W/Cu(Ag)/S complexes containing bridging diphosphine ligands: Synthesis,structures and optical properties

The substitution reactions of [Et₄N]₂[WOS₃MCN] (M = Cu, Ag) with dppe (dppe = 1,2-bis(diphenylphosphino) ethane) in DMF afforded a tetranuclear cluster [Et₄N]₂[WOS₃Cu(dppe)]₂ · H₂O (1) and a polymer [WEE′S₂Ag(dppe)]₂ · CH₃CN (3) (E = 0.636S + 0.364O, E′ = 0.581O + 0.419S), respectively. Treatment of 1 with AgI at elevated temperature yielded polymeric complex [WS₄Cu₂(dppe)₂]_n (2). X-ray single crystal structural analyses revealed that in both 1 and 2, the W/Cu/S cluster units are linked by two dppe ligands to form a 10-membered [–Cu–P–C–C–P–]₂ ring. In the polymeric structure of 2, the W and Cu atoms form a helical chain whereas in 3 the cluster units (WEE′S₂Ag) are bridged by dppe ligands affording a zig-zag chain structure. The optical absorption spectra and the solid-state photoluminescent properties of the title complexes are also studied.     

Syntheses, structures and properties of silver(I) complexes with flexible 1,3,5-tris(pyridylmethoxyl)benzene ligands

Five new silver(I) complexes [Ag₂(L₂)₂](BF₄)₂·CH₃CN·CH₃OH (1), [Ag(L₂)(CF₃SO₃)] (2), [Ag(L₃)]ClO₄·CH₃OH (3), [Ag₂(L₃)₂](CF₃SO₃)₂·CH₃CN·CH₃OH·H₂O (4) and [Ag(L₃)]PF₆·2CH₃CN (5) [L₂=1,3,5-tris(2-pyridylmethoxyl)benzene, L₃=1,3,5-tris(3-pyridylmethoxyl)benzene] were synthesized and characterized by single crystal X-ray diffraction analyses. In complexes 1-5, ligands L₂ and L₃ show different conformations and act as three-connectors, while the Ag(I) atom serves as three-connecting node to result in the formation of 2D and 3D frameworks. Complexes 1 and 2 with different counteranions have similar 2D network structure with the same (4,8²) topology. Complex 3 has a 3D structure with (10,3)-a topology while complexes 4 and 5 have the same 2D (6,3) topological structure. The results showed that the structure of organic ligands and counteranions play subtle but important role in determining the structure of the complexes. In addition, the photoluminescence and anion-exchange properties of the complexes were investigated in the solid state at room temperature.     

Synthesis, structure, DNA-binding properties and antioxidant activity of silver(I) complexes containing V-shaped bis-benzimidazole ligands

A V-shaped ligand bis(2-benzimidazol-2-ylmethyl)benzylamine L(1) with its two derivatives bis(N-methylbenzimidazol-2-ylmethyl)benzylamine L(2) and bis(N-benzylbenzimidazol-2-ylmethyl)benzylamine L(3) have been prepared. Reaction of these shape-specific designed ligands with Ag(pic) (pic = picrate) afforded three novel complexes, namely, [Ag(2)L(1)(2)](pic)(2)1, [Ag(2)L(2)(2)](pic)(2)·2DMF 2 and [AgL(3)(pic)] 3. The ligands and complexes were characterized on the basis of elemental analysis, UV-Vis, IR, NMR spectroscopy and X-ray crystallography. Complex 1 is a dinuclear metallacycle with a 2-fold rotational symmetry in which two syn-conformational L(1) ligands are connected by two linearly coordinated Ag(I) atoms. Due to the strong interaction between two adjacent Ag(I) atoms, the coordination mode of the central Ag(I) atom can be described as T-shaped. Complex 2 consists of a centrosymmetric dinuclear pore canal structure assembled from two nearly linearly coordinated Ag(I) atoms and two L(2) ligands. The structure of complex 3 adopts a four-coordinate environment for AgN(2)O(2), with the counterion participating in an eight-shaped geometry. In order to explore the relationship between the structure and biological properties, the DNA-binding properties have been investigated by viscosity measurements, electronic absorption, and fluorescence. The results suggest that the ligands and complexes bind to DNA in an intercalation mode, and their binding affinities for DNA are also different. Moreover, the three Ag(I) complexes also exhibited potential antioxidant properties in vitro studies.     

Synthesis,spectral characterization,properties and structures of copper(I) complexes containing novel bidentate iminopyridine ligands

Four new ligands, (4-methyl-phenyl)-pyridin-2-ylmethylene-amine (A), (2,3-dimethyl-phenyl)-pyridin-2-ylmethylene-amine (B), (2,4-dimethyl-phenyl)-pyridin-2-ylmethylene-amine (C) and (2,5-dimethyl-phenyl)-pyridin-2-ylmethylene-amine (D), and their corresponding copper(I) complexes, [Cu(A)₂]ClO₄ (1a), [Cu(B)₂]ClO₄ (1b), [Cu(C)₂]ClO₄ (1c), [Cu(D)₂]ClO₄ (1d), [Cu(A)(PPh₃)₂]ClO₄ (2a), [Cu(B)(PPh₃)₂]ClO₄ (2b), [Cu(C)(PPh₃)₂]ClO₄ (2c) and [Cu(D)(PPh₃)₂]ClO₄ (2d), have been synthesized and characterized by CHN analyses, ¹H and ¹³C NMR, IR and UV–Vis spectroscopy. The crystal structures of [Cu(B)₂]ClO₄ (1b), [Cu(C)₂]ClO₄ (1c) and [Cu(A)(PPh₃)₂]ClO₄ · 1/2CH₃CN (2a) were determined from single crystal X-ray diffraction. The coordination polyhedron about the copper(I) center in the three complexes is best described as a distorted tetrahedron. A quasireversible redox behavior is observed for the complexes.     

Luminescent heteroleptic copper(I) complexes with polydentate benzotriazolyl-based ligands

Transition Metal Chemistry - Bis(benzotriazol-1-yl)phenylmethane CHPh(btz)2 and tris(benzotriazol-1-yl)methane CH(btz)3 were used as N-donor ligands to prepare luminescent heteroleptic copper(I)...     

Polymeric complexes of silver(I) with diphosphine ligands: self-assembly of a puckered sheet network structure

The syntheses and structures of polymeric silver(I)-diphosphine complexes are reported, in which the silver(I) center is surrounded by 1, 2, or 3 phosphorus atoms. When rigid diphosphine ligands are used in combination with weakly coordinating anions, linear polymers are obtained that contain both diphosphine and anion bridges. However, with excess of a diphosphine with a long, flexible, spacer group, a remarkable puckered sheet structure, comprised of fused giant 54-membered rings, is obtained that is a coordination polymer analogue of laminated materials such as micas and clays. The polymeric chain and sheet structures may be considered to be formed by ring-opening polymerization of cyclic precursors.     

Synthesis and structures of cyclic gold complexes containing diphosphine ligands and luminescent properties of the high nuclearity species

A mixture of cyclic gold(I) complexes [Au(2)(μ-cis-dppen)(2)]X(2) (X = OTf 1, PF(6)3) and [Au(cis-dppen)(2)]X (X = OTf 2, PF(6)4) is obtained from the reaction of [Au(tht)(2)]X (tht = tetrahydrothiophene) with one equivalent of cis-dppen [dppen = 1,2-bis(diphenylphosphino)ethylene]. The analogous reaction with trans-dppen or dppa [dppa = bis(diphenylphosphino)acetylene] affords the cyclic trinuclear [Au(3)(μ-trans-dppen)(3)]X(3) (X = OTf 11, PF(6)12) and tetranuclear [Au(4)(μ-dppa)(4)]X(4) (X = OTf 13, PF(6)14, ClO(4)15) gold complexes, respectively. Recrystallization of 15 from CH(2)Cl(2)/MeOH yielded a crystal of the octanuclear gold cluster [Au(8)Cl(2)(μ-dppa)(4)](ClO(4))(2)16. Attempts to prepare dicationic binuclear gold(II) species from the reaction of a mixture of 3 and 4 with halogens gave a mixture of products, the components of which confirmed to be acyclic binuclear gold(I) [Au(2)X(2)(cis-dppen)] (X = I 5, Br 7) and cyclic mononuclear gold(III) [AuX(2)(cis-dppen)]PF(6) (X = I 6, Br 8) complexes. Complexes 11-14 reveal weak emission in butyronitrile glass at 77 K, but they are non-emissive at room temperature. Ab initio modelling was performed to determine the charge state of the gold atoms involved. Extensive structural comparisons were made to experimental data to benchmark these calculations and rationalize the conformations.     

Polymeric silver(I) complexes with pyridyl dithioether ligands: experimental and theoretical investigations on the coordination properties of the ligands

The reactions of four flexible tetradentate ligands, 1,3-bis(2-pyridylthio)propane (L1), 1,4-bis(2-pyridylthio)butane (L2), 1,5-bis(2-pyridylthio)pentane (L3) and 1,6-bis(2-pyridylthio)hexane (L4) with AgX (X = BF4-, ClO4-, PF6-, or CF3SO3-) lead to the formation of seven new complexes: [AgL1(BF4)]2 (1), [[AgL2](ClO4)]infinity (2), [[AgL2(CH3CN)](PF6)]infinity (3), [[AgL3](BF4)(CHCl3)]2 (4), [[AgL3(CF3SO3)](CH3OH)(0.5)]infinity (5), [[Ag2L4(2)](BF4)2]infinity (6), and [[AgL4](PF6)]infinity (7), which have been characterized by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that complexes 1 and 4 possess dinuclear macrometallacyclic structures, and complexes 2, 3 and 5-7 take chain structures. In all the complexes, the nitrogen atoms of ligands preferentially coordinate to silver atoms to form normal coordination bonds, while the sulfur atoms only show weak interactions with silver atoms and the intermolecular AgS weak contacts connect the low-dimensional complexes into high-dimensional supramolecular networks. Additional weak interactions, such as pi-pi stacking, F...F weak interactions, Ag...O contacts or C-H...O hydrogen bonds, also help to stabilize the crystal structures. It was found that the parity of the -(CH2)n- spacers (n = 3-6) affect the orientation of the two terminal pyridyl rings, thereby significantly influence the framework formations of these complexes. The coordination features of ligands and their conformation changes between free and coordination states have been investigated by DFT calculations.     

Structures and spectral properties of heteroleptic copper (I) complexes: A theoretical study based on density functional theory

The structures and electronic absorption spectra of newly synthesized heteroleptic copper (I) complexes [CuL₁L₂]⁺ (L₁ = phen-imidazole and/or L₂ = dipyrido [3,2-a:2’,3’-c] phenazine derivatives) are analyzed under the light of density functional theory (DFT) and time-dependent DFT (TD-DFT). The ground states geometries, characterized by π-stacking interactions, have been optimized using PBE-D functional taking into account dispersion correction. The UV-visible theoretical absorption spectra have been calculated using B3LYP functional in vacuum and taking into account solvent corrections by means of the polarized continuum model (PCM). Whereas the PBE-D functional is well adapted to the determination of the structures, it does underestimate drastically the transition energies. The spectra are characterized by high density of states, mainly metal-to-ligand-charge-transfer (MLCT) and intra-ligand (IL), between 600 nm and 250 nm. Most of the complexes show an intense band in the near-UV energy domain (～320 nm) corresponding to an IL transition. The lowest part of the absorption spectra, starting at 600 nm, corresponds to MLCT transitions leading to a shoulder observed experimentally between 400 and 500 nm. The upper part of the spectra, beyond 300 nm, puts in evidence strong mixing between ligand-to-ligand-charge-transfer (LLCT), IL and MLCT states.     

Syntheses, molecular structures, electrochemical behavior, theoretical study, and antitumor activities of organotin(IV) complexes containing 1-(4-chlorophenyl)-1-cyclopentanecarboxylato ligands

The organotin(IV) compounds [Me(2)Sn(L)(2)] (1), [Et(2)Sn(L)(2)] (2), [(n)Bu(2)Sn(L)(2)] (3), [(n)Oct(2)Sn(L)(2)] (4), [Ph(2)Sn(L)(2)] (5), and [PhOSnL](6) (6) have been synthesized from the reactions of 1-(4-chlorophenyl)-1-cyclopentanecarboxylic acid (HL) with the corresponding diorganotin(IV) oxide or dichloride. They were characterized by IR and multinuclear NMR spectroscopies, elemental analysis, cyclic voltammetry, and, for 2, 3, 4 and 6, single crystal X-ray diffraction analysis. While 1-5 are mononuclear diorganotin(IV) compounds, the X-ray diffraction of 6 discloses a hexameric drumlike structure with a prismatic Sn(6)O(6) core. All these complexes undergo irreversible reductions and were screened for their in vitro antitumor activities toward HL-60, BGC-823, Bel-7402, and KB human cancer cell lines. Within the mononuclear compounds, the most active ones (3, 5) are easiest to reduce (least cathodic reduction potentials), while the least active ones (1, 4) are the most difficult to reduce. Structural rearrangements (i.e., Sn-O bond cleavages and trans-to-cis isomerization) induced by reduction, which eventually can favor the bioactivity, are disclosed by theoretical/electrochemical studies.     

A series of luminescent Cu(I) mixed-ligand complexes containing 2,9-dimethyl-1,10-phenanthroline and simple diphosphine ligands

A series of Cu(I) mixed-ligand complexes containing dmp (2,9-dimethyl-1,10-phenanthroline) and one of simple diphosphine ligands (Ph2P(CH2)nPPh2) were prepared. Among the complexes, [Cu(dppp)(dmp)]PF6 (n=3) and [Cu2(dppb)2(dmp)2](PF6)2 (n=4) were characterized by X-ray structure analyses. The dppp complex has been characterized as a mononuclear complex, while [Cu2(dppb)2(dmp)2]2+ exists as a dinuclear complex in which two dppb ligands bridge between the two Cu(I) atoms. Although the distorted tetrahedral structures around the central metals of the two complexes are similar, the P-Cu-P angles are different between the two complexes. All of the series of complexes show photoluminescence in solution, and the intensity of the luminescence increases with n (n=2-4). The non-radiative rate constants of the complexes decrease markedly with n although radiative rate constants of the complexes are similar.     

Formation of N-heterocyclic diphosphine ligands from Ag(I)-assisted condensation reactions between bdppeda and formaldehyde and their binuclear silver(I) complexes

The reaction of [Ag(MeCN)(4)]ClO(4) with N,N,N',N'-tetra(diphenylphosphanylmethyl)ethylenediamine (dppeda) in CH(2)Cl(2)/MeOH afforded an unexpected cationic binuclear complex [Ag(2)(L(1))(2)(η,η-μ-ClO(4))(2)](ClO(4))(2) (L(1) = N,N'-bis(diphenylphosphanylmethyl)-3H-4,5-dihydroimidazole-1-ium) (1). Compound 1 was also prepared in high yield from reactions of [Ag(MeCN)(4)]ClO(4) with N,N'-bis(diphenylphosphanylmethyl)ethylenediamine (bdppeda) in the presence of formaldehyde (HCHO) or formic acid (HCOOH). Analogous reactions of AgCl with bdppeda and HCHO resulted in the formation a neutral binuclear complex [Ag(2)(L(2))(2)(μ-Cl)(2)] (L(2) = N,N-bis(diphenylphosphanylmethyl)-tetrahydroimidazole) (2). Treatment of 1 with concentrated HCl gave rise to a partially anion-exchanged product [Ag(2)(L(1))(2)(μ-Cl)(2)](ClO(4))(2) (3). Compounds 1 and 3 have a similar cationic binuclear structure, in which a [Ag(2)(η,η-μ-ClO(4))(2)] or [Ag(2)(μ-Cl)(2)] ring is sandwiched by two in situ-formed cationic L(1) ligands. The L(1) ligand may be generated by the Ag(I)-assisted condensation reaction between bdppeda and HCHO or HCOOH. Compound 2 holds a neutral binuclear structure, in which a [Ag(2)(μ-Cl)(2)] ring is connected by two in situ-formed L(2) ligands from its top and bottom sites. The neutral ligand L(2) may be produced from another Ag(I)-assisted condensation reaction between bdppeda and HCHO. The in situ formation of the L(1) and L(2) ligands provides a new route to the N-heterocyclic diphosphine ligands, and an interesting insight into the coordination chemistry of their metal complexes.     

Two silver(I) complexes based on dicarboxylate and flexible bis(benzimidazole) ligands: synthesis,crystal structures,sensing and photocatalytic properties

Transition Metal Chemistry - Two Ag(I) complexes, namely [Ag2(L1)2(HMIP)2·H2O]n (1) and [Ag2(L2)2(HPA)2]n (2) (L1?=?1,6-bis(2-methylbenzimidazol-1-yl)hexane,...     

Synthesis and structures of gold(I) phosphine complexes containing monoanionic selenocarbamate ester ligands

A series of mono- and dinuclear gold(I) phosphine complexes of the type [Au{SeC(OMe)NPh}(P)] [P = PPh₃, PTA, P(o-tolyl)₃, P(p-MeOC₆H₄)₃] and [Au₂{SeC(OMe)NPh}₂(μ-PP)] (PP = dppm, dppe, dppp, dppf, dppee) were prepared from the reaction of the appropriate chlorogold(I) phosphine complexes with N-phenyl-O-methylselenocarbamide in the presence of base. These new complexes were fully characterised by spectroscopic techniques and, in several cases, by X-ray crystallography. The differences in the solid-state structures of these selenium complexes were compared with those of some sulfur analogues.     

Photophysical properties of copper(I) and zinc(II) complexes containing phosphinoquinoline ligands

Several copper(I) and zinc(II) complexes with 8-(diphenylphosphino)quinoline (PPh₂qn) or 8-diphenylphosphinoquinaldine (PPh₂qna) have been prepared. These ligands contain both imine and phosphine moieties, which can act as coordinating groups. X-ray analysis of the Cu(I) complexes reveals that [Cu(PPh₂qn)₂]PF₆ (Cu-1) and [Cu(PPh₂qn)₂]PF₆ (Cu-2), coordinated by two PPh₂qn and PPh₂qna ligands respectively, are obtained. In the Zn(II) complexes, a structural study shows that [ZnCl₂(PPh₂qn)] (Zn-1), [ZnBr₂(PPh₂qn)] (Zn-2) and [ZnI₂(PPh₂qn)] (Zn-3) are coordinated by one PPh₂qn ligand and two of the corresponding halogeno ligands (Cl⁻, Br⁻ and I⁻). In the solid state Cu-1 and Cu-2 show luminescence which is assigned to a ³MLCT transition involving π∗ of the quinoline group, as shown in the [Cu(dmp)(diphosphine)]⁺ complexes; due to the reduced bulkiness of the coordination sphere around the copper atom, no emission is observed in solution. Zn-1 shows a similar emission band to that of free PPh₂qn at both room temperature and 77 K. It suggests the emission bands should be assigned to a ligand-centered (LC) transition. In the solid state, it is found that the emissive energy of the complexes shift to lower energy and the energy depends on the halogeno ligands in the zinc complexes.     

Electrophosphorescent homo- and heteroleptic copper(I) complexes prepared from various bis-phosphine ligands

Homo- and heteroleptic copper(I) complexes obtained from various chelating bis-phosphine ligands and Cu(CH3CN)4BF4 have been used for the preparation of light emitting devices.     

Structure and emission properties of mixed-ligand Cu(I) complexes containing phosphinesulfide ligands

Mixed-ligand Cu(I) complexes containing phosphinesulfide ligands were synthesized, and the structure and emission properties were studied for the Cu(I) complexes. X-ray crystallographic study showed that a chelating phosphinesulfide and diimine are coordinated to Cu(I) center. Coordination geometry around Cu(I) center of each complex is described as a distorted tetrahedron. Some of the complexes show photoluminescence in the solid state.