Straightforward Preparation Method for Complexes Bearing a Bidentate N-Heterocyclic Carbene To Introduce Undergraduate Students to Research Methodology

Abstract

A laboratory experiment for students in advanced inorganic chemistry is described. In this experiment, students prepare two metal complexes with a potentially bidentate-carbene ligand. The complexes are synthesized by reaction of a bis-imidazolium salt with silver(I) oxide or palladium(II) acetate. Silver and palladium complexes are binuclear and mononuclear species, respectively, in which the carbene ligand behaves in a different coordination mode. The reaction conditions are straightforward and the complexes air-stable species, even though the palladium compound must be prepared using air-free techniques. Students must also assign the signals in the 1H and 13C-{1H} NMR spectra. The complexes showed a fluxional behavior in solution as can be deduced from their 1H NMR spectra. The students are given the 3D structures of the complexes as an aid to understand this dynamic behavior. The students should also use the FAB–mass spectrum of the silver complex and the concept of isotopic pattern in order to discri...