posted on 2015-07-06, 00:00authored byStefanie Kobialka, Christina Müller-Tautges, Melanie
T. S. Schmidt, Gregor Schnakenburg, Oldamur Hollóczki, Barbara Kirchner, Marianne Engeser
We report the synthesis and characterization
of 12 new dinuclear
gold(I) N-heterocyclic carbene (NHC) complexes and the corresponding
imidazolium precursors. The focus lies in a systematic study of conformational
changes and intra- and intermolecular gold–gold and π–π
interactions of dinuclear gold(I) carbene complexes. Common to all
members of the series of gold macrocycles are NHC ligands on the basis
of imidazole with ethyl side chains and bromide as well as hexafluorophosphate
counterions, respectively. The compounds vary in the length of a flexible
alkyl linker between the NHC units. For the methylene and ethylene
bridged macrocycles, a ring inversion movement can be observed by
VT-NMR. In total, 11 molecular structures have been characterized
by X-ray diffraction. Open ring conformations with intermolecular
π–π and Au–Au interactions prevail, but
a backfolded conformation with a short intramolecular Au–Au
distance has been found for the ethylene-bridged species. The presence
of Au–Au interactions could be proven by quantum chemical calculations.