A new polymorph of a cobalt(III) Schiff base complex exhibits a one‐dimensional C—H⋯O hydrogen‐bonded extended structure with helical 21 symmetry

In a new polymorph of acetato(2,2′‐{imino­bis(E)‐propane‐3,1‐diylnitrilo­methyl­idyne]}diphenol­ato)­cobalt(III), Co(C₂₀H₂₃N₃O₂)(C₂H₃O₂)], in the space group P2₁/c, the Co^III ion is six‐coordinate, with unequal Co—O_phenolate distances that average 1.908 (12) Å and more similar Co—N_imine distances averaging 1.937 (4) Å. The acetate ion occupies the sixth coordination site and forms an intra­molecular hydrogen bond (H⋯O = 1.95 Å) with the Co‐bound NH group of the penta­dentate chelate. The extended structure is a one‐dimensional (aryl)C—H⋯O(carbonyl) hydrogen‐bonded polymer with 2₁ (helical) symmetry and is thus distinct from the simple hydrogen‐bonded stack of the P2₁/n polymorph Matsumoto, Imaizumi & Ohyoshi (1983). Polyhedron, 2 , 137–139].