₂L, copper(II) acetate, and 2,4,6-trimethylaniline in methanol forms a mixture of products which includes a discrete mononuclear complex Cu(L′)₂, 2m (where HL′ is a bidentate ligand), in addition to the tetranuclear Cu₄L₄ species, 2c. In both tetranuclear cubane species, the tridentate H₂L is both a chelating and a bridging ligand, after deprotonation of the enolic and the phenolic OH. The copper(II) centers are five-coordinate with a [N, O₄] donor set from the ligands. The coordination geometry about each copper is distorted square pyramidal with one nitrogen and two oxygen from one ligand and two oxygen from adjacent ligands in the next unit of the cubane. In mononuclear 2m, the ligand is bidentate and the coordination geometry around copper(II) is square planar. The absorption spectra strongly suggest that tetranuclear 1 interacts with CT-DNA.     

Ruthenium(II) complexes of azoimine and α-diimine ligands: synthesis,spectroscopic and electrochemical properties,crystal structures and DFT calculations

Five octahedral ruthenium(II) complexes with azoimine–quinoline (Azo) and α-diimine (L) ligands having the general formula [Ru^II(L)(Azo)Cl](PF₆) (1–5) {Azo: PhN=NC(COMe)=NC₉H₆N, L = 4,4′-dimethoxy-2,2′-bipyridine (dmeb) (1), 4,4′-di-tertbutyl-2,2′-bipyridine (dtb) (2), 1,10-phenanthroline (phen) (3), 5-chlorophenanthroline (Clphen) (4), or 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) (5)} were prepared by stepwise addition of the tridentate azoimine (H₂Azo) and α-diimine (L) pro-ligands to RuCl₃ in refluxing EtOH. The tridentate azoimine–quinoline ligands coordinate to ruthenium via the Azo-N′, N′-imine and N″-quinolone nitrogen atoms. The spectroscopic properties (IR, UV/Vis, ¹H, ¹³C and ¹⁹F NMR) and electrochemical behavior of complexes 1–5 and the X-ray crystal structures of complexes 2 and 3 are presented. The coordination of Ru(II) to these strong π-acceptor ligands (Azo and L) results in a large anodic shift for the Ru(III/II) couples of 1.63–1.72 V versus NHE. The electronic spectra in MeCN and IR spectra in CH₂Cl₂ for complex 3 in its oxidized 3 ⁺ and reduced 3 ^? forms were investigated. The calculated absorption spectrum of 3 in MeCN was used to assign the UV–Vis absorption bands.     

Manganese(II) and silver(Ι) complexes based on the V-shaped ligand,bis(2-benzimidazolylmethyl)amine: synthesis,crystal structures,DNA-binding properties,and antioxidant activities

Two Mn(II) and Ag(I) complexes, [Mn(IDB)₂](pic)₂ (pic?=?picrate) (1) and [Ag₂(IDB)₂](pic)₂ (2) (IDB?=?bis(2-benzimidazolylmethyl)amine), have been synthesized and characterized by elemental analysis, IR, UV–vis spectral measurements, and X-ray single-crystal diffraction. Single-crystal X-ray diffraction revealed that Mn(II) is six-coordinate by six nitrogens from two IDB as a distorted octahedron, and the Ag(I) complex revealed two Ag(I) ions bonded to two IDB ligands through six nitrogens, resulting in an asymmetric binuclear structure. The complexes can bind to DNA through an intercalative mode, and the affinity for DNA is stronger for the Mn(II) complex than the Ag(I) complex; the Mn(II) complex exhibits excellent antioxidative activity.     

One-dimensional heterobimetallic cyanide-bridged Fe(III)–Mn(II) complex: Synthesis,crystal structure,and magnetic properties

A new cyanide-bridged heterobimetallic Fe(III)–Mn(II) complex {[MnL][FebpdBrb]} [FebpdBrb]_n· 2nH₂O has been synthesized by using pyridinecarboxamide trans-dicyanideiron as the building block. The X-ray diffraction analysis has revealed the one-dimensional infinite structure of the complex consisting of the alternating [Mn(L)]²⁺ and [Fe(bpdBrb)(CN)₂]^– units forming a cyanide-bridged cationic polymeric chain, with [Fe(bpdBrb)(CN)₂]^– as the free anions. The antiferromagnetic coupling between the neighboring Fe(III) and Mn(II) ions through the bridging cyanide group has been revealed. The magnetic coupling constant has been determined as of J =–3.17 cm^–1.     

Synthesis,characterization, crystal structure,and DNA binding of two copper(II)–hydrazone complexes

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO₄]·ClO₄·[Cu(L)Cl] (1) and [Cu(HL)₂]·1.5ClO₄·0.5OH (2) (where HL?=?(E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 10³, 1.88 × 10⁴, and 4.66 × 10⁴ M^?1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.