Volatile and thermally stable silver pyrazolate complexes containing N-heterocyclic carbene ligands

Abstract

Treatment of [Ag((CF3)2pz)]3 or [Ag(tBu,C3F7)pz)]3 (pz = pyrazolate) with various stable N-heterocyclic carbenes (NHC) afforded silver(I) complexes containing pyrazolate and NHC ligands in 10–81% crystalline yields. These complexes were analyzed by spectral and analytical techniques and by X-ray crystal structure determinations. The solid state structures showed monomeric, dimeric, or tetrameric formulations, depending upon the pyrazolate and NHC substituents. To evaluate their potential as thin film growth precursors, [Ag((CF3)2pz)]3, [Ag(tBu,C3F7)pz)]3, and the new complexes were evaluated by thermogravimetric analyses, sublimation studies, thermal decomposition temperatures, and solution reduction experiments with potential reducing agents. The decomposition temperatures were higher for complexes containing (CF3)2pz ligands (203 to 293 °C) than for those containing (tBu,C3F7)pz ligands (160 to 200 °C). The complexes sublimed between 110 and 140 °C at 0.2 Torr. Solution reactions of several complexes with aqueous hydrazine, 1,1-dimethylhydrazine, formic acid, and tBuNH2 led to the formation of silver metal. Several of the new complexes have promising precursor properties for use in thin film growth by the atomic layer deposition and chemical vapor deposition techniques.