Synthesis,Crystal Structure,Thermal, Spectroscopic and Magnetic Properties of a 2D Grid‐like Copper(II) μ‐1,1 Isocyanato Coordination Polymer with Pyrazine Bridges

Reaction of copper(II) cyanate with pyrazine leads to the formation of [Cu(NCO)₂(pyrazine)]_n ( 1 ), in which the Cu²⁺ cations are coordinated by two nitrogen atoms of the pyrazine ligands, as well as by four nitrogen atoms of the cyanate anions within a slightly distorted octahedral coordination. In the crystal structure the Cu²⁺ cations are connected by the pyrazine ligands into chains which are further linked by the cyanate anions through asymmetric μ‐1,1‐NCO coordination into layers. On heating compound 1 transforms quantitatively to copper(II) cyanate which decompose to elemental copper on further heating. No ligand deficent intermediates are observed. Magnetic measurements reval an antiferromagnetic ordering at lower temperatures mediated by the π‐system of the aromatic pyrazine ligand as well as net ferromagnetic interactions mediated by the μ‐1,1‐NCO bridging cyanato anions. A search in the Cambridge Crystal Structure Database shows that the terminal coordination mode in cyanato complexes as well as their azido and thiocyanato analogs is obviously energetically favored. In addition, a comparison of their symmetric and asymmetric end‐on (μ‐1,1) as well as end‐to‐end (μ‐1,3) bridging modes reveal interesting correlations.     

Synthesis,Crystal Structures,and Thermal Properties of New Zinc(II) Thiocyanato Coordination Compounds

Reaction of zinc(II) thiocyanate with pyrazine, pyrimidine, pyridazine, and pyridine leads to the formation of new zinc(II) thiocyanato coordination compounds. In bis(isothiocyanato‐N)‐bis(μ₂‐pyrazine‐N,N) zinc(II) ( 1 ) and bis(isothiocyanato‐N)‐bis(μ₂‐pyrimidine‐N,N) zinc(II) ( 2 ) the zinc atoms are coordinated by four nitrogen atoms of the diazine ligands and two nitrogen atoms of the isothiocyanato anions within slightly distorted octahedra. The zinc atoms are connected by the diazine ligands into layers, which are further linked by weak intermolecular S ··· S interactions in 1 and by weak intermolecular C–H ··· S hydrogen bonding in 2 . In bis(isothiocyanato‐N)‐bis(pyridazine‐N) ( 3 ) discrete complexes are found, in which the zinc atoms are coordinated by two nitrogen atoms of the isothiocyanato ligands and two nitrogen atoms of the pyridazine ligands. The crystal structure of bis(isothiocyanato‐N)‐tetrakis(pyridine‐N) ( 4 ) is known and consists of discrete complexes, in which the zinc atoms are octahedrally coordinated by two thiocyanato anions and four pyridine molecules. Investigations using simultaneous differential thermoanalysis and thermogravimetry, X‐ray powder diffraction and IR spectroscopy prove that on heating, the ligand‐rich compounds 1 , 2 , and 3 decompose without the formation of ligand‐deficient intermediate phases. In contrast, compound 4 looses the pyridine ligands in two different steps, leading to the formation of the literature known ligand‐deficient compound bis(isothiocyanato‐N)‐bis(pyridine‐N) ( 5 ) as an intermediate. The crystal structure of compound 5 consists of tetrahedrally coordinated zinc atoms which are surrounded by two isothiocyanato anions and two pyridine ligands. The structures and the thermal reactivity are discussed and compared with this of related transition metal isothiocyanates with pyrazine, pyrimidine, pyridazine, and pyridine.     

Thermal Decomposition Reactions for the Exploration of New Coordination Polymers based on Mn(NCS)2 and Pyridazine

Reaction of different ratios of manganese(II) thiocyanate with pyridazine in water at room temperature leads always to the formation of the pyridazine‐rich 1:4 compound (1:4 = ratio between metal and neutral co‐ligand) Mn(NCS)₂(pyridazine)₄ ( 1 ). In the crystal structure of 1 , the Mn²⁺ cations are coordinated by two nitrogen atoms of terminal N‐bonded thiocyanato anions and four nitrogen atoms of pyridazine ligands within slightly distorted octahedra. However, in one reaction single crystals of the new compound Mn₃(NCS)₆(pyridazine)₄(H₂O) · (pyridazine) ( 2 ) were obtained. In its crystal structure the manganese atoms are linked into chains by µ‐1, 3 and µ‐1, 1 bridging thiocyanato anions as well as bridging pyridazine ligands. Heating rate dependent DTA‐TG measurements of 1 reveal a multi‐step thermal decomposition, in which three new pyridazine‐deficient compounds of composition Mn(NCS)₂(pyridazine)₃ ( 3 ), Mn(NCS)₂(pyridazine)₂ ( 4 ) and Mn(NCS)₂(pyridazine) ( 5‐Mn ) are formed. IR‐spectroscopic investigations indicate that on heating more condensed coordination networks with µ‐1, 3‐ and µ‐1, 1‐bridging thiocyanato anions has formed. Magnetic measurements show only Curie‐Weiss paramagnetism for compounds 1 , 3 and 4 , whereas in the 1:1 compound 5 an antiferromagnetic ordering is observed at T_N = 14 K. Surprisingly, the most pyridazine deficient compound 5 transforms into 2 after storage for several weeks.     

Syntheses,Structures, and Thermal Reactivity of New ZnII and CdII Thio‐ and Selenocyanato Coordination Compounds

Reaction of Zn^II and Cd^II thiocyanate or selenocyanate with pyrazine leads to the formation of new Zn^II and Cd^II coordination compounds. The structures of [Zn(NCSe)₂(pyrazine)₂]_n ( 1A ), [Cd(NCS)₂(pyrazine)₂]_n ( 2A ) and [Cd(NCSe)₂(pyrazine)₂]_n ( 3A ) consist of octahedrally coordinated metal cations which are surrounded by two terminal N‐bonded anions and two μ₂‐bridging pyrazine molecules. The metal cations are connected via the pyrazine ligands into layers, which are further linked by weak intermolecular S···S respectively Se···Se interactions. Investigations on the thermal degradation behavior of 1A , 2A , and 3A using simultaneous differential thermoanalysis and thermogravimetry as well as X‐ray powder diffraction, IR‐ and Raman spectroscopy prove that on heating, the pyrazine‐rich compound 1A decomposes in one step into zinc selenocyanate without the formation of a pyrazine‐deficient intermediate. In contrast, for compounds 2A and 3A a stepwise decomposition is observed, leading to the formation of the pyrazine‐deficient compounds [Cd(NCS)₂(pyrazine)]_n ( 2B‐I and 2B‐II ) and [Cd(NCSe)₂(pyrazine)]_n ( 3B ) as intermediates. The structures and the thermal reactivity are discussed and compared with that of related transition metal thiocyanates and selenocyanates with pyridine as N‐donor ligand.     

Synthesis,Structure and Magnetic Properties of Two Cobalt(II) Dicyanamide (dca) Complexes with Heterocyclic Nitrogen Donors Tetra(2‐pyridyl)pyrazine (tppz) and 2,4,6‐Tri(2‐pyridyl)‐1,3,5‐triazine (tptz): [Co2(tppz)(dca)4]·CH3CN and [Co(tptz)(dca)(H2O)](dca)

Two new transition metal dicyanamide complexes [Co₂(tppz)(dca)₄]·CH₃CN ( 1 ) [tppz=tetra(2‐pyridyl)pyrazine, dca=dicyanamide] and [Co(tptz)(dca)(H₂O)](dca) ( 2 ) [tptz=2,4,6‐tri(2‐pyridyl)‐1,3,5‐triazine] were synthesized and characterized by single crystal X‐ray diffraction analysis. In 1 each cobalt(II) atom is coordinated to three dca anions and one tppz molecule to form a distorted octahedral geometry, the neigbour two cobalt(II) atoms are bridged by one tppz ligand to form a dimer, then the cobalt(II) atoms in each dimer are joined together to form a ladder chain structure. In 2 the coordination geometry around the central metal is also distorted octahedral, each cobalt(II) atom is coordinated by two dca anions, one tptz molecule and one water ligand to form a cationic part, and the cationic part is linked with the free dca anions via the electrostatic attraction to give an infinite chain structure. Magnetic susceptibility measurement in the range of 2–300 K indicates that there are antiferromagnetic couplings between adjacent metal ions in 1 (T>29 K, (=?9.78 K, C=4.92 cm³·K·mol^?1) and ferromagnetic couplings in 2 (T>150 K, (=7.97 K, C=2.59 cm³·K·mol^?1) respectively.     

Metamagnetism and Single‐Chain Magnetic Behavior in a Homospin One‐Dimensional Iron(II) Coordination Polymer

Reaction of FeCl₂?4 H₂O with KNCSe and pyridine in ethanol leads to the formation of the discrete complex [Fe(NCSe)₂(pyridine)₄] ( 1 ) in which the Fe^II cations are coordinated by two N‐terminal‐bonded selenocyanato anions and four pyridine co‐ligands. Thermal treatment of compound 1 enforces the removal of half of the co‐ligands leading to the formation of a ligand‐deficient (lacking on neutral co‐ligands) intermediate of composition [Fe(NCSe)₂(pyridine)₂]_n ( 2 ) to which we have found no access in the liquid phase. Compound 2 is obtained only as a microcrystalline powder, but it is isotypic to [Cd(NCSe)₂(pyridine)₂]_n and therefore, its structure was determined by Rietveld refinement. In its crystal structure the metal cations are coordinated by two pyridine ligands and four selenocyanato anions and are linked into chains by μ‐1,3 bridging anionic ligands. Magnetic measurements on compound 1 show only paramagnetic behavior, whereas for compound 2 an unexpected magnetic behavior is found, which to the best of our knowledge was never observed before for a iron(II) homospin compound. In this compound metamagnetism and single‐chain magnetic behavior coexist. The metamagnetic transition between the antiferromagnetically ordered phase and a field‐induced ferromagnetic phase of the high‐spin iron(II) spin carriers is observed at a transition field H_C of 1300 Oe and the single‐chain magnetic behavior is characterized by a blocking temperature T_B, estimated to be about 5 K.     

Crystal Growth,Structure, and Magnetic Properties of a Two‐dimensional Triangular Lattice Magnet,Cu2(OH)3HCO2

We prepared single crystals of basic copper formate Cu₂(OH)₃HCO₂ ( 1) by hydrolysis of formate anions in an aqueous solution of copper formate. X‐ray structure analysis showed that this material has a two‐dimensional triangular lattice network with S=1/2. The temperature dependence of magnetic susceptibility revealed antiferromagnetic ordering at 5.4 K. A spin‐flop transition was observed at about 20 kOe at 2 K, thereby indicating metamagnetic‐like behavior. The saturation magnetization was almost one‐half of the theoretical value at 2 K under 70 kOe. The magnetic behaviors of 1 were also discussed with regard to its crystal structure. The preparation method presented herein is convenient and available for single crystal growth of metal hydroxide derivatives with various anions.     

Three New Iron(II) Thiocyanato Coordination Polymers Based on 4,4′‐Bipyridine as Ligand and the Influence of Methanol on Their Structures

Reaction of iron(II) thiocyanate with 4,4‐bipyridine (bipy) in methanol leads to the formation of three new solvates of different composition depending on the reaction conditions: At room temperature two new ligand‐rich 1:2 (1:2 = ratio between metal and N‐donor ligand) polymorphic forms [Fe(NCS)₂(bipy)₂ · 2MeOH]_n ( 1I ) and [Fe(NCS)₂(bipy)(MeOH)₂ · (bipy)]_n ( 1II ) are obtained, whereas solvothermal conditions leads to the formation of the new ligand‐deficient 1:1 compound [{Fe(NCS)₂(bipy)(MeOH)}₂]_n ( 2 ). All crystal structures were determined by X‐ray single crystal structure analysis. In the crystal structure of modification 1I the metal atoms are coordinated by four bridging bipy ligands, which connect them into layers. The methanol molecules occupy voids in the structure. Compared to 1I in modification 1II the crystal structure contains of linear Fe–bipy–Fe chains, which are further connected by hydrogen bonds between coordinating MeOH and noncoordinated bipy ligands into layers. The ligand‐deficient 1:1 compound 2 shows a completely different coordination topology with linear Fe–bipy–Fe chains, which are connected by coordinating methanol molecules into double‐chains. In all compounds the thiocyanato anions are terminal N‐bonded to the metal atoms. Investigation of the thermal behavior of compound 1I shows a two‐step decomposition, in which ligand‐deficient intermediates are formed. Magnetic measurements on 1I reveal Curie–Weiss paramagnetism with increasing antiferromagnetic interactions on cooling.     

Dimorphic Modification of the Trinuclear Nickel(II) Complex [Ni3(NCS)6(pdz)6]: Synthesis,Crystal Structure,Thermal, Magnetic and Spectroscopic Properties

Reaction of nickel(II) thiocyanate and pyridazine (pdz) as organic spacer ligand leads to the formation of the ligand‐rich 1:2 (1:2 = metal to ligand ratio) trinuclear nickel(II) complex of composition [Ni₃(NCS)₆(pdz)₆]. Depending on the reaction solvent, different polymorphic modifications are obtained: Reaction in acetonitrile leads to the formation of the new modification 1I and reaction in ethanol leads to the formation of modification 1II reported recently. In their crystal structures discrete [Ni₃(NCS)₆(pdz)₆] units are found, in which each of the Ni²⁺ cations exhibits a NiN₆ distorted octahedral arrangement. The central Ni²⁺ cation is coordinated by four bridging pdz ligands and two thiocyanato anions in trans positions. Both thiocyanato anions exhibit the end‐on bridging mode. The peripheral Ni²⁺ cations are bridged by one thiocyanato anion and by two pdz ligands with the central Ni²⁺ cation. Further they are coordinated by two terminal N‐bonded thiocyanato anions and one terminal N‐bonded pdz ligand. The structure of 1I was determined by X‐ray single crystal structure investigation and emphasized by infrared spectroscopy. Magnetic measurements revealed a quasi Curie behavior with net ferromagnetic interactions for 1I and net antiferromagnetic interactions for 1II . Solvent‐mediated conversion experiments clearly show that modification 1I represents the thermodynamic most stable form at room temperature and that modification 1II is metastable. On thermal decomposition, both modification transform quantitatively in a new ligand‐deficient intermediate. Elemental analysis revealed a 3:4 compound of composition [Ni₃(NCS)₆(pdz)₄]. A structure model supported by IR spectroscopic investigations was assumed, in which three coordination modes of the thiocyanato anion exist, resulting in a 2D polymeric network.     

Synthesis and Characterization of Copper(II) and Zinc(II) Tricyanomethanide (tcm) Complexes with Di(2‐pyridyl)amine (dpyam) as Co‐ligands: [Cu(dpyam)(tcm)2], [Cu(dpyam)(tcm)(OAc)] and Zn(dpyam)2(tcm)2

Three new transition metal tricyanomethanide complexes [Cu(dpyam)(tcm)₂] ( 1 ), [Cu(dpyam)(tcm)(OAc)] ( 2 ) and Zn(dpyam)₂(tcm)₂ ( 3 ) were synthesized and characterized by single crystal X‐ray diffraction analysis. In 1 each copper(II) atom is coordinated to three tcm anions and one dpyam molecule to form a square pyramide geometry. In 2 the coordination geometry around the central metal is also square pyramidal, and each copper atom is surrounded by two tcm anions, one dpyam ligand and one OAc. Both 1 and 2 display a µ_1,5‐tcm bridged infinite chain structure. In 3 each zinc(II) atom is coordinated by two tcm anions and two dpyam molecules to form a distorted octahedral geometry. Different from the former two complexes, 3 shows a mononuclear structure. Magnetic susceptibility measurement in the range 2–300 K indicates that there are weak antiferromagnetic couplings between adjacent copper(II) ions in 1 (J=?0.03 cm^?1) and 2 (J=?0.11 cm^?1) respectively.     

Synthesis and Crystal Structures of Manganese(II) and ­Cobalt(II) Complexes with 2, 6‐Dimethoxybenzoic Acid and Additional N‐Donor Ligands

Three coordination compounds [Mn₃(dmb)₆(H₂O)₄(4, 4′‐bpy)₃(EtOH)]_n ( 1 ) and [M(dmb)₂(pyz)₂ (H₂O)₂] [M^II = Co ( 2 ), Mn ( 3 )] (Hdmb = 2, 6‐dimethoxybenzoic acid, 4, 4′‐bpy = 4, 4′‐bipyridine, pyz = pyrazine) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. Compound 1 consists of infinite 1D polymeric chains, in which the metal entities are bridged by 4, 4′‐bpy ligands. There are four crystallographically independent Mn^II atoms in the linear chain with different coordination modes, which is only scarcely reported for linear polymers. The isostructural crystals of 2 and 3 are composed of neutral mononuclear complexes. In crystal the complexes are combined into chains by intermolecular O–H ··· N hydrogen bonds and π–π interactions between antiparallel pyrazine molecules.     

Two novel organic–inorganic hybrid materials from tetrachloridometallate(II) salts and 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium

Two organic–inorganic hybrid compounds have been prepared by the combination of the 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium cation with perhalometallate anions to give 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium tetrachloridocobaltate(II), (C₁₂H₁₂N₂)[CoCl₄], (I), and 4‐[(E)‐2‐(pyridin‐1‐ium‐2‐yl)ethenyl]pyridinium tetrachloridozincate(II), (C₁₂H₁₂N₂)[ZnCl₄], (II). The compounds have been structurally characterized by single‐crystal X‐ray diffraction analysis, showing the formation of a three‐dimensional network through X—H...Cl_nM⁻ (X = C, N⁺; n = 1, 2; M = Co^II, Zn^II) hydrogen‐bonding interactions and π–π stacking interactions. The title compounds were also characterized by FT–IR spectroscopy and thermogravimetric analysis (TGA).     

Two Keggin Templated Supramolecular Compounds by Exerting the Chelate and Linking Dual Roles of the Ligand 2, 2′‐Biimidazole

Two new Keggin templated supramolecular compounds, [Zn₂(H₂biim)₅(SiM₁₂O₄₀)] · 4H₂O [M = W ( 1 ), Mo ( 2 )] (H₂biim = 2, 2′‐biimidazole), were synthesized under hydrothermal conditions by using the ligand 2, 2′‐biimidazole. They were characterized by single‐crystal X‐ray diffraction, elemental analyses, IR and photoluminescence spectroscopy as well as cyclic voltammetry. The two isostructural compounds are constructed by two discrete supramolecular moieties: the inorganic chains consist of Keggin anions and metal‐organic chains constructed by [Zn₂(H₂biim)₅]⁴⁺ subunits. In the dinuclear [Zn₂(H₂biim)₅]⁴⁺ subunit, the H₂biim ligands exhibit a dual role, chelating and linking. The metal‐organic chains further construct a 3D supramolecular framework with channels, in which the Keggin‐based inorganic chains are accommodated. The electrochemical behaviors of compounds 1 and 2 bulk‐modified carbon paste electrodes ( 1 ‐CPE, 2 ‐CPE) were studied.     

A New Chair‐shaped Conformation Containing HgHgOHgHgO: Synthesis and Structure of Hg4(L2)2(NO3)4 (L2 = morpholin‐4‐ylpyridin‐2‐ylmethyleneamine)

. The complex Hg₄(L²)₂(NO₃)₄ ( 1 ) (L² = morpholin‐4‐ylpyridin‐2‐ylmethyleneamine) has been synthesized and characterized by CHN analysis, IR, and UV/Vis spectroscopy. The crystal structure of 1 was determined using single‐crystal X‐ray diffraction. The crystal structure of 1 contains four mercury atoms, four nitrate anions (two terminal and two bridge ones) and two L² ligand molecules. A chair shape, six‐membered ring is formed with the sequence OHgHgOHgHg built from Hg–Hg dumbbells and oxygen atoms from the nitrate co‐ligands. In the crystal structure, the asymmetric unit of the compound is built up by one‐half of the molecule. It contains the Hg₂²⁺ moiety with a mercury–mercury bonded core, in which one diimine ligand is coordinated to one of the mercury atoms. The nitrate anions act as anisobidentate and bidentate ligands.     

两个含双(3,5－二甲吡唑基)甲烷配体的铅(II)配合物的合成与结构表征

Reactions of lead（Ⅱ） nitrate or perchlorate with bis（3,5-dimethylpyrazolyl）methane （dmpzm）, produced two new Pb（Ⅱ） chelated complexes [Pb（dmpzm）2X2] （X=NO3^- 1, ClO4^- 2）. Both compounds were structurally characterized by elemental analysis, IR spectroscopy, thermal analysis, and single crystal X-ray diffraction. Both compounds are mononuclear with a distorted square antiprismatic PbN4O4 coordination geometry incorporating a pair of O,O＇-bidentate anions and N,N＇-bidentate dmpzm ligands. In the crystals of 1 or 2, the methyl or methylene groups of dmpzm ligand interact with the oxygen atoms of nitrates or perchlorates to afford intra- and intermolecular hydrogen bonding, thereby forming a two-dimensional network 1 or a three-dimensional structure 2.     

Cyclometalated Iridium(III) and Rhodium(III) Complexes Containing Naphthyridine Ligands: Synthesis,Characterization and Biological Studies

The synthesis, crystal structure, and biological activity of new bis‐cyclometalated compounds [M(ptpy)₂(4‐chloro‐2‐methyl‐1,8‐naphthyridine)]PF₆ [M = Rh ( 1 ); M = Ir ( 2 ); ptpy = 2‐(p‐tolyl)pyridinato] and [M(ptpy)₂(2‐methyl‐1,8‐naphthyridine)]PF₆ [M = Rh ( 3 ); M = Ir ( 4 )] are described. The new compounds were prepared by the reaction of [{M(μ‐Cl)(ptpy)₂}₂] (M = Rh, Ir) with the corresponding naphthyridine ligands. The molecular structures of compounds 1 , 3 , and 4 were confirmed by single‐crystal X‐ray diffraction studies.     

Novel 1D Copper(II) Helical Chain Formed by Weak Coordination‐driven Self‐assembly: Synthesis,Structure, and Magnetic Property

A novel 1D copper(II) helical chain is constructed through the connection of tetranuclear copper(II) units [Cu₄(L)(Py)₄] (H₈L=N,N′‐(BINOL‐3,3′‐dicarboxyl)‐disalicylhydrazide, where BINOL is 1,1′‐binaphthalenyl‐2,2′‐diol, py=pyridine) by weak coordination‐driven self‐assembly, and characterized by IR, single crystal X‐ray diffraction, thermogravimetric analysis, and X‐ray power diffraction analysis. Interestingly, the helical chains are packed in an alternating left‐(M) and right‐handed (P) chirality, the orientation of the helices was determined by the axial chirality of the ligand. The complex shows antiferromagnetic interactions between the copper centers.     

Isostructural organic–inorganic hybrid compounds: triethylcholine tribromidocadmate and triethylcholine tribromidomercurate

In order to search for new anionic architectures and develop useful organic–inorganic hybrid materials in halometallate systems, two new crystalline organic–inorganic hybrid compounds have been prepared, i.e. catena‐poly[triethyl(2‐hydroxyethyl)azanium [[bromidocadmate(II)]‐di‐μ‐bromido]], {(C₈H₂₀NO)[CdBr₃]}_n, (1), and catena‐poly[triethyl(2‐hydroxyethyl)azanium [[bromidomercurate(II)]‐di‐μ‐bromido]], {(C₈H₂₀NO)[HgBr₃]}_n, (2), and the structures determined by X‐ray diffraction analysis. The compounds are isostructural, crystallizing in the space group P2₁/n. The metal centres are five‐coordinated by bromide anions, giving a slightly distorted trigonal–bipyramidal geometry. The crystal structures consist of one‐dimensional edge‐sharing chains of MBr₅ trigonal bipyramids, between which triethylcholine counter‐cations are intercalated. O—H...Br hydrogen‐bonding interactions are present between the cations and anions.     

Magnetic Interactions through Imidazolate‐Bridges: Synthesis,Spectroscopy, Crystal Structure and Magnetic Properties of μ‐Imidazolato‐Bridged Copper(II) Complexes

The synthesis, characterization and crystal structures of substituted imidazolate bridged binuclear copper(II) complexes, [Cu₂(dien)₂(L)](ClO₄)₃, where dien = diethylenetriamine, L = imidazolate (im^—) ( 1 ), 2‐methylimidazolate (mim^—) ( 2 ) and benzimidazolate (bim^—) ( 3 ), are reported. The copper(II) ions of 1 — 3 posses a square planar coordination environment with dien coordinating as a tridentate ligand and the fourth position being occupied by a nitrogen atom of the bridging μ‐imidazolato group. In all three compounds the tendency to form additional long apical bonds at the copper(II) ions to the oxygen atoms of the perchlorate anions is observed. Temperature depended susceptibility data of polycrystalline samples reveal an antiferromagnetic coupling of the copper(II) atoms in 1 — 3 with J = —63.8, —75.4 and —36.8 cm^—1, respectively. Significant changes for these coupling constants could not be observed for measurements on frozen aqueous solutions. ESR spectra for solids and frozen solutions are consistent with intramolecular antiferromagnetic exchange interaction between the metal ions. From the data reported it can be concluded that the predominate mechanism for transmitting exchange coupling through the imidazolate bridge is due to a σ exchange pathways.     

Synthesis,Structure and Magnitic Properties of a Diphenoxobridged Binuclear Copper（Ⅲ） Complex

A mixed-ligand copper(Ⅱ） complex[Cu2(phen)2(HL^1)2]-(ClO4)2(1) was synthesized.X-ray analyses reveal that 1 has a bis(μ2-phenoxo)-bridged dicopper(Ⅱ） structure.2D hydrogen-bonded network is formed utilizing the N-H,O-H and C-H groups of the (HL^1) ligands (H2L^1=N-(2-hydroxybenzyl)ethanolamine),the C-H groups of the phenanthrolines and the perchlorate anions.Variable temperature magnetic properties of 1 have shown comparatively weak antiferromagnetic interactions with respect to the bridge angles, which have been ascribed to the unfavorable overlaps of the magnetic orbitals fo the highly distorted copper coordination polyhedra and the pyramidal distortions at the phenoxo oxygen atoms.