Effect Of Counterions Research Articles

Photochromism of four 1D coordination polymers based on 1-(2-carboxyethyl)-4,4′-bipyridinium ligand

Photoresponsive viologen units have been widely used to impart metal-organic materials with photochromic properties. Herein, four novel one-dimensional (1D) double chain-like coordination polymers (CPs) {[Ni0.5(CBbpy) (H2O)]Br·H2O}n (1), {[Co0.5(CBbpy) (H2O)]Br·H2O}n (2), {[Cu(CBbpy)2(H2O)]Br2·H2O}n (3), {[Cu(CBbpy)2(H2O)]Cl·Br·2H2O}n (4) based on 1-(2-carboxyethyl)-4,4′-bipyridinium bromide (HCBbpyBr) with different metal ions (Ni2+, Co2+, Cu2+, Cu+) have been prepared where the CBbpy molecules act as bidentate N- and O-donor ligands in the four polymers. The crystal structures and photochromic properties of compounds 1–4 are studied. Compounds 1 and 2 have no photochromism observed, while compound 3 exhibits reversible electron-transfer (ET) photochromism and compound 4 exhibits a near irreversible ET color change. Four compounds have similar structure but different photochromic properties, the effects of metal ions and counter anions on the photochromic behaviors of four compounds have been explored.

Copper (II) complexes of 3,5‐di‐tert‐butyl‐2‐hydroxybenzoylhydrazones of 2‐formylpyridine and 2‐acetylpyridine, with tautomeric azine‐scaffold‐based architecture: Synthesis, crystal structures, the effect of counteranions on complexation, and their anti‐microbial and anti‐tuberculosis evaluation

A series of air‐ and moisture‐stable copper (II) complexes of 3,5‐di‐tert‐butyl‐2‐hydroxy‐N′‐(pyridin‐2‐ylmethylene)benzohydrazide (L1H) and 3,5‐di‐tert‐butyl‐2‐hydroxy‐N′‐(1‐(pyridin‐2‐yl)ethylidene)benzohydrazide (L2H) were synthesized. The two newly designed hydrazone Schiff base ligands with the tautomeric azine‐scaffold involving N, N and O ligating architecture were derived from the condensation of 3,5‐di‐tert‐butyl‐2‐hydroxybenzoylhydrazide with 2‐formylpyridine and 2‐acetylpyridine, respectively. The resultant ligands and their copper complexes were characterized using various spectro‐analytical techniques, like infrared (IR), 1H‐NMR, 13C‐NMR, electron paramagnetic resonance, electronic spectroscopy, thermogravimetric analysis and conductance measurements. The interesting inter‐convertible E/Z geometrical isomeric forms of the ligand L1H was established by NMR and IR spectra. In addition, the molecular structures of L2H, C3 and C4 were unambiguously established using the single‐crystal X‐ray diffraction technique. The dichlorido‐bridged dinuclear square pyramidal complexes, with the [Cu2(μ‐Cl)2L2] type of core units, were resulted for the complexes C1 and C3, whereas z‐in compressed mononuclear 1:2 (M:L) octahedral complex geometries resulted for C2, C4 and the rest of the complexes even when various copper (II) precursor salts with different counteranions were used. The ligands and their complexes were investigated for the anti‐microbial activities against gram‐positive and gram‐negative bacteria. The ligand L2H and its complexes C3 and C4 exhibited better anti‐tuberculosis activity than the controls.

Optimisation of octahedral iron(II) and cobalt(II) spin-crossover metal complex for thermoelectric application

Four spin-crossover (SCO) complexes with general formulae, [M2(CH3COO)4(L)2] and [M(L)3](BF4)2, where M = Fe(II) and Co(II), containing extended π-conjugated bipyridyl ligand and N3-Schiff bases appended with linear C16 carbon chains at the N atoms were successfully synthesized and characterized. Correlation of its structural properties to thermoelectric behavior is investigated: (1)structure of complexes, (2)choice of metal centre and (3)choice of counter ions. It was found that the structure of the molecule, i.e. molecular versus ionic has the largest impact on the SCO behavior. We found that the molecular complexes with higher percentage of high-spin (73.4% HS for Fe-dinuc and 78% HS for Co-dinuc) have produced the highest Seebeck values in mV K−1 (−0.57 ± 0.01 for Fe-dinuc and −0.58 ± 0.01 for Co-dinuc) due to the weaker metal-to-ligand bonds resulting in the increase mobility of the I− during agglomeration formed, thus increased the entropy in the solution. Additionally, choice of metal centre also was a factor to determine the magnitude of Seebeck performance due to the spin state transition during electron transfer. For counter ion effect, it has the effect of determining the sign of the Seebeck value where I− is easier to oxidize/reduce process compared to CH3COO− and BF4− due to lower redox potential. These findings will assist in a systematic molecule design pathway for high potential SCO complexes for thermoelectric applications.

Effect of counter-ions on the solution conformation and adsorption behaviors of comb-like polycarboxylates on calcium carbonate

Three kinds of polycarboxylate ether (PCE) polymers with the same length of side chains but different backbone length were synthesized by aqueous free radical polymerization. Adding counter-ions (i.e., Na+, Ca2+) to dilute PCE solutions was found to induce a more complicated conformational change, since the screening of the electrostatic intramolecular repulsion and the different complexation behaviors of Ca2+ with carboxylic groups. Further characterization on the adsorption indicated that the differences of the adsorption ability resulted from the difference in the solution conformation of PCE molecule. PCE of a medium backbone length studied herein possesses a more extended polymer backbone due to the intermolecular steric hindrance, which result in more carboxylic groups could be accessible for adsorption. Obviously, the solution conformation of PCE strongly impacts the accessible carboxylic group contribution to adsorption. In this way it may provide a new insight to design the polymer structures of PCE with superior adsorption ability.

A comparative study of the counterion effect on the perrhenate-catalyzed deoxydehydration reaction

Counterions have a significant effect on the efficiency of the deoxydehydration (DODH) reaction. Four perrhenate salts, Z+ReO4− (Z = Na+, K+, NH4+, and Bu4N+), were tested in the DODH reaction of a vicinal diol in the presence of PPh3 as the reductant. In addition, a new perrhenate salt, (2-ppyH)[ReO4] (2-ppyH+ = 2-phenylpyridinium cation), has been synthesized and characterized by X-ray crystallography and utilized as an efficient catalyst in the DODH reaction. Since so far computational studies related to the influence of the counterion in the different steps of the DODH mechanism are scarce, we have carried out a comparative investigation of the counterion effect using density functional theory (DFT) calculations. The DODH mechanism of the conversion of phenyl-1,2-ethanediol to styrene in the presence of the five perrhenate salts mentioned above, as well as bare perrhenate (ReO4−) was studied from an energetic point of view. The catalytic tests and concomitant DFT computations confirmed the general mechanistic aspect in which the counterion plays an active role in all stages of the reaction mechanism including intermediate structures, Gibbs free energy changes (ΔG°g and ΔG°sol), transition states, and activation barrier energies. The role of counterion type has been considered in three key steps of the reaction mechanism, including the proton-transfer from diol to oxo-ligand in the rhenium moiety, the nucleophilic attack of the P atom from PPh3 on the oxo-ligand, the dissociation of the OPPh3 ligand, and the olefin extrusion from the Re(V)-diolate intermediate for each perrhenate salt. The crucial roles played by the counterion in terms of structure arrangement during transition states and the activation energy barriers are finally discussed.

Improving Homogeneous Cationic Gold Catalysis through a Mechanism-Based Approach.

Homogeneous gold catalysis is regarded as a landmark addition to the field of organic synthesis. It is the most effective way to activate alkynes for the addition of a diverse host of nucleophiles. However, the literature reveals that a relatively high catalyst loading is needed in many gold-catalyzed applications (1-10 mol %), which is impractical in large-scale synthesis or multistep synthesis because of the high price and recyclization difficulty of the gold. A more thorough understanding of the factors that operate on homogeneous gold catalysis can provide better guidelines for the future design of more efficient gold-catalyzed reactions. In this Account, we will summarize our group's extensive investigation of factors impacting cationic gold catalysis, namely, the effects of ligands, counterions, additives, and catalyst decay and deactivation, using a mechanism-based approach with the aim of improving the efficiency of homogeneous gold catalysis. Through NMR-assisted kinetic studies, we investigated the above factors. Our systematic ligand effect investigation provided a clearer understanding of how ligands influence each of the three stages in the gold catalytic cycle. On the basis of this study, we synthesized a novel phosphine ligand and achieved parts per million-level gold catalysis by manipulating the electron density of the substituents and the steric strain around phosphorus. Our investigation of counterion effects led to the design of a gold affinity index and hydrogen-bonding basicity index for counterions, which can forecast the reactivity of counterions in cationic gold catalysis. We studied the adverse silver effects in cationic gold catalyst activation and proposed a more efficient practical guide. Our additive effect investigation revealed that additives that are good hydrogen-bond acceptors increase the efficiency of gold-catalyzed reactions in those occurrences where protodeauration is the rate-determining step. The first detailed experimental analysis of gold catalyst decay and the influence of each component in the reaction system (substrate, counterion, solvent) on the decay process was also conducted. We found that high-gold-affinity impurities (halides, bases) in solvents, starting materials, filtration, or drying agents decrease the reactivity of a gold catalyst but that a suitable acid activator can reactivate the gold catalyst and enable the reaction to proceed smoothly at competitively low gold catalyst loadings. The effects of acid additives were also systematically investigated using typical reactions. We are convinced that better mechanistic understandings will offer clearer guidelines for the search for more efficient gold-catalyzed reactions.

Effect of Counterions on the Formation and Structures of Ce(III) and Er(III) Chloranilate Frameworks

Lanthanide-containing benzoquinoid-type frameworks have been of significant interest due to their potential for application in high-density information storage and processing, photoluminescence, and sensing. With physical and chemical properties linked to the dimensionality of coordination polymers, control of network topology is desirable in generating targeted materials. The use of various cations as templates in the synthesis of Ce(III) and Er(III) frameworks has been investigated in this study. 2D (6,3) sheets of composition [M2(can)3(H2O)6]·solvate (M = Ce or Er, can = chloranilate) are formed with the tetraalkylammonium cations, tetramethylammonium or tetrabutylammonium. When the aromatic cation 1-(diphenylmethyl)-pyridinium (DPMP+) is incorporated in the reaction mixture, anionic diamond-type networks of composition [M(can)2]− (M = Ce or Er) are formed, with the cation occupying adamantane-type cavities. The use of tetraphenylphosphonium also yields a diamond-like network but only in the case of [Ce(can)2]−. When methyltriphenylphosphonium is employed, 3D anionic networks with unusual connectivity are obtained.

Effects of counter ions on electrochromic behaviors of asymmetrically substituted viologens

We present effects of counter anions on electrochromic behavior of asymmetrically substituted viologens, 1-hexyl-1′-nonafluorohexyl viologens (HERFVs). For this purpose, two anions, hexafluorophosphate ([PF6]–) and bis(trifluorosulfonyl)imide ([TFSI]–), were employed for both HERFVs and 1-butyl-3-methylimidazolium ([BMIM]+)-based ionic liquids. The HERFV-containing electrochromic devices (ECDs) exhibited apparent dependence on the counter ions in terms of optical contrast, switching speed, long-term cyclic stability, coloration efficiency, and memory effect. Specifically, the ECDs based on [HERFV][PF6]2 showed a redox response at −1.0 V with a color change from colorless to blue. Meanwhile, the coloration of [HERFV][TFSI]2 appeared at −3.0 V, and a significantly long optical memory effect was observed with unstable cyclic repeatability. We attributed this discrepancy to the nature of counter ions, such as size and electronegativity, which may influence the electron transfer process during redox reactions. These results demonstrated that counter anions can exert a significant impact on the EC behaviors of asymmetrically substituted viologens. The presented approach suggests a potential tool for controlling EC properties of viologen derivatives for applications in transmissive windows and eye wear.

Counter anion effects on the energy density of Ni(II)-chelated tetradentate azamacrocyclic complex cation as single redox couple for non-aqueous flow batteries

Tailoring the energy density of Ni(II)-chelated complex cation is accomplished by substituting various counter anions. Larger-sized anions are favored for increasing both the solubility and working voltage. The former advantage with larger-sized anion can be readily assumed since the binding energy is smaller to allow a higher solubility in solvents. The latter comes from the fact that Ni(II)(cyclam) complex cation in square-planar geometry shows a higher working voltage. Furthermore, the solubility of redox couple is enhanced by increasing the dielectric constant of used solvent. Consequently, the largest anion (TFSI−) demonstrates the most promising physicochemical/electrochemical properties; the energy density of redox couple reaches 27.3 W h L−1 with the working voltage, 2.55 V. The Ni(cyclam)[TFSI]2 shows very reversible electrochemistry in 1.0 M TEABF4 in EC/PC (1:1 = v/v) electrolyte and presents stable cycleability at non-flowing coin type static cell.

Facile Non‐enzymatic Lactic Acid Sensor Based on Cobalt Oxide Nanostructures

AbstractIn this study, we have investigated the effect of counter anions on the morphology of cobalt oxide nanostructures. The nanostructures of cobalt oxide are prepared by a low temperature aqueous chemical growth method. The morphology of cobalt oxide nanostructure material was investigated by scanning electron microscopy and the crystalline structure was studied by powder X‐ray diffraction technique. The cobalt oxide nanostructures exhibit the nanowire, lump, bundle of the nanowire and flower‐like morphologies. The XRD study has revealed a cubic phase of cobalt oxide nanostructures. The electro‐catalytic properties of cobalt oxide nanostructures were explored through cyclic voltammetry and amperometric techniques by sensing of lactic acid in the alkaline media. The cobalt oxide nanostructures prepared from cobalt nitrate have shown a well‐resolved redox peak. The proposed mechanism for the non‐enzymatic lactic acid sensor is elucidated by considering the morphology and cyclic voltammetry response. The limit of detection for the sensor was found to be 0.006 mM and it exhibits a linear range from 0.05–3 mM of lactic acid as shown by cyclic voltammetry. The amperometric response has shown the excellent current‐concentration response and the linear range of sensor was found to be 0.1 mM to 5.5 mM. The lactic acid sensor is stable, selective and can be used for practical applications. This study provides an excellent alternative analytical tool for the determination of lactic acid.

Effect of counter-ions on electromembrane extraction of non- steroidal antiinflammatory drugs

The paper describes a comprehensive study of the importance of cations to improve the efficiency and mass transfer in the electromembrane extraction for the determination of non-steroidal antiinflammatory. The procedure has been demonstrated to be adequate for the analysis of the selected non-steroidal anti-inflammatory drugs in human urine samples. Effects of donor and acceptor solution composition were examined studying the presence of different counter-ions in both aqueous solutions demonstrating to be an important parameter in the transference of the analytes across the membrane. Other parameters that are also critical for electromembrane, such as the organic solvent, the voltage, the extraction time and the donor solution volume were also optimized. The extracts were analyzed by high performance liquid chromatography with diode array and fluorescence detection. The highest enrichment factor was achieved using a pH7 donor composition adjusted with KOH and an acceptor composition at pH12 adjusted with NaOH. The enrichment factors were within the range of 85 and 133 for all compounds after 20min extraction, using a voltage of 60V, a stirring speed of 600rpm and 1-octanol as support liquid membrane. Detection and quantitation limits were within 0.1–1.5ngmL−1 and 0.3–3.0ngmL−1, respectively. The presence of K+ and Na+ as counter ions in the donor and the acceptor solution, respectively, demonstrated a higher enrichment compared to previous reported methods for the determination of non-steroidal antiinflammatory by electromembrane extraction using NaOH/NaOH as counter-ions.

Direct conversion of methane to methanol over Cu exchanged mordenite: Effect of counter ions

Direct conversion of methane (CH4) to methanol (DMTM) is a promising, but very challenging process for the utilization of abundant CH4 as a low carbon resource. In this context, Cu loaded zeolites, mordenite (MOR) in particular, were recognized as the most effective system to perform DMTM. In this work, different Cu salts were used to exchange with MOR, by which the effect of counter ions on the catalytic performance towards DMTM was investigated. The prepared catalysts were characterized and evaluated systematically. It was found that the counter ions affected the speciation of Cu sites, probably due to their capability in extraction of protons from MOR and the influence on the hydrolysis state of the Cu2+ in aqueous solution. These behaviors adjusted the association between Cu2+ and the exchangeable protons in MOR. As a result, varied DMTM performance was observed. Among the used Cu salts, Cu(CH3COO)2 exchanged MOR showed the highest performance, achieving stable CH3OH yield of 117 ± 28 μmol/g in 5 consecutive cycles, these values are among the highest for Cu loaded MOR zeolites in open publications.

Effect of counter ions on physical properties of imidazole-based proton conductors

Heterocycles are an interesting class of compounds for crystal engineering due to their ability to form moderate and weak hydrogen bonds. The physical properties of the newly synthesized proton conducting materials: imidazolium phthalate (salt 1) and imidazolium terephthalate (salt 2) were investigated. These salts differ in the acidic moiety: for salt 1 the carboxylic groups are in ortho position and for salt 2 in the para position of the phenyl ring. The structures of salts 1 and 2 were studied by NMR and X-ray diffraction combined with DFT calculations. The study of critical points and structure of these crystals shows that there are two types of intermolecular hydrogen bonding: medium strength hydrogen bonds (NH⋯O) and weak hydrogen bonds (CH⋯O). These intermolecular hydrogen bonding system types allow us to describe conductive properties using the Grotthuss mechanism. In the electrical conduction mechanism acid molecules, as well as imidazole ions are involved. In salt 1 the oscillating properties as a function of temperature were examined and show an additional band above the temperature of 373 K which is related to the presence of a phthalic acid anhydride. Salt 1 with ortho substitution has good conductive properties (σmax ∼10−1 S/m), while the salt 2 with para substitution has good thermal stability (melting point 464 K).

Discovery and Elucidation of Counteranion Dependence in Photoredox Catalysis.

Over the past decade, there has been a renewed interest in the use of transition metal polypyridyl complexes as photoredox catalysts for a variety of innovative synthetic applications. Many derivatives of these complexes are known, and the effect of ligand modifications on their efficacy as photoredox catalysts has been the subject of extensive, systematic investigation. However, the influence of the photocatalyst counteranion has received little attention, despite the fact that these complexes are generally cationic in nature. Herein, we demonstrate that counteranion effects exert a surprising, dramatic impact on the rate of a representative photocatalytic radical cation Diels-Alder reaction. A detailed analysis reveals that counteranion identity impacts multiple aspects of the reaction mechanism. Most notably, photocatalysts with more noncoordinating counteranions yield a more powerful triplet excited state oxidant and longer radical cation chain length. It is proposed that this counteranion effect arises from Coulombic ion-pairing interactions between the counteranion and both the cationic photoredox catalyst and the radical cation intermediate, respectively. The comparatively slower rate of reaction with coordinating counteranions can be rescued by using hydrogen-bonding anion binders that attenuate deleterious ion-pairing interactions. These results demonstrate the importance of counteranion identity as a variable in the design and optimization of photoredox transformations and suggest a novel strategy for the optimization of organic reactions using this class of transition metal photocatalysts.

Interactions of star-like polyelectrolyte micelles with hydrophobic counterions

Hydrophobicity of a counterion has a profound effect on the interaction with polyelectrolytes similar to that of multivalency. Specifically, understanding this interaction in weak polyelectrolyte micelles might assist in developing nanocarriers for pH-controlled encapsulation and release.We used star-like weak polyelectrolyte micelles of polystyrene-block-poly(2-vinyl pyridine) (PS-P2VP) with fixed aggregation number as a model polyelectrolyte, and cobalt bis(1,2-dicarbollide) (COSAN) as a model hydrophobic anion. We used NMR to assess the mobility of the polymer segments in the presence of varying amounts of COSAN, and at varying protonation degrees of the polyelectrolyte. Same experiments with indifferent electrolyte (NaCl) were used as a control. Furthermore, we used coarse-grained simulations to obtain a detailed picture of the effect of hydrophobic counterions on the conformation of the micelles.A small amount of hydrophobic counterions causes morphological changes within the micelles, whereas a bigger amount causes precipitation. This was confirmed both in simulations and in experiments. Furthermore, adsorption of the counterions induces ionization of the collapsed segments of the polyelectrolyte. Although the COSAN/P2VP system is rather specific, the generic model used in the coarse-grained simulations shows that the observed behavior is a consequence of synergy of hydrophobic and electrostatic attraction between polyelectrolytes and hydrophobic counterions. Our study provides general insights into the molecular mechanisms of these interactions.

Structure rearrangement of periodic mesoporous organosilicas through a post-synthesis approach

The structure of ethane-bridged PMOs was tailored for the first time through a post-synthesis method upon the addition of different sodium salts. It is proposed that the counterions can affect the surfactant micelles inside the PMOs, and further hydrothermal treatment will lead to a structure rearrangement of PMOs around the micelles. However, the results show that the effect of counterions on the structure of PMOs in the post-synthesis method is less pronounced compared with that of the effect in the direct-synthesis method, and additional surfactant is essential for maintaining the structure ordering of the materials.

Aggregation Behavior of Imidazolium‐Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions

AbstractThree kinds of imidazolium‐based amino acid ionic liquid surfactants (AAILS), 1‐tetradecyl‐3‐methylimidazolium L‐aminopropionic acid salt ([C14mim][Ala]), 1‐tetradecyl‐3‐methylimidazolium L‐2‐pyrrolidinecarboxylic acid salt ([C14mim][Pro]), and 1‐tetradecyl‐3‐methylimidazolium L‐aminohydrocinnamic acid salt ([C14mim][Phe]), were synthesized by employing natural amino acids as counterions. Their adsorption and self‐aggregation behaviors in aqueous solution were investigated systematically by means of surface tension and electrical conductivity measurements. Surface tension results indicate that surface properties and micellization behavior of AAILS are significantly affected by counterions. The micellization of [C14mim][Pro] and [C14mim][Phe] is entropy‐driven at low temperatures but enthalpy‐driven at high temperatures, whereas [C14mim][Ala] is enthalpy‐driven throughout the whole temperature range, owing to the variation in hydrophobicity and size of amino acid counterions. The surface activity of [C14mim][Phe] is superior to that of conventional imidazolium‐based ionic liquid surfactants with the same hydrocarbon chain length, 1‐tetradecyl‐3‐methylimidazolium bromide (C14mimBr), indicating that the aromatic counterion can promote the micellar formation process.

Demulsification of water-in-oil emulsions using ionic liquids: Effects of counterion and water type

Demulsification of crude oil emulsions is of significant interest in the petroleum industry. This study aims to investigate the effect of ionic liquid (IL) counterions and water type (distilled water (DW) and laboratory formulated seawater (SW)) on the demulsification of water-in-oil (W/O) emulsions. Three ILs belonging to the phosphonium compounds with different counterions were used. These ILs were designated as THPC (contains chloride ion), THPD (contains decanoate ion), and THPDc (contains dicyanamide ion). Emulsions were formed using DW and SW while demulsification tests were conducted at temperatures of 60 °C and 80 °C. According to the demulsification outcomes at 60 °C, THPC was the best candidate for breaking W/O emulsions produced from DW while THPD and THPDc were excellent candidates for destabilizing emulsions produced from SW. The optimal percentage demulsification efficiency (DE) achieved for emulsions from DW was 99% with just 1000 ppm THPC while 1000 ppm THPD and 700 ppm THPDc are adequate to bring about excellent water separation in emulsions formulated from SW. THPD and THPDc also attained the maximum percentage DE of 99%.On the other hand, at elevated temperature (80 °C), THPC, THPD, and THPDc attained nearly the same water separation in the W/O emulsions produced from DW and SW with a demulsifying capacity of 99%. However, demulsification activities at this temperature (80 °C) in the W/O emulsions formed using SW were very fast as compared to what was observed in the case of emulsions obtained from DW. Thus, salts present in SW have propensities to accelerate the destabilization of crude oil emulsions. Viscosity and elastic modulus time sweep measurements reveal that the tested ILs can collapse the natural emulsifiers (asphaltenes and resins) existing at the water-oil interfaces.

Effect of Counter Anions on Solid Electrolyte Interphase Formation on Graphite Electrodes in Propylene Carbonate-based Electrolyte Solutions

Effect of Counter Anions on Solid Electrolyte Interphase Formation on Graphite Electrodes in Propylene Carbonate-based Electrolyte Solutions

Imidazolyl-phenyl (IMP) anions: a modular structure for tuning solubility and coordinating ability.

The effect of counteranion upon a cation's solution-phase reactivity depends on a subtle interplay of weak interactions. Although these effects are widely appreciated in synthesis and catalysis, probing and controlling anion-cation interactions remains a significant challenge. Here we report the synthesis, characterisation and reactivity of the IMP anions, a family of anions with a coordinating ability that can be tuned for a given application. The anions are robust, compatible with both strongly basic and acidic media, suitable for isolation of unstable organometallic species, and effective as counteranions for homogeneous catalysis. IMP anions are prepared in two steps: deprotonation of substituted 2-phenylimidazoles with NaH, followed by addition of 2 equiv. B(C6F5)3. The anions prepared feature a range of functionality, including nitro, ester, amide, amine and alcohol groups. Based on the spectroscopic properties of [Pd(IPr)(C(O)C9H6N)] [IMP-R], the coordinating ability of [IMP-R]- ranges between BF4- and BArF4-, depending on the polarity of the R group. Gold complexes of type [L-Au-L'][IMP-R] have been isolated and characterised, resulting in the first X-ray structure of a (η2-diphenylacetylene)Au complex. [(tBuXPhos)Au(MeCN)][IMP-R] catalyses [2 + 2] cyclisation of alkenes and alkynes, as well as the hydroalkoxylation of alkynes. Unlike SbF6- and BArF4-, the [IMP-H]- and [IMP-CF3]- salts are sufficiently soluble to efficiently promote cyclisations in toluene with [(tBuXPhos)Au(MeCN)]+.