Mononuclear Cations Research Articles

Dichlorido(crown ether)lanthanoid(III) tetrachloroaluminate complexes

Reactions between LnCl3, AlCl3 and a crown ether (18-crown-6 and dibenzo18-crown-6) in MeCN have led to the isolation of four new lanthanoid halide crown ether complexes, [PrCl(μ-Cl)(18-crown-6)]2[AlCl4]2·2MeCN (1), [YbCl2(18-crown-6)][AlCl4]·MeCN (2), and [LnCl(μ-Cl)(dibenzo18-crown-6)}2][AlCl4]2·6.5MeCN (Ln = La, 3, Pr, 4). 1 was also obtained by unexpected halide transfer on addition of 18-crown-6 (18C6) to MeCN solutions of [Pr(MeCN)9][AlCl4]3. Complexes 1, 3 and 4 have dinuclear chloride-bridged nine-coordinate cations, and 2 has an eight coordinate mononuclear cation.

Highly stable VSi-beta zeolite synthesized by a post-synthesis strategy for efficiently catalyzing styrene epoxidation

To enhance the doping of vanadium in zeolites and achieve high stability, the selection of vanadium precursors containing specific vanadium species can effectively overcome this crucial problem. Two series of VxSi-Beta(A) and VxSi-Beta(N) zeolites have been prepared by a two-step post-synthesis method at pH = 1 and pH = 7. The properties and environments of vanadium in samples are investigated by UV–vis, XPS, EPR, H2-TPR and 51V MAS NMR. The bonding between vanadium and framework in VSi-Beta(A) is stronger than that of VSi-Beta(N). After the two are calcined or hydrated, the vanadium species in the former are relatively stable, while the pseudo-tetrahedral V(V) species and pseudo-octahedral V(V) species in the latter are interconverted. The changes of vanadium species in the supernatant during the preparation have been investigated by 51V static NMR. At low concentration and pH = 1, there is a unique mononuclear cation (VO2+) in the aqueous NH4VO3 solution, which is favorable for the interaction with the negatively charged hydroxyl nests generated after the nitric acid dealumination, and enables the V atoms to be tightly inserted into the framework. In styrene epoxidation, the type of V(V) species in the catalyst could significantly affect its catalytic performance, and the catalytic activity and stability of VxSi-Beta(A) are superior than that of VxSi-Beta(N).

An ionic gold(III)–zinc(II) pseudo-polymeric compound of [H3O][Au{S2CN(CH2)5}2]3[ZnCl4]2: Synthesis, supramolecular architecture and anti-tuberculosis activity

An ionic Au(III)-Zn(II) dithiocarbamato-chlorido compound of [H3O][Au{S2CN(CH2)5}2]3[ZnCl4]2 (1) has been synthesised by the reaction of binuclear zinc(II) pentamethylenedithiocarbamate with a H[AuCl4]/2.0 M HCl solution. The obtained complex was successfully characterised by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. There are six ionic moieties in the unit cell of 1: (i) three dithiocarbamato-gold(III) cations, one of which is structurally inequivalent to the other two; (ii) two symmetrically related tetrachloridozincate(II) anions and (iii) one hydronium cation that is disordered over four positions with equal occupancies of 0.25. The compound exhibits a rather complicated supramolecular structure, including pseudo-binuclear gold-rich [Au2(S2CNPm)4]2+ cations and {[ZnCl4]2}4– counter anions, which are stabilised by secondary Au···S and Cl···Cl interactions, respectively. In turn, the former pseudo-binuclear formations involving centrosymmetric mononuclear cations of [Au(S2CNPm)2]+ give the pseudo-polymeric cationic chains of (···[Au2(S2CNPm)4]2+···[Au(S2CNPm)2]+···)n; while the latter, pseudo-binuclear zinc(II) anions, {[ZnCl4]2}4–, as the double linkers combine the neighbouring cationic chains yielding a two-dimensional pseudo-polymeric network. The results on the biological activity of 1in vitro against the non-pathogenic strain Mycolicibacterium smegmatis (MIC 0.05 µg/disc) and virulent strains Mycobacterium tuberculosis H37Rv (0.14–0.19 µg/mL) and CN-40 (0.11–0.14 µg/mL) indicate a high efficiency of the studied Au(III)–Zn(II) compound against mycobacteria.

The di(thiourea)gold(I) complex [Au{S=C(NH2)2}2][SO3Me] as a precursor for the convenient preparation of gold nanoparticles

Abstract The synthesis of [Au{S=C(NH2)2}2][SO3Me] (1) (a) by the anodic oxidation of gold metal in an anolyte of thiourea and methansulfonic acid and (b) by the reaction of Au(OH)3 with an aqueous solution of methanesulfonic acid in the presence of thiourea is reported. The structure of 1 in the solid state has been determined by single-crystal X-ray diffraction showing a linear S–Au–S unit with the thiourea ligands in a leaflet structure folded by 113.2(3)°. The cation of complex 1 is a dimer, based on short S · · · C interactions between two adjacent mononuclear cations. The thermal decomposition behavior of 1 was studied by TG and TG-MS confirming that it decomposes under inert gas or oxygen atmosphere in four steps in the temperature range of 200–650°C. Initial decomposition starts with the release and fragmentation of one of the thiourea ligands, followed by the anion degradation. Powder X-ray diffraction studies specified the formation of gold metal. Based on this observation, complex 1 was used as precursor for the formation of gold nanoparticles (Au NPs) in 1-hexadecylamine (c = 4.0 mol L−1) at T = 330°C without any addition of reducing agents. TEM, electron diffraction, and UV/Vis spectroscopy studies were carried out. Au NPs of size 15 ± 4 nm were formed, showing the characteristic surface plasmon resonance at 528 nm.

Self-Assembly of Ag+/[PW11NbO40]4- Complexes in Nonaqueous Solutions.

Self-assembly between Ag+ and [PW11NbO40]4- in N- and O-donor solvents (nitriles and amides) has been studied. In the case of dimethylformamide (DMF), formation of a yellow [Ag4(DMF)12][PW11NbO40] (1a) metastable phase and a colorless [Ag4(DMF)10][PW11NbO40] (1) stable phase was observed. In acetonitrile (CH3CN), the product was [Ag(CH3CN)4]2{[Ag(CH3CN)3]2[PW11NbO40]} (2a). By contrast, [SiW12O40]4- of the same size and charge as [PW11NbO40]4- produces [Ag(CH3CN)3]4[SiW12O40] (3a). Partial desolvation of 2a and 3a leads to Ag4[PW11NbO40]·7.5CH3CN (2) and Ag4[SiW12O40]·7.5CH3CN (3), respectively. The CH3CN molecules in the structure of 2 are labile, and this compound was used as the starting material to study solvent-exchange processes in N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMA), diethylformamide (DEF), and benzonitrile (PhCN) solutions. These solvent reactions yield [Ag(DMA)4][Ag3(DMA)6][PW11NbO40] (4), [Ag2(NMP)4(CH3CN)]2[PW11NbO40]·1.3NMP (5a), [Ag2(NMP)5]2[PW11NbO40] (5b), Ag4[PW11NbO40]·9.5DEF (6), and [Ag(PhCN)4]2[{Ag(PhCN)3}2PW11NbO40] (7). All products were isolated and characterized by single-crystal X-ray diffraction (except for 2 and 3), IR, elemental analysis, and thermogravimetric analysis techniques. The O-donor solvents favor polynuclear, solvent-bridged cationic aggregates. In the case of DMF, DMA, and DEF discrete, tri- and tetranuclear polycations are observed, while in the case of NMP, the formation of infinite polycationic structures takes place. By contrast, the N-donor solvents (CH3CN and PhCN) favor mononuclear cations, which can exist either as distorted tetrahedral, isolated [Ag(Solv)4]+ cations or as pseudotriangular {Ag(Solv)3}+ units, additionally coordinated to a polyoxometalate. Screening of the luminescent properties for solid samples of 1-7 revealed that only 5a/5b and 7 are emissive. In particular, the sample containing 5a and 5b demonstrates long-lived phosphorescence with a 30 ms lifetime.

Magnetism and electrical conductivity of molecular semiconductor, [FeII(DMF)4(TCNQ)2](TCNQ)2, with fractionally charged TCNQ units

We report the synthesis of a semiconducting material, [FeII(DMF)4(TCNQ)2](TCNQ)2 (1), which contains partially charged TCNQδ− anions (TCNQ = 7,7,8,8-tetracyanoquinodimethane, 0 < δ < 1). Compound 1 was prepared by different routes, using (Et3NH)(TCNQ)2, a mixture of TCNQ and LiTCNQ, or a mixture of TCNQ and NaTCNQ, to obtain the structure with fractionally charged TCNQδ− anions. The crystal structure of 1 is formed by mononuclear cations [Fe(DMF)4(TCNQ)2]2δ+, the TCNQ units of which form infinite π-π stacks with non-coordinated TCNQδ− counter ions. A detailed examination of X-ray diffraction data, supplemented by inductively coupled plasma mass spectrometry, indicates that some of the non-coordinated TCNQδ− anions, likely, form bonds to a partially occupied Na+ site, thus causing slightly different crystal packing in the vicinity of some Fe(II) centers. This finding is indirectly corroborated by the results of Mössbauer spectroscopy, which shows that the transition metal site corresponds to the high-spin Fe(II) ion, but two such sites are present, with slightly different quadrupole splitting parameters. Temperature-dependent conductivity measurements reveal semiconducting behavior, with the room-temperature conductivity of 0.125 S/cm and the charge-hopping activation energy of 180 meV.

Diversity of Coordination Modes in a Flexible Ditopic Ligand Containing 2-Pyridyl, Carbonyl and Hydrazone Functionalities: Mononuclear and Dinuclear Cobalt(III) Complexes, and Tetranuclear Copper(II) and Nickel(II) Clusters

Syntheses, crystal structures and characterization are reported for four new complexes [Cu4Br2(L)4]Br2 (1), [Ni4(NO3)2(L)4(H2O)](NO3)2 (2), [Co2(L)3](ClO4)3 (3) and [Co(L)2](ClO4) (4), where L− is the monoanion of the ditopic ligand N′-(1-(pyridin-2-yl)ethylidene)pyridine-2-carbohydrazide (LH) built on a picolinoyl hydrazone core fragment, and possessing a bidentate and a tridentate coordination pocket. The tetranuclear cation of 1·0.8H2O·MeOH is a strictly planar, rectangular [2 × 2] grid. Two 2.21011 L− ligands bridge adjacent CuII atoms on the short sides of the rectangle through their alkoxide oxygen atoms, and two 2.11111 ligands bridge adjacent CuII atoms on the long sides of the rectangle through their diazine groups; two metal ions are 5-coordinate and two are 6-coordinate. The tetranuclear cation of 2·0.2H2O·3EtOH is a square [2 × 2] grid. The two 6-coordinate NiII atoms of each side of the square are bridged by the alkoxide O atom of one 2.21011 L− ligand. The dinuclear cation of 3·0.8H2O·1.3MeOH contains two low-spin octahedral CoIII ions bridged by three 2.01111 L− ligands forming a pseudo triple helicate. In the mononuclear cation [Co(L)2]+ of complex 4, the low-spin octahedral CoIII center is coordinated by two tridentate chelating, meridional 1.10011 ligands. The crystal structures of the complexes are stabilized by a variety of π–π stacking and/or H-bonding interactions. Compounds 2, 3 and 4 are the first structurally characterized nickel and cobalt complexes of any form (neutral or anionic) of LH. The 2.01111 and 1.10011 coordination modes of L−, observed in the structures of complexes 3 and 4, have been crystallographically established for the first time in coordination complexes containing this anionic ligand. Variable-temperature, solid-state dc magnetic susceptibility and variable-field magnetization studies at 1.8 K were carried out on complexes 1 and 2. Antiferromagnetic metal ion···metal ion exchange interactions are present in both complexes. The study reveals that the cation of 1 can be considered as a practically isolated pair of strongly antiferromagnetically coupled (through the diazine group of L−) dinulear units. The susceptibility data for 2 were fit to a single-J model for an S = 1 cyclic tetramer. The values of the J parameters have been rationalized in terms of known magnetostructural correlations. Spectral data (infrared (IR), ultraviolet/visible (UV/VIS), 1H nuclear magnetic resonance (NMR) for the diamagnetic complexes) are also discussed in the light of the structural features of 1–4 and the coordination modes of the organic and inorganic ligands that are present in the complexes. The combined work demonstrates the ligating flexibility of L−, and its usefulness in the synthesis of complexes with interesting structures and properties.

Synthesis, crystal structure and spin exchange coupling in polynuclear carboxylates with {Li2(VO)2} metal core

Crystals of binuclear complex [(VO)2(µ-OH)(µ-Piv)2(bpy)2](OTf) (1) have been obtained by the reaction of [VO(H2O)5](OTf)2 (OTf=CF3SO3−, Piv=(CH3)3CCO2−) with 2,2′-bipyridine (bpy) and lithium trimethylacetate (pivalate), Li(Piv), in a ratio of 1:1:2 in MeCN. Change of the reagent ratio to 1:1:3 resulted in the bimetallic compound [Li2(VO)2(µ-Piv)6(bpy)2] (2), which was isolated in the form of 2·MeCN and 2·CH2Cl2 solvates. Replacement of Li(Piv) with lithium trifluoroacetate Li(Tfac) (Tfac=CF3CO2−) results in the bimetallic compound [Li2(VO)2(µ-Tfac)6(bpy)2] (3). A similar reaction with lithium trichloroacetate, Li(Tcac) (Tcac=CCl3CO2−), in ethanol gives the mononuclear complex [VO(Tcac)(bpy)2](OTf) (4). The structures of 1–4 were determined by single crystal X-ray diffraction. The magnetic properties (2–300K) and EPR spectra of compounds 1–3 have been studied. Using the ESEEM (electron spin echo envelope modulation) method it has been shown that the mononuclear cation [VO(Tcac)(bpy)2]+ of complex 4 has partial spin density transfer from the VIV atom to donor ligands (in particular, the bpy nitrogen atoms). According to EPR spectroscopy data and quantum-chemical calculations, a similar spin density distribution is observed for 2 and 3, though spin exchange in these compounds is hindered by lithium ions, which contain no spin density and block electron density delocalization in the bridging system between the “magnetic” vanadium ions. Electrochemical properties of compounds 2 and 3 confirm the vanadium(IV) oxidation state.

A new phosphorescent heteroleptic cuprous complex with a neutral 2-methylquinolin-8-ol ligand: synthesis, structure characterization, properties and TD-DFT calculations.

Luminescent CuI complexes have emerged as promising substitutes for phosphorescent emitters based on Ir, Pt and Os due to their abundance and low cost. The title heteroleptic cuprous complex, [9,9-dimethyl-4,5-bis(diphenylphosphanyl)-9H-xanthene-κ2P,P](2-methylquinolin-8-ol-κ2N,O)copper(I) hexafluorophosphate, [Cu(C10H9NO)(C39H32OP2)]PF6, conventionally abbreviated as [Cu(Xantphos)(8-HOXQ)]PF6, where Xantphos is the chelating diphosphine ligand 9,9-dimethyl-4,5-bis(diphenylphosphanyl)-9H-xanthene and 8-HOXQ is the N,O-chelating ligand 2-methylquinolin-8-ol that remains protonated at the hydroxy O atom, is described. In this complex, the asymmetric unit consists of a hexafluorophosphate anion and a whole mononuclear cation, where the CuI atom is coordinated by two P atoms from the Xantphos ligand and by the N and O atoms from the 8-HOXQ ligand, giving rise to a tetrahedral CuP2NO coordination geometry. The electronic absorption and photoluminescence properties of this complex have been studied on as-synthesized samples, whose purity had been determined by powder X-ray diffraction. In the detailed TD-DFT (time-dependent density functional theory) studies, the yellow emission appears to be derived from the inter-ligand charge transfer and metal-to-ligand charge transfer (M+L')→LCT excited state (LCT is ligand charge transfer).

Supramolecular structures of Fe(II) and Co(II) complexes based on the conjugated Schiff-base ligands

Three new complexes [Fe(L1)2(NCS)2(CH3OH)2] (I), [Co(L2)2(CH3OH)2(H2O)2](ClO4)2 · L2 · 2H2O (II), and [Co(L1)3(H2O)2](ClO4)2 · L1 (III) (L1 = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene; L2= 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) have been prepared and structurally characterized by X-ray single crystall diffraction. Complexes I and II are mononuclear. Complex III has a 1D chain structure. Complex I is assembled by intermolecular O-H⋯N hydrogen bonds leading to 2D structure. In complex II, mononuclear complex cations are linked into 1D chain through hydrogen bonds. Then the chains get into 2D structure by intermolecular O-H⋯N hydrogen bonds too. In complex III, coordinated ligand L1 acts as a ditopic bridge to produce 1D coordination chain. The self-complementary intermolecular O-H⋯N hydrogen bonds assemble the chains into 2D sheets.

Bromidobis[2-(pyridin-2-yl)methanol-κ2N,O]copper(II) bromide monohydrate

The title compound, [CuBr(C6H7NO)2]Br·H2O, is an ionic mononuclear complex in which the [CuBr(C6H7NO)2](+) cation possesses distorted square-pyramidal geometry. The Cu(II) centre is coordinated by two neutral 2-(pyridin-2-yl)methanol (2-pyMeOH) ligands and a terminal bromide ligand. The 2-pyMeOH ligands are coordinated in a bidentate chelating manner through the pyridine N and hydroxy O atoms, forming a five-membered chelate ring with the Cu(II) centre. The planes of the pyridine rings are twisted by 58.71 (14)° with respect to each other. The charge is balanced by a noncoordinating bromide anion which, together with a solvent water molecule, links the components through hydrogen bonds into infinite chains propagating along the a axis. The mononuclear cations appear to associate in pairs through weak interactions between the metal atom of one cation and the halogen atom of an adjacent cation.

Structure and magnetism of heptanuclear complex encapsulated the octacyanomolybdate(IV) core

Abstract A new heptanuclear complex [{Cu(TPA)CN}6Mo(CN)2][ClO4]8 (1) (TPA = tris(2-pyridylmethyl)amine) was formed by the reaction of [Cu(TPA)]2 + cations and K4Mo(CN)8. The octacyanomolybdate core is encapsulated by six mononuclear copper cations via cyano bridges. 1 Crystallizes in monoclinic space group P21/n with a = 22.30(2) A, b = 27.13(3) A, c = 24.35(2) A, β = 94.10(2)°, and Z = 4. Variable temperature magnetic measurements have demonstrated that very weak antimagnetic interaction between the nearest paramagnetic CuII centers at low temperature is exhibited, transferred by ―NC―Mo―CN― bridging units.

Crystal structure of a new supramolecular Ni(II) N 6-benzylaminopurine compound

A new mononuclear Ni(II) N6-benzylaminopurine supramolecule [Ni(6-BA-H2)2(H2O)4]·(R)2·4H2O (1) (6-BA = N6-benzylaminopurine (C5H2N3NH)(NH)CH2(C6H5), H3R = 5-sulfosalicylic acid (C6H3)CO2H· (OH)SO3H) is firstly synthesized by the volatile method. Compound 1 possesses a 3D supramolecular structure built via H-bonds and π-π stacking interactions. In the structure, a mononuclear [Ni(6-BA-H2)2(H2O)4]6+ cation, in which the Ni(II) ion is 6-coordinated, bears six positive charges, and a fully deprotonated R3− anion is located in the void surrounding the mononuclear cation to balance the charge.

Solvent-Induced Reversible Crystal-to-Amorphous Transformation Properties of Cobalt(II) 4-Aminomethylpyridine-Sulfate with Chromotropism

The crystalline CoII coordination compound with empirical formula [Co(Hampy)2(H2O)4](SO4)2(H2O)3 (1); ampy = 4-aminomethylpyridine was obtained. The structure contains a mononuclear [Co(Hampy)2(H2O)4]4+ cation unit, two sulfate ions, and three lattice water molecules. The Co2+ cation shows an elongated octahedral geometry comprised of four oxygen atoms from water molecules at equatorial positions and two nitrogen atoms from Hampy ligands which are protonated at NH2. Each mononuclear cation unit is assembled by intermolecular hydrogen bonding and π–π stacking interactions by the coordinated and lattice water molecules, amino group, and sulfate anions to form a 3D supramolecular network. Investigations of the dynamic structural behaviour demonstrate that the title compound exhibits a solvent-induced reversible crystal-to-amorphous transformation with chromotropism when exposed to water and methanol vapour. This indicates that the dehydrated amorphous form, [Co(Hampy)2(SO4)2] 1A, may be utilised as an indicator for humidity and methanol vapour.

Compensation effect. A DFT study of the activation of N2O over M-CHA (M = Fe2+, Co2+, RuO2+, RuO+)

The compensation effect is investigated using DFT calculations of the activation of the N2O molecule over mononuclear cations (Fe2+, Co2+) and cationic oxo-particles (RuO2+, RuO+), identified as perspective active sites. Constrained MD simulations are used to calculate Helmholtz free energies of activation at 300K, 420K, and 700K. Reaction rates calculated according to the transition state theory are used to construct Arrhenius plots (AP). Activation energies, derived from the AP, are 60.9kJ/mol, 77.2kJ/mol, 99.4kJ/mol, and 105.1kJ/mol for RuO+, Fe2+, Co2+, and RuO2+, respectively. A linear dependence between enthalpy of activation ΔH‡ and entropy of activation ΔS‡ is observed only when the reaction exhibits the isokinetic behavior. The change of entropy of activation is approximately three orders smaller than the change of enthalpy. For the activation of N2O, a rare case of the anticompensation is observed. The reaction rates computed for the temperature range between 300K and 700K increase in order: RuO+>Fe2+>Co2+>RuO2+.

Crystal structures and spectroscopic analyses of two Co(II) N 6-benzylaminopurine supramolecules

Two mononuclear Co(II) N 6-benzylaminopurine compounds, [Co(6-BA-H2)2(H2O)4] · (R)2 · 4.5H2O (1) and [Co(6-BA-H)2(H2O)Cl3]Cl · H2O (2) (6-BA = N 6-benzylaminopurine (C5H2N3NH)(NH)CH2(C6H5), H3R = 5-sulfosalicylic acid (C6H3)CO2H(OH)SO3H), are reported. Compound 1 possesses a 3-D supramolecular structure built via H-bond and π–π stacking interactions that contains a mononuclear six-coordinate [Co(6-BA-H2)2(H2O)4]6+. Compound 2 also exhibits a 3-D supramolecular framework with mononuclear six-coordinate cation [Co(6-BA-H)2(H2O)Cl3]+. Luminescence studies at room temperature show that 1 (λ ex = 268 nm) displays two strong fluorescent emissions centered at 326.8 nm and 356.9 nm, while 2 (λ ex = 233 nm) exhibits a weaker peak emitted at 342.8 nm upon 6-BA-complexation of two different second ligands H3R/Cl− with Co(II).

Hydrothermal synthesis and crystal structure of a novel nickel(II) complex: [Ni(H2Bibzim)3Cl2 · 2H2O] (H2Bibzim = 2,2-Bibenzimidazole)

A novel organic-inorganic hybrid compound based on weak intermolecular interactions formulated as Ni(H2Bibzim)3Cl2 · 2H2O (H2Bibzim = 2,2-bibenzimidazole, formula, C14H10N4) has been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction analyses, and IR spectra. It crystallizes in the orthorhombic system, space group Pbcn, Z = 2, a = 20.8530(19), b = 15.7838(14), c = 12.3159(11) A, V = 4053.7(6) A3, Mr = 1736.84, ρc = 1.423g/cm3, λ = 0.71073 A, μ(MoKα) = 0.664 mm−1, F(000) = 1792, R = 0.0283 and wR = 0.0707 for 3746 observed reflections with I > 2σ(I). The complex is composed of mononuclear cations [Ni(H2Bibzim)3]2+, chlorine anions, and lattice water molecules, which are linked into a two-dimensional supramolecular architectures via hydrogen bonds and π-π-stacking interactions.

An antiferromagnetically coupled dimeric Ni(II) complex anion and its counter cationic monomeric Ni(II) complex, and some other mononuclear transition metal compounds using some neutral ligands

Synthesis and single crystal X-ray diffraction studies of four transition metal complexes [Mn(L 1)](ClO 4) 2 ( 1), [Cu(L 1)](ClO 4) 2 ( 2), [Ni 2(L 2)(NCS) 6][Ni(L 1)] ( 3) and [Mn(bzpy)(NCS) 2] ( 4) with neutral ligands [L 1 = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-yl phenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine, L 2 = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}piperazine-1yl)ethyl]amine, bzpy = 2-benzoylpyridine] are reported. The trinuclear nickel(II) complex 3 is made of a dinuclear anion and a mononuclear cation. Variable-temperature magnetic susceptibility and variable-field magnetisation studies performed on 3 suggest weak antiferromagnetic coupling ( J = −0.7 cm −1) between the two metals of the dinuclear entity, but no magnetic interaction between the anionic and cationic counterparts.

(1H-Benzimidazole-5-carboxylic acid-κN3)(1H-benzimidazole-6-carboxylic acid-κN3)silver(I) perchlorate

The reaction of 1H-benzimidazole-5-carb­oxy­lic acid with silver nitrate in the presence of perchloric acid under hydro­thermal conditions yielded the title complex, [Ag(C8H6N2O2)2]ClO4, which comprises of an [Ag(C8H6N2O2)2] mononuclear cation and a perchlorate anion. The AgI ion is coordinated by two N atoms from two different neutral 1H-benzimidazole-5-carb­oxy­lic acid ligands with an N—Ag—N bond angle of 163.21 (14)°, forming an [Ag(C8H6N2O2)2] mononuclear cation. Although both ligands in the mononuclear cation are monodentate with one N atom coordinated to the metal ion, they are different: one is N3 coordinated to the Ag I ion and the N1 atom protonated, the other with the N1 coordinated to the Ag I ion and the N3 atom protonated (and thus formally a 1H-benzimidazole-6-carb­oxy­lic acid rather than a 1H-benzimidazole-5-carb­oxy­lic acid ligand). The planes of the two planar ligands are roughly perpendicular, making a dihedral angle of 84.97 (2)°. The packing of the ions is stablized by extensive O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, and by remote Ag⋯O inter­actions [3.002 (3), 3.581 (5) and 3.674 (5) Å].

Bis[5-(2-pyridyl)pyrazine-2-carbonitrile]silver(I) tetrafluoridoborate

In the title mononuclear complex, [Ag(C10H6N4)2]BF4, the AgI atom adopts a square-planar N4 coordination geometry and is surrounded by two 5-(2-pyrid­yl)pyrazine-2-carbonitrile ligands. The tetra­fluorido­borate anions link the mononuclear cations through inter­molecular C—H⋯F hydrogen-bonding inter­actions, forming an infinite tape structure along [110]. Other weak inter­actions occur: π–π stacking with centroid–centroid distances of 3.820 (2) and 3.898 (1) Å between pyridyl rings and 3.610 (2) and 3.926 (2) Å between pyrazinyl rings as well as F⋯π contacts involving the tetra­fluorido­borate anions and pyrazine rings [F⋯centroid = 2.999 (3) Å]; these combine with the hydrogen-bonding inter­actions to link the mononuclear cations into a three-dimensional supra­molecular architecture.