Bridging Chloride Ions Research Articles

Specific features of Copper(II) chloride complexes with Caffeine: Synthesis, Structure, DFT calculations

The present article is devoted to the consideration of the interconversions of copper(II) chloride complexes with caffeine (caf) ([CuII2(μ2-Cl)2(caf)2(H2O)2] (1),[CuII3(μ-Cl)6(caf)(H2O)]n (1a), [Cu4(μ2-Cl)6(μ4-O)(caf)4](1b), 2[CuII(caf)Cl2].0.25THF (1c), [CuII(caf)2Cl2] (2)), depending on the synthesis conditions, and to studies on the four-nuclear copper(II) bromide complex with acetamide (AcAm) ([Cu4(μ2-Br)6(μ4-O)(AcAm)4](3)). The results obtained have been confirmed by different methods (powder XRD, single crystal XRD analysis, IR-, ESI-MS-, EPR-spectroscopy, and magnetic properties studies). Two bromide ions in (3) are non-equivalent to the other four and this fact may result in the modification of the exchange integral between bonded copper ions. Single crystal XRD data have been compared with the results of DFT calculations. It has been found that the thermodynamic stability of the complexes grows with an increase in the number of copper atoms and bridging chloride ions and a decrease in the number of water molecules in the formula unit of the compound. The calculation results for complexes with acetamide are in a good correlation with those of caffeine and experimental data.

Pyridyl-imidazole copper compounds

Three 4-(2’-pyridyl)imidazole (4-pyim) complexes of copper(II) have been synthesized and studied structurally and magnetically. The structures of [CuCl2(4-pyim)] (1), [CuCl(4-pyim)2]2Cl2(H2O)10 (2), and [Cu(CuCl4)(4-pyim)2][Cu(H2O)(4-pyim)2](CuCl4)(H2O)4 (3) are reported. Single-crystal X-ray diffraction measurements show that 1 crystallizes in the monoclinic space group P21/n with a four-coordinate Cu(II) ion forming dimers via semi-coordinate bonds to bridging chloride ions. The structure of 1 shows the copper and chloride ions disordered over two sites. Compound 2 crystallizes in the triclinic space group P – 1 with five-coordinate Cu(II) ions in a highly distorted geometry between square pyramidal and trigonal bipyramidal. It has an extensive hydrogen bonding network created by 10 lattice water molecules, chloride ions, and nitrogen atoms in the ligands. Compound 3 crystallizes in the monoclinic space group Cc with both four- and five-coordinate Cu(II) ions present in the lattice; the five-coordinate Cu(II) ions display highly distorted geometries. All three compounds have hydrogen bonding and π-stacking interactions among the 4-pyim rings. Magnetic susceptibility data were collected on 1. Magnetic susceptibility data of 1 shows that it exhibits modest antiferromagnetic interactions which are best fit using a honeycomb model [(2J = −2.6(2) K), 2J’ = −1.6(2) K, ]. Disorder in the crystal structure decreases the rate of growth of the correlation length at low temperatures, lowering the temperature of the expected maximum in χ below the range of the data.

Revisiting the Role of Hydrogen Bonding in the Strong Dimer Superexchange of a 2D Copper(II) Halide Honeycomb-Like Lattice: Structural and Magnetic Study.

The title compound H2L(CuCl3H2O)Cl (H2L = 1-(4'-pyridinium)pyridin-4-ol-ium), 1) was synthesized and investigated structurally and magnetically as well as via a first-principles, bottom-up theoretical analysis of the potential magnetic superexchange pathways. Compound 1 can be described structurally as a well-isolated, distorted 2D-honeycomb lattice with two potential exchange pathways: a dimeric interaction via hydrogen-bonded pairs of (CuCl3H2O) ions and a chain structure via bridging chloride ions. Surprisingly, the experimental magnetic data are best fitted using both a simple dimer model with a Curie-Weiss correction for interdimer exchange (Jdimer = -107.4(1) K, θ = -1.22(4) K) and a strong-rung ladder model (Jrung = -105.8(7) K, Jrail = 2(7) K). Theoretical analysis at the UB3LYP/6-31+G(d) level supports the strong exchange observed through the [CuCl4(H2O)]2- dimer moiety superexchange pathway (-102 K = -71 cm-1). However, the apparent vanishingly small exchange through the single halide bridge is merely a brute average of competing ferromagnetic (FM) (+24.8 K = +17.0 cm-1) and antiferromagnetic (AFM) (-21.0 K = -14.6 cm-1) exchange interactions. Our computational study shows that these fitting parameters carry no physical meaning since a honeycomb plaquette must be taken as magnetic building block for 1. The competition between FM and AFM pair interactions leads to geometrical frustration in 1 and could induce interesting magnetic response at low temperatures, if the magnetic exchange is adequately tuned by modifying substituents in ligands and, in turn, interactions within the crystal packing.

Crystal structure of hexa-μ-chlorido-μ4-oxido-tetra-kis-{[1-(2-hy-droxy-eth-yl)-2-methyl-5-nitro-1H-imidazole-κN 3]copper(II)} containing short NO2⋯NO2 contacts.

The title tetra-nuclear copper complex, [Cu4Cl6O(C6H9N3O3)4] or [Cu4Cl6O-(MET)4] [MET is 1-(2-hy-droxy-eth-yl)-2-methyl-5-nitro-1H-imidazole or metronidazole], contains a tetra-hedral arrangement of copper(II) ions. Each copper atom is also linked to the other three copper atoms in the tetra-hedron via bridging chloride ions. A fifth coordination position on each metal atom is occupied by a nitro-gen atom of the monodentate MET ligand. The result is a distorted CuCl3NO trigonal-bipyramidal coordination polyhedron with the axial positions occupied by oxygen and nitro-gen atoms. The extended structure displays O-H⋯O hydrogen bonding, as well as unusual short O⋯N inter-actions [2.775 (4) Å] between the nitro groups of adjacent clusters that are oriented perpendicular to each other. The scattering contribution of disordered water and methanol solvent mol-ecules was removed using the SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9-16] in PLATON [Spek (2009 ▸). Acta Cryst. D65, 148-155].

A new ladder-type dichloro(2,2-dimethyl-1,3-diaminopropane) copper complex: Synthesis, structural studies and selective sensing behavior towards a ketone molecule

A new coordination compound with the formula [Cu(dmpd)Cl2], where dmpd stands for 2,2-dimethylpropane-1,3-diamine, was prepared and structurally characterised by elemental analyses, IR and UV/Vis spectroscopic studies. The single crystal X-ray crystallographic study revealed the copper cation to be six coordinated in the complex by two amine nitrogen atoms and four chloride ions. The copper atom adopts a distorted tetragonal bipyramidal geometry, with two bridging chloride ions located at the polyhedron apexes. Furthermore, to obtain insight into the structure, theoretical studies were performed. The complex exhibits a strong photoluminescence property in tetrahydrofuran and shows a strong sensing behaviour towards a ketone molecule, proving it to be a good candidate for sensing measurements.

Copper(II) halide complexes of aminopyridines: Syntheses, structures and magnetic properties of [(5CAP)2CuX2] and [(5BAP)nCuX2] (X = Cl, Br)

Reaction of 2-amino-5-halopyridine molecules with Cu(II) halides in the solid state via mechanochemical techniques produced four coordination complexes, (5BAP)2CuBr2 (2a), (5BAP)2CuCl2 (3), (5CAP)2CuCl2 (4), (5CAP)2CuBr2 (5) [5BAP = 2-amino-5-bromopyridine; 5CAP = 2-amino-5-chloropyridine]. In all compounds, the 5BAP or 5CAP ligands are coordinated to the Cu(II) ion through the pyridine N atom along with two halide ions. Compounds 2 and 3 crystallized in the P-1 and P21/c space groups, respectively. Temperature dependent magnetic susceptibility data for 2 were fit to the antiferromagnetic rectangle model (J = –4.5(2) K; α = 0.89(17)), while the data for 3 were fit to the uniform chain model (J = –4.20(6) K), indicating a significant difference in the interchain interactions. Both 4 and 5 crystallize with the 5CAP ligands in the syn-conformation in the space groups I2/a and P21/n, respectively. Compound 4 formed the expected dimeric structure via bridging chloride ions and the magnetic data were successfully fit to the dimer model (J = –2.57(5) K), while 5 unexpectedly formed a structural chain via Br…Br contacts which exhibits very weak antiferromagnetic interactions. An intermediate structure, (5BAP)(H2O)CuBr2 (1), was prepared and characterized via mechanochemical methods along with an isomer of (5BAP)2CuBr2 (2b).

Crystal structure of bis-[μ-bis-(di-phenyl-phosphan-yl)methane-κ(2) P:P']-μ-chlorido-chlorido-1κCl-(1-phenyl-thio-urea-2κS)disilver aceto-nitrile hemisolvate.

In the dinuclear title complex, [Ag2Cl2(C7H8N2S)(C25H22P2)2]·0.5CH3CN, each AgI ion displays a distorted tetra­hedral coordination geometry with two P atoms from two bis­(di­phenyl­phosphan­yl)methane (dppm) ligands, one bridging chloride ion, one terminal chloride ion and one terminal S atom from the N,N′-phenyl­thio­urea (ptu) ligand. The dppm ligands and the bridging chloride ion force the two Ag atoms into close proximity, with a short Ag⋯Ag separation of 3.2064 (2) Å. In the crystal, complex mol­ecules are linked by N—H⋯Cl hydrogen bonds forming a dimer. The dimers are linked via weak C— H⋯Cl hydrogen bonds forming a two-dimensional supra­molecular architecture in the yz plane. In addition, an intra­molecular N—H⋯Cl hydrogen bond is observed.

Hexa-μ2-chlorido-μ4-oxido-tetra-kis[(morpholine-κN)copper(II)] methanol disolvate.

In the title solvate, [Cu4(μ2-Cl)6(μ4-O)(C4H9NO)4]·2CH3OH, each Cu2+ ion in the tetra­nuclear complex has a trigonal–bipyramidal coordination arising from three bridging chloride ions in equatorial positions and the central μ4-O2− ion and morpholine N atom in axial positions. The morpholine rings adopt chair conformations, with the N—Cu bonds in equatorial orientations. In the crystal, the components are linked by N—H⋯O and O—H⋯O and O—H⋯Cl hydrogen bonds, which generate a three-dimensional network. One methanol mol­ecule is disordered over two sets of sites in a 0.642 (9):0.358 (9) ratio.

Mn(II) complexes of three [2 + 2] macrocyclic Schiff base ligands. Synthesis and X-ray crystal structure of the first binuclear–di(binuclear) cocrystal

The [2+2] cyclocondensation reactions of N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane (L22py), N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane (L23py) and N-(2-pyridylmethyl)-N-(3-aminopropyl)-1,3-diaminopropane (L33py) with 2,6-diformyl-4-methylphenol (dfp) in the presence of MnCl2 4H2O in equimolar ratios are reported. The resulting compounds, (1), (2) and (3), respectively, were characterized by IR spectroscopy, elemental analysis and mass spectrometry. The X-ray crystal structure analysis of (3) showed that it contains a novel cocrystal of a binuclear Mn(II) macrocyclic cation and a di(binuclear) one. The Mn(II) ions in the latter binuclear and di(binuclear) cations are five and six-coordinate respectively. The two binuclear parts in the di(binuclear) cation are bonded through two bridging chloride ions. The macrocyclic ligand in the above cations also has two different conformational structures, but in both cases it catches a proton. The analytical data show that compounds (1) and (2) probably have similar structures to (3).

Copper(II) Complexes of N,N‐Diisopropylpicolinamide – Solvatochromic and Thermochromic Phase Change of a Monomeric Complex to a Ferromagnetically Coupled Dimeric Complex

AbstractThe synthesis and characterization of mononuclear [Cu(L)2(Cl)2] (1), dinuclear [{CuCl(L)}2(μ‐Cl)2] (2), and another mononuclear complex [Cu(L)2(ClO4)2] (3) with a bidentate N,N‐diisopropylpicolinamide ligand (abbreviated L) are described. Complexes 1 and 2 were obtained from the same reaction mixture and show thermo‐ and solvatochromic behavior. Complex 1 shows irreversible thermochromism by changing into 2 upon heating at 160 °C. These two complexes also show solvatochromism in various solvents. The coordination geometry of the metal ions in 1 and 3 is distorted octahedral, whereas 2 has CuII ions in a distorted square‐pyramidal geometry. Variable‐temperature magnetic susceptibility measurements for the dinuclear copper complex show a ferromagnetic interaction between the CuII ions. The chromotropism has been attributed to a change in geometry from octahedral with terminal chloride ligands to a distorted square‐pyramidal coordination with bridging chloride ions.

Use of [SbF6]−to Isolate Cationic Copper and Silver Adducts with More than One Ethylene on the Metal Center

A cationic tris(ethylene)copper(I) and tris(ethylene)silver(I) adduct has been isolated using hexafluoroantimonate counterion. X-ray crystallographic analysis shows that the metal atom in these adducts coordinates to three ethylene molecules in a trigonal planar fashion, forming a spoke-wheel arrangement. In [M(C2H4)3][SbF6] adducts (M = Cu, Ag, Au), the average M–C distances of 2.189 A for Cu and 2.410 A for Ag can be compared with the corresponding distance of 2.268 A for Au and show that the copper(I) complex has the shortest while the silver adduct displays the longest M–C distances. These agree well with the computed values (2.172, 2.408, and 2.308 A for Cu, Ag, and Au analogues, respectively) and follow the same trend as the covalent radii of M(I). Structural data on [μ3-Cl{Cu(C2H4)2}3][SbF6]2, which features bis(ethylene)copper(I) moieties, are also presented. It has a trigonal planar Cu3Cl core with a triply bridging chloride ion bonded to three trigonal planar copper centers. Ethylene molecules a...

Crystallographic and magnetic studies of the 2-pyridone/copper halide system

A series of copper halide complexes have been prepared employing 2-pyridone as a ligand. The compounds [CuBr2(2-pyridone)2]2 (1), [CuCl2(2-pyridone)2]2 (2), [CuCl2(2-pyridone)]2 (3), [CuCl2(2-pyridone)3] (4), and [CuCl2·2H2O]2[(2-pyridone)2] (5) were prepared and their structures and magnetic properties studied. Compounds 1 and 2 are dimeric species with the Cu(II) ions bridged by a pair of O-atoms from 2-pyridone molecules. Compound 3 is also a dimer, but in this case bridged by a pair of chloride ions. Only compound 4 is monomeric with fairly well isolated copper(II) ions, while compound 5 is a coordination polymer with the Cu(II) ions linked into chains via pairs of bridging chloride ions. Analysis of the magnetic data reveals that 1 and 2 exhibit significant antiferromagnetic interactions, while 4 is very weakly antiferromagnetic. Compounds 3 and 5 show weak ferromagnetic interactions. Data for 1 and 2 were fit to the antiferromagnetic dimer model with a Curie–Weiss correction to account for interdimer interactions: 1, J=−41.7(1)K, θ=−0.8(1)K; 2, J=−38.2(1)K, θ=−0.7(1)K. Data for 3 were fit to the ferromagnetic dimer model with a Curie–Weiss correction for interdimer interactions:); 2, J=9.4(6), θ=−3.2(3). Interactions in both 4 and 5 were sufficiently weak that data were fit only to the Curie–Weiss expression resulting in θ-values of −0.50(7) and 0.58(4)K respectively.

Catena-Poly[[(benzil bis{[(pyridin-2-yl)methylidene]hydrazone}-κ4N,N′,N′′,N′′′)mercury(II)]-μ-chlorido-[dichloridomercury(II)]-μ-chlorido

In the title coordination polymer, [Hg2Cl4(C26H20N6)]n, one HgII ion is coordinated by four N atoms from the benzylbis((pyridin-2-yl)methyl­idenehydrazone) ligand and two Cl− ions in a very distorted cis-HgCl2N4 octa­hedral geometry. The other HgII ion is coordinated in a distorted tetra­hedral geometry by four Cl− ions. Bridging chloride ions link the HgII ions into a chain propagating in [010]: the Hg—Cl bridging bonds are significantly longer than the terminal bonds. The dihedral angle between the central benzene rings of the ligand is 83.3 (2)°. The packing is consolidated by weak C—H⋯Cl hydrogen bonds and C—H⋯π inter­actions.

Di-μ-chlorido-bis{chlorido[(R)/(S)-1,5-diphenyl-3-(2-pyridyl-κN)-2-pyrazoline-κN2]zinc(II)}

In the centrosymmetric binuclear title compound, [Zn2Cl4(C20H17N3)2], the coordination geometry of the ZnII ion can be described as a distorted ZnN2Cl3 trigonal bipyramid (τ = 0.89), arising from the N,N′-bidentate ligand, a terminal chloride ion and two bridging chloride ions. The N atoms occupy one axial and one equatorial site and the terminal chloride ion occupies an equatorial site. The dihedral angle between the pyridine and pyrazole rings is 12.8 (2)°. In the crystal, aromatic π–π stacking [centroid–centroid separations = 3.812 (3) and 3.848 (3) Å] and C—H⋯Cl and C—H⋯π inter­actions help to establish the packing.

Catena-Poly[bis(trimethylphenylammonium) [hexa-μ-chlorido-dichloridotricuprate(II)]]: an alternating zigzag chain of CuCl4and Cu2Cl6complexes

The title compound, {(C(9)H(14)N)(2)[Cu(3)Cl(8)]}(n), consists of parallel chains of alternating quasiplanar Cu(2)Cl(6) and planar CuCl(4) complexes separated by trimethylphenylammonium cations. Both inorganic complexes possess inversion symmetry. Pairs of neighboring chloride ions of the CuCl(4) complex each form a symmetric bridge and an asymmetric bridge to Cu(2)Cl(6) complexes on either side. The Cu(2)Cl(6) complex contains two symmetric chloride bridges between the copper cations with a terminal chloride bound to each five-coordinated Cu(II) ion. The CuCl(4) complex completes its coordination environment by forming two long semicoordinate contacts to the bridging chloride ions of neighboring Cu(2)Cl(6) complexes. The use of the bridging rather than the terminal chloride ions to form semicoordinate contacts generates a new zigzag chain structure that differs from the straight chain structures found for other A(2)Cu(3)Cl(8) compounds. The zigzag chain structure is adopted so as to conform to the shorter repeat distance dictated by stacking of the organic cations.

Octakis(dimethylammonium) hexa-μ2-chlorido-hexachloridotrinickelate(II) dichloride: a linear trinickel complex with asymmetric bridging

The title compound, (C2H8N)8[Ni3Cl12]Cl2, crystallizes as linear [Ni3Cl12]6- complex anions with inversion symmetry, separated from one another by dimethylammonium cations and noncoordinated chloride ions. The gross structural arrangement of the trinickel complex is as a segment of face-sharing NiCl6 octahedra similar to the (NiCl3)n chains of CsNiCl3-type compounds. On closer inspection, the regular coordination geometry of the complex consists of octahedral NiCl6 in the center linked by two symmetrically bridging chloride ions to square-pyramidal NiCl5 on each end. A long semicoordinate bond is formed by each of the terminal Ni(II) cations, to give a 5+1 coordination geometry and form an asymmetric bridge to the central Ni(II) cation. The dimethylammonium cations surround the complex with an extensive hydrogen-bonding network, linking the complex to the noncoordinated chloride ions. Asymmetric bridging in the complex arises from short hydrogen bonds from the same dimethylammonium cation to the apical and asymmetric bridging chloride ions, causing the complex to scissor outward.

Novel carbon-centered heteroscorpionate ligands: Cu(I) complexes and luminescence properties

Herein, we describe the synthesis of N,N′,S donor ligands 2-(1-(3,5-diisopropyl-1 H-pyrazol-1-yl)-3-(methythio)propyl)-4-methoxy-3,5-dimethylpyridine (L1) and 2-(1-(3,5-diisopropyl-1 H-pyrazol-1-yl)-2-(methythio)ethyl)-4-methoxy-3,5-dimethylpyridine (L2). Cu(I) complexes were prepared by reacting L1 or L2 with [Cu(CH 3CN) 4]BF 4 or CuCl. The coordination behavior of the thioether arm of the ligands was found to determine the nuclearity of the resulting complexes, in which [Cu(L1)PPh 3]BF 4 ( 1) is polynuclear, [Cu(L2)PPh 3]BF 4 ( 2) is mononuclear, while [Cu(L1)] 2(BF 4) 2 ( 3), [Cu(L2)CH 3CN] 2(BF 4) 2 ( 4), and [Cu(L1)Cl] 2 ( 5) are dinuclear. In the dimeric complex [Cu(L2)Cl] 2 ( 6), the sulfur atoms are not metal-bound. Rather, the two bridging chloride ions link the two copper centers. Compounds 4– 6 are luminescent in the solid state, and exhibit emission bands centered at 490 nm ( 4), 544 nm ( 5), and 562 nm ( 6), respectively. Their excitation spectra display bands at 280 nm and 380 nm. According to DFT calculations, the HOMO is distributed partially over the metal centers and partially over the chloride anions ( 5 and 6) or the sulfur atoms ( 4) of the ligands, while the LUMO is a π∗ antibonding pyridine orbital. This suggests that the emission properties are derived from metal-to-ligand charge-transfer (MLCT), halide-to-ligand charge-transfer (XLCT), and ligand-to-ligand charge-transfer (LLCT) excited states.

Di-μ-chlorido-bis{aquachlorido[3-ethyl-4-phenyl-5-(2-pyridyl)-4H-1,2,4-triazole-κ2N1,N5]manganese(II)}

In the centrosymmetric dinuclear title compound, [Mn2Cl4(C15H14N4)2(H2O)2], the MnII atom is coordinated by an N,N′-bidentate ligand, a water mol­ecule, a terminal chloride ion and two bridging chloride ions in a distorted MnN2OCl3 octa­hedral geometry. The Mn⋯Mn separation is 3.6563 (9) Å. In the crystal structure, O—H⋯N and O—H⋯Cl hydrogen bonds help to establish the packing.

Metal−Metal Communication in Copper(II) Complexes of Cyclotetraphosphazene Ligands

Copper(II) chloride and bromide react with the pyridyloxy-substituted cyclotetraphosphazene ligands, octakis(2-pyridyloxy)cyclotetraphosphazene (L(1)), and octakis(4-methyl-2-pyridyloxy)cyclotetraphosphazene (L(2)), to form the dimetallic complexes, [L(CuX2)2] (L = L(1), X = Br; L = L(2), X = Cl or Br), and [{L(1)(CuCl2)2}n]. Single crystal X-ray crystallography shows the complex [{L(1)(CuCl2)2}n] to be a coordination polymer propagated by interligand "Cu(mu-Cl)2Cu" bridges whereas [L(2)(CuCl2)2] forms discrete dimetallic cyclotetraphosphazene-based moieties. The variable temperature magnetic susceptibility data for [{L(1)(CuCl2)2}n] are consistent with a weak antiferromagnetic exchange interaction between the copper(II) centers occurring via the bridging chloride ions. [L(2)(CuCl2)2] and [L(CuBr2)2] (L = L(1) and L(2)) exhibit normal Curie-like susceptibilities. The abstraction of a chloride ion, using [Ag(MeCN)4](PF6), from each copper site in [L(2)(CuCl2)2], affords the new complex, [L(2)(CuCl)2](PF6)2, in which the two copper(II) ions are separated by "N-P=N-P=N" phosphazene bridges. Electron spin resonance and variable temperature magnetic measurements indicate the occurrence of weak antiferromagnetic coupling between the unpaired electrons on the copper(II) centers. Density Functional Theory (DFT) calculations on the [L(2)(CuCl)2](2+) dication and the related cyclotriphosphazene complex, [L(4)(CuCl2)2] (L(4) = hexakis(4-methyl-2-pyridyloxy)cyclotriphosphazene), have identified "electron-density-bridge" molecular orbitals which involve Cu 3d orbitals overlapping with the non-bonding N-based molecular orbitals on the phosphazene rings as the pathway for this interaction.

Di-μ-chlorido-bis{chlorido[2-(2-furylmethyliminomethyl)pyridine-κ2N,N′]nickel(II)}

The title dinuclear nickel(II) complex, [Ni2Cl4(C11H10N2O)2], lies on a centre of symmetry located at the centroid of the four-membered ring formed by the two Ni atoms and the bridging chloride ions. The NiII atom is five-coordinated in a square-pyramidal geometry by the imine and pyridine N atoms of the Schiff base ligand, and by one terminal and two bridging Cl atoms. The Ni⋯Ni distance is 3.506 (2) Å. The O atom of the furan substituent in the ligand unit is not involved in coordination to the Ni atom.