Get access

Silver-Containing Ionic Liquids with Alkylamine Ligands

Authors

  • Daphne Depuydt,

    1. KU Leuven-University of Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee (Belgium)
    Search for more papers by this author
  • Dr. Neil R. Brooks,

    1. KU Leuven-University of Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee (Belgium)
    Search for more papers by this author
  • Dr. Ir. Stijn Schaltin,

    1. KU Leuven-University of Leuven, Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, P.O. Box 2450, B-3001 Heverlee (Belgium)
    Search for more papers by this author
  • Prof. Dr. Luc Van Meervelt,

    1. KU Leuven-University of Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee (Belgium)
    Search for more papers by this author
  • Prof. Dr. Ir. Jan Fransaer,

    1. KU Leuven-University of Leuven, Department of Metallurgy and Materials Engineering, Kasteelpark Arenberg 44, P.O. Box 2450, B-3001 Heverlee (Belgium)
    Search for more papers by this author
  • Prof. Dr. Koen Binnemans

    Corresponding author
    1. KU Leuven-University of Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee (Belgium)
    • KU Leuven-University of Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee (Belgium)

    Search for more papers by this author

Abstract

The synthesis, structure and electrochemical properties of several silver-containing liquid metal salts have been investigated. These ionic liquids comprise of a silver-containing cation with a silver centre coordinated by two or more alkylamine ligands and a bis(trifluoromethylsulfonyl)imide (Tf2N) anion. With the monodentate amines tert-butylamine (tBuAm), iso-butylamine (iso-BuAm), sec-butylamine (sec-BuAm), 2-ethylhexylamine (2-EtHexAm), di(2-ethylhexyl)amine and piperidine (pip), compounds with the formula [Ag(L)2][Tf2N] are formed, several of which are room-temperature ionic liquids and all melt at or below 100 °C. In the case of [Ag(L)2][Tf2N] (L=tBuAm, iso-BuAm and pip), single-crystal X-ray diffraction shows that, in the solid state, the silver centres are two-fold coordinated by two amine ligands and the anion and cation exist as separated ion pairs. With ethylenediamine (en), two different compounds were formed, depending on the silver-to-ligand ratio and their structures were elucidated by X-ray diffraction. [Ag(en)][Tf2N] has a very high melting point and is polymeric in the solid state, with en ligands coordinated to different silver(I) centres, creating one-dimensional chains. [Ag(en)2][Tf2N], on the other hand, is a room-temperature ionic liquid, with four-coordinate silver(I) centres, but is actually polymeric in the solid state. The electrodeposition behaviour of [Ag(2-EtHexAm)2][Tf2N] and [Ag(en)2][Tf2N] was investigated both at room temperature and at 90 °C and it was possible to achieve very high current densities in unstirred solutions and to electrodeposit closed, crack-free, silver coatings. A crystal of [Ag2(en)Cl2] was obtained from a solution of [Ag(en)][Tf2N] in deuterochloroform and its structure is described.

Ancillary