title: Liquid Nickel Salts: Synthesis, Crystal Structure Determination, and Electrochemical Synthesis of Nickel Nanoparticles.
abstract: New nickel-containing ionic liquids were synthesized, characterized and their electrochemistry was investigated. In addition, a mechanism for the electrochemical synthesis of nanoparticles from these compounds is proposed. In these so-called liquid metal salts, the nickel(II) cation is octahedrally coordinated by six N-alkylimidazole ligands. The different counter anions that were used are bis(trifluoromethanesulfonyl)imide (Tf2 N(-) ), trifluoromethanesulfonate (OTf(-) ) and methanesulfonate (OMs(-) ). Several different N-alkylimidazoles were considered, with the alkyl sidechain ranging in length from methyl to dodecyl. The newly synthesized liquid metal salts were characterized by CHN analysis, FTIR, DSC, TGA and viscosity measurements. An odd-even effect was observed for the melting temperatures and viscosities of the ionic liquids, with the complexes with an even number of carbon atoms in the alkyl chain of the imidazole having a higher melting temperature and a lower viscosity than the complexes with an odd number of carbons. The crystal structures of several of the nickel(II) complexes that are not liquid at room temperature were determined. The electrochemistry of the compounds with the lowest viscosities was investigated. The nickel(II) cation could be reduced but surprisingly no nickel deposits were obtained on the electrode. Instead, nickel nanoparticles were formed at 100 % selectivity, as confirmed by TEM. The magnetic properties of these nanoparticles were investigated by SQUID measurements.
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Sniekers
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Ken
authors.initials: K
authors.lastname: Verguts
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Neil R
authors.initials: NR
authors.lastname: Brooks
authors.affiliation: Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 - P.O. Box 2450, 3001, Heverlee, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: Schaltin
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Thanh Hai
authors.initials: TH
authors.lastname: Phan
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Thi Mien
authors.initials: TM
authors.lastname: Trung Huynh
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Van Meervelt
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: De Feyter
authors.affiliation: Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 - P.O. Box 2450, 3001, Heverlee, Belgium.
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Seo
authors.affiliation: Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 - P.O. Box 2450, 3001, Heverlee, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Fransaer
authors.affiliation: Department of Chemistry, KU Leuven, Celestijnenlaan 200 F - P.O. Box 2404, 3001, Heverlee, Belgium. Koen.Binnemans@chem.kuleuven.be.
authors.forename: Koen
authors.initials: K
authors.lastname: Binnemans
keywords: X-ray diffraction; electrochemistry; ionic liquids; magnetic properties; nanoparticles