The first-row transition-metal series of tris(ethylenediamine) diacetate complexes [M(en)](OAc) (M is Mn, Fe, Co, Ni, Cu, and Zn).

The crystal structures of the first-row transition-metal series of tris(ethylenediamine-κN,N')metal(II) diacetate, M(CHN), with M = Mn, Fe, Co, Ni, Cu, and Zn, are reported. The complexes are all isostructural, crystallizing in a centrosymmetric triclinic cell and possessing an asymmetric unit composed of one [M(en)] cation and two symmetrically independent acetate anions. In the unit cell, the two complex cations are inversion-generated enantiomers, possessing the energetically favoured Δ(λλλ) and Λ(δδδ) configurations. The complex cations and acetate anions combine through a series of N-H...O hydrogen bonds to generate a three-dimensional network in the crystals. The other notable feature of the series is a significant Jahn-Teller distortion for the d Cu complex.