Ligand Effects in Low-Valent Co(I) Clathrochelate Complexes

Clathrochelate complexes of cobalt are known in the oxidation states I, II, and III. Low-valent Co(I) complexes are highly reactive compounds, and there is only limited knowledge about their structures in the solid state. Herein, we describe the crystallographic analyses of three low-valent clathrochelate complexes, along with analyses of the corresponding Co(II) precursors. Two different ligand environments were studied: a) ligands with alkyl substituents, which render the complexes highly reducing, and b) potentially redox non-innocent ligands. Our analyses show that the ligands have a large effect on the redox potentials, but only a small effect on the geometry and the electronic state of the central Co ion.