Toward molecular rotors: tetra-N-heterocyclic carbene Ag(i)-halide cubane-type clusters

Abstract

1,3-Bis(3′-butylimidazol-1′-yl)benzene diiodide (2a), 1,3-bis(3′-but-3′′-enyl-imidazolium-3′-yl)benzene diiodide (2b), 1,3-bis(3′-pent-4′′-enyl-imidazolium-3′-yl)benzene diiodide (2c), 1,3-bis(4′-butyl-1′,2′,4′-triazolium-1′-yl)benzene diiodide (2d), or 1,3-bis(4′-butyl-1′,2′,4′-triazolium-1′-yl)benzene dibromide (2e) was reacted with Ag₂O yielding unprecedented tetra-N-heterocyclic carbene-Ag(I)-X cubane-type clusters. These were characterized by ¹H and ¹³C NMR spectroscopy, ESI-TOF MS, elemental analysis, and X-ray crystallography. Results from VT ¹³C NMR spectroscopy and cross-over experiments are consistent with intramolecular exchange suggesting that the Ag(I) complexes are molecular rotors.