Syntheses,topological networks and properties of four complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand

Reactions of metal acetates with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) and co-ligands gave rise to four new complexes, namely [Zn₂(3-abpt)(beta)(DMF) (H₂O)₂]_n·nH₂O (1), [Zn(3-abpt)(ip)]_n·3nH₂O (2), [Zn(3-abpt)(ip)(H₂O)₂]_n·2nH₂O (3), and [Cu₂(3-abpt)₂(C₆H₅COO)₄(H₂O)₂]_n·2nH₂O (4) (ip = isophthalate, beta = 1,2,4,5-benzenetetracarboxylate). Compound 1 is a 3D coordination polymer with uncommon 3,4-connected (6².8)₂(6².8².10²) network. Compounds 2–4 are all 1D coordination polymers, which exhibit diversity structures. Compound 2 is a tubular-like chain, 3 is a ring-like network, and 4 is a zigzag chain. Their thermal stabilities and the photoluminescence of 1 have also been investigated.     

Transition metal complexes of 2-amino-3-chloro-5-trifluoromethylpyridine: syntheses,structures, and magnetic properties of [(TMCAPH)2CuBr4] and [(TMCAPH)2CuCl4]

The reaction of CuX₂ (X = Br or Cl) with 2-amino-3-chloro-5-trifluoromethylpyridine in aqueous acids (HX; X = Br or Cl) yields bis(2-amino-3-chloro-5-trifluoromethylpyridinium)tetrabromocuprate(II) (1) and bis(2-amino-3-chloro-5-trifluoromethylpyridinium)tetrachlorocuprate(II) (2). These compounds have been characterized by IR, powder X-ray diffraction (XRD), single crystal XRD, combustion analysis, and temperature-dependent magnetic susceptibility. Compound 1 crystallizes in the monoclinic space group P2₁/c with three ions in the asymmetric unit, whereas 2 crystallizes in the triclinic space group P 1, and the asymmetric unit contains 18 ionic moieties. Both compounds exhibit antiferromagnetic exchange via the double halide exchange pathway and singlet ground states, with stronger exchange observed for 1. Both compounds exhibit multiple potential magnetic exchange pathways, but fitting of the data to available analytical models suggests that the magnetic exchange constants 2J/k _B are ～50 K in 1 and ～6 K in 2, respectively.     

Co(II) halide complexes with 2-amino-3-methylpyridinium and 2-amino-5-methylpyridinium: synthesis,crystal structures,and magnetic properties

Reaction of CoX₂ · nH₂O with either 2-amino-3-methylpyridine (3-MAP) or 2-amino-5-methylpyridine (5-MAP) in aqueous acid gave complexes, (3-MAPH)₂CoX₄ or (5-MAPH)₂CoX₄ (H₂O) _n [n = 0,1; X = Cl, Br; 3-MAPH = 2-amino-3-methylpyridinium, 5-MAPH = 2-amino-5-methylpyridinium]. The 3-MAPH salts are formed in the triclinic crystal system while the 5-MAPH salts are formed in the monoclinic crystal system. Three of these compounds exhibit weak antiferromagnetic interactions along with varying degrees of single-ion anisotropy, however, 1 shows easy-plane anisotropy and exhibits a mixture of ferromagnetic and antiferromagnetic interactions.     

Syntheses,crystal structures and magnetic study of two binuclear manganese(II) complexes with aromatic N-oxide as bridging ligand

Two new binuclear complexes, [Mn₂(μ-dmpo)₂(SCN)₄(H₂O)₂] (1) (where dmpo?=?3,5-dimethylpyridine N-oxide), [Mn₂(μ-po)₂(H₂O)₆I₂]I₂ (2) (where po?=?pyridine N-oxide), have been synthesized and their crystal structures determined by X-ray crystallography. Complexes 1 and 2 crystallize in monoclinic, space group P2₁/c, with unit cell dimensions a?=?8.8836(18)?Å, b?=?15.450(3)?Å, c?=?15.484(3)?Å, β?=?91.020(3)° for 1, and a?=?8.8352(13)?Å, b?=?17.927(3)?Å, c?=?8.3338(12)?Å, β?=?103.765(2)° for 2. In each binuclear complex two Mn(II) were bridged by two 3,5-dimethylpyridine N-oxides or by two pyridine N-oxides and the distances between the bridged Mn(II) ions are 3.599?Å for 1 and 3.552?Å for 2. Variable temperature (4–300?K) magnetic measurements were performed for 1 and the susceptibility data were fitted by using a binuclear Mn(II) magnetic coupling formula producing the 2J?=??2.17?cm^?1.     

Four Zn(II)/Cd(II)-3-amino-1,2,4-triazolate frameworks constructed by in situ metal/ligand reactions: Structures and fluorescent properties

Four Cd(II) and Zn(II) complexes with the in situ-generated ligand of 3-amino-1,2,4-triazolate (AmTAZ⁻) were isolated from the solvothermal reactions of the corresponding Cd(II) or Zn(II) salts with 5-amino-1H-1,2,4-triazole-3-carboxylic acid (AmTAZAc). Their structures were determined by single-crystal X-ray diffraction analysis. [Zn(AmTAZ)(CH₃COO)] (1) presents a two-dimensional framework constructed from Zn(II) ions and μ₃-AmTAZ⁻ ligands. A remarkable feature of [Zn₄(AmTAZ)₄(SO₄)(OH)(C₂O₄)_0.5]·2H₂O (2) is the construction of the building units of octagonal cylinders which interact with each other by sharing one face or overlapping, resulting in the formation of a three-dimensional framework with three kinds of 1D channels. [Cd(AmTAZ)Br] (3) crystallizes in a chiral space group P2₁2₁2₁, giving a homochiral three-dimensional framework with two types of helical channels (left- and right-handed). Different from the others, the 3-amino-1,2,4-triazole molecules in [Cd(AmTAZH)SO₄] (4) behave as neutral μ₂-2,4-bridges to connect the two-dimensional CdSO₄ sheets into a three-dimensional framework. Of all, 2 and 3 display different fluorescent properties probably due to different metal ions, coordination environments and structural topologies.     

Four anthraquinone-1,5-disulfonate-based metal complexes incorporating N-heterocyclic coligands: synthesis,crystal structures,and fluorescence

Four new anthraquinone-1,5-disulfonate (L)-based metal complexes with N,N-bidentate chelating coligands, {[Pb(phen)₂(L)]?·?4H₂O} _n (1), {[Mn₂(2,2′-bipy)₂(H₂O)₆(L)]?·?L?·?6H₂O} (2), [Co(phen)₂(H₂O)(L)] (3), and [Zn(phen)₂(H₂O)(L)] (4) (phen = 1,10-phenanthroline and 2,2′-bipy?=?2,2′-bipyridine), have been hydrothermally synthesized and were structurally characterized by single-crystal X-ray diffraction, elemental analyses, FT-IR spectra, thermogravimetric curves, and solid luminescence spectra. Structural analysis suggests that 1 is a polymeric 1D zigzag chain bridged by dianionic L. In contrast, the other three complexes have discrete centrosymmetric binuclear structure for 2 and isolated isomorphic mononuclear entities for 3 and 4, which are further assembled into 3D supramolecular networks by abundant hydrogen-bonding and/or π–π stacking interactions. Additionally, 2 and 4 exhibit favorable luminescent emissions, suggesting they are potential candidates for light emission materials.     

Trinuclear and dinuclear Ni(II) complexes constructed by bridging oxygen: crystal structures,magnetic, and thermal properties

The reaction of H₂L (N,N ′-bis(5-ethyl-1,3,4-thiadiazol-2-yl)-2,6-pyridinedicarboxamide) with Ni(II) salts gave crystals of two new complexes, [Ni₃(µ₃-O)(H₂L)(L)₂] · 2DMF (1) and [Ni₂(µ-H₂O)(CH₃OH)(DMF)(L)₂] · H₂O · CH₃OH (2). The complexes were characterized by elemental analysis, IR, thermal analysis, and X-ray single crystal diffraction. Complex 1 is a trinuclear complex containing a triangle frame in the center formed by three Ni(II) atoms with a bridging µ₃-O. Complex 2 is dinuclear formed by two Ni(II) atoms with a bridging H₂O. H₂L coordinates to metal centers as a pentadentate ligand in 1 and tetradentate in 2. Thermal analysis shows that the thermal stability of 1 is higher than that of 2. In addition, the magnetic properties of 2 are also reported.     

Copper(II), nickel(II) and cobalt(II) complexes of 4-cyanobenzonic acid: syntheses, crystal structures and spectral properties

Three new metal complexes, Cu(4-Hcba)₂(4-cba)₂(Py)₂ (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)₂]₂(Py)₂ (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO₃)₂ (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–HO for 1 and symmetrical OHO for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–Hπ interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out.     

Two 1-D and 2-D cobalt(II) complexes: synthesis,crystal structures,spectroscopic and electrochemical properties

Two new cobalt(II) complexes, [Co(L³)₂]·CH₃OH·CH₃COCH₃ (1) (HL³ = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime) and Co(L⁴)₂ (2) (HL⁴ = 1-(2-{[(E)-3,5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), have been synthesized via complexation of Co(II) acetate tetrahydrate with HL¹ and HL². HL¹, HL², and their corresponding Co(II) complexes were characterized by IR, ¹H NMR spectra, as well as by elemental analysis and UV–Vis spectroscopy, respectively. The crystal structures of the complexes have been determined by single-crystal X-ray diffraction. 1 and 2 display that extensive hydrogen bonds and C–X···π bonding interactions construct the 1-D infinite chain [Co(L³)₂]·CH₃OH·CH₃COCH₃ and Co(L⁴)₂ into 2-D supramolecular frameworks. The electrochemical properties of two Co(II) complexes were also investigated by cyclic voltammetry.     

Two 2-dimensional cadmium(II) coordination polymers with 3-amino-5-methylthio-1,2,4-triazolate ligand

Reactions of cadmium(II) salts with 3-amino-5-methylthio-1H-1,2,4-triazole (Hamstz) afforded two cadmium(II) coordination polymers, [Cd₂(amstz)₂Cl₂]_n (1) and [Cd₂(amstz)₂(NO₃)₂]_n (2). Compounds 1 and 2 feature 2-D layered structures based on the dinuclear [Cd₂(amstz)₂] subunits. The cadmium coordination polyhedra are tetrahedral and tetragonal pyramidal in 1 and 2, respectively, due to the presence of different coordinated anions, Cl^? and NO₃^?. Compounds 1 and 2 exhibit photoluminescence emission with maxima at 620 and 621 nm upon excitation at 470 and 472 nm, respectively, which can be attributed to the ligand-to-metal charge transfer emssion.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

Synthesis,crystal structure and magnetism of 1D cobalt(II) coordination polymer with thiocyanate as bridging ligand

A one-dimensional coordination polymer [Co(μ _1,3-NCS)₂(npdo)₂] _n (npdo?=?4-nitropyridine N-oxide) has been synthesized and structurally determined by X-ray crystallography. The complex crystallizes in the orthorhombic space group of Pbcn with a?=?22.688(5)?Å, b?=?7.2636(17)?Å, c?=?10.299(2)?Å. Adjacent Co(II) ions are coordinated by two μ _1,3-SCN^? bridging ligands, forming a one-dimensional chain along the c axis and the npdo coordinates to Co(II) ion as a terminal ligand. The thermal variation of the magnetic moments of the complex reflects the antiferromagnetic interaction between the bridged Co(II) ions above 20?K and the ferromagnetic transition or the strong short-range spin interaction below 20?K.     

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.     

Two cobalt(II) complexes based on 2-propyl-4,5-imidazoledicarboxylic acid: syntheses,crystal structures,and properties

Two complexes, [Co(H₂pimdc)₂(H₂O)₂]?·?2DMF (1) and [Co(H₂pimca)₂(H₂O)₂]?·?4H₂O (2), have been designed, synthesized, and characterized (X-ray single crystal analysis, thermal analysis, electrochemical analysis, and infrared spectrum) based on the imidazole ligand [H₃pimdc?=?2-propyl-4,5-imidazoledicarboxylic acid]. Both compounds have 3-D hydrogen-bonding networks. Because of different coordination of water, 1 forms a layer-like geometry via hydrogen bonds, but 2 forms a fishingnet-like latticed geometry via hydrogen bonds.     

Synthesis,structures and magnetic properties of copper (II) and cobalt (II) complexes containing pyridyl-substituted nitronyl nitroxide and 3,5-dinitrobenzoate

Four new metal-radical complexes - [Cu(NIT3Py)₂(DTB)₂] 1, [Co(NIT3Py)₂(DTB)₂(CH₃OH)₂] 2, [Cu(NIT4Py)₂(DTB)₂(H₂O)₂] 3, [Co(NIT4Py)₂(DTB)₂(H₂O)₂] 4, (NIT3Py = 2-(3^′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], NIT4Py = 2-(4^′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], DTB = 3,5-dinitrobenzoic anion) have been synthesized by using transition metal ions, nitronyl nitroxide radicals as spin carriers, and incorporating 3,5-dinitrobenzoic acid (DTB) as a coligand.     

Syntheses, crystal structures and magnetic properties of Ni(II)–2,4-pyridine-dicarboxylates

Two new complexes [Ni(pydc)(H₂O)₂]_n (1) and [Ni₂(pydc)₂(H₂O)₅]_n (2) (H₂pydc = 2,4-pyridinedicarboxylic acid) have been obtained by hydrothermal synthetic method and characterized by single crystal X-ray analysis. In 1 six-coordinate Ni(II) ions are coordinated by pydc ligands to form 2-D layer structures; while in 2 six-coordinate Ni(II) ions are only connected into 1-D zigzag chains constructed by dinuclear nickel units. Although the coordination geometries around Ni(II) centers in both complexes are similar, their structure topologies are greatly tuned by coordination modes of pydc. Variable temperature magnetic susceptibility studies have shown that both compounds 1 and 2 may display antiferromagnetic coupling between paramagnetic metal centers mediated by bridging carboxylate groups.     

Characterization and crystal structures of copper(II), cobalt(II), and nickel(II) complexes with two kinds of piperidine carboxylic acids

Copper(II) complex with -piperidine-3-carboxylic acid ( -Hpipe-3):[Cu( -pipe-3)₂(H₂O)] and cobalt(II) and nickel(II) complexes with piperidine-4-carboxylic acid (Hpipe-4):[M(Hpipe-4)₂(H₂O)₄]Cl₂ (M: Co, Ni) have been prepared and characterized by means of IR and powder diffuse reflection spectra, thermal analysis, and magnetic susceptibility. The crystal structures of these complexes have been determined by X-ray diffraction. The crystal of [Cu( -pipe-3)₂(H₂O)] is orthorhombic with the space group Pbcn. The copper atom is in a square pyramidal geometry, ligated by two carboxylato oxygen atoms, two nitrogen atoms, and a water molecule. One molecule of this complex consists of either -piperidine-3-carboxylic acid or -piperidine-3-carboxylic acid. The crystals of [M(Hpipe-4)₂(H₂O)₄]Cl₂ are monoclinic with space group P2₁/n. In these complexes the metal atom is in an octahedral geometry ligated by two carboxylato oxygen atoms and four water molecules.     

Three new polynuclear tetracarboxylato-bridged copper(II) complexes: Syntheses, X-ray structure and magnetic properties

The synthesis, crystal structure and magnetic measurements of three new polynuclear tetracarboxylato-bridged copper(II) complexes, i.e. {[Cu₄(phen)₂(μ-O₂CC₂H₅)₈] · (H₂O)}_n (1), [Cu₂(μ-O₂CC₆H₄OH)₄(C₇H₇NO)₂] · 6H₂O (2) and [Cu₂(μ-O₂CCH₃)₄(C₇H₇NO)₂] (3) (phen = 1,10-phenanthroline, O₂CC₆H₄OH = 3-hydroxy benzoate, C₇H₇NO = 4-acetylpyridine) are reported. All compounds consist of dinuclear units, in which two Cu(II) ions are bridged by four syn,syn-η¹:η¹:μ carboxylates, showing a paddle-wheel cage type with a square-pyramidal geometry, arranged in different ways. The structure of compound 1 consists of an one-dimensional structure generated by an alternating classical dinuclear paddle-wheel unit and an unusual dinuclear Cu₂(μ-OCOC₂H₅)₂(μ-O₂CC₂H₅)₂(phen)₂unit, which are connected to each other via a syn,anti-triatomic propionato bridge in an axial-equatorial configuration. The adjacent chains are connected to generate a 2D structure through the face-to-face π–π interaction between phen rings. Structures of compounds 2 and 3 both consist of a symmetric dinuclear Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of 4-acetylpyridine ligand at the apical position, and just differ in the substituents of the equatorial ligands.

The magnetic properties have been measured and correlated with the molecular structures. It is found that in the two classical paddle-wheel compounds the Cu(II) ions are strongly antiferromagnetically coupled with J = −278.5 and −287.0 cm⁻¹ for complexes 2 and 3, respectively. In compound 1 the magnetic susceptibility could be fitted with two different, independent Cu(II) units, one strongly coupled and one weakly coupled; the paddle-wheel dinuclear unit has the strongest antiferromagetic coupling with a value for J of −299.5 cm⁻¹, whereas the Cu(II) ions in the propionato-bridged dinuclear unit of 1 display a very weak antiferromagnetic coupling with a value for J = −0.75 cm⁻¹, due to the orthogonality of the magnetic orbitals. Also the exchange within the chain is therefore very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes.     

Synthesis,characterization, and crystal structures of cobalt(II), copper(II), and zinc(II) complexes of a bidentate iminophenol

A bidentate iminophenol (HL = 2-((4-methoxyphenylimino)methyl)-4,6-di-tert-butylphenol derived from condensation of 4-methoxyaniline and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) was mixed with divalent metal salts to form the corresponding mononuclear metal complexes [M^II(L)₂] (M = Co (1), Cu (2), and Zn (3)). The complexes are characterized by different spectroscopic and analytical tools. X-ray crystal structures of the complexes revealed homoleptic mononuclear complexes with MN₂O₂ coordination. The cobalt(II) (1) and zinc(II) (3) complexes display a pseudo-tetrahedral coordination geometry, whereas the copper(II) complex (2) exhibits a distorted square-planar coordination. The zinc(II) complex (3) emits at 460 nm with a twofold enhancement of emission with respect to the free iminophenol.     

Syntheses,crystal structures and thermal behavior of three Mn(II) complexes with 4-acyl pyrazolone derivatives

Three new manganese complexes, [Mn(PPeAP-INH)(CH₃OH)₂]_n(CHCl₃) (1) [PPeAP-INH=N-(1-phenyl-3-phenylethyl-4-ethylene-5-pyrazolone isoniazid, INH = isoniazid], [Mn₂(PM4MbP-INH)₂(CH₃OH)₄](CH₃OH) (2·CH₃OH), [PM4MbP-INH=N-(1-phenyl-3-methyl-4-(p-methylbenzoylene)-5-pyrazolone) isoniazid)] and [Mn₂(PPePeP-INH)₂(CH₃OH)₄] (3) [PPePeP-INH=N-(1-phenyl-3-phenylethyl-4-phenylethylene-5-pyrazolone) isoniazid] have been prepared, aiming at the formation of extended coordination polymer with Mn(II) ions. Formation of the corresponding manganese-ligand complexes has been monitored and characterized by chemical and spectroscopic techniques. X-ray diffraction analyses of available single crystals revealed 1D polymeric patterns of supramolecular system. Among them, the dimers of 2 and 3, bridged by two methanol molecules, are extended by hydrogen bond of O–H···N to form the 1D chain. In these three new complexes which are all octahedral coordination environments, the N(5) atom of the pyridine heterocycles plays a very important role in building the bridged polymeric chain.