1,3-Diazabutadiene (DAB) systems are well known compounds in literature. There are known to be highly π-accepting ligands due to their diimine system. Additionally, several coordination modes have been reported for this highly flexible ligand. DAB complexes have already found applications in catalysis and have been reported as catalysts for C-H bond activations, ethylene polymerization, Mizoroki-Heck couplings, and hydrogenation of alkynes to alkenes. However, reports on the use of DAB ligands for the formation of copper(I) complexes are scarce and their potential as catalysts has merely started to be explored. Copper is an earth abundant, inexpensive and low-toxicity alternative to well-established transition metals used in catalysis. Therefore, it is of great interest to explore novel copper(I) complexes, their rich coordination chemistry and to examine their reactivity in catalysis. Copper(I) complexes are already established catalysts in reactions such as Ullman type biaryl coupling, 1,3-dipolar cycloaddition or the enantioselective hydrogenation of carbonyls. We have recently prepared and characterized three related families of copper(I) complexes bearing diazabutadiene ligands (DAB): homoleptic [Cu(DABR)2]BF4, heteroleptic [Cu(DABR)(NCMe)2]BF4 and neutral [CuCl(DABR)] complexes. The complexes are readily prepared and air stable. In this contribution, we will also present the application of our complexes in the reduction of aryl azides without an obvious reducing agent where the reaction mechanism has been studied using DFT. Additionally, we will show the potential of these complexes in the industrially important hydroamination reaction, and in particular, in the addition of primary amines onto alkynes and allenes.

Preparation and characterization of copper(I) diazabutadiene complexes and catalytic applications

253rd National Meeting (2017)

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