Abstract
Adding to the versatile class of ionic liquids, we report the detailed structure and property analysis of a new class of asymmetrically substituted imidazolium salts, offering interesting thermal characteristics, such as liquid crystalline behavior, polymorphism or glass transitions. A scalable general synthetic procedure for N-polyaryl-N'-alkyl-functionalized imidazolium salts with para-substituted linker (L) moieties at the aryl chain, namely [LPh(m) Im(H) R](+) (L=Br, CN, SMe, CO(2) Et, OH; m=2, 3; R=C(12) , PEG(n) ; n=2, 3, 4), was developed. These imidazolium salts were studied by single-crystal X-ray diffraction (SC-XRD), NMR spectroscopy and thermochemical methods (DSC, TGA). Furthermore, these imidazolium salts were used as N-heterocyclic carbene (NHC) ligand precursors for mononuclear, first-row transition metal complexes (Mn(II) , Fe(II) , Co(II) , Ni(II) , Zn(II) , Cu(I) , Ag(I) , Au(I) ) and for the dinuclear Ti-supported Fe-NHC complex [(OPy)(2) Ti(OPh(2) ImC(12) )(2) (FeI(2) )] (OPy=pyridin-2-ylmethanolate). The complexes were studied concerning their structural and magnetic behavior via multi-nuclear NMR spectroscopy, SC-XRD analyses, variable temperature and field-dependent (VT-VF) SQUID magnetization methods, X-band EPR spectroscopy and, where appropriate, zero-field (57) Fe Mössbauer spectroscopy.