Generating New Coordination Compounds via Multireference Simulations, Genetic Algorithms, and Machine Learning: The Case of Co(II) and Dy(III) Molecular Magnets.

The design of coordination compounds with target properties often requires years of continuous feedback loop between theory, simulations, and experiments. In the case of magnetic molecules, this conventional strategy has indeed led to the breakthrough of single-molecule magnets with working temperatures above liquid nitrogen's boiling point, but at significant costs in terms of resources and time. Here, we propose a computational strategy capable of accelerating the discovery of new coordination compounds with the desired electronic and magnetic properties. Our approach is based on a combination of high-throughput multireference ab initio methods, genetic algorithms, and machine learning. While genetic algorithms allow for an intelligent sampling of the vast chemical space available, machine learning reduces the computational cost by prescreening molecular properties in advance of their accurate and automated multireference ab initio characterization. Importantly, the presented framework is able to generate novel organic ligands and explore chemical motifs beyond those available in pre-existing structural databases. We showcase the power of this approach by automatically generating new Co-(II) and Dy-(III) mononuclear coordination compounds with record magnetic properties in a fraction of the time required by either experiments or brute-force ab initio approaches. In the case of Dy compounds, simulations uncover new nontrivial chemical strategies toward pentagonal bipyramidal complexes with record-breaking values of magnetic anisotropy.