The First Macrocyclic Square-Planar Cobalt(III) Complex Relieves Ring Strain by Forming a Nonplanar Amide

Even if metal center and ligand are not perfectly matched, a complex can be formed—though not without “sacrifices”. In crystalline [Co(η4‐1)]⊖ cobalt(III) is square‐planar coordinated; the ligand must rotate a CO group out of the CoN4 plane in order to reduce the ring strain. [Me4N] [Co(η4‐1)] forms bright red crystals.