Toward Luminescent Iron Complexes: Unravelling the Photophysics by Computing Potential Energy Surfaces

Abstract

Due to its high societal impact, the replacement of precious metals used in technological devices by more abundant and eco-friendly metals, such as iron, has stimulated significant scientific efforts in the last years. In the present review, we focus on different computational strategies and techniques used to characterize the potential energy surfaces (PESs) that govern the photophysical pathways of a wide variety of FeII complexes. The different procedures are discussed in terms of accuracy, computational cost and availability of the implementations, and illustrated with specific examples taken from the literature. The determination of minimum energy paths (MEPs) and the optimization of minimum energy crossing points (MECPs) are particularly emphasized since they can be combined to provide connected and optimized PESs independent from any a priori selected coordinate. The use of such computational techniques is exemplified in detail through a recent study on the influence of the facial and meridional isomerism in the triplet PESs of a pyridylcarbene Fe(II) complex, and its implications in the decay mechanism of each isomer.