Cu(II) Reduction without Reductants: Insights from Theory

A topic issue in sustainable technologies is the production of Cu_xO (x=1,2) nanomaterials with tailored composition and properties. They can be fabricated through bottom-up processes that involve unexpected changes in the metal oxidation state and open intriguing challenges on the copper redox chemistry. How Cu^(II) complexes can lead to Cu^(I) species in spite of the absence of any explicit reducing agent is a question only recently answered by investigating the fragmentation of a Cu^(II) precursor for Cu oxide nanostructures by computer simulations and ESI-MS with multiple collisional experiments (ESI/MSn). Here we show that a Cu-promoted CH bond activation leads to reduction of the metal center and formation of a Cu^I-C-NCCN six-membered ring. Such 6-ring moiety is the structural motif for a new family of cyclic Cu^(I) adducts, characterized by a bonding scheme that may shed unprecedented light on high-temperature Cu chemistry. In particular, in this contribution we describe how collisions with hot atoms may activate Cu^(II) species to a configuration prone to the reduction. Besides its relevance for the fabrication of Cu-oxide nanostructures, the hydrogen-abstraction/proton-delivery/electron-gain mechanism of Cu^(II) reduction described herein could be a general property of copper and might help to understand its redox reactivity.

Poster presented at the 39th International Conference and Expo on Advanced Ceramics and Composites - Daytona Beach (FL) 25-31 Jan 2015