Effect of the chemical structure of a tetradentate equatorial ligand on the spin-crossover properties of the Fe (III) complexes chain structures: Electron paramagnetic resonance study

The effect of the chemical structure of the equatorial ligand on the spin state of the Fe (III) ion in a series of 1-D chain complexes of the general formula [Fe(L)(tvp)]BPh₄·nCH₃OH, where L = dianions of Schiff base containing a different number of aromatic groups: N,N′-ethylenebis (salicylaldimine) (salen) 1 , N,N′-ethylenebis (acetylacetone)2,2′-imine (acen) 2 , N,N′-ethylenebis (benzoylacetylacetone)2,2′-imine (bzacen) 3 , and tvp = 1,2-di(4-pyridyl)ethylene, was studied by ultraviolet–visible (UV–vis) and electron paramagnetic resonance (EPR) methods. The values of exchange interactions, thermodynamic parameters of spin-crossover, and electronic structure features of the Fe (III) complexes were estimated from the EPR data. The substitution of a fragment of the equatorial ligand L in the series salen–acen–bzacen changes the local symmetry of the complex in the 1-D chain, thereby affecting the spin variable properties.     

Syntheses, crystal structures, and magnetic characterization of five new dimeric manganese(III) tetradentate Schiff base complexes exhibiting single-molecule-magnet behavior

Tetradentate Schiff base ligands H2L (H2saltmen, H2salen, H2-5-Brsalen, and H2-3,5-Brsalen), derived from the condensation of the corresponding salicylaldehyde or its derivatives with 1,1,2,2-tetramethylethyldiamine or 1, 2-diaminoethane, reacted with Mn(III) acetate or perchlorate salts and sodium azide or sodium cyanate to produce five Mn(III) dimer complexes, [Mn(saltmen)(O2CCH3)]2.2CH3CO2H (1), [Mn(saltmen)(N3)]2 (2), [Mn(salen)(NCO)]2 (3), [Mn(3,5-Brsalen)(3,5-Brsalicylaldehyde)]2 (4), and [Mn(5-Brsalen)(CH3OH)]2(ClO4)2 (5). These new complexes have been characterized by IR, elemental analyses, crystal structural analyses, and magnetic studies. Within these Mn(III) dimeric complexes, two Mn(III) ions are connected by phenolate oxygen atoms with acetate, azide, cyanate, a 3,5-Brsalicyladehyde anion, and a neutral methanol molecule as the axial ligands for complexes 1-5, respectively. Complexes 1-4 exhibit intradimer ferromagnetic exchange and display frequency dependence of ac magnetic susceptibility, possibly showing single-molecule-magnet (SMM) behavior. In contrast, complex 5 shows an intradimer antiferromagnetic coupling probably originating from the relatively shorter Mn-O distance, compared to those of complexes 1-4.     

Syntheses,Structures and Electrochemistry Properties of Two Dicyanamide Manganese(III) Complexes [Mn(5‐Brsalen)(dca)]·CH3OH and [Mn(3‐Meosalphen)(dca)(H2O)]

Two manganese(III)‐dicyanamide compounds, [Mn(5‐Brsalen)(dca)] · CH₃OH ( 1 ) and [Mn(3‐Meosalphen)(dca)(H₂O)] ( 2 ) (dca = dicyanamide anion, [N(CN)₂]^–), were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal X‐ray structure analysis, and cyclic voltammetry. The structure of complex 1 is an infinite zigzag chain of hexacoordinate Mn^III ions, in which the adjacent manganese atoms are connected by dca in μ_1,5‐bridging mode. The molecular structure of complex 2 consists of a hexacoordinate Mn^III atom, which generates a slightly distorted octahedral arrangement, and a dimer structure is formed by intermolecular hydrogen bonding interactions. The electrochemical properties of the two complexes were measured by cyclic voltammetry.     

Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N′-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL¹) and (E)-2-cyano-N′-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL²), with MnCl₂·4H₂O in methanol resulted in [Mn(HL¹)Cl₂(CH₃OH)] (1) and [Mn(HL²)Cl₂(CH₃OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV–Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL²)Cl₂(CH₃OH)] (2) resulted in higher conversion than [Mn(HL¹)Cl₂(CH₃OH)] (1).     

Syntheses,crystal structures,and magnetic properties of five new coordination compounds bearing ferrocenedicarboxylate ligands

Five new coordination compounds, {[Mn(L)(CH₃OH)₂] · CH₃OH · H₂O} _n (1), {[Cd(L)(DMF)₂(H₂O)] · H₂O} _n (2), {[Co(L)(CH₃OH)₄] · CH₃OH}₂ (3), {[Cd(L)(phen)(CH₃OH)] · CH₃OH} _n (4), and {[Mn(L)(phen)(H₂O)] · CH₃OH} _n (5) (L = 5-ferrocene-1,3-benzenedicarboxylic acid, phen = 1,10-phenanthroline) were obtained from different metal salts and L with or without 1,10-phen under mild conditions. Complex 1 is a 1-D ladder-like chain composed of 8-membered rings A and 16-membered rings B, which arrange alternately. Complex 2 is an infinite linear chain, further bridged to form a parallel double chain through different hydrogen-bond interactions. Complex 3 is a discrete dinuclear structure, while 4 is a neutral 1-D infinite zigzag coordination chain. Complex 5 is a 1-D linear chain with phen and ferrocene groups of L as pendants hanging on the different sides of the main chain. Variable temperature magnetic susceptibilities of 1 were measured and weak antiferromagnetic exchange interactions between the neighboring Mn(II) ions were found with J = ?0.95 cm^?1.     

两种新型μ－氧桥联－双铁(III)席夫碱配合物：X-衍射分析，IR, UV-Vis, CD光谱，磁性质和电化学性质

热力学稳定的带有大环配体的μ－氧桥联－双铁配合物，由于其两个铁中心之间的有趣的电子结构和磁相互作用而受到广泛关注。μ－氧桥联－双铁席夫碱配合物，[{Fe(tbusalphn)}₂(μ-o)] (1)和[{Fe(R,R-salchxn)}₂(μ-o)] (2), 通过用咪唑或N－甲基咪唑的水溶液处理相应的单核铁氯化物，Fe(L)Cl，而获得。1和2的晶体结构通过x-射线结构分析而被确定。1属于三斜晶系，P－1空间群。2属于单斜晶系，P2₁/c空间群。由于1的配体带有庞大的叔丁基取代基，导致形成μ－氧桥联－双铁配合物时的空间拥挤，因此，其Fe-O-Fe夹角为176.5 ^o，几乎成平角。而2则由于配体上没有庞大的取代基，其Fe-O-Fe夹角为149.6^o，明显小于1的Fe-O-Fe夹角。 本文还对两种μ－氧桥联－双铁席夫碱配合物及相应的单核铁氯化物的红外光谱、紫外－可见吸收光谱及圆二色光谱性质进行了研究。与相应的单体铁配合物相比较，生成μ－氧桥联－双铁席夫碱配合物后，出现一新的红外吸收带，归属于ν_Fe-O-Fe振动。有趣的是，其数值与Fe-O-Fe夹角大小相对应。1和2除具有明显不同的Fe-O-Fe夹角外，它们的圆二色光谱却是相似的。 对1和2的磁性质研究表明，在这类化合物中两个铁(III)离子之间存在着强烈的分子内抗铁磁性偶合作用。另外，本文还采用循环伏安法对1和2的电化学性质进行了研究。     

Coumarin-naphthohydrazone ligand with a rare coordination mode to form Mn(II) and Co(II) 1-D coordination polymers: synthesis,characterization, and crystal structure

The hydrazone (E)-3-hydroxy-N’-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (H₂L) was synthesized from the reaction of 3-acetylcoumarin and 3-hydroxy-2-naphthoic hydrazide in methanol. Compounds [Mn(H₂L)(NO₃)₂(CH₃OH)]·CH₃OH (1a), [Mn(HL)(NO₃)(CH₃OH)]_n (1b), [Co(HL)(NO₃)(CH₃OH)]_n (2), and [Cu(HL)(NO₃)] (3) were obtained by reaction of an equimolar amount of H₂L with nitrate salts of Mn(II), Co(II), or Cu(II) in methanol. The reaction of ligand and Mn(NO₃)₂·4H₂O was also carried out in the presence of sodium azide which led to the 1-D coordination polymer, [Mn(HL)(N₃)(CH₃OH)]_n (4). All of the synthesized compounds were characterized by elemental analyses and spectroscopic methods. Single-crystal X-ray analysis of 1–4 indicated that H₂L is neutral (in 1a) or mononegative ligand (in 1b, 2, 3 and 4). In 1b, 2 and 4 the 1-D polymeric chain is found by a rare coordination mode of this kind of hydrazone ligand since the naphtholic oxygen is coordinated to the neighboring metal ions while the NH moiety of hydrazone remains intact, also confirmed by FT-IR spectroscopic studies. The thermal stability of 2 and 4 were also studied from 30–1000 °C.     

Syntheses,structures, and properties of CdII and CoII complexes with 5-(pyridin-4-yl)isophthalate

A N-donor containing carboxylic ligand, 5-(pyridin-4-yl)isophthalic acid (H₂L), was applied to construct two new coordination polymers [Cd(L)(DMF)] _n (1, DMF?=?N,N-dimethylformamide) and {[Co(L)(H₂O)₂]?·?0.5CH₃OH?·?1.5H₂O} _n (2) under different conditions. The complexes were characterized by IR, elemental, and thermogravimetric analyses, powder and single crystal X-ray diffraction. In 1 each L^2? links four Cd^II to form a 3-D framework, while in 2 each L^2? connects three metals to form a 2-D layer structure, which is further connected together by hydrogen bonds to form a 3-D architecture. The thermal stability of the complexes and the photoluminescence of 1 were investigated.     

Studies of the catalytic activity of Fe(III)(salen) complexes as epoxidation catalysts

Two new Fe(III)(salen) complexes, FeL¹ClO₄·2H₂O (1) and FeL²ClO₄ (2) [L¹ = N,N′-ethylenebis(3-formyl-5-methylsalicylaldimine) and L² = N,N′-cyclohexenebis(3-formyl-5-methylsalicylaldimine)], have been synthesized and characterized. The catalytic activity of the complexes for epoxidation of alkenes has been investigated in the presence of two terminal oxidants PhIO and NaOCl, with two solvents CH₃CN and CH₂Cl₂. As alkenes styrene and (E)-stilbene have been chosen for investigation; styrene is a better substrate than electron-rich (E)-stilbene. The study also suggests that unlike their Mn(III) counterparts, 1 and 2 are poor epoxidation catalysts; catalysis proceeds with formation of one intermediate, rather than forming more than one intermediate depending on the terminal oxidant used. Use of exogenous neutral donor ligands such as Py, PyNO and 1-MePy is effective to improve catalytic behavior.     

Syntheses and crystal structure of binuclear μ-oxamido copper(II) complexes containing 1,4,7-triazacyclononane as a terminal ligand

Two new binuclear copper(II) complexes, Cu(tacn)Cu(oxpn)(ClO₄)₂·C₂H₅OH (1), and Cu(tacn)Cu(oxap)(ClO₄)₂·CH₃OH (2), have been prepared from the planar fragment Cu(oxpn) and Cu(oxap) (tacn denotes 1,4,7-triazacyclononane, oxpn and oxap stand for the dianions of N,N′-bis(3-aminopropyl)oxamide, and N,N′-bis(2-aminopropyl)oxamide, respectively). The complexes have been characterized by means of elemental analyses and IR, and UV spectra. The crystal structure of compound 1 shows that copper(II) coordinates to the four nitrogen atoms of oxpn in a square-planar environment and the other copper(II) ion is in a distorted square-pyramidal environment.     

Effects of wavelength and substituents on iron(III) photoreduction in trans-[Fe(R-sal-R‵-en)(CH3OH)(NCS)] complexes

Photoredox reactions in irradiated methanolic solutions of trans-[Fe(R′-sal-R₂-en) (CH₃OH)(NCS)] complexes, where R′-sal-R₂-en^2? are tetradentate open-chain N,N′-1,1-R₂-ethylenebis(R′-salicylideneiminato) ligands (R?=?H or CH₃; R′?=?H, 5-Cl, 5-Br, 3,5-Br₂, 3-OCH₃, 4-OCH₃), have been explored and a mechanism suggested. The complexes are redox-stable in the dark in methanol. Continuous irradiation of solutions in the region of intraligand (IL) or ligand-to-metal charge transfer (LMCT) transitions leads to photoreduction of Fe(III) to Fe(II) and formation of formaldehyde (CH₂O). Formation of polystyrene-containing bonded NCS, when irradiating the complexes in the presence of styrene used as a radical scavenger, indicates that the primary photoreduction of Fe(III) to Fe(II) is accompanied by oxidation of NCS^? to the ^?NCS radical. R′-sal-R₂-en ligands have little effect on the photoinduced redox processes. The quantum yield of Fe(II) formation, Φ_Fe(II), as a quantitative parameter of photoredox efficiency, decreases significantly with increasing wavelength of incident radiation, and is slightly influenced by the peripheral groups, R, of R′-sal-R₂-en.     

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.     

Syntheses,structures, and properties of two 2-D Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and polycarboxylate ligands

Two 2-D Cd(II) complexes, {[Cd(imb)(bdc)(H₂O)]·CH₃OH}_n (1) and {[Cd(imb)(Hbtc)(CH₃OH)]·2H₂O·CH₃OH}_n (2), have been synthesized by reactions of CdCl₂·2.5H₂O with 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,3-benzenedicarboxylic acid (H₂bdc) or 1,3,5-benzenetricarboxylic acid (H₃btc). Single-crystal X-ray diffraction shows that 1 possesses an infinite 2-D layered structure in which all the carboxylates chelate Cd(II) and imb bridge Cd(II) ions. Complex 2 also features an infinite 2-D layered structure and imb ligands also bridge Cd(II) ions, but two carboxylates of each 1,3,5-benzenetricarboxylate coordinate to Cd(II) in monodentate or chelating mode, leaving the third one, which is not deprotonated, uncoordinated. IR spectra, fluorescent properties, and thermogravimetric analyses of both complexes have been investigated.     

Syntheses,crystal structures,and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H₂O)]₂·2H₂O (1) and [Fe(Hbtec)(bpy)(H₂O)]₂·2H₂O (2) (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P2₁/c with two Fe(III) ions bridged by two Hbtec^3? ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (3¹²·4²⁸·5⁵). Thermal stabilities and luminescent properties of the two complexes have also been investigated.     

Synthesis,characterization, and X-ray crystal structure of the manganese(III) complex Mn(Sal<Subscript>2</Subscript>hn)(CH<Subscript>3</Subscript>OH)(N<Subscript>3</Subscript>) [Sal<Subscript>2</Subscript>hn = N,N′-bis(salicylidene)-1,2-hexanediamine]

The new manganese(III) complex, Mn(Sal₂hn)(CH₃OH)(N₃), where Sal₂hn = N,N′-bis(salicylidene)-1,2-hexanediamine, was prepared from a reaction mixture containing Sal₂hn, MnCl₂ · 2H₂O, and NaN₃ (2: 1: 8 molar ratio) in methanol and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In the title complex, the Mn(III) center is in a distorted octahedral coordination geometry with the basal plane formed by the N₂O₂ donors of the tetradentate Schiff base dianion; the two phenolate O atoms and the two imine N atoms are each mutually in the cis position. The azide ion and the O atom of the methanol molecule occupy the other two positions of the octahedron. The hydrogen bond O(3)-H(3O)⋯N(5) links the mononuclear Mn(Sal₂hn)(CH₃OH)(N₃) units into a 1D chain extended along the x axis. The crystal structure is further stabilized by C(7)-H(7)⋯N(3) and C(16)-H(16)⋯N(5) hydrogen bonds.     

Syntheses,structures, and luminescence of coordination compounds based on N-containing polycarboxylates

Six coordination compounds constructed by two structurally related flexible nitrogen-containing polycarboxylate ligands 2,2′-(2,2′-(ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methylene)bis(azanediyl)dibenzoic acid (H₂L1) and 5,5′-(2,2′-(ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methylene)bis(azanediyl)diisophthalic acid (H₄L2) have been synthesized: [Ni(H₂O)₆]?·?L1?·?(C₂H₅OH)_0.5?·?H₂O (1), [Co(L1)(L3)]?·?CH₃OH (2), [Ni(L1)(L3)]?·?CH₃OH (3), [Zn(L1)(L3)]?·?CH₃OH (4), [Cd(L1)(L3)]?·?CH₃OH (5), and [Zn(L2)_0.5(phen)]?·?C₂H₅OH (6), where L3?=?3,4?:?9,10?:?17,18?:?23,24-tetrabenzo-1,12,15,26-tetraaza-5,8,19,22-tetraoxacyclooctacosan and phen?=?1,10-phenanthroline. The crystal structures have been determined by single-crystal X-ray diffraction. Compound 1 displays a discrete structure, which is further linked by hydrogen bonds to form a 2-D supramolecular layer. Compounds 2–5 display similar structures. These compounds possess 1-D meso-chain structures linked by L1 and metals. The C–H?···?π interactions from neighboring chains extend the chains in different directions, giving a 3-D plywood network. Compound 6 possesses 2-D layers, which are further linked by hydrogen-bonding interactions to generate a 3-D supramolecular architecture.     

Synthesis, crystal structures and magnetic properties of cyanide-bridged macrocyclic complexes

Three cyanide-bridged dodecanuclear macrocyclic wheel-like complexes [Cr(bpmb)(CN)₂]₆[Mn(5-Brsalpn)]₆·12H₂O (1), [Co(bpmb)(CN)₂]₆[Mn(5-Brsalpn)]₆·12H₂O (2) and [Co(bpmb)(CN)₂]₆[Mn(5-Clsalpn)]₆·24H₂O·8CH₃CN (3) [bpmb²⁻= 1,2-bis(pyridine-2-carboxamido)-4-methylbenzenate dianion; 5-Brsalpn²⁻ = N,N′-propylenebis(5-bromosalicylideneaminato) dianion; 5-Clsalpn²⁻ = N,N′-propylenebis(5-chlorosalicylideneaminato) dianion] have been synthesized and their crystal structures and magnetic properties have been investigated. The three compounds are structurally isomorphous and consist of alternating Mn(III)-Schiff base cations and [M(bpmb)(CN)₂]⁻ anions, generating cyanide-bridged nanosized dodecanuclear macrocyclic structures with an approximate diameter of 2 nm. The study of the magnetic properties of complex 1 reveals an antiferromagnetic interaction between the Cr(III) and Mn(III) ions through the cyanide bridges. A best-fit to the magnetic susceptibility of the complex leads to a magnetic coupling constant of J _CrMn = −2.65(6) cm⁻¹ on the basis of a one-dimensional alternating chain model with the Hamiltonian $ H = - J_{CrMn} \sum\limits_{i = 0}^N {S_i \cdot S_{i + 1} } $ H = - J_{CrMn} \sum\limits_{i = 0}^N {S_i \cdot S_{i + 1} } .     

One-dimensional cyanide-bridged Fe(III)–Mn(II) magnetic complexes with different configurations derived from a new pentacyanoiron(III) building block

Two cyanide-bridged heterometallic Fe^III–Mn^II complexes with formula {[Mn(bipy)(H₂O)]₂[Fe(2-CH₃im)(CN)₅]₂}_n·nCH₃OH·4nH₂O (2) (bipy?=?2,2′-bipyridine) and {[Mn(MAC)][Fe(2-CH₃im)(CN)₅]}_n·nDMF·3nH₂O (3) (MAC?=?2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene) have been successfully synthesized by assembling a newly designed pentacyanoiron(III) precursor [PPh₄]₂[Fe(CN)₅(2-CH₃im)]·2CH₃OH (1) and two Mn(II) compounds containing bulky ancillary organic ligands as segments, and characterized by elemental analysis, infrared (IR) spectroscopy, and X-ray structure determination. X-ray diffraction analysis revealed one-dimensional (1D) ladder-like double or linear single infinite-chain structures for complex 2 and 3, respectively, indicating the obvious steric influence of the auxiliary ligand(s) on the structural type. Experimental and theoretical investigations on the magnetic properties of the complexes showed the antiferromagnetic coupling between the cyanide-bridged low-spin Fe(III) ion and high-spin Mn(II) ion.

     

Synthesis, structure, magnetic properties and DFT calculations of two hydroxo-bridged complexes based on Mn(III)(Schiff-Bases)

Two hydroxo-bridged complexes, {[Mn(III)(3-CH(3)O)salen](2)[Cr(III)(salen)(OH)(2)]}ClO(4)·6H(2)O (1) and {[Mn(III)(5-CH(3))salen](2)(OH)}ClO(4)·3H(2)O (2) [salen = N,N'-ethylenebis(salicylideneiminato) dianion], have been synthesized by the hydrolysis of the corresponding Mn(III)(Schiff-Bases) derivatives and [Cr(salen)(H(2)O)(2)]Cl precursors. X-Ray structure characterization reveals the discrete linear arched trinuclear structure of 1 and the 1D chain arrangement of 2. Magnetic experimental data and density functional theory (DFT) calculations both indicate the dominant antiferromagnetic interaction mediated by the hydroxo-bridges in both 1 and 2. Frequency-dependent AC susceptibilities reveal slow relaxation of 1 in low temperature. It is worth noting that the structure and magnetic properties of 1 is comparable to a reported cyano-bridged SMM, K[(5-Brsalen)(2)(H(2)O)(2)Mn(2)Cr(CN)(6)]·2H(2)O.     

Copper(II) Complexes with N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea (L) and a Derivative of L: Synthesis,Structure, and Fluorescent Properties

Three copper(II) complexes, [Cu₂(OAc)₄L₂] · 2CH₃OH ( 1 ), [CuBr₂L′₂(CH₃OH)] · CH₃OH ( 2a ), and [CuBr₂L′₂(DMSO)] · 0.5CH₃OH ( 2b ) {L = N‐(9‐anthracenyl)‐N′‐(3‐pyridyl)urea and L′ = N‐[10‐(10‐methoxy‐anthronyl)]‐N′‐(3‐pyridyl)urea} have been synthesized by the reaction of L with the corresponding copper(II) salts. Complex 1 shows a dinuclear structure with a conventional “paddlewheel” motif, in which four acetate units bridge the two Cu^II ions. In complexes 2a and 2b , the anthracenyl ligand L has been converted to an anthronyl derivative L′, and the central metal ion exhibits a distorted square pyramidal arrangement, with two pyridyl nitrogen atoms and two bromide ions defining the basal plane and the apical position is occupied by a solvent molecule (CH₃OH in 2a and DMSO in 2b ).