The crystal structure of meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III) 7,7,8,8-tetracyano-2,5-dimethyl-p-quinodimethanide, [MnTMesP][DMTCNQ]·2p-C6H4Me2 provides the first example of a cis-1,2-μ-coordination motif having an infinite zigzag chain structure. [MnTMesP][DMTCNQ]·2p-C6H4Me2 crystallizes in a triclinic space group. The zigzag one-dimensional (1-D) chain is non-uniform and each acceptor does not lie on a centre of symmetry, although all acceptors are crystallographically equivalent. The ionic ground state of the complex was determined on the basis of X-ray photoelectron spectroscopy, crystallographic data, as well as the νCN at 2184 and 2160 cm−1. The susceptibility (χ) of the complex obeys the Curie–Weiss equation, χ = 1/(T
−
θ), where θ is −10 ± 1 K (130 < T < 250 K), and +23 ± 1 K (T > 250 K). A minimum of χT(T) characteristic of 1-D antiferromagnetic coupling is observed at 115 K. Above 50 K, χT(T) can be fitted by the Seiden model for non-interacting chains comprised of alternating g = 2, quantum S = 2 and classical S = 1/2 spins, with J/kB = −39 K for H = −2JSi·Sj. The in-phase component, χ′(T), in a.c. susceptibility measurements shows a sharp maximum at 2.3 K associated with the ordering temperature, Tc, of the material.