COBALT DIMER: A DIFFICULT CASE FOR THE DFT, BUT A PRELIMINARY STEP TOWARDS THE STUDY OF REACTIONS CATALYZED BY COBALT CLUSTERS.
Abstract
As part of research for the hydrogen economy, cobalt-based catalysts have a remarkable catalytic activity. Understanding the mechanisms underlying hydrogenation / dehydrogenation processes is a major challenge for a successful ecological transition.
As highlighted in the literature, a bottom-up approach, from the simplest models to real systems, is fundamental for unveiling reaction mechanisms, and then proposing in silico catalysts adjusted for optimal action. It is known that the origin of the versatile catalytic action of transition metal complexes comes from the existence of many energetically close or even quasi-degenerated electronic states, and different accessible spin states, which allows changes in the spin state during a reaction process. This is what makes the theoretical description of these systems so complex.
Cobalt remains one of the last 3d transition elements for which the experimental electronic spectrum of the dimer has not been assigned.4 In addition, the vibration frequencies calculated in the literature for cobalt dimer depend strongly on the method used, in particular for DFT calculations. In addition, a deviation of about 50 cm-1 from the experimental data is common.
Given the energy and environmental challenges, it seems essential to us to determine whether a methodology based on the DFT could correctly describe cobalt dimer. This is the work we want to present here.
Domains
Chemical Sciences
Origin : Files produced by the author(s)