Bridging Anions Research Articles

Enhancing Cycle Life of Rechargeable Zinc Hybrid Batteries in a Low-Cost, Nonfluorinated Dual-Cation Electrolyte.

Rechargeable zinc batteries (RZBs) are highly attractive as energy storage solutions due to their low cost and sustainability. Nevertheless, the use of fluorine-free zinc electrolyte systems to create affordable, ecofriendly, and safe RZBs has been largely overlooked in the battery community. Previously, we showcased the utilization of a fluorine-free, nonaqueous electrolyte comprising zinc dicyanamide (Zn(dca)2) in dimethyl sulfoxide (DMSO) to enable the electrochemical cycling of zinc. Herein we present a dual-cation-based electrolyte, [1.0 M Na(dca) +1.0 M Zn(dca)2]/DMSO, in pursuit of a rechargeable zinc hybrid battery. Fourier-transform infrared spectroscopy and molecular dynamics simulation studies indicate that the presence of Na(dca) diminishes ion-pairing in Zn(dca)2 through [dca]- anion bridging between Zn2+ and Na+ ions, thereby enhancing Zn2+ ion transport in the electrolyte. Thus, the electrolyte exhibits high ionic conductivity and transference numbers (tZn2+) of 7.9 mS cm-1 and 0.83, respectively, at 50 °C, making it particularly suitable for high-temperature battery applications. Furthermore, we demonstrate, for the first time, the cycling of a full cell with a zinc anode and triphylite sodium iron phosphate cathode (NFP) in an organic electrolyte, showcasing stable performance over 100 cycles at 0.1C rate. These encouraging findings pave the way for affordable battery technologies using, fluorine-free electrolyte.

Structures and Single-Molecule Magnet Behavior of Dy3 and Dy4 Clusters Constructed by Different Dysprosium(III) Salts.

Using the Schiff base ligand H2L-pyra (N'-(2-hydroxybenzoyl)pyrazine-2-carbohydrazonamide) with multiple dentate sites, the trinuclear DyIII-based complex [Dy3(HL-pyra)2(L-pyra)2(CH3COO)3]·2H2O (1) was synthesized. By analyzing the fragmented assembly process and fine-tuning the bridging anions, complex [Dy4(HL-pyra)2(L-pyra)4(NO3)2(H2O)2]·8H2O (2) with different nuclear numbers was successfully synthesized. Magnetic studies demonstrated that 1 did not exhibit magnetic relaxation behavior under the external field; however, 2 exhibited zero-field single-molecule magnetic relaxation behavior with an effective energy barrier (Ueff) of 197.44 K. This is attributed to the improved anisotropy of the single ion after the normalization of the crystal structure, thus realizing the molecular magnetic switching. Moreover, magnetic dilution analysis of 2 demonstrated that the weak magnetic interaction between metal ions inhibited the occurrence of quantum tunneling of magnetization (QTM), resulting in high-performance single-molecule magnet (SMM) behavior. The reasons for the magnetic difference between these two complexes were analyzed using ab initio calculation and magneto-structural correlations. This study provides a reasonable prediction of the ideal configuration of the approximately parallelogram DyIII-based SMMs, thus offering an effective approach for synthesizing Dy4 complexes with excellent properties.

The performance and mechanism of sulfidated nano-zero-valent iron for the simultaneous stabilization of arsenic and cadmium

Co-contamination of soil and groundwater with arsenic (As) and cadmium (Cd) is widespread. Sulfidized Nanoscale Zero-Valent Iron (S-nZVI) is effective in removing As and Cd from contaminated environments. However, the mechanisms governing As and Cd removal from systems containing both species are still unclear. This study investigated the effectiveness of S-nZVI in the simultaneous removal of Cd(II) and As(III) from contaminated solutions and their interaction mechanisms. Adsorption experiments were conducted under aerobic conditions to investigate the effect of Cd(II) and As(III) on their co-immobilisation at different As(III) and Cd(II) concentrations. S-nZVI was characterised before and after the reaction to elucidate the mechanism of its simultaneous immobilisation of As(III) and Cd(II). Batch experiments revealed that the presence of Cd(II) and As(III) together considerably promotes the passivation of S-nZVI. The adsorption of Cd(II) at Cd:As = 1:3 was 198.37 mg/g, which was 27.6 % higher than that in Cd(II)-only systems, and the adsorption of As(III) at As:Cd = 1:3 was 204.05 mg/g, which was 175 % higher than that in As(III)-only systems. The results of X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that the removal of Cd(II) and As(III) by S-nZVI involves electrostatic adsorption, complexation and oxidation reactions, amongst which electrostatic adsorption and ternary-complex generation are responsible for the synergistic effect. As and Cd ions can form two types of surface complexes with FeOH or FeS on the outer layer of S-nZVI: anionic bridging to form Fe–As–Cd and cationic bridging to form Fe–Cd–As. This investigation elucidates the synergistic action of Cd(II) and As(III) during their removal using S-nZVI. Thus, S-nZVI is a promising material for the combined removal of Cd(II) and As(III), which can mitigate environmental pollution.

Hydrazido complexes prepared by methylation of an anionic end-on bridging dinitrogen dititanium complex.

Here we report stepwise methylation of end-on bridging dinitrogen to a hydrazido ligand to a pentamethylhydrazinium salt, which is mediated by a titanium system with a tripodal aryloxide supporting ligand. The results constitute a synthetic cycle for pentamethylhydrazinium formation from dinitrogen and methyl iodide. We also describe silylation of the dinitrogen complex and carboxylation of the hydrazido complex.

From field-induced to zero-field SMMs associated with open/closed structures of bis(ZnDy) tetranuclear complexes: a combined magnetic, theoretical and optical study.

We have prepared a bis(compartmental) Mannich base ligand H4L (1,4,8,11-tetraaza-1,4,8,11-tetrakis(2-hydroxy-3-methoxy-5-methylbenzyl)cyclotetradecane) specifically designed to obtain bis(TMIILnIII) tetranuclear complexes (TM = transition metal). In this regard, we have succeeded in obtaining three new complexes of the formula [Zn2(μ-L)(μ-OAc)Dy2(NO3)2]·[Zn2(μ-L)(μ-OAc)Dy2(NO3)(OAc)]·4CHCl3·2MeOH (1) and [TM2(μ-H2L)2(μ-succinate)Ln2(NO3)2] (NO3)2·2H2O·6MeOH (TMII = Zn, LnIII = Dy (2); TMII = Co, LnIII = Dy (3)). Compound 1 contains two different bis(ZnDy) tetranuclear molecules that cocrystallize in the structure, in which acetato bridging ligands connect the ZnII and DyIII ions within each ZnDy subunit. This compound does not exhibit slow magnetic relaxation at zero field, but it is activated in the presence of an applied dc magnetic field and/or by Dy/Y magnetic dilution, showing two relaxation processes corresponding to each of the two different bis(ZnDy) units found in the structure. As revealed by the theoretical calculations, magnetic relaxation in 1 is single-ion in origin and takes place through the first excited state of each DyIII ion. When using the succinato dicarboxylate bridging ligand instead of acetate, compounds 2 and 3 were serendipitously formed, which have a closed structure with the succinate anion bridging two ZnDy subunits belonging to two different ligands. It should be noted that only compound 2 exhibits slow relaxation of magnetization in the absence of an external magnetic field. According to experimental and theoretical data, 2 relaxes through the second excited Kramers doublet (Ueff = 342 K). In contrast, 3 displays field-induced SMM behaviour (Ueff = 203 K). However, the Co/Zn diluted version of this compound 3Zn shows slow relaxation at zero field (Ueff = 347 K). Ab initio theoretical calculations clearly show that the weak ferromagnetic coupling between CoII and DyIII ions is at the origin of the lack of slow relaxation of this compound at zero field. Compound 2 and its diluted analogues 2Y and 3Zn show hysteresis loops at very low temperature, thus confirming their SMM behaviour. Finally, compounds 1 and 2 show DyIII based emission even at room temperature that, in the case of 2, allows us to extract the splitting of the ground 6H15/2 term, which matches reasonably well with theoretical calculations.

Pyrazolate vs. phenylethynide: direct exchange of the anionic bridging ligand in a cyclic trinuclear silver complex.

Cyclic trinuclear Ag(I) pyrazolate interacts with phenylacetylene forming a mix-ligand complex in which one pyrazolate ligand is changed to phenylethynide. The CC- fragment coordinates only to two silver(I) atoms via one carbon atom demonstrating unique μ2-η1 σ-coordination with close Ag-C bond lengths and Ag-C-C angles. The complex exhibits blue emission under UV irradiation.

Advancements and challenges in molecular/hybrid perovskites for piezoelectric nanogenerator application: A comprehensive review

Molecular perovskites are a class of materials that have attracted considerable attention in recent years due to their unique physical characteristics, structural properties, and diverse applications. These materials are also known as Hybrid Organic-Inorganic Perovskite (HOIP) and are denoted by the general formula ABX3. HOIP materials feature an organic or inorganic molecular cation (A), a metal or molecular cation (B), and a molecular anionic bridging ligand (X). The perovskite structure comprises BX6 octahedra that share corners, forming a three-dimensional network. The remarkable properties of molecular perovskites arise from their intrinsic polarization, resulting from the presence of polar organic cations in hybrid perovskites that possess a constant electric dipole moment. The alignment of these dipoles plays a crucial role in the properties of molecular perovskites. Consequently, this polarization can be harnessed to capture ambient mechanical energy and convert it into electrical energy. This review paper provides a comprehensive overview of molecular perovskites, focusing on their physical characteristics, synthesis methods, and multifunctional applications, particularly in piezoelectric nanogenerators. Furthermore, it addresses the challenges and opportunities associated with boosting their piezoelectric performance and integrating them with nanogenerator technology and flexible devices. Recent advances and breakthroughs in molecular perovskite-based nanogenerators are highlighted, including lead-free, metal-free, double perovskite materials, etc. Finally, the paper proposes future directions and perspectives for further research and innovation in this dynamic field.

Hydrogen Bonds Stabilize Chloroselenite Anions: Crystal Structure of a New Salt and Donor-Acceptor Bonding to SeO2.

The single-crystal X-ray diffraction structure characterizing a new 4-methylbenzamidinium salt of chloroselenite [C8H11N2][ClSeO2] is reported. This is only the second crystal structure report on a ClSeO2- salt. The structure contains an extended planar hydrogen bond net, including a double interaction with both O atoms of the anion (an R228 ring in Etter notation). The anion has the shortest Se-Cl distances on record for any chloroselenite ion, 2.3202(9) Å. However, the two Se-O distances are distinct at 1.629(2) and 1.645(2) Å, attributed to weak anion-anion bridging involving the oxygen with the longer bond. DFT computations at the RB3PW91-D3/aug-CC-pVTZ level of theory reproduce the short Se-Cl distance in a gas-phase optimized ion pair, but free optimization of ClSeO2- leads to an elongation of this bond. A good match to a known value for [Me4N][ClSeO2] is found, which fits to the Raman spectroscopic evidence for this long-known salt and to data measured on solutions of the anion in CH3CN. The assignment of the experimental Raman spectrum was corrected by means of the DFT-computed vibrational spectrum, confirming the strong mixing of the symmetry coordinate of the Se-Cl stretch with both ν2 and ν4 modes.

Rare Earth Nitrate Hybrid Double Perovskites [Me4N]2[MLn(NO3)6] (M = Na-Cs; Ln = La-Gd, ex. Pm).

An exploration of the synthetic and structural phase space of rare earth hybrid double perovskites A2B'BX6 (A = organocation, B' = M+, B = M3+, X = molecular bridging anion) that include X = NO3- and B' = alkali metal is reported, complementing earlier studies of the [Me4N]2[KB(NO3)6] (B = Am, Cm, La-Nd, Sm-Lu, Y) (Me4N = (CH3)4N+) compounds. In the present efforts, the synthetic phase space of these systems is explored by varying the identity of the alkali metal ion at the B'-site. Herein, we report three new series of the form [Me4N]2[B'B(NO3)6] (B = La-Nd, Sm-Gd; B' = Na, Rb, Cs). The early members of the Na-series crystallize in the trigonal space group R3̅ from La to Nd where a phase transition occurs in the phase between 273 and 300 K, going from R3̅ to the high-symmetry, cubic space group Fm3̅m. The preceding trigonal members of the Na-series also undergo phase transitions to cubic symmetry at temperatures above 300 K, establishing a decreasing trend in the phase-transition temperature. The remainder of the Na-series, as well as the Rb- and Cs-series, all crystallize in Fm3̅m at 300 K. The temperature-dependent phase behavior of the synthesized phases is studied via variable-temperature spectroscopic methods and high-resolution powder X-ray diffractometry. All phases were characterized via single-crystal and powder X-ray diffraction and Fourier transform infrared (FT-IR) and Raman spectroscopic methods. These results demonstrate the versatility of the perovskite structure type to include rare earth ions, nitrate ions, and a suite of alkali metal ions and serve as a foundation for the design of functional rare earth hybrid double perovskite materials such as those possessing useful multiferroic, optical, and magnetic properties.

Citrate modulation of CoAl(OH)x Catalyst/Sb–TiO2 nanorods interface boosting photocarrier separation and injection for enhanced water oxidation

The design of an oxygen evolution catalyst (OEC) coupled photoanode ensuring effective charge separation, transfer, and injection is always desirable for enhanced water oxidation kinetics. Here, we have designed Sb-doped TiO2 nanorods (NRs) photoanode coupled with the ultrathin amorphous CoAl(OH)x OEC via citrate anion bridging. The CoAl(OH)x performs as a hole scavenger OEC, a hole storage layer, surface defect passivation layer, and also generates a band banding leading to the built-in potential at the semiconductor/catalyst interface favoring rapid hole separation. The citrate linking improves the CoAl(OH)x/Sb–TiO2 interfacial bonding and reduces the interfacial impedance to boost the photocarrier separation. Citrate bridging also serves as an efficient hole extraction layer and transportation pathway and promotes oxygen vacancy formation, which favors adsorbing OH− during the OER. As a result, the CoAl(OH)x/cit/Sb–TiO2 NRs photoanode exhibits a superior photocurrent density of 1.73 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (VRHE), close to the theoretical maxima of titanium dioxide, with a very low onset potential of 0.12 VRHE and an extremely high hole injection efficiency of 93.1%. This work demonstrates an effective design strategy to boost the performance of OER catalyst coupled photo harvesting semiconductor photoanodes to achieve efficient solar water splitting.

Breathing Behaviour Modification of Gallium MIL-53 Metal-Organic Frameworks Induced by the Bridging Framework Inorganic Anion.

Controlling aspects of the μ2 -X- bridging anion in the metal-organic framework Ga-MIL-53 [GaX(bdc)] (X- =(OH)- or F- , bdc=1, 4-benzenedicarboxylate) is shown to direct the temperature at which thermally induced breathing transitions of this framework occur. In situ single crystal X-ray diffraction studies reveal that substituting 20 % of (OH)- in [Ga(OH)(bdc)] (1) for F- to produce [Ga(OH)0.8 F0.2 (bdc)] (2) stabilises the large pore (lp) form relative to the narrow pore (np) form, causing a well-defined decrease in the onset of the lp to np transition at higher temperatures, and the adsorption/desorption of nitrogen at lower temperatures through np to lp to intermediate (int) pore transitions. These in situ diffraction studies have also yielded a more plausible crystal structure of the int-[GaX(bdc)] ⋅ H2 O phases and shown that increasing the heating rate to a flash heating regime can enable the int-[GaX(bdc)] ⋅ H2 O to lp-[GaX(bdc)] transition to occur at a lower temperature than np-[GaX(bdc)] via an unreported pathway.

Exploring the Co-Crystallization of Kojic Acid with Silver(I), Copper(II), Zinc(II), and Gallium(III) for Potential Antibacterial Applications.

Co-crystallization of kojic acid (HKA) with silver(I), copper(II), zinc(II), or gallium(III) salts yielded three 1D coordination polymers and one 0D complex in which kojic acid was present as a neutral or anionic terminal or bridging ligand. All reactions were conducted mechanochemically via ball milling and manual grinding, or via slurry. All solids were fully characterized via single-crystal and/or powder X-ray diffraction. As kojic acid is a mild antimicrobial compound that is widely used in cosmetics, and the metal cations possess antibacterial properties, their combinations were tested for potential antibacterial applications. The minimal inhibition concentrations (MICs) and minimal biocidal concentrations (MBCs) for all compounds were measured against standard strains of the bacteria P. aeruginosa, S. aureus, and E. coli. All compounds exerted appreciable antimicrobial activity in the order of silver, zinc, copper, and gallium complexes.

Crystal structure of a heterotrimetallic 12-metallacrown-4 with 2-propylvalerate anion bridges

The synthesis and single-crystal X-ray structure for tetraaquatetrakis(μ-2-propylvalerato)tetrakis(μ4-salicylhydroximato)dysprosiumtetramanganesesodium dimethylformamide tetrasolvate, [DyMn4Na(C7H4NO3)4(C8H15O2)4(H2O)4]·4C3H7NO or DyNa(2-PV)4[12-MCMnIII Nshi-4](H2O)4·4DMF, 1, where MC is metallacrown, shi3− is salicylhydroximate, 2-PV is 2-propylvalerate, and DMF is N,N-dimethylformamide, is reported. The slightly domed metallamacrocycle contains four ring MnIII ions and four shi3− ligands that generate an [MnIII—N—O] repeat unit that recurs four times. The ring MnIII ions are five-coordinate with a square-pyramidal shape. Furthermore, the metallacrown binds both a DyIII ion and a Na+ ion in the central cavity. The central ions are located on opposite faces of the cavity with the DyIII ion located on the convex side of the MC and the Na+ ion located on the concave side. Each central ion is eight-coordinate although they possess different geometries. The DyIII ion has a square-antiprismatic shape, while the Na+ ion has an extremely distorted biaugmented trigonal–prismatic shape. The four 2-propylvalerate anions help to tether the DyIII to the MC cavity by forming bridges between the DyIII ion and each ring MnIII ion. Moreover, the interstitial DMF molecules are hydrogen bonded to the water molecules that complete the coordination environment of the Na+ ion. The metallacrown framework (excluding the DyIII and Na+ ions), the bridging 2-propylvalerate, and the interstitial DMF molecule experience whole-molecule disorder due to the rotational orientation of the metallamacrocycle. Additionally, the main moiety alkyl chain of the 2-propylvalerate is disordered over two additional orientations, and the main moiety interstitial DMF molecule is disordered over one additional orientation. The main moiety of the metallacrown framework refined to 0.9030 (14), while the minor B-moiety refined to 0.0971 (14). The main moiety alkyl chain of the 2-propylvalerate refined to 0.287 (3): 0.309 (3): 0.307 (3), and the minor B-moiety alkyl chain refined to 0.0971 (14). Lastly, the main moiety interstitial DMF refined to 0.549 (3): 0.354 (3), and the minor B-moiety DMF refined to 0.0971 (14).

On closed-shell interactions between heavy main-group elements.

A series of di- and polymetal complexes involving closed-shell, heavy main-group atoms and ions shows a selection of special physical properties. These involve short metal-metal contacts, low entropies of formation and, most interestingly, strong Raman bands at low wavenumbers. These results together with the constitution of the coordination compounds, where the majority of electrons are assembled on the highly polarizable metal atoms and ions, experimental results have been interpreted in terms of direct, partial covalent metal-metal bonding. Previous theoretical studies have challenged this view and instead attributed the obvious attractive forces involved to secondary-type of interactions, such as dispersion. This study utilizes a multitude of theoretical tools, such as natural bond order (NBO) and natural energy decomposition analysis (NEDA), non-covalent interaction (NCI) analysis, electron localization functions (ELFs), and atoms-in-molecules (AIM) to characterize the interactions in models comprising closed-shell dimers, as well as experimentally studied ring and cage systems constituting the main reason for the hypotheses on metal-metal interactions. The results show that all experimental results can be attributed to the covalent interactions between the electron-rich, metal centers and the bridging anions in ring and cage coordination compounds of high symmetry, where the experimentally observed effects can be traced to the combination of covalent interactions between the metal centers and the anions along the edges of the ring and cage systems in combination with the cooperative effects generated by the high symmetry of these ring and cage systems.

Magnetic structure and properties of the vanthoffite mineral Na6Mn(SO4)4

A detailed analysis of the magnetic properties of a vanthoffite type mineral Na6Mn(SO4)4 basedon dc magnetization, low temperature neutron powder diffraction and theoretical calculations is reported. The mineral crystallizes in a monoclinic system with space group P21/c, where MnO6 octahedra are linked via SO4 tetrahedra. This gives rise to super-exchange interaction between two Mn2+ ions mediated by two nonmagnetic bridging anions and leads to an antiferromagnetic ordering below 3 K. The magnetic structure derived from neutron powder diffraction at 1.7 K depicts an antiferromagnetic spin arrangement in the bc plane of the crystal. The magnetic properties are modelled by numerical calculations using exact diagonalization technique, which fits the experimental results and provides antiferromagnetic ground state of Na6Mn(SO4)4.

Synthesis and crystal structure of hydrated μ-oxa-lato-bis-{bis-[3-methyl-5-(pyridin-2-yl)-1H-1,2,4-triazole]iron(II)} bis-(toluene-sulfonate) 2.75-hydrate.

In the title compound [Fe2(C2O4)(C8H8N4)4](CH3C6H4SO3)2·2.75H2O, the two FeII ions have a highly distorted octa-hedral FeN4O2 environment formed by two bidentate triazole-based chelating ligands and a bis-bidentate oxalate bridging anion that connects the metal ions. Stabilization within the crystal structure is provided via a system of O-H⋯O and N-H⋯O hydrogen bonding, which determines the formation of a two-dimensional architecture along the a-axis direction.

Synthesis and structural characterization of some 1:1 adducts of silver(I) salts with (hindered) PR3 bases (R = phenyl, o-tolyl, cyclohexyl)

Syntheses, spectroscopy and single crystal X-ray structural characterizations are recorded for a number of adducts AgX: PR3 (1:1)n obtained from the reaction of silver(I) salts with sterically hindered tertiary phosphine bases, extending previous studies. With tris(o-tolyl)phosphine, P(o-tolyl)3, binuclear adducts AgX: P(o-tolyl)3 (1:1)2 are defined, in arrays with eight-membered central rings [(o-to1yl)3PAg(μ-tfa)2AgP(o-tolyl)3] (1) (tfa = trifluoroacetate, O.CO.CF3) where two independent atoms of the anion bridge to the two silver atoms, and four-membered central rings where one atom bridges (Cl, NCO, acetate (= 'ac', O.CO.CH3)) (complexes 2–4); the perchlorate (5) is intermediate, one perchlorate bridging via one oxygen and the other by two. The nitrate is mononuclear, [(o-tolyl)3PAgO2NO], (6) with chelating nitrate. The bromide takes a tetranuclear 'cubane' form (7). With the cyanide, an interesting 2:1 AgCN: (o-tolyl)3P adduct (8) is defined as a two-dimensional polymer. The archetypical cubane series with triphenylphosphine is extended with a new bromide structure, MeCN solvated [(Ph3P)AgBr]4.0.22MeCN (9), to encompass also the cyanate [(Ph3P)Ag(NCO)]4 (10), isomorphous with the previously defined Cu/As/I chloroform solvate. The 'cubane' form is defined also for a further iodide polymorph AgI: Pcy3 (1:1)4 (11).

Facile Synthesis of the Dicyanophosphide Anion via Electrochemical Activation of White Phosphorus: An Avenue to Organophosphorus Compounds.

Organophosphorus compounds (OPCs) have gained tremendous interest in the past decades due to their wide applications ranging from synthetic chemistry to materials and biological sciences. We describe herein a practical and versatile approach for the transformation of white phosphorus (P4) into useful OPCs with high P atom economy via a key bridging anion [P(CN)2]-. This anion can be prepared on a gram scale directly from P4 through an electrochemical process. A variety of OPCs involving phosphinidenes, cyclophosphanes, and phospholides have been made readily accessible from P4 in a two-step manner. Our approach has a significant impact on the future preparation of OPCs in laboratory and industrial settings.

Supramolecular assemblies in an unprecedented asymmetric salamo-based dinuclear nickel(II) complex bearing two different coordination modes

An unprecedented dinuclear Ni(II) complex [{Ni2(L)(HL)(μ-OAc)(H2O)}2]·3CH3CH2OH is successfully synthesized by the complexation of an asymmetric salamo-based ligand (H2L) and Ni(II) acetate tetrahydrate and characterized by elemental analyses, UV-Vis and IR spectra, and X-ray crystallography analyses. Surprisingly, in the asymmetric unit of the Ni(II) complex, a fully deprotonated ligand (L)2– unit and a partially deprotonated ligand (HL)– unit wrapps two Ni(II) atoms, with the μ-OAc– anion bridging two adjacent Ni(II) atoms. The two Ni(II) atoms possess different coordination environments and twisted octahedral geometries. The hexacoordinated Ni(II) atom (Ni1) is located in the N2O4 donor cavity, but another hexacoordinated Ni(II) atom (Ni2) is located in a NO5 donor coordination environment. Meanwhile, a1D chain structure is formed by two N—O⋯π interactions. Hirshfeld surfaces and fluorescent properties are investigated.

Metallophilic interactions in silver(I) dicyanoaurate complexes.

This manuscript reports four new gold(I)-silver(I) complexes with 2-(2-pyridyl)-1,8-naphthyridine (pyNP) and terpyridine (terpy) as ancillary ligands, having formulae [Ag(pyNP)(Au(CN)2)]2 (1), [Ag2Au2(μ-CN)2(CN)2(pyNP)2] (2), [Ag2Au(μ-CN)2(terpy)2][Au(CN)2] (3) and [Ag4Au4(μ-CN)8(terpy)2(py)] (4). Complexes 1 and 2 are structural isomers obtained from different solvents. The Au(CN)2- anion is not coordinated and establishes intramolecular Au⋯Ag,Ag interactions in 1. In contrast, it is monocoordinated to silver atoms via a CN fragment in compound 2 and no metallophilic interaction is observed. In compound 3, one Au(CN)2 anion bridges two Ag(terpy) fragments. In this complex an infinite array of gold atoms is found, exhibiting aurophilic interactions of 3.415 Å. In complex 4 the 3D architecture observed in the crystal packing is driven by Au⋯Au and Au⋯Ag metallophilic interactions. All compounds have been structurally and vibrationally characterized to better understand the crystal forces. In addition, a solution chemistry study in different solvents by ESI-MS spectrometry was performed to comprehend the speciation and solvent effects. Finally, DFT calculations were carried out to analyze the Ag⋯Au interactions and also the π-stacking interactions that are relevant in the crystal packing of some structures. Special attention has been paid to the bifurcated nature of the Au⋯Ag,Ag interactions in compound 1 that has been analyzed theoretically using the quantum theory of atoms-in-molecules (QTAIM) and the Natural Bond Orbital (NBO) computational tools.