Role of Anionic Backbone in NHC-Stabilized Coinage Metal Complexes: New Precursors for Atomic Layer Deposition

Funding Information: The authors at RUB thank the German Research Foundation for funding this project (DFG‐DE‐18‐1 and DFG‐DE‐28‐1); the authors at Aalto University acknowledge funding from the Academy of Finland (Profi 3). All the authors also acknowledge funding from the DAAD‐PPP project (57610451) for supporting this work. The authors wish to acknowledge the use of the RawMatTERS Finland Infrastructure (RAMI) at Aalto University. A.P. gratefully acknowledges the PoDoCo funding. Open Access funding enabled and organized by Projekt DEAL. Publisher Copyright: © 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.Cu and Ag precursors that are volatile, reactive, and thermally stable are currently of high interest for their application in atomic-layer deposition (ALD) of thin metal films. In pursuit of new precursors for coinage metals, namely Cu and Ag, a series of new N-heterocyclic carbene (NHC)-based CuI and AgI complexes were synthesized. Modifications in the substitution pattern of diketonate-based anionic backbones led to five monomeric Cu complexes and four closely related Ag complexes with the general formula [M(tBuNHC)(R)] (M=Cu, Ag; tBuNHC=1,3-di-tert-butyl-imidazolin-2-ylidene; R=diketonate). Thermal analysis indicated that most of the Cu complexes are thermally stable and volatile compared to the more fragile Ag analogs. One of the promising Cu precursors was evaluated for the ALD of nanoparticulate Cu metal deposits by using hydroquinone as the reducing agent at appreciably low deposition temperatures (145–160 °C). This study highlights the considerable impact of the employed ligand sphere on the structural and thermal properties of metal complexes that are relevant for vapor-phase processing of thin films.Peer reviewe