Electrochemistry and speciation of Au(+) in a deep eutectic solvent: growth and morphology of galvanic immersion coatings.

In this study we compare the electrochemical and structural properties of three gold salts AuCl, AuCN and KAu(CN)2 in a Deep Eutectic Solvent (DES) electrolyte (Ethaline 200) in order to elucidate factors affecting the galvanic deposition of gold coatings on nickel substrates. A chemically reversible diffusion limited response was observed for AuCl, whereas AuCN and KAu(CN)2 showed much more complicated, kinetically limited responses. Galvanic exchange reactions were performed on nickel substrates from DES solutions of the three gold salts; the AuCN gave a bright gold coating, the KAu(CN)2 solution give a visibly thin coating, whilst the coating from AuCl was dull, friable and poorly adhesive.

EXAFS study into the speciation of metal salts dissolved in ionic liquids and deep eutectic solvents.

The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs M(I) ions form [MCl2](-) and [MCl3](2-) complexes, while all M(II) ions form [MCl4](2-) complexes, with the exception of Ni(II), which exhibits a very unusual coordination by glycol molecules.

From discrete monomeric complexes to hydrogen-bonded dimeric assemblies based on sterically encumbered square planar palladium(II) ONN-pincers.

The 2-(3-biphenyl-2-ol)-6-iminepyridines, 2-(3-C12H8-2-OH)-6-(CH=NAr)C5H3N (Ar = 2,6-i-Pr2C6H3 (L1a-H), 2,4,6-Me3C6H2 (L1b-H)), have been prepared in high yield via sequential Suzuki coupling, deprotection and condensation reactions from 2-methoxybiphenyl-3-ylboronic acid and 2-bromo-6-formylpyridine. Treatment of L1-H with Pd(OAc)2 or (MeCN)2PdCl2 results in deprotonation of L1-H to afford the discrete square planar ONN-chelates, [{2-(3-C12H8-2-O)-6-(CHNAr)C5H3N}Pd(OAc)] (Ar = 2,6-i-Pr2C6H3 (1a), 2,4,6-Me3C6H2 (1b)) and [{2-(3-C12H8-2-O)-6-(CH=NAr)C5H3N}PdCl] (Ar = 2,6-i-Pr2C6H3 (2a), 2,4,6-Me3C6H2 (2b)), in good yield, respectively; conversion of 1 to 2 using aqueous sodium chloride has been demonstrated. Selective reduction of the imino unit in L1-H with LiAlH4 proceeds smoothly to yield the 2-(3-biphenyl-2-ol)-6-(methylamine)pyridines, 2-(3-C12H8-2-OH)-6-(CH2-NHAr)C5H3N (Ar = 2,6-i-Pr2C6H3 (L2a-H), 2,4,6-Me3C6H2 (L2b-H)), which on reaction with Pd(OAc)2 give [{2-(3-C12H8-2-O)-6-(CH2-NHAr)C5H3N}Pd(OAc)] (Ar = 2,6-i-Pr2C6H3 (3a), 2,4,6-Me3C6H2 (3b)).