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Copper-, manganese-, and zinc-based ionic liquids (Cu{NH2CH2CH2OH}6[CH3(CH2)3CH(C2H5)CO2]2(2), Cu{NH(CH2CH2OH)2}6[CH3(CH2)3CH(C2H5)CO2]2(3A), Cu{NH(CH2CH2OH)2}6[CF3SO3]2(3B), Cu{NH(CH2CH2OH)2}6[(CF3SO2)2N]2(3C), Mn{NH(CH2CH2OH)2}6[CF3SO3]2(4), and Zn{NH2CH2CH2OH}6[CF3SO3]2(5)) are synthesized in a single-step reaction. Infrared data suggest that ethanolamine preferentially coordinates to the metal center through the amine group in 2and the hydroxyl group in 5. In addition, diethanolamine coordinates through the amine group in 3A, 3C, and 4and the hydroxyl group in 3B. The compounds are viscous (>1000 cP) at room temperature, but two (3Cand 4) display specific conductivities that are reasonably high for ionic liquids (>20 mS cm−1). All of the compounds display a glass transition (Tg) below −50 °C. The cyclic voltammograms (CVs) of 2, 3A, 3B, and 3Cdisplay a single quasi-reversible wave associated with Cu(ii)/Cu(i) reduction and re-oxidation while 5shows a wave attributed to Zn(ii)/Zn(0) reduction and stripping (re-oxidation). Compound 4is the first in this new family of transition metal-based ionic liquids (MetILs) to display reversible Mn(ii)/Mn(iii) oxidation and re-reduction at 50 mV s−1using a glassy carbon working electrode. [ABSTRACT FROM AUTHOR]

An iron-based ionic liquid, Fe((OHCH2CH2)2NH)6(CF3SO3)3, is synthesized in a single-step complexation reaction. Infrared and Raman data suggest NH(CH2CH2OH)2primarily coordinates to Fe(iii) through alcohol groups. The compound has Tgand Tdvalues of −64 °C and 260 °C, respectively. Cyclic voltammetry reveals quasi-reversible Fe(iii)/Fe(ii) reduction waves. [ABSTRACT FROM AUTHOR]

Rates of steady oxygen-isotope exchange differ in interesting ways for two sets of structural oxygens in the [HxTa6O19](8-x)-(aq) Lindqvist ion when compared to published data on the [HxNb6O19]8-x(aq) version. Because of the lanthanide contraction, the [HxTa6O19](8-x-(aq) and [HxNb6O19](8-x-(aq) ions are virtually isostructural and differ primarily in a full core (Kr vs Xe) and the 4f14 electrons in the [HxTa6O19](8-x-(aq) ion. For both molecules, both pH-dependent and -independent pathways are evident in isotopic exchange of the 12 μ2-O(H) and 6 ηO sites. Rate parameters for ηO exchange at conditions where there is no pH dependence are, for the Ta(V) and Nb(V) versions respectively, k0298 = 2.72 × 10-5 s-1 and 9.7 × 10-6 s-1, ΔH‡ = 83.6 ± 3.2 and 89.4 kJ·mol-1, and ΔS‡ = -51.0 ± 10.6 and -42.9 J·mol-1·K-1. For the μ2-O sites, K0298 = 1.23 × 10-6 s-1, ΔH‡ = 70.3 ± 9.7 and 88.0 kJ·mol-1, and ΔS‡ = -116.1 ± 32.7 and -29.4 J·mol-1·K-1. Protonation of the 6 ηO sites is energetically unfavored relative to the 12 μ2-O bridges in both molecules, although not equally so. Experimentally, protonation labilizes both the μ2-O(H) and ηO sites to isotopic exchange in both molecules. Density-functional electronic- structure calculations indicate that proton affinities of structural oxygens in the two molecules differ with the [HxTa6O19](8-x)-(aq) anion having a smaller affinity to protonate than the [HxNb6O19]8-x(aq) ion. This difference in proton affinities is evident in the solution chemistry as pKa = 11.5 for the [HTa6O19]7-(aq) ion and pKa = 13.6 for the [HNb6O19]7-(aq) ion. Most striking is the observation that ηO sites isotopically equilibrate faster than the μ2-O sites for the [HxTa6O19](8-x)-(aq) Lindqvist ion but slower for the [HxNb6O19](8-x)-(aq) ion, indicating that predictions about site reactivities in complicated structures, such as the interface of aqueous solutions and oxide solids, should be approached with great caution. [ABSTRACT FROM AUTHOR]

Discusses the preparation and characterization of a coordination polymer composed of a mixed-addenda polyoxometalate bridged by aquated Cu(II) units. Selective aerobic sulfoxidation of thioethers; Spectrum screening of combinations of redox-active transition metal cations and oxidizing anions; Catalytic activity; X-ray crystallography.

Discusses the synthesis of a carbonate-encapsulated sandwich-type yttrium poloxymetalates. Reaction of a A-α-PW[sub 9]O[sub 34][sup 9-] with YCl[sub 3] in an aqueous Na[sub 2]CO[sub 3] solution; Production of the first dianion-encapsulated A-type sandwich polyoxometalate; X-ray structure of the complex; Sandwiching of three Y (III) ions between two A-α-PW[sub 9]O[sub 34][sup 9-] moieties.

The demetalation process of 10 multi-iron Wells—Dawson polyoxometalates is studied by cyclic voltammetry and controlled potential coulometry. Eight sandwich-type complexes (α α α α-Na16[(NaOH2)2 (FeIII)2 (X2W15O56)2], α αβ α-Na14[(NaOH2)(FeIIIOH2)(FeIII)2(X2W15O56)2], αβ β α-Na12[(FeIIIOH2)2(FeIII)2(X2W15O56)2], and αβ βα-Na14[(MnIIOH2)2-(FeIII)2 (X2W15O56)2] (where X = P(V) or As(V))) and two monomeric complexes (α-Na11(P2(FeIIICI)2(FeIIIOH2)W15O59)] and α-Na11[(As2(FeIIICI)2FeIIIOH2)W15O59)]) were selected for this study. All 10 complexes show Fe(III) waves which are well-separated from the redox activity of the W(Vl) centers. At room temperature and under mild conditions, iron release from the complexes is observed upon reduction of the Fe(III) centers. This release is controlled by the ionic strength of the medium, the nature and concentration of the anions present in the supporting electrolyte, and by the pH of the solution. This behavior parallels those described for most siderophores which depend on the same parameters. [ABSTRACT FROM AUTHOR]