Benzothiazolin-2-ylidene gold(I) complexes as precursors for gold nanoparticles

• First examples of benzothiazolin-2-ylidene gold(I) complexes are reported. • The complexes are structurally and spectroscopically characterized. • The behavior of the complexes towards chemical reduction is explored. • Au NPs stable in solution and in the solid state are obtained. The preparation of gold(I) complexes with benzothiazolin-2-ylidene ligands is described herein. These previously unreported complexes can be conveniently prepared from the corresponding benzothiazolium precursors using the so-called weak base route and have been spectroscopically and structurally characterized. Combined structural and computational analysis confirms enhanced π-accepting character of benzothiazolin-2-ylidine ligands in comparison with conventional (benz)imidazolin-based NHCs. The obtained complexes are reasonably stable and have been used as precursors for ligand-stabilized gold nanoparticles by controlled reduction with potassium hydride. The reaction produces 3 nm sized gold nanoparticles that are stable in solution as well as in the solid state and can be characterized both spectroscopically (NMR, UV–Vis) and by transmission electron microscopy (TEM).