Synthesis, crystal structures and spectroscopic properties of two novel oxamido-bridged trinuclear complexes [Cu2M] (M = Cu, Zn)

Based on the complex ligand CuL (H₂L = 2,3-dioxo-5,6:14,15-dibenzo-7,13-diphenyl-1,4,8,12-tetraazacyclo-pentadeca-7,13-diene), two novel oxamido-bridged trinuclear complexes have been prepared. They are of the formula Cu(CuL)₂(ClO₄)₂ · 4C₂H₅OH (1) and [(CuL)₂Zn(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH (2). The crystal structures of the two complexes have been determined by X-ray crystallography. In complex (1), the central Cu is in a complete square-planar environment, bonding to four oxygen atoms of the oxamido macrocyclic ligand, while in complex (2), the Zn center is six-coordinate in an octahedral geometry, the four oxygen donors from macrocyclic ligand form the basal plane and the axial positions are occupied by other oxygen atoms from C₂H₅OH molecules. The spectroscopic properties have been investigated and the EPR spectra have been simulated by WINEPR and SimFonia programs.     

Structure and Magnetism of two Polynuclear Complexes Containing both Macrocyclic and Azido Ligands

The two complexes of formula [Cu₂(CuL)₂(μ‐N₃)₄] · 2CH₃OH ( 1 ) and [Cu₂(NiL)₂(μ‐N₃)₄] · 2CH₃OH ( 2 ) (CuL and NiL, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐dien), were synthesized and structurally determined. The magnetic susceptibility data of 1 and 2 were analyzed. For complex 1 , magnetic measurements show alternating ferromagnetic and antiferromagnetic exchange couplings J₁ = 23.67 cm^–1, J₂ = –189.11 cm^–1, zJ’ = –0.62 cm^–1. For complex 2 , the doubly bridged asymmetric EO promotes a ferromagnetic interaction between Cu^II and Cu^II ions(J = 40.764 cm^–1).     

Heterometallic Polynuclear Complexes of Macrocyclic ­Oxamide with Pyrazine‐2, 3‐dicarboxylic Acid: Synthesis,Crystal Structure,and Magnetic Properties

Three novel complexes, namely [Zn(CuL)(pzdc)]₂ · 5H₂O ( 1 ), [Zn(NiL)(pzdc)]₂ · 5H₂O ( 2 ), and [Gd₂(pzdc)₂(NiL)₆](ClO₄)₂ · 6H₂O ( 3 ) (CuL and NiL, H₂L = 2, 3‐dioxo‐5, 6, 14, 15‐dibenzo‐1, 4, 8, 12‐tetraazacyclo‐pentadeca‐7, 13‐dien and H₂pzdc = pyrazine‐2, 3‐dicarboxylic acid) were synthesized and structurally determined. Complexes 1 and 2 are tetranuclear [Zn^II₂M^II₂] (M = Ni ( 1 ), Cu ( 2 ), respectively) molecules including both oxamide and pzdc^2– bridges. The structure of compound 3 consists of pyrazine‐2, 3‐dicarboxylate and oxamido‐bridged, and is arranged in different butterfly‐like octanuclear molecules. The magnetic susceptibility data of 3 were analyzed.     

Synthesis,structure and properties of a binuclear complex {[Mn(bpy)2(CuL)(H2O)2](ClO4)2} and its CuL precursor (H2L = 2,3-dioxo-5,6 : 14,15-dichlorobenzo-7,13-diphenyl-1,4,8,12-tetraazacyclo-pentadeca-7,12-diene)

A binuclear complex {[Mn(bpy)₂(CuL)(H₂O)₂](ClO₄)₂} (2) and its CuL (1) precursor (H₂L?=?2,3-dioxo-5,6?:?14,15-dichlorobenzo-7,13-diphenyl-1,4,8,12-tetraazacyclo-pentadeca-7,12-diene; bpy?=?2,2′-dipyridyl) have been synthesized and characterized structurally. Complex 1 consists of the neutral [CuL] fragments and methanol molecules. In complex 2, [Mn(bpy)₂(CuL)]²⁺ cation, two water molecules and two perchloric anions make up of the crystal. Mn(II) is coordinated by four nitrogen atoms from two 2,2′-dipyridyl and two oxygen atoms from the Cu(II) precursor. Magnetic characterization of 2 exhibits an antiferromagnetic interaction between Cu(II) and Mn(II) ions, with J?=??74.1?cm^?1.     

Synthesis,Structure and Luminescence of Cd3Cu2 and Cd2Ni4 Heteronuclear Complexes with Macrocyclic Oxamide and 5‐Sulfosalicylicate

Two novel heteronuclear complexes [Cd₃(SSAL)₂(CuL)₂(H₂O)₄]_n ( 1 ) and [Cd₂(HSSAL)₂(NiL)₄] · 4H₂O ( 2 ) were synthesized and structurally determined, where SSAL is the fully deprotonated 5‐sulfosalicylic ion (CuL and NiL, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclopentadeca‐7,13‐diene). Compound 1 displays a 1D ladder‐like chain and all these chains are further interlinked through hydrogen bonds resulting in a 2D architecture. The structure of 2 consists of 5‐sulfosalicylates and an oxamido‐bridge and is arranged in butterfly‐like hexanuclear molecules. The luminescent properties of compounds 1 and 2 are also discussed.     

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.     

Two 3d‐4f Heterometallic Coordination Polymers of Macrocyclic Oxamide with Benzotriazole‐5‐carboxylate Co‐ligand: Syntheses,Crystal Structures and Magnetic Properties

Two heterometallic 3d–4f coordination polymers, [Gd(CuL)₂(Hbtca)(btca)(H₂O)] · 2H₂O ( 1 ) and [Er(CuL)₂(Hbtca)(btca)(H₂O)] · H₂O · CH₃OH ( 2 ) (CuL, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐dien; H₂btca = benzotriazole‐5‐carboxylic acid) were synthesized by solvothermal methods and characterized by single‐crystal X‐ray diffraction. Complexes 1 and 2 exhibit a double‐strand meso‐helical chain structures formed by [Ln^IIICu^II₂] (Ln^III = Gd, Er) units by oxamide and benzotriazole‐5‐carboxylate bridges. They are isomorphic except that one free water molecule of 1 is replaced by a methanol molecule. All 1D chains are further interlinked by hydrogen bonds resulting in a 3D supramolecular architecture. The magnetic properties of the compound 1 and 2 are also discussed.     

[Cu(phen)2(μ‐IDA)Cu(phen)](ClO4)2·CH3OH: tridentate and monodentate binding to two copper(II) species by a bridging ligand

The stoichiometric reaction of 1,10‐phenanthroline (phen), imino­di­acetic acid (IDA‐H₂) and Cu(ClO₄)₂ in a H₂O–CH₃OH (2:1) solution yields μ‐imino­diacetato‐2:1κ⁴O,N,O′:O′′‐tris(1,10‐phenanthroline)‐1κ⁴N,N′;2κ²N,N′‐dicopper(II) diperchlorate methanol solvate, [Cu₂(C₄H₅NO₄)(C₁₂H₈N₂)₃](ClO₄)₂·CH₃OH. The IDA ligand bridges the two Cu^II ions via a carboxyl­ate group and uses one further N and an O atom of the second carboxylate group to complete a fac‐tridentate coordination at one Cu centre. A phen ligand completes a distorted square‐pyramidal coordination at this metal atom, although there is weak coordination by a perchlorate O atom at a sixth position. The second Cu centre has a distorted trigonal–bipyramidal coordination to two phen moieties and a carboxyl­ate O atom.     

Syntheses,Crystal Structure,and Magnetic Properties of a Self‐assembling Dicopper(II) Helicate with Novel Bipyridine Ligand

A novel double helical dicopper(II) complex was synthesized by reaction of a polydentate ligand L = 2,2′‐bipyridyl‐6,6′‐bis(2‐acetylpyrazinohydrazone) with copper(II) perchlorate in CH₃CN. The self‐assembling process was studied by UV‐Vis spectrometric titration experiments which revealed the formation of dinuclear complexes [Cu₂L₂](ClO₄)₄. The structure of dicopper double‐helicate was confirmed by X‐ray diffractometry. Each copper(II) center occupies a distorted octahedral environment. Variable‐temperature magnetic measurements reveal weak antiferromagnetic interactions between Cu(II) ion centers with J = ?0.63 cm^?1.     

Synthesis,crystal structure and magnetic properties of [(LCu)(MeOH)Cu(phen)-(MeOH)]ClO4·NO3 (H2L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclo-pentadeca-7,13-diene)

A dinuclear copper(II) [(LCu)(MeOH)Cu(phen)(MeOH)]ClO₄·NO₃ macrocyclic complex (where H₂L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclo-pentadeca-7,13-diene; phen = 1,10-phenanthroline) has been synthesized and characterized by means of elemental analysis and its i.r. spectrum. Its crystal structure has been determined by single-crystal X-ray diffraction. In the complex, both the copper ions are penta-coordinated and have a distorted square pyramid configuration. Magnetic susceptibility measurements show antiferromagnetic exchange interactions (J = –207.64 cm^–1) between the copper(II) ions.     

Two new tetranuclear complexes of the macrocyclic oxamide [MCu3] (M = Cd, Mn, macrocyclic oxamide = 1,4,8,11-tetraazacyclotradecanne-2,3-dione): syntheses, spectra and magnetic properties

Two new tetranuclear complexes of macrocyclic oxamide [Cd(CuL)₃](NO₃)₂·2.5H₂O 1, [Mn(CuL)₃(OH)₂](ClO₄)₂·Mn(H₂O)₆·4.5H₂O 2 (L = 1,4,8,11-tatraazacyclotradecanne-2,3-dione) have been synthesized, structurally characterized and preliminary investigated by magnetic studies. The structures of the title complexes consist of a tetranuclear units MCu₃ (M = Cd, Mn), the packing diagram shows two-dimensional and three-dimensional system through intermolecular weak interactions. The temperature-dependent magnetic susceptibilities of complex 2 were analyzed by an approximate treatment leading to J = −33 cm⁻¹, g_Cu = 2.10, g_Mn = 1.95 indicating antiferromagnetic exchange between Cu(II) and Mn(II) ions.     

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.     

Synthesis,Structure, and SOD‐like Activity of a Copper(II) Complex Containing a Bistriazole Group

The dinuclear complex [Cu₂(HL)₂(H₂O)₂](ClO₄)₂ ( 1 ) [H₂L = 5′‐(pyridin‐2‐yl)‐1‐H,2′‐H‐3, 3′‐bis(1, 2,4‐triazole)] was obtained and fully characterized. It exhibits a centrosymmetry configuration, in which each copper(II) ion is pentacoordinate with four nitrogen atoms of two triazole ligands and one oxygen atom from a water molecule. The net atomic charges distribution and atomic orbital contribution to frontier molecular orbitals were obtained using the Gaussian 98 program with Hartree‐Fock method at LANL2DZ level, indicating that the copper(II) ion has the potential to accept the electron of O₂ ^{· –}. The complex showed quasi‐reversible one‐electron Cu^II/Cu^I redox waves with redox potentials of –0.034 V. The SOD‐like activity (IC₅₀) of 1 was measured to be 0.18 ± 0.01 μM by xanthine/xanthine oxidase‐NBT assay at pH 7.8. The relatively high SOD activity suggests that the positive charge of protonated triazole can effectively steer O₂ ^{· –} to and from the active copper ion.     

Magnetic Exchange Interactions in Dinuclear Copper(II) and Nickel(II) Complexes with μ‐Oxalato Bridges. The Structure of μ‐Oxalato(O,O′, O″, O‴)‐bis{[1, 8‐di(2‐pyridyl)‐3, 6‐dithiaoctane‐N,N′, S,S′]nickel(II)} Dinitrate Dihydrate

A copper(II) and two nickel(II) dinuclear oxalato‐bridged compounds of formulae [{Cu(bpdto)}₂(μ‐ox)](ClO₄)₂ ( 1 ), [{Ni(bpdto)]₂(μ‐ox)](ClO₄)₂( 2 ), and [{Ni(bpdto)}₂(μ‐ox)](NO₃)₂·2H₂O ( 3 ), where bpdto = 1, 8‐bis(2‐pyridyl)‐3, 6‐dithiaoctane and ox = oxalate = C₂O₄^2— anion, have been synthesized and characterized. The crystal structure of 3 was determined by single‐crystal X‐ray analysis. It is a dinuclear complex with i symmetry in which the oxalate ligand is coordinated in bis(didentate) fashion to the inversion centre‐related nickel atoms. The distorted octahedral environment of each nickel atom is completed by two sulphur atoms in the equatorial plane and by two pyridyl nitrogen atoms in axial positions. Magnetic susceptibility measurements over the range 5 — 299K, show antiferromagnetic interactions that are weak in 1 (J = —12.8 cm^—1) and strong in 2 and 3 (J = —37.8 and —40.9 cm^—1, respectively), which in the case of 3 is in keeping with the observed structural parameters.     

The synthesis,crystal structures and antimicrobial studies of C‐methyl‐substituted hexaaza macrocycle of Cu(II) having aromatic pendant arm

Cu(II) complexes of 14‐membered hexaaza macrocyclic ligand with C‐methyl substituent of the type [CuL](X)₂ (where L = 3,10‐bisbenzyl‐6,13‐dimethyl‐1,3,5,8,10,12‐hexaazacyclotetradecane, and X = ClO₄⁻, PF₆⁻) were synthesized by tandem reaction. They were characterized by spectral and single‐crystal X‐ray diffraction techniques. The complexes show distorted octahedral geometry and the counter ions are weakly coordinated to the metal ion at the axial positions. The macrocyclic ring adopts the trans‐III configuration with six‐ and five‐membered chelate rings in chair and gauche conformation, respectively. It was observed that in the solid state the arrangement of the coordination sphere is distorted octahedral whereas, in solution, a square‐planar structure is predominant. The molar conductance of the complexes indicates that the axially bonded anions are almost dissociated in acetonitrile solution. The Electron Paramagnetic Resonance (EPR) spectrum of complex 1 is axial and consistent with a d_x² − _y² ground state. The [CuL](ClO₄)₂ was found to be active against the tested microorganism. Copyright © 2011 John Wiley & Sons, Ltd.     

A New Dinuclear Copper (II) Complex of a Bis‐macrocyclic Ligand: Synthesis,Characterization, Crystal Structure and Magnetic Properties

A new dinuclear Cu(II) complex, [Cu₂L(N₃)₂](ClO₄)₁.₅ (OH)_4.5 · 2H₂O 0.5C₂H₅OH (1), of a bis‐macrocyclic ligand, 2,6‐bis(l,4,7,10‐tetraazacyclododecan‐10‐ylmethyl)‐methoxybenzene (L), has been synthesized, characterized and structurally determined by X‐ray diffraction analysis. Complex 1 crystallizes in orthorhombic crystal system, Pca2(l) space group with a = 1.5371(3), b = 1.6641(3), c = 3.0950(6) nm, V = 7.917(3) nm³, F_w = 904.62, Z=8, D_c= 1.529 g/cm³ and final R = 0.0568, wR = 0.1406 for 10410 observed reflections with I≥2σ (I). Both Cu(II) centers in the structure are coordinated by four nitrogen atoms of 1,4,7, 10‐tetraazacyclododecane (cyclen) and a nitrogen donor of the axial azide anion. Each Cu(II) center is in a square‐pyramidal coordination environment, and the intra‐and nearest inter‐molecular Cu? Cu nonbonding distances are 0.9855 and 0.7298 nm, respectively. Variable temperature magnetic susceptibility measurements in the range of 4.2–300 K indicate mat there exists weak intra‐ and inter‐molecular antiferromagnetic coupling between the Cu(II) centers with 27= ?4.2 cm^?1 and Θ = ?0.47 K.     

Tris(2,2′‐bioxazoline‐κ2N,N′)copper(II) diperchlorate and tris(2,2′‐bioxazoline‐κ2N,N′)­nickel(II) diperchlorate

In the two isomorphous title compounds, viz. tris­[2,2′‐bi(4,5‐di­hydro‐1,3‐oxazole)‐κ²N,N′]copper(II) diperchlorate, [Cu(C₆H₈N₂O₂)₃](ClO₄)₂, (I), and tris­[2,2′‐bi(4,5‐di­hydro‐1,3‐oxazole)‐κ²N,N′]­nickel(II) diperchlorate, [Ni(C₆H₈N₂O₂)₃](ClO₄)₂, (II), the M^II ions each have a distorted octahedral coordination geometry formed via six N atoms from three 2,2′‐bioxazoline ligands. For each ligand, the two five‐membered rings are nearly coplanar. It is noteworthy that the Jahn–Teller effect is stronger in (I) than in (II). The three‐dimensional supramolecular structures of (I) and (II) are formed via weak hydrogen‐bonding interactions between O atoms from per­chlorate anions and H atoms from 2,2′‐bioxazoline ligands.     

Synthesis,structure and magnetism of a hydrogen-bond-linked three-dimensional network of a novel nickel(II)–cobalt(II)–nickel(II) complex containing a new macrocyclic mononuclear complex ligand

A novel trinuclear complex, [Co(NiL)₂(H₂O)₂](ClO₄)₂ · 2C₂H₅OH, was prepared by self-assembly using [NiL] as a new complex ligand; L is the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. The structure of the trinuclear complex was determined by X-ray crystallography. The Co^II ion is at the center of the trinuclear complex cation and occupies a distorted octahedral O₆ environment, approximating to O _h with a ⁴ T _1g ground state for Co^II that has an unquenched spin–orbit coupling reflected in the magnetic properties. Two Ni^II ions reside in completely same and slightly distorted square-planar N₄ coordination geometries. Co^II and each Ni^II are bridged by an oxamido group from one of the two macrocyclic ligands (L). O—H...O and ... interactions link the trinuclear fragments, perchlorate ions and C₂H₅OH molecules to form a three-dimensional supramolecular architecture.     

Spin topology and ferromagnetic coupling: synthesis and magnetic properties of [CuII3CrIII] tetranuclear complexes of [14]N4 macrocyclic oxamides

Three novel tetranuclear macrocyclic complexes, [(CuL¹)₃Cr](ClO₄)₃·3H₂O (1), [(CuL²)₃Cr](ClO₄)₃·3H₂O (2) and [(CuL³)₃Cr](ClO₄)₃·3H₂O (3) [L¹, L² and L³ are the dianions of three [14]N₄ and [15]N₄ macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene,2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene, respectively], have been prepared and characterized. These complexes are the first examples of Cu₃Cr species exhibiting spin topology with all the spins parallel in the ground state. Cryomagnetic studies on (1) (2–300 K) and (3) (77–300 K) revealed that the Cu^II and Cr^III ions interact ferromagnetically through the oxamido bridge, with the exchange integral J = 6.7 cm^–1 for (1) and J = 6.3 cm^–1 for (3) based on = –2J _{i j} . The ferromagnetic interaction has been rationalized in terms of strict orthogonality of the magnetic orbitals. The oxamido bridge is also more efficient than the oxalato bridge at propagating the ferromagnetic interaction.     

Heterometallic Trinuclear Complexes of Macrocyclic Oxamide: Synthesis,Crystal Structures,and Magnetic Properties

Two heterometallic trinuclear complexes of macrocyclic oxamide [Co(Ni L¹ )₂ L² (H₂O)] · 3H₂O ( 1 ) and [Mn(Ni L¹ )₂ L² (H₂O)] · 0.5CH₃OH · 1.5H₂O ( 2 ) (H₂ L¹ = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclopentadeca‐7,13‐diene, H₂ L² = 5‐sulfosalicylic acid) were synthesized and structurally characterized by elemental analysis, IR spectroscopy, and X‐ray diffraction. Single‐crystal X‐ray analyses reveal that both the complexes contain discrete neutral trinuclear [(Ni L¹ )₂M L² (H₂O)] (for 1 and 2 , M = Co, Mn, respectively) moieties. The structures of 1 and 2 have oxamido‐bridged trinuclear [M^IINi^II₂] units and consist of one‐dimensional chains formed by strong intermolecular hydrogen bonds. Furthermore, the magnetic properties of complex 1 were investigated and discussed in detail.