One Ligand Fits All: Formation and Stabilization of a Single‐Ligand Arenethiolato Cobalt(II) Complex via Metal‐π Coordination from a Bulky Acylamino Group

Abstract

AbstractMetalloproteins activate inert molecules under mild conditions by exploiting the low‐coordinated metal centers formed in protein pockets. The creation of biomimetic metal centers using bulky ligands is an attractive strategy in bioinorganic chemistry. Herein, we report a highly bulky arenethiolato ligand containing acylamino groups that forms a neutral single‐ligand Co(II) complex. X‐ray analysis revealed that the amide NH group of the ligand was deprotonated to form an S,N‐chelate, and the cobalt center was stabilized by strong π coordination. The cobalt center exhibited a quasi‐square‐planar geometry inducing a low‐spin configuration in the solid state and in toluene, which was revealed by SQUID and ESR measurements. By contrast, Co(II)‐π coordination could be reversibly replaced by THF molecule, resulting in a high‐spin state. The novel structure was induced by the local coordination space, wherein the binding atoms were appropriately positioned, as in the hydrophobic pockets of proteins.