Binuclear Silver Research Articles

Synthesis and structural characterization of new dinuclear silver(I) complexes: Different coordination modes of substituted 1,2,4-triazine ligands

Abstract Two new binuclear silver(I) complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PDT) and 3,5,6-tris(2-pyridyl)-1,2,4-triazine (TPT) ligands, [Ag2(PDT)2(NO3)2], 1, and [Ag2(TPT)2(NO3)2], 2, have been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy, and also studied by thermal and electrochemical analysis as well as by X-ray crystallography. The individual dinuclear complexes in 1 are extended into a one-dimensional layered structure by weak Ag···CPDT (η3) interactions. The interesting features of the Ag(I) complexes are the different coordination modes of the ligands. The supramolecular features in these complexes are controlled by weak directional intra and intermolecular interactions.

Syntheses, crystal structures of Ni(II), Ag(I)-enoxacin complexes, and their antibacterial activity

Two metal–enoxacin complexes, [Ni(H-Ex)2(H2O)2](NO3)2 (1) and Ag2(H-Ex)4(NO3)2 (2) (where H-Ex = enoxacin, Ex = deprotonated enoxacin), have been synthesized and characterized by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction. Complex 1 is composed of a [Ni(H–Ex)2(H2O)2]2+ core with two uncoordinated nitrates. The Ni(II) lies on the inversion site in a slightly distorted octahedral environment. Complex 2 is a binuclear silver(I) complex, in which two Ag(I) ions are bridged by a weakly bonding bidentate . The coordination modes of enoxacin are monodentate for 2 and bidentate for 1. In addition, 1 and 2 were screened for their activities against several bacteria and showed activities similar to that of free enoxacin; the test compounds were more active against Gram-negative bacteria than Gram-positive bacteria.

Anion-directed assembly of metal–organic coordination complexes from 1,3-imidazolidine-2-thione ligand and silver salts

Five novel silver (Ι) complexes with 1,3-imidazolidine-2-thione ligand formulated as [Ag 2(η 1-SC 3H 6N 2) 6]SO 4 ( 1), [Ag 2(μ 2-SC 3H 6N 2) 2(η 1-SC 3H 6N 2) 4](NO 3) 2 ( 2), [Ag(μ 2-SC 3H 6N 2)Br] n ( 3), [Ag 2(μ 2-SC 3H 6N 2) 3(CH 3COO) 2] n ( 4), [Ag(μ 2-SC 3H 6N 2)Cl] n ( 5) have been synthesized under similar conditions except for different anions and solvents. They are structurally characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. Complex 1 is a binuclear complex, with SO 4 2− anions as the counteranions. Complex 2 is a molecular binuclear silver cluster, with NO 3 − anions as the counteranions. Complex 3 shows a novel 2D lamella structure constructed by the S atom of 1,3-imidazolidine-2-thione ligand and Br − anions, and exhibits 12-membered metallacyclic rings in its structure. Complex 4 is a novel 2D layered polymer with a graphite-like array of silver (I) ions, with CH 3COO − anion coordinated to silver(I) ions by O atom. Complex 5 shows a 3D diamond-like network structure constructed by the sulfur atom of 1,3-imidazolidine-2-thione ligand and Cl − anions.

Di-μ-bromido-tris(triphenylphosphine)-1κP,2κ2P-disilver(I) tetrahydrofuran 0.85-solvate

In the title binuclear silver(I) complex, [Ag2Br2(C18H15P)3]·0.85C4H8O, the two independent silver(I) ions are briged by two bromide ions. One AgI ion is coordinated by two triphenyl­phosphine groups with a square-planar geometry, while the second is coordinated by one triphenyl­phine group with a trigonal-planar geometry. The structure is very similar to that of the dichloro­methane solvate reported by Zhu, Huang & Zheng [Chin. J. Struct. Chem. (1994), 13, 325–327]. The tetrahydrofuran solvent molecule is disordered and was refined with a fixed occupancy of 0.85.

A binuclear silver(I) perchlorate macrocycle based on 2,5-bis[( E)-(3-pyridyl)methylene]cyclopentanone: Crystal structure and solution behavior

The homobinuclear complex [Ag(MeC N)(OClO 3)(μ-L)] 2 (L = 2,5-bis[( E)-(3-pyridyl)methylene]cyclopentanone) ( 3) has been prepared by the diffusion-controlled reaction of [AgClO 4] ( 1) dissolved in acetonitrile with equimolar amounts of L ( 2) in chloroform. The coordination complex 3 was characterized by single-crystal X-ray diffraction studies, showing that in the solid state a 26-membered disilver macrocycle is formed. The four coordination sites at the silver metal center are occupied by two nitrogen donor atoms of neighboring ligands, one nitrogen donor atom of an acetonitrile solvent molecule and an oxygen donor atom from a weakly-coordinated OClO 3 counter-anion. During a 6 months period compound 3 in the solid state does not undergo any visible changes upon action of ambient light (NMR check), whilst dimethylsulfoxide (DMSO) solutions of 3 on exposure to sunlight undergo a rapid ( ca. 1 day) photochemical transformation, namely trans/ cis-isomerization and [2+2] cycloaddition reactions. This phenomenon is explained by the dissociation of 3 to the starting components 1 and 2 in DMSO and acetonitrile solutions, as has been demonstrated by 1H NMR spectroscopy and ESI-TOF mass-spectrometry.

Positive Homotropic Allosteric Binding of Silver(I) Cations in a Schiff Base Oligopyrrolic Macrocycle

The binuclear silver(I) complex of a Schiff base oligopyrrolic macrocycle was prepared in high yield and fully characterized. UV-visible absorption and 1H NMR spectroscopic analyses reveal that coordination of Ag(I) cations is subject to a strong positive homotropic allosteric effect.

Discrete Metal Complexes of Two Multiply Armed Ligands

The syntheses and metal complexes of 1,2,4,5-tetrakis(8-quinolyloxymethyl)benzene 1 and hexakis(8-quinolyloxymethyl)benzene 2 are described. X-Ray crystal structures are reported of the free ligand 1, a binuclear silver(i) and a tetranuclear copper(i) complex of 1, as well as a binuclear cobalt(ii) and trinuclear palladium(ii) and silver(i) complexes of 2. Within these discrete metal complexes the ligands are found to adopt a range of coordination modes, with considerable variation in the relative orientations of the ligand arms as a result of the flexibility imparted by the CH2O linker units.

Synthesis and Crystal Structures of Binuclear Metallocyclophane with N-Heterocyclic Carbene Linkage by the π−π Stacking Interaction

The synthesis and crystal structures of binuclear silver(I) and mercury(II) metallocyclophanes with N-heterocyclic carbene linkages by the π−π stacking interaction are described.

Silver coordination chemistry of a new versatile "Janus"-type N(2),O(2)-bichelating donor, formation of an unprecedented supramolecular network of binuclear silver building blocks containing a five-coordinate beta-diketonate, and isolation of unexpected silver-tin-silver heterotrimetallic complexes from silver metathesis reactions.

Synthetic, spectroscopic, and single-crystal X-ray studies are reported for several complexes of silver(I) with the N(2),O(2)-bichelating Q(py) ligand (HQ(py) = 1-(2-pyridyl)-3-methyl-4-trifluoroacetylpyrazol-5-one). Direct interaction between HQ(py) and AgNO(3) in methanol, in the presence of NaOCH(3), affords derivative Ag(Q(py)), showing a polynuclear structure composed of dinuclear building blocks with two different Ag environments and two Q(py) donors differently connected. By adding neutral ligands such as PR(3) (R = Ph, Cy, C(6)H(4)-o-CH(3), C(6)H(4)-p-F, Bu(i)) to Ag(Q(py)), dinuclear Ag(Q(py))(PR(3)) derivatives have been isolated, containing bridging N(2),O-exotridentate Q(py) donors spanning a pair of AgPR(3) moieties. Reaction of Ag(Q(py))(PPh(3)) with excess PPh(3) produces the mononuclear Ag(Q(py))(PPh(3))(2) containing N(2)-chelate Q(py). Ag(Q(py)) interacts with 1,2-bis(diphenylphosphino)ethane (dppe) yielding the derivative Ag(Q(py))(dppe), having a polynuclear structure in the solid state which is seemingly disrupted in solution, with the formation of two new species, a mononuclear neutral compound and a dinuclear ionic one. By the interaction of Ag(Q(py)) with nitrogen donors L (L = imidazole (imH), 1-methylimidazole (Meim), 1-methyl-2-mercaptoimidazole (Hmimt), 1,10-phenanthroline (phen)), mononuclear species Ag(Q(py))(L) have been obtained, where Q(py) is coordinated to silver in N(2)-chelating mode. Ag(Q(py))(PPh(3))(2) reacts with SnRCl(3) (R = Ph, Bu(n)) affording heterotrimetallic [[(Ph(3)P)(2)AgCl](2)SnRCl(3)] derivatives.

Metallacrown ethers: synthesis and structural investigation of silver metallamacrocycles

The bis-monodentate ligands 1 and 2 based on the interconnection of two pyrazolyl units by CH 2(CH 2OCH 2) n CH 2 ( n=3 or 4) spacers, respectively, lead to the formation of either mono nuclear silver metallamacrocycle 10 in the case of 1 or binuclear silver metallamacrocycle 11 in the case of 2 . Both complexes have been characterised in the solid state by X-ray diffraction on single crystals.

Preparation, Structural Characterization and Luminescent Property of Binuclear Silver (I) Complex Formed by Benzotriazole and 1‐Hydroxymethyl Benzotriazole

AbstractDinuclear silver (I) six‐membered ring complex [Ag2 (bta)2 ‐(hmbta)2] (ClO4)2 (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH3CN)4ClO4. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm3 and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm3 and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement.

Silver(I) complexes derived from versatile multidentate chelating ligand

Three novel Ag(I) coordination polymers, [{Ag 3(bpsp) 2·dmf·MeCN}(ClO 4) 3] n ( 1), [Ag 2(bpsp) 2](NO 3) 2 ( 2) and [{Ag 4(bpsp) 2(NO 3) 2·dmf}(NO 3) 2] n ( 3), were synthesized by self-assembly of AgX (X=ClO 4 −, NO 3 −) with bpsp (bpsp=2,6-bis[(2-pyrimidinyl)methylsulfanyl]-pyridine). X-ray single-crystal diffraction analyses showed that the versatile multidentate chelating ligand bpsp ligates coordinately flexible Ag(I) into 1 in a one-dimensional(1-D) zigzag chain polymer, 2 in a helical dimer and 3 in two independent 1-D zigzag chains (chain A and B), respectively. In 1, one bpsp ligand acts in an unusual pentadentate mode with two sulfur atoms and three nitrogen atoms from a pyridine ring and different pyrimidine rings coordinating to three different Ag atoms; the other bpsp ligand acts in a tridentate mode with three nitrogen atoms from the pyridine ring and different pyrimidine rings bridging three different Ag atoms. The bpsp ligand in 2 functions in another tridentate mode with one sulfur atom and a nitrogen atom of the pyridine ring chelating with Ag(I) and with one nitrogen atom of the pyrimidine ring ligating the other Ag(I) to form a binuclear silver(I) helicate. For chain A in 3, the bpsp ligand can serve in an unusual tetradentate fashion, in which a sulfur atom and a nitrogen atom of the pyridine ring chelate with the Ag atom to form a stable five-membered ring, and two nitrogen atoms from different pyrimidine rings bridge two Ag atoms in different directions. Similar to the bpsp molecule of pentadentate fashion in 1, bpsp molecule also serves as a pentadentate ligand in the chain B of 3. Ag atoms adopt three, one, and four different coordination fashions in 1, 2, and 3, respectively.

NMR observation of hydrolysis of acetonitrile to acetamide catalyzed by binuclear silver cryptate

NMR analyses (TOCSY, HMQC and DOSY) indicate that, in the presence of water, acetonitrile is exclusively hydrolyzed to acetamide catalyzed by bisilver cryptate complex, which contains coordinating acetonitrile molecule.

Spectroscopic Evidence for Argentophilicity in Structurally Characterized Luminescent Binuclear Silver(I) Complexes

A spectroscopic and structural investigation of binuclear silver(I) complexes supported by aliphatic phosphine ligands, namely [Ag(PCy3)(O2CCF3)]2 (1), [Ag2(μ-dcpm)2]X2 (X = CF3SO3, 2; PF6, 3; dcpm = bis(dicyclohexylphosphino)methane), and [Ag2(μ-dcpm)(μ-O2CCF3)2] (4), is described. X-ray structural analyses of 1−4 reveal Ag−Ag separations of 3.095(1), 2.948 (av), 2.923 (av), and 2.8892(9) A, respectively. Due to the optical transparency of the phosphine ligands, the UV−vis absorption band at 261 nm in CH3CN for 2 and 3 is assigned to a 4dσ* → 5pσ transition originating from Ag(I)−Ag(I) interactions. The argentophilic nature of this band is verified by the resonance Raman spectrum of 2 with 273.9 nm excitation, where virtually all of the Raman intensity appears in the Ag−Ag stretch fundamental (80 cm-1) and overtone bands. Complexes 2 and 3 exhibit photoluminescence in the solid state at room temperature.

Synthesis and structural characterization of binuclear silver(I) complexes bridged by three polydentate phosphine ligands

The reaction of AgNO 3 with 3,6-bis(diphenylphosphino)pyradazine, L 1, in the ratio of 2:3 in dichloromethane afforded the new binuclear complex [Ag 2(μ-L 1) 3(η 2-NO 3) 2] ( 1), while the reaction of AgClO 4 with 2,6-bis(diphenylphosphino)pyridine, L 2, in the ratio of 2:3 in dichloromethane afforded [Ag 2(μ-L 2) 3](ClO 4) 2 ( 2). The reaction of [Ag 2(μ-L 3) 2(MeCN) 2](ClO 4) 2 (L 3 = (2-diphenylphosphino-6-pyrazol-1-yl)pyridine) with dppm gave the ligand substitution product [Ag 2(μ-L 3) 2(μ-dppm)](ClO 4) 2 ( 3), in high yield. The structures of all three compounds have been determined by single crystal X-ray analysis.

Cryptands with Large Cavity Lengths Over 16 Å and N8O6Hetero-donors: Template Macrobicyclization and Structure of a Binuclear Copper(I) Cryptate

Hetero-tritopic N8O6 cryptands L1 and L2 were synthesized via 2 + 3 silver(I) template Schiff-base macrobicyclization of tris(2-aminoethyl)amine and tris(3-aminopropyl)amine with 4,4′-methylenedioxy-dibenzaldehyde, respectively. The resulting binuclear silver(I) cryptates [Ag2L1](CIO4)2 (1) and [Ag2L2](CIO4)2 (2) were characterized by various methods (elemental analyses, IR, UV-Vis, 1H and 13C NMR, and FAB mass spectra). The binuclear copper(I) cryptate [Cu2L1I(BF4)2·DMF·EtOH·H2O (3) was synthesized by transmetallation with 1 and studied by spectroscopic and X-ray structural analyses. It crystallizes in the monoclinic, space group P21/n with a = 16.088(5), b = 11.941(4), c = 34.08(1) Å, β = 91.69(2)°, Z = 4. d = 1.41 g cm−3. R 1 = 0.117, wR2 = 0.111 (on 3859 observed with I > 2σ(I)). The bicopper(I) cryptate looks like a twisted elongated ellipsoid, possessing cavity length 16.4Å and Cu(1) Cu(2) separation 12.132(5) Å. The two Cu(I) centers have similarly high stability towards oxidation. The cryptate does not show any reactivity or inclusion towards 4,4′-bipyridine, imidazole, N− 3, Na+, K+ and NH+ 4, mainly due to the highly effective distorted tetrahedron coordination around each Cu(I) enter and twisting among the three bridging-chains in the cryptand.

Synthesis of the New Polydentate Phosphine Ligand 1-[(Diphenylphosphino)methyl]-4- (2-pyridyl)piperazine and Structural Characterization of Its Binuclear Silver(I) and Mononuclear Iron(0) Complexes.

A new nonrigid PN-phosphine ligand, 1-[(diphenylphosphino)methyl]-4-(2-pyridyl)piperazine (L1), has been synthesized and its centrosymmetric binuclear silver(I) complex [Ag(μ-L1)(O3SCF3)]2, 1, and mononuclear iron(0) complex Fe(CO)3(L1)2, 2, have been structurally characterized by single-crystal X-ray analysis.

Binuclear silver(I) complexes with polydentate phosphine ligands 2-(diphenylphosphino)-6-[3-(2′-pyridyl)pyrazol-1-yl]pyridine and 2-(diphenylphosphino)-6-(pyrazol-1-yl)pyridine

The new polydentate, pyridine-based phosphine ligand 2-(diphenylphosphino)-6-[3-(2′-pyridyl)-pyrazol-1-yl]pyridine (L2) has been synthesized. The reaction of L2 with [Ag(MeCN)4][ClO4] resulted in the formation of the binuclear silver(I) complex [Ag2(µ-L2)2(ClO4)2], which is stabilized by significant π–π stacking interactions between its inter-ligand pyridyl fragments. In contrast, the reaction of 2-(diphenylphosphino)-6-(pyrazol-1-yl)pyridine (L1) with [Ag(MeCN)4][ClO4] gave the binuclear complex [Ag2(µ-L1)2(MeCN)2][ClO4]2, which exhibits a weak metal–metal interaction.

Influence of anions and crystallisation conditions on the solid-state structure of some binuclear silver(I) complexes supported by triazolopyrimidine bridges

The reaction of silver salts AgX (X = NO3 or ½SO4) with [1,2,4]triazolo[1,5-a]pyrimidine (tp) in aqueous media afforded the silver(I) binuclear complexes [Ag2(NO3)2(µ-tp-N 3,N 4)2] 1, [Ag2(SO4)(µ-tp-N 3,N 4)2(H2O)]·H2O 2, [Ag2(SO4)(µ-tp-N 3,N 4)3(H2O)]·3H2O 3 and [Ag2(SO4)2(Htp)2] 4. The compounds have been structurally characterised by spectroscopic methods (IR, 1H, 13C NMR) and X-ray crystallography (1, 2 and 3). The X-ray results show that the complexes comprise dimeric units in which the silver atoms are bridged by two (1, 2) or three (3) tp ligands, giving rise to intermetallic contacts of 3.117(1), 3.127(1) and 3.089(1) A respectively for 1, 2 and 3. The crystallisation conditions and/or the nature of the anion appear to play an important role in the stereochemistry of the silver centres. The NMR studies in D2O suggest that the ligand exhibits in solution the same co-ordination mode as found in the solid state.

Structure of a binuclear silver(I) complex [Ph3PAg(O2CCH2Ph)

The reaction of [Ph3PAgI]4 with sodium phenylacetate in MeOH and CH2Cl2 at room temperature gave rise to a binuclear silver complex with triphenylphosphine and phenylacetate mixed ligands, [Ph3PAg(O2CCH2Ph)]2. The crystal and molecular structure of the complex has been determined by single crystal X-ray diffraction analysis. The space group is $$P\bar 1$$ witha=9.198(2),b=9.516(2),c=13.842(3) A, α=102.00(3), β=108.34(3), γ=93.58(3)°,Z=1, andDc=1.506 g cm−3. The silver atoms are each coordinated by one phosphorus atom from triphenylphosphine and two oxygen atoms from the carboxylate groups in a T-shape. The complex is further characterized by its IR,1H, and31P NMR spectra.