meta-Phenylene-bridged double Schiff base copper(II) complexes as building blocks for 1D coordination polymers: Synthesis,crystal structure and magnetic properties

The new double Schiff-base ligands H₆ipa-hyhb and H₆ipa-hyhh were synthesized by condensation of a 4,6-diformylresorcinol derivative (ipa) with 4-hydroxy-butanoic acid hydrazide (hyhb) and 6-hydroxy-hexanoic acid hydrazide (hyhh). The reaction with copper(II) perchlorate in the presence of an appropriate co-ligand (Him = imidazole, Hpz = pyrazole) leads to the novel coordination polymers {[Cu₂(H₄ipa-hyhb)(Hpz)₂](ClO₄)₂}_n (1), {[Cu₂(H₄ipa-hyhb)(Him)₂](ClO₄)₂}_n (2), and {[Cu₂-(H₄ipa-hyhh)(Hpz)₂](ClO₄)₂}_n (3). These coordination polymers are composed of primary building blocks with the general formula [Cu₂(H₄ipa-X)(L)₂]²⁺ (X = hyhb, hyhh; L = Him, Hpz) which are linked by coordination of the hydroxyl groups of the ligand side chains at the apical position of copper(II) centers of adjacent building blocks. The resulting chains possess different topologies and therefore different supramolecular structures due to the variation in length of the ligand alkyl side chains. For the complexes 1 and 2 double hydroxyalkyl-bridged distorted ladder like chains are formed. Whereas in case of complex 3 single hydroxyalkyl-bridged chains are obtained which assemble to hydrogen bonded double chains. In the case of 1 and 2 these chains are cross-linked by hydrogen bonding interactions with the perchlorate counterions, whereas for 3 additional π–π stacking interaction are observed. The temperature-dependent magnetic measurements indicate weak antiferromagnetic interactions with coupling constants J = −26.1 cm⁻¹ (1), J = −28.2 cm⁻¹ (2), and J = −26.5 cm⁻¹ (3). The magnetic exchange interaction is solely the result of a coupling within the dinuclear complex moieties through the central resorcinol moiety.     

Synthesis,characterization and structures of copper(II) complexes with amide-based ligands: Unusual formation of a linear trimer and a zig-zag chain and their contrast magnetic behaviour

The present work illustrates the versatile coordination modes of the amide-based ligands towards copper(II) ion. The reaction of the deprotonated form of the ligand, [L¹]²⁻ with CuCl₂ affords a linear trinuclear complex, [Cu₃(L¹)₂(Cl)₂(H₂O)] (1) which has been characterized thoroughly including single crystal structure analysis. The structure of 1 shows that one of the arm of the flexible ligand flips to coordinate second copper(II) centre, resulting in the formation of a trinuclear complex. On the other hand, ligand H₂L² in its deprotonated form reacts with Cu(II) ion to give complex 2 with general formula, [Cu(L²)]_n (2). The crystal structure of the complex 2 shows that each copper is square-pyramidal with 5th coordination coming from the O-atom of the amide group from a neighbouring complex. This results in the generation of an one-dimensional zig-zag chain. The variable temperature magnetic measurements of the complexes, 1 and 2 show that while Cu ions in the former are antiferromagnetically coupled (J = −110.34 cm⁻¹), a weak ferromagnetic interaction (J = +3.08 cm⁻¹) exists in the later. A rationale, based on the orbital overlap from the copper ions and associated ligands, is provided for the observed magnetic coupling between the copper ions.     

Synthesis and crystal structure of two copper(II) complexes with coordinated decavanadate ion

Two new compounds containing decavanadate ions coordinated to copper centers, (2-hepH⁺)₂[{Cu(H₂O)₂(O,N-2-hep)}₂V₁₀O₂₈]·6H₂O (2-hepH⁺ = 2-(2-hydroxyethyl)pyridinium; 2-hep = 2-(2-hydroxyethyl)pyridine) (1), [{Cu(2-amp)₂(H₂O)}₂H₂V₁₀O₂₈]·4H₂O (amp = 2-(aminomethyl)pyridine) (2), have been prepared and characterized by elemental analyses and IR spectroscopy. The structure of 1 consists of trinuclear units [{Cu(H₂O)₂(O,N-2-hep)}₂V₁₀O₂₈]²⁻, 2-hepH⁺ cations and molecules of water of crystallization. A trinuclear unit [{Cu(2-amp)₂(H₂O)}₂H₂V₁₀O₂₈] is a principal part also in the structure of 2, but the bonds of decavanadate group to the copper complexes are much weaker than in 1.     

Synthesis,crystal structure,Hirshfeld surfaces,and spectral properties of Cu(II) and Co(II) complexes with 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole

A new asymmetrical substituted triazole, 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole (L) and its complexes, cis-[Cu₂ L ₂Cl₄]·2CH₃CN (1) and trans-[CoL ₂Cl₂]·2H₂O·2CH₃CN (2), have been synthesized and characterized by IR, single-crystal X-ray diffraction, thermogravimetric analyses and Hirshfeld surfaces. In the structure, two L are mainly stabilized by an intermolecular C–H?N hydrogen bond. In 1 (or 2), each L involves a doubly-bidentate (or chelating bidentate) coordination mode through one pyridine and two nitrogens (or one) of triazole, respectively. Complex 1 has a distorted trigonal bipyramidal [CuN₃Cl₂] core with two cis Cl^? while 2 shows a distorted octahedron [CoN₄Cl₂] with two trans Cl^?. We also prepared molecular Hirshfeld surface and fingerprint plot for L, 1 and 2, which revealed the influence of different metals on coordinate of L.     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.     

One-dimensional and two-dimensional coordination polymers constructed from copper(II) nodes and polycarboxylato spacers: Synthesis,crystal structures and magnetic properties

Four new coordination polymers were obtained by employing polycarboxylato spacers and cationic copper(II) complexes as nodes: ^∞₂[Cu₃(trim)₂(NH₃)₆(H₂O)₃] (1); ^∞₁[Cu(tmen)(dhtp)] (2), ^∞₁[Cu(tmen)(hitp)(H₂O)] (3), ^∞₁[Cu(tmen)(nitp)] (4). (H₃trim = trimesic acid, H₂dhtp = 2,5-dihydroxy-terephthalic acid; H₂hitp = 5-hydroxy-isophthalic acid, H₂nitp = 5-nitro-isophthalic acid; tmen = N,N,N′,N′-tetramethyl-ethylenediamine). The crystal structures of the four compounds have been solved. Compound 1 consists of 2D coordination polymers with heart-shaped meshes, while compounds 2–4 contain infinite zigzag chains. The role of the hydrogen bond interactions in sustaining the supramolecular solid-state architectures in compounds 1 and 3 is discussed. The cryomagnetic investigation of compounds 1, 2, and 4 reveals antiferromagnetic interactions between the copper ions.     

Synthesis and X-ray crystal structures of three copper(II) complexes of 1,4- bis (di-2-pyridylmethyl)phthalazine

The synthesis and X-ray crystal structures of three discrete copper(II) complexes of 1,4-bis(di-2-pyridylmethyl)phthalazine (L) are reported. The complexes 1–3 have Cu₂L, Cu₃L and Cu₂L₂ composition and display interesting relationships to previously reported complexes of this ligand.     

Dinuclear copper(II) complexes of a novel 3-(aminomethyl)naphthoquinone Mannich base: Synthesis,structural, magnetic and electrochemical studies

A novel versatile tridentate 3-(aminomethyl)naphthoquinone proligand, 3-[N-(2-pyridylmethyl)aminobenzyl]-2-hydroxy-1,4-naphthoquinone (HL), was obtained from the Mannich reaction of 2-hydroxy-1,4-naphthoquinone (Lawsone) with 2-aminomethylpyridine (amp) and benzaldehyde. The reactions of HL with CuCl₂·2H₂O yielded two novel dinuclear copper(II) complexes, [Cu(L)(H₂O)(μ-Cl)Cu(L)Cl] (1b), [CuCl(L)(μ-Cl)Cu(amp)Cl] (2) and a polymeric compound, [Cu(L)Cl)]_n (1a), whose relative yields were sensitive to temperature, reagents concentration and presence of base. The crystalline structures of 1b and 2 were determined by X-ray diffraction studies. The two copper atoms in complex 1b are connected by a single chloro bridge with a Cu?Cu separation of 4.1342(8) Å and Cu(1)–Cl(1)–Cu(2) angle of 109.31(4)°. In complex 2 the two copper atoms are held together by a chloro and a naphthalen-2-olate bridges [Cu(1)–Cl(2)–Cu(2) and Cu(1)–O(1)–Cu(2) angles being 83.31(3) and 109.70(9)°, respectively, and the Cu?Cu separation, 3.3476(9) Å]. As expected, variable-temperature magnetic susceptibility measurements of complex 1b showed weak antiferromagnetic intramolecular coupling between the copper(II) centers, with J = −5.7 cm⁻¹, and evidenced for complex 2 strong antiferromagnetic coupling, with J ∼ −120 cm⁻¹. Furthermore, the magnetic behaviour of compound 1a suggested an infinite 1D coordination polymeric structure in which the copper(II) centers are connected by Cl–Cu–Cl bridges. Solution data (UV–Vis spectroscopy and cyclic voltammetry) indicated structural changes of 2 and 1a in CH₃CN, and evidenced conversion of polymer 1a into dimer 1b.     

Synthesis,crystal structure and magnetic property of a three-dimensional manganese(II) complex

The solvothermal reaction of MnCl₂·4H₂O, H₂asp and CH₃ONa gave rise to a new manganese(II) complex, {[Mn(asp)(H₂O)]·(H₂O)₂} _n (1) (H₂asp?=?5-aminoisophthalic acid). Single-crystal X-ray diffraction analysis reveals that complex 1 is a three-dimensional consisting of two-dimensional layers extended by hydrogen bonding interactions. The two-dimensional layer contains 8-, 14-, and 16-membered rings. A variable temperature magnetic measurement of 1 displays weak antiferromagnetic behavior.     

High-dimensional mixed-valence copper cyanide complexes: Syntheses,structural characterizations and magnetism

Reactions of CuCl₂ with different CN complexes in presence of a neutral ancillary ligand lead to two novel mixed-valence Cu complexes [Cu^II(bpy)Cu^I(CN)₃]_n, 1 (bpy = 2,2′-bipyridine) and {[Cu^II(tn)₂][Cu^I₄(CN)₆]}_n2 (tn = 1,3-diaminopropane). For compound 1, the asymmetric unit involves two Cu ions Cu1 and Cu2 (Cu^I and Cu^II centres, respectively) which strongly differ in their environments. The Cu1 ion presents a CuC₄ pseudo-tetrahedral geometry, while the Cu2 ion presents a CuN₅ slightly distorted square-pyramidal geometry. The extended structure of 1 is generated by three cyano ligands which differ in their coordination modes. One CN group has a μ₃ coordination mode and bridges two Cu^I and one Cu^II ion, while the two other CN groups act as μ₂ bridges leading to a sophisticated 3-D structure. As for 1, the asymmetric unit of 2 involves three crystallographically different Cu ions (Cu1A and Cu1B, presumably Cu^I centres, and Cu2 presumably Cu^II centres). The Cu2 ion presents centrosymmetric CuN₄ coordination environments involving four nitrogen atoms from two bidentate tn ligands; while the Cu1A and Cu1B ions are three coordinated to cyano groups. The structure can be described as formed by 18-membered “[Cu^I(CN)]₆” planar metallocycles that are connected to their six neighbors to generate 2-D sheets; these sheets stack forming infinite hexagonal channels in which the [Cu(tn)₂]²⁺ units are located. Magnetic measurements show an unexpected weak ferromagnetic coupling (θ = 0.239(1) K) of the Cu^II ions through the long and “a priori diamagnetic” –NC–Cu^I–CN– bridges in compound 1 and an essentially paramagnetic behavior in compound 2.     

Supramolecular self-assembly of two Cu(II) complexes with 1,2,4-triazole derivatives: syntheses,crystal structures and magnetic properties

Two two-dimensional coordination complexes, {[Cu₄(BTM)₆(OPA)₄] · 4DMF · 3H₂O} _n (1) and {[Cu(BDTM)(OH)](ClO₄) · 2H₂O} _n (2) (BTM = bis(1,2,4-triazol-1-yl)methane, BDTM = bis(3,5-dimethyl-1,2,4-triazol-1-yl)methane, OPA²⁻ = ortho-phthalic dianion, DMF = N,N-dimethylformamide), were synthesized and structurally characterized. Each Cu(II) ion locates in a distorted square pyramidal geometry in 1, in which OPA²⁻ ligands bridge Cu²⁺ ions along a axis to form a magnetic transmission chain and BTM ligands act as flexible spacers to construct the two-dimensional layer structure. In 2, each Cu²⁺ ion adopts tetra-coordination geometry to two hydroxyl groups and two triazolyl nitrogen atoms from two different BDTM ligands. Two hydroxyl groups bridge two Cu²⁺ ions to form a rhombic diamond, and four BDTM ligands connect four diamonds to form a 36-membered macrocyclic structure with large channels along a axis. Magnetic properties revealed that both OPA²⁻ and OH⁻ mediate anti-ferromagnetic interactions between Cu²⁺ ions with J = − 0.06(3) and −301.9(2) cm⁻¹ for 1 and 2, respectively. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis,crystal structure,magnetic properties and second harmonic generation of a new noncentrosymmetric coordination compound:Triaqua(4-amino-6-methoxypyrimidine) cuprate(Ⅱ)sulfate

The chemical preparation, crystal structure and infrared spectroscopic characterization of the triaqua(4-amino-6-methoxypyrimidine) cuprate(II) sulfate, [Cu(C_5H_7N_3)(H_2O)_3]SO_4, is reported. The compound crystallizes in the noncentrosymmetric orthorhombic space group P2_12_12_1 with lattice parameters a = 7.9025(3), b = 11.1189(4), c = 12.9720(4) , V = 1139.81(7) ~3 and Z = 4. The Cu(II) cation is fivecoordinated, in an early half-way between square pyramidal and trigonal bipyramidal fashion, by two nitrogen atoms of the 4-amino-6-methoxypyrimidine ligand and three water oxygen atoms. In the atomic arrangement, the organic ligands and the 5-connected Cu centers are linked with each other to give a 1-D corrugated hybrid chain running along the b-axis direction. The chains are interconnected by the SO_4~(2-) anions via O–H...O, O–H...S, C–H...O and N–H...O hydrogen bonds to form layers spreading parallel to the(011) plane. The vibrational absorption bands were identified by infrared spectroscopy. Quantitative measurements of the second harmonic generation(SHG) of a powdered sample at 1064 nm were performed and a relative efficiency of 5.2 times the KDP standard was observed. Magnetic properties were also defined to characterize the complex. Magnetic measurements revealed that this material had a onedimensional antiferromagnetic character. The magnetic parameters were g = 2.11 and 2J/k B = -36 K.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Coordination chemistry of 2-hydroxymethylbenzimidazole complexes with copper(II) and cadmium(II) ions: Similarities and differences

The new Cu(II) and Cd(II) complexes of the biologically relevant ligand 2-hydroxymethylbenzimidazole: [CdL₂(NO₃)₂] 1, ([CuL₂(NO₃)](NO₃)(H₂O) 2, [CdL₃](NO₃)₂L(EtOH)_0.253, mer-[CuL₃](NO₃)₂(H₂O)(i-PrOH) 4 have been synthesized and characterized by elemental analyses, UV–Vis, IR, Raman, EPR, NMR, X-ray diffraction and magnetic measurements. X-ray studies have confirmed a bidentate fashion of coordination of the 2-CH₂OHBIm to the Cd(II) as well to Cu(II) ions. This results in the formulation of a five-membered chelate ring in which both N(imidazole) and O(hydroxymethyl) donors of ligand are involved. A comparison of Cu(II) 4 and Cd(II) 3 model complexes shows that both metals may form complexes which exhibit identical structures (distorted octahedral) forming chromophores of the MN₃O₃ type. On the contrary, the polyhedra of metal complexes containing two ligands are different. The copper complex 2 is a five-coordinated with tetragonal pyramid as coordination polyhedron (CuN₂O₃) but cadmium forms an eight-coordinated (CdN₂O₆) complex 1. Weak C–H?π type interactions which were extracted from X-ray data of 1 were confirmed by the ¹³C NMR method. The IR data indicated that Cd(II) is a considerably better acceptor (Lewis acid) than Cu(II) ion for the N, O-donor ligand. The similarities and differences revealed in the coordination behaviour of Cu(II) and Cd(II) towards N, O-donor ligand should be treated as a test on possibility of the copper(II) ions to be displaced by cadmium(II), for example, in the intracellular sites.     

Synthesis,crystal structure and magnetic properties of a new binuclear copper(II)-copper(II) complex of a macrocyclic oxamide

The binuclear metal complex [Cu(μ-exoO₂)cyclamCu(bpy)](ClO₄)₂·H₂O (bpy?=?2,2′-bipyridine and (exoO₂)cyclam?=?1,4,8,11-tetraazacyclotradecanne-2,3-dione) has been synthesized and characterized by single-crystal X-ray analysis and spectroscopic and magnetic measurements. The structure consists of homobinuclear [Cu(μ-exoO₂)cyclamCu(bpy)]²⁺ cations, a weakly coordinated water molecule and perchlorate ions. In each binuclear unit, Cu1, coordinated by four nitrogen atoms of the macrocyclic organic ligand is connected to Cu2 via the exo-cis oxygen atoms of the macrocyclic ligand with Cu···Cu separations of 5.151?Å; Cu2 assumes square-pyramidal geometry. Magnetic properties measured at 2–300?K show antiferromagnetic exchange between adjacent copper(II) ions.     

Synthesis and structure of mononuclear copper(II) complexes with acyclic Schiff-base ligands containing organotellurium substituents: a comparative study with selenium analogs

Tellurium-bearing acyclic Schiff bases, 2,6-bis({N-[2-(phenyltellurato)ethyl]}benzimidoyl)-4-methylphenol (HL³ ) and 2,6-bis({N-[3-(phenyltellurato)propyl]}benzimidoyl)-4-methylphenol (HL⁴ ) of the Te₂N₂O type have been prepared by condensation of 4-methyl-2,6-dibenzoylphenol (mdbpH) with the appropriate phenyltellurato(alkyl)amine. HL³ and HL⁴ have been characterized by mass spectrometry, IR, electronic and ¹H-NMR spectroscopies and cyclic voltammetry. Their reactions with Cu(II) acetate monohydrate in a 2?:?1 molar ratio in methanol yield [(C₆H₂(O)(Me){(C₆H₅)C=N(CH₂)_nTe(C₆H₅)}{(C₆H₅)C=O})₂Cu] (3 (n?=?2), 4 (n?=?3)) as suggested by analytical and spectroscopic data and single crystal X-ray crystallography of 3. In both complexes, one arm of the ligand undergoes hydrolysis at the C=N position and two molecules of the partially hydrolyzed ligand coordinate to Cu(II) through imido nitrogen and the phenolic oxygen. The telluriums do not form part of the copper(II) distorted square planar coordination sphere which has a trans-CuN₂O₂ core. Electrochemical studies of 3 and 4 indicate quasi-reversible reductions (E°′?=??1.113?V (3) and ?1.149?V (4)) corresponding to the reduction of copper(II) to copper(I). The interactions of 3 and 4 with calf thymus DNA, investigated by spectrophotometry and cyclic voltammetry, indicate that 3 and 4 bind to DNA via intercalation, and the binding affinity of 3 is lower than that of its selenium analog.     

Synthesis, spectral characterization and crystal structure of copper(II) complexes of 2-benzoylpyridine-N(4)-phenylsemicarbazone

An interesting series of nine new copper(II) complexes [Cu₂L₂(OAc)₂]·H₂O (1), [CuLNCS]·½H₂O (2), [CuLNO₃]·½H₂O (3), [Cu(HL)Cl₂]·H₂O (4), [Cu₂(HL)₂(SO₄)₂]·4H₂O (5), [CuLClO₄]·½H₂O (6), [CuLBr]·2H₂O (7), [CuL₂]·H₂O (8) and [CuLN₃]·CH₃OH (9) of 2-benzoylpyridine-N(4)-phenyl semicarbazone (HL) have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on the EPR studies, spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x²-y² orbital. The structure of the compound, [Cu₂L₂(OAc)₂] (1a) has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed monoclinic space group P2₁/n. The coordination geometry about the copper(II) in 1a is distorted square pyramidal with one pyridine nitrogen atom, the imino nitrogen, enolate oxygen and acetate oxygen in the basal plane, an acetate oxygen form adjacent moiety occupies the apical position, serving as a bridge to form a centrosymmetric dimeric structure.     

Syntheses,crystal structures,and spectral properties of Mn(II) and Co(II) complexes with 3-(p-chlorophenyl)- 4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole

Two new complexes, trans-[MnL₂(NCS)₂] (1) and trans-[CoL₂(H₂O)(EtOH)](ClO₄)₂?·?H₂O (2) with asymmetrical triaryltriazole ligands [L?=?3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole], have been synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray diffraction. In the complexes each L adopts a chelating bidentate mode via the nitrogen of pyridyl and triazole. Both complexes have a similar distorted octahedral core with two NCS^? ions in the trans position in 1, while one H₂O and one EtOH are present in the axial sites in 2.