Volumetric Properties of the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} System at Temperatures from (283.15 to 333.15) K and Pressures from (0.1 to 35) MPa

Densities of pure 1-butyl-3-methylimidazolium methylsulfate, [C₄mim][MeSO₄], and its mixtures with methanol have been measured. Measurements were made with an accuracy of ±0.2 kg·m^?3, using a vibrating-tube densimeter, over the temperature and pressure ranges (283.15–333.15) K and (0.1–35) MPa, respectively. The experimental densities for the pure ionic liquid and alcohol have been correlated by the Tait equation. The results for the {x ₁[C₄mim][MeSO₄] + (1 ? x ₁)MeOH} system have been correlated by a van Laar equation involving parameters that are dependent on temperature and pressure. Excess volumes have been obtained directly from the experimental densities, while isobaric expansivities, isothermal compressibilities, and related excess properties were calculated from the correlation equation. Exceptionally strong pressure and temperature influences on these properties were observed.     

Controlled Redox Chemistry at Cerium within a Tripodal Nitroxide Ligand Framework

Ligand reorganization has been shown to have a profound effect on the outcome of cerium redox chemistry. Through the use of a tethered, tripodal, trianionic nitroxide ligand, [((2‐tBuNOH)C₆H₄CH₂)₃N]^3? (TriNO_x^3?), controlled redox chemistry at cerium was accomplished, and typically reactive complexes of tetravalent cerium were isolated. These included rare cationic complexes [Ce(TriNO_x)thf][BAr^F₄], in which Ar^F=3,5‐(CF₃)₂‐C₆H₃, and [Ce(TriNO_x)py][OTf]. A rare complete Ce–halide series, Ce(TriNO_x)X, in which X=F^?, Cl^?, Br^?, I^?, was also synthesized. The solution chemistry of these complexes was explored through detailed solution‐phase electrochemistry and ¹H NMR experiments and showed a unique shift in the ratio of species with inner‐ and outer‐sphere anions with size of the anionic X^? group. DFT calculations on the series of calculations corroborated the experimental findings.     

The influence of an electric field on the wetting of an SiO2 film by ionic liquids

The electrowetting of a dielectric SiO₂ film 100 nm thick by drops (D = 2–3 mm) of [C₄mIm][PF₆], [C₆mIm][PF₆], and [C₆mIm][BTI] ionic liquids was studied at |U| ≤ 60 V in a ～10^?8 mbar vacuum. Electrocapillary curves of the dependence of the wetting angle on electric field potential were constructed with an accuracy of ±1 deg. In conformity with the Young-Lippman equation, the wetting angle θ° decreased by the parabolic law from 51° to 43° for [C₄mIm][PF₆], from 48° to 38° for [C₆mIm][PF₆], and from 35° to 27° for [C₆mIm][BTI] as |U| increased at 298 K. The electrocapillary curve branches were situated symmetrically in the (θ°, U) coordinates with respect to the line passing through the point U = 0; that is, zero-charge potential is zero for the electrowetting of the dielectric film by the ionic liquids. The capacitance of the double electrical layer at the ionic liquid-dielectric interface was determined. This value was found to be 4.65, 2.93, and 1.73 μF/m² for the electrowetting of the SiO₂ film at 298 K by the ionic liquids specified, respectively.     

Anomalies in the polymerization kinetics of 4-dimethylaminostyrene initiated with trichloracetic acid in nitrobenzene

The relative permittivities (?_r²⁰) of 4-dimethylaminostyrene (I) and of 0.5–3.0 M solutions of N,N-dimethyl-4-toluidine (DMT) were measured in nitrobenzene (NB) and in a mixture of NB with diisopropyl ether (NB + E), the DMT solutions modelled those of I. An increase in [DMT] from 0.5 to 3.0 M caused a decrease in ?_r²⁰ from 32.3 to 18.3 in NB, while only from 20.8 to 18.3 in (NB + E) at fixed [NB]. The great difference between the ?_r²⁰ of 0.5 and 3.0 M DMT solutions in NB explains the previously observed drop in the percentage rate of polymerization (R_P) of I, in NB initiated with CCl₃COOH, with increasing [I]_o. In (NB + E) mixture with fixed [NB], the percentage R_P and the limiting viscosity number [ν] of polyl increase with increasing [I]_o. The observed dependences of both R_P (in Msec^?1) and [ν] on [I]₀ confirm the validity of the suggested polymerization scheme for I initiated with CCl₃COOH, and make possible determination of the characteristics of the elementary polymerization reactions.     

Hydrogen bond induced chiral symmetry breaking in the crystallization of nickel(II) complexes

A pair of enantiomers formulated as {Δ-cis-[Ni(en)₂OAc][ClO₄]} _n (Δ-1) and {Λ-cis-[Ni(en)₂OAc][ClO₄]} _n (Λ-1) (en = diaminoethane, OAc^? = acetate anion) were obtained when nickel acetate was reacted with diaminoethane and sodium perchlorate in the absence of any chiral source, whereas the reactions of nickel acetate with 1,3-propanediamine and sodium perchlorate only gave a centrosymmetric complex [Ni(1,3-pn)₂OAc][ClO₄] (2) (1,3-pn = 1,3-propanediamine). Single-crystal X-ray diffraction analyses of all three complexes indicated that the central Ni(II) atoms all have a distorted octahedral coordination geometry, being coordinated by four nitrogen atoms of the diamine ligands, plus two oxygen atoms of OAc^?. In complexes Δ-1 and Λ-1, the monomers of {Δ-cis-[Ni(en)₂OAc]}⁺ and {Λ-cis-[Ni(en)₂OAc]}⁺ are connected through intermolecular hydrogen bonds to generate one-dimensional right- and left-handed homochiral helical chains, respectively, while the monomers of [Ni(1,3-pn)₂OAc]⁺ are linked by similar intermolecular hydrogen bonds to form one-dimensional zigzag chains instead of helical chains. The chiral natures of complexes Δ-1 and Λ-1 have been confirmed by circular dichroism spectroscopy.     

Characterization of electrically conductive vanadate glass containing tungsten oxide

New conductive glass with a composition of 20BaO·10Fe₂O₃·xWO₃·(70 ? x)V₂O₅ (x = 10–50) was investigated by means of Mössbauer spectroscopy. A marked decrease in quadrupole splitting (Δ) was observed after the isothermal annealing at 500 °C for 1,000 min, due to the structural relaxation of 3D-network composed of FeO₄, VO₄, and VO₅ units. After the isothermal annealing, a marked increase in the electrical conductivity (σ) was observed from 1.7 × 10^?5 to 1.0 × 10^?1 S cm^?1 when “x” was 10, whereas comparable σ values of 1.1 × 10^?4 and 2.0 × 10^?4 S cm^?1 were observed when “x” was 40. These results evidently show that structural relaxation of 3D-network structure involved with a marked increase in σ is intrinsic of “vanadate glass”. XRD pattern indicated several weak peaks due to needle-like BaFe₂O₄ and α-Fe₂O₃ when the glass sample with “x” of 20 was annealed at 500 °C for 1,000 min. SEM study proved the formation of needle-like BaFe₂O₄ just on the surface of the sample, whereas hexagonal BaFe₁₂O₁₉ were observed in the annealed sample with “x” of 40. Chemical durability of WO₃-containing vanadate glass was investigated by immersing each glass sample into 20 %-HCl solution for 72 h.     

Synthesis, spectral and thermal studies of new copper (II) complexes with 1,2-di(imino-2-aminomethylpyridil)ethane

New copper (II) complexes of Schiff bases with 1,2-di(imino-2-aminomethylpyridil)ethane with the general composition CuLX _m (H₂O) _x , [L = Schiff base, X = Cl^?, Br^?, NO₃ ^?, ClO₄ ^?, CH₃COO^?, m = 2; X = SO₄ ^2?, m = 1] were prepared by template synthesis. The complexes were characterized by elemental analysis, conductivity measurements, magnetic moments, IR, UV–VIS and EPR spectra. The thermal behavior of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Infrared spectra of all complexes are in good agreement with the coordination of a neutral tetradentate N₄ ligand to the cooper (II) through azomethinic and pyridinic nitrogen. Magnetic, EPR and electronic spectral studies show a monomeric distorted octahedral geometry for all Cu(II) complexes. Conductance measurements suggest the non-electrolytic nature of the compounds, except for copper (II) nitrate and perchlorate complexes which are 1:2 electrolytes. Heats of decomposition, ΔH, associated with the exothermal effects were also determined.     

Structure and Reactivity of Iron(0)-Phenyltellurolate [PPN][PhTeFe(CO)4]

Anionic iron(0) tetracarbonyl with terminal phenyltellurolate ligand PhTe^?, [PhTeFe(CO)₄]^?, has been synthesized and characterized. The title compound was obtained by addition of (PhTe)₂ to [PPN][HFe(CO)₄] THF solution dropwise. [PPN][PhTeFe(CO)₄] crystallizes in the monoclinic space group C c, with a = 16.119(4) Å, b = 13.141(3) Å, c = 19.880(8) Å, β = 93.04(3)°, V = 4205(2) ų, and Z = 4. The [PhTeFe(CO)₄]^? anion is a trigonal-bipyramidal complex in which the phenyltellurolate ligand occupies an axial position with Fe-Te bond length 2.630(5) Å and the Fe-Te-C(Ph) angle is 103.4(5)°. The neutral iron(0)-telluroether compound, (PhTeMe)Fe(CO)₄, was prepared by alkylation of the [PhTeFe(CO)₄]^?. Protonation of [PhTeFe(CO)₄]^?and reaction of H₂Fe(CO)₄ and PhTe)₂ ultimately lead to formation of the known dimer Fe₂(μ-TePh)₂(CO)₆ and H₂.     

Oxygen-ionic conductors based on substituted bismuth molybdates with column-type structural fragments

The possibility of synthesizing oxygen-ionic conductors from substituted bismuth molybdates containing [Bi₁₂O₁₄] _n ⁸ⁿ⁺ columns, MoO₄ tetrahedra, and isolated Bi ions in their structure was studied. The specifics of their structure and electric conductivity were investigated. The general formula of the solid solutions can be recorded as Bi₁₃Mo_{5 ? x} Me _x O_{34 ? δ}, where Me is the fouror five-valent d metal (Ti, Zr, V, Nb). The electric conductivity of doped bismuth molybdates considerably increased compared with that of the matrix compound. The electric conductivity reached 5.5 × 10^?3 S cm^?1 at 700°C and 1.8 × 10^?4 S cm^?1 at 350°C for the zirconium-doped compound with x = 0.4. The porosity of the ceramics was less than 5%; the thermal expansion coefficient was of the order of 14 × 10^?6 K^?1. Based on the set of their characteristics, these compounds are recommended as materials for membranes of electrochemical devices.     

Über [Ag(S9)]−, ein symmetrisches zehngliedriges Ringsystem Darstellung,Struktur und spektroskopische Charakterisierung der schwefelreichen Verbindung [(PPh3)2N][Ag(S9)] · S8

About [Ag(S₉)]^?, a Symmetric Ten-Membered Ring System; Preparation, Structure, and Spectroscopic Characterization of the Sulfur Rich Compound [(PPh₃)₂N][Ag(S₉)] · S₈ Orange [(PPh₃)₂N][Ag(S₉)] · S₈ ( 1 ) could be obtained by reaction of a definite S_x^2?-solution with AgNO₃ and characterized by vibrational spectra (IR/Raman) and X-ray structure analysis. The anion [Ag(S₉)]^? shows a symmetric conformation of a ten-membered ring system. 1 crystallizes in the triclinic space group P1 (a = 1383.8(4), b = 1429.5(4), c = 1540.5(5) pm, α 62.38(2), β 68.05(2), γ 65.86(2)°, V = 2399.1 · 10⁶ pm³, Z = 2; R = 0.077 for 5433 independent reflections (F₀ > 3.92 σ(F₀))).     

Studies of unusual oxidation states of transition metals III-kinetics and mechanism of oxidation of triethanolamine by diperiodatoargenate(III) ion in aqueous alkaline medium

The kinetics of oxidation of triethanolamine (TEA) by diperiodatoargenate(III) anion, [Ag(HIO₆)₂]^5?, has been studied in aqueous alkaline medium by conventional spectrophotometry. The reaction is pseudo-first-order in [Ag(III)] disappearance with k_obs = (k₁ + k₂[OH^?]) K₁K₂[TEA]/{[H₂IO₆^3?]_e + K₁ + K₁K₂[TEA]}, where k₁ = 8.05 × 10^?3 S^?1, k₂ = 0.46 M^?1 S^?1, K₁ = 6.15 × 10^?4 M, and K₂ = 537 M^?1 at 25°C, and μ = 0.30 M. Based on the inference that an inner-sphere complex is formed by indirect replacement of a ligand of [Ag(HIO₆)₂]^5? by a TEA molecule, a reaction mechanism has been proposed. The complex undergoes redox by two modes, both internal and one hydroxide ion assisted.     

ortho-, meta- and para-nitrophenylgold(I) complexes

Treatment of [BzPh₃P][AuCl₂] with [Hg(x-C₆H₄NO₂)₂] (x = o, m, or p) gives anionic gold(I) complexes of the type [BzPh₃P][Au(R)Cl](R = o-, m- or p-C₆H₄NO₂, Bz = C₆H₅CH₂). The chloro ligand in [Au(o-C₆H₄NO₂)Cl]^? can be replaced by bromo or iodo ligands by use of NaBr or NaI. The anions [Au(R)Cl]^? react with neutral monodentate ligands, L, to give neutral mononuclear complexes [Au(R)L] (R = o-C₆H₄NO₂, L = PPh₃, AsPh₃; R = m-C₆H₄NO₂, L = PPh₃) and with 1,2-bis(diphenylphosphino)ethane (dpe) to give [Au₂(R)₂(dpe)] (R = o-C₆H₄NO₂). The corresponding [Au(p-C₆H₄NO₂)Cl]^? reacts with PPh₃ or AsPh₃ to give mixtures containing [AuClL]. The anionic ortho-nitrophenylgold(I) complex is much more stable than its meta- or para-nitrophenyl isomers. These are thought to be the first reports of nitrophenylgold(I) complexes.     

Extraction of Palladium(II) and Platinum(IV) from Hydrochloric Acid Solutions with Trioctylammonium Nitrate Ionic Liquid without Dilution

The fundamental properties and extraction capability of an ionic liquid (IL), trioctylammonium nitrate ([HTOA][NO₃]), for Pd^II and Pt^IV, are investigated. At room temperature, [HTOA][NO₃] is a solid (melting point: 30.7 °C), but it becomes a liquid (melting point: 16.7 °C) when saturated with water. Water-saturated [HTOA][NO₃] exhibits a viscosity of 267.1 mPa·s and an aqueous solubility of 2.821?×?10^?4 mol·dm^?3 at 25 °C, and can be used as an extraction solvent without dilution. [HTOA][NO₃] exhibits an extremely high extraction capability for Pd^II and Pt^IV in dilute hydrochloric acid (0.1–2 mol·dm^?3 HCl); the distribution ratio reaches 3 × 10⁴ for both the metals. From electrospray ionization mass spectrometry analysis, the species extracted in the IL phase are [PdCl₃]^? and [PdCl₂(NO₃)]^? for Pd^II and [PtCl₆]^2? and [PtCl₅]^? for Pt^IV. A majority of the other transition metals are considerably less or marginally extracted into [HTOA][NO₃] from a 0.1 mol·dm^?3 hydrochloric acid solution. The extraction capacity of [HTOA][NO₃] is greater than that of other hydrophobic ILs such as [HTOA]Cl and bis(trifluoromethanesulfonyl)imide-based ILs. The metals extracted into the IL phase are quantitatively back-extracted using an aqueous solution containing thiourea and nitric acid. By controlling the thiourea concentration and shaking time, Pd^II and Pt^IV are mutually separated to some extent in the back extraction process. The IL phase used for the back extraction can be reused for the forward extraction of these metals after scrubbing it with an aqueous nitric acid solution.     

THE EPR SPECTRA OF TETRADENTATE SCHIFF BASE COMPLEXES OF COPPER (II) I. N,N'-Bis-(acetylacetone) ethylenediimine and N,N'-Bis-(1,1,1-trifluoroacetylacetone) ethylenediimine

Abstract

The EPR spectrum of N, N'-bis-(acetylacetone)ethylenediimino Cu(II), [Cu-en(acac)₂], and N, N'-bis-(1,1,1-trifluoroacetylacetone)ethylenediimino-Cu(II), [Cu-en(tfacac)₂], have been studied in doped single crystals of the corresponding Ni(II) chelate. The parameters in the usual doublet spin-Hamiltonian are found to be: Cu[en(acac)₂], g_z =2.183 ± 0.003, g_x =2.047 ± 0.004, g_y =2.048 ± 0.004, A_z =204.8 × 10^?4cm^?1, A_x =31.5 × 10^?4cm^?1, A_y =27.1 × 10^?4 cm^?1, A_zN= 12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.3 × 10^?4 cm^?1: Cu[en(tfacac)₂], g_z =2.192 ± 0.002, g_x =2.048 ± 0.004, g_y =2.046 ± 0.004, A_z =200.8 × 10^?4 cm^?1, A_x =31.1 × 10^?4 cm^?1, A_y =28.3 × 10^?4 cm^?1, A_zN =12.8 × 10^?4 cm^?1 and A_xN =A_yN =14.6 × 10^?4 cm^?1. These parameters are related to coefficients in the molecular orbitals of the complex. It is found that the α-bonding is quite covalent and there is significant in-plane σ-bonding. From the nitrogen hyperfine structure it is determined that the hybridization on the nitrogen is sp².     

Selenium speciation in paired serum and cerebrospinal fluid samples

Se speciation was performed in 24 individual paired serum and cerebrospinal fluid (CSF) samples from neurologically healthy persons. Strong anion exchange (SAX) separation, coupled to inductively coupled plasma–dynamic reaction cell–mass spectrometry (ICP-DRC-MS), was employed. Species identification was done by standard matched retention time, standard addition and by size exclusion chromatography followed from SAX (2-D SEC-SAX-ICP-DRC-MS) and by SAX followed from CE-ICP-DRC-MS (2-D SAX-CE-ICP-DRC-MS). Limit of detection (LoD, 3?×?standard deviation (SD) of noise) was in the range of 0.026–0.031 μg/L for all investigated species and thus was set uniformly to 0.032 μg/L. Quality control for total Se determination was performed by analysing control materials “human serum” and “urine”, where determined values met target values. Several Se species were found in both sample types having following median values (sequence: serum/CSF, each in μg Se/L): total Se, 58.39/0.86; selenoprotein P (SePP), 5.19/0.47; Se-methionine (SeM), 0.23/<LoD; glutathione peroxidase (GPx), 4.2/0.036; thioredoxinreductase (TrxR), 1.64/0.035; Se IV, 12.25/0.046; Se-human serum albumin (Se-HSA), 18.03/0.068. Other Se species, such as Se-cystine (SeC), Se VI and up to four non-identified compounds were monitored (if ever) only in very few samples usually close to LoD. Therefore, their median values were <LoD. Linear relationships based on median values provide information about Se-species passage across neural barriers (NB): SePP_-serum is significantly correlated to total Se_-serum when the latter was >?65 μg/L; however, SePP_-CSF appeared independent of SePP_-serum. For Se-HSA_-serum versus (vs.) Se-HSA_-CSF, a weak linear relationship was found (r ²?=?0.1722). On the contrary, for anti-oxidative Se-enzymes, higher r ² values were calculated: GPx_-serum vs. GPx_-CSF, r ²?=?0.3837; TrxR_-serum vs. TrxR_-CSF, r ²?=?0.6293. Q _-Se-species values (= ratios of CSF_-Se-species/serum_-Se-species) were compared with the Q _-Alb value (HSA_-CSF/HSA_-serum?=?clinical index of NB integrity) for deeper information about NB passage of Se species. The Q _-Se-HSA value (3.8?×?10^?3) was in accordance to the molecular mass dependent restriction at NB (Q _-Alb at 5.25?×?10^?3). Increased Q values were seen for TrxR (21.3?×?10^?3) and GPx (8.3?×?10^?3) which are not (completely) explained by molecular size. For these two anti-oxidative Se-enzymes (GPx, TrxR), we hypothesize that there might be either a facilitated diffusion across NB or they might be additionally synthesized in the brain.     

Determination of the population,depopulation and the anisotropic spin lattice relaxation rates in the photoexcited triplet state of phenazine. A light modulation-EPR study

The photoexcited triplet state of phenazine in toluene glasses at 35 K is investigated by light modulation-EPR spectroscopy. From the transient EPR spectra and the kinetics in the three canonical orientations (p = x, y, z) the rate parameters are determined. Thus, the depopulation rate constants k_p, the anisotropic spin lattice relaxation rate constants W_p, and the ratios between the population constants A_p are calculated: k_x = (2.2 ± 0.3) × 10² s^?1, k_y = (0.21 ± 0.04) × 10² s^?1, k_z = (0.06 ± 0.03) × 10² s^?1, W_x = (8.6 ± 0.9) × 10³ s^?1, W_y = (11.0 ± 1.0) × 10³ s^?1, W_z = (14.0 ± 1.4) × 10³ s^?1, and A_x: _Ay:A_z ≈ 1:0.04:0.02. It is concluded therefore that the in-plane spin state |τ_x > is the active one.     

Ionic liquid assisted synthesis of flowerlike Cu2O micro-nanocrystals

Novel flowerlike Cu2O micro-nanocrystals were prepared by a greener reductive reaction of cupric acetate monohydrate with ethylene glycol in aqueous solutions of [C8mim]X (X = Cl , Br , BF4 , PF6 ) and [Cnmim][BF4] (n = 4, 6, 8). The obtained microstructures of Cu2O were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR). The effects of cations, anions and concentration of the ionic liquids on the morphology of Cu2O were examined in some details. The results suggest that the formation of flowerlike Cu2O was governed by a [C8mim][BF4] controlled reductive reaction mechanism. As one of their applications, the Cu2O nanoparticles were used for the photocatalytic degradation of methylene blue in aqueous solution, and high photocatalytic activity was observed.     

Kinetics and mechanism of the reduction of μ-adi-di[N,N′-bis{salicylideneethylenediaminatoiron(III)}] by dithionate ion

The kinetics and mechanism of the reduction of the μ-adi-di[N,N′-bis{salicylideneethylenediaminatoiron(III)}] complex, [Fe₂adi], by dithionate ion, S₂O₆ ^2?, have been investigated in aqueous perchloric acid at 29 °C, I = 0.05 mol dm^?3 (NaClO₄) and [H⁺] = 5.0 × 10^?3 mol dm^?3. Spectrophotometric titrations indicated that one mole of the reductant was oxidized per mole of oxidant. Kinetic profiles indicated first-order rate with respect to [Fe₂adi] but zeroth-order dependence on [S₂O₆ ^2?]. The rate of reaction increased with increase in [H⁺], decreased with increased dielectric constant, but was invariant to changes in ionic strength of the medium. Addition of small amounts of AcO^? and Mg²⁺ ions did not catalyse the reaction. A least-squares fit of rate against [H⁺]² was linear (r ² = 0.984) without intercept. The reaction was analysed on the basis of a proton-coupled outer-sphere electron transfer mechanism.     

High-temperature defect structure and electrical conduction in Ni1−xMgxO

The ionic transference number, the electrical conductivity, and Seebeck coefficient of Ni_1?xMg_xO (0.1 ≤ x ≤ 0.9) were measured as functions of temperature (900–1400°C) and oxygen partial pressure (10²–10⁵ Pa). The contribution of ionic conduction to the total conductivity of Ni_0.9Mg_0.1O was of the order of 10^?3?10^?2 at 900–1300°C, which led us to assume that the electronic conduction was predominating in Ni_1?xMg_xO (x ≤ 0.9). The electrical conductivities of both undoped and Al-doped Ni_1?xMg_xO depended on the $\text{1}\text{4}$ power of P_O2, which indicated a significant impurity effect on the defect equilibria and was interpreted as showing that doubly ionized cation vacancies were the dominant point defects at high temperatures. Analyses of the difference in the temperature dependences of conductivity and Seebeck coefficient showed that band-like conduction took place in the NiO-rich composition range (x ≤ 0.1), while thermally activated hopping of small polarons occurred in Ni_1?xMg_xO with x ≥ 0.3. The calculated drift mobility abruptly decreased in the composition region where the conduction mechanism changed.     

Ion activities and copper electrode reactions in magnesium sulphate solutions

Thermodynamic and kinetic studies have revealed conventional mean-ion and convenient single-ion activity coefficients for copper(II), magnesium and sulphate ions and standard exchange rates for either step of the liquid Cu(Hg)/Cu(II) electrode and of the solid Cu/Cu(II) electrode, all in 0.005 mol kg^?1 CuSO₄+0.005 mol kg^?1 H₂SO₄+(x?0.01) mol kg^?1MgSO₄ (for x=0.2 to 3) at 25°C. With increasing x, the sulphate activity coefficient steadily falls, the copper(II) and magnesium activity coefficients go through a minimum near x=1, and the standard rates fall. The kinetic changes with x reveal some information on double-layer and ligand effects.