Ferrimagnetic ordering of a methylthio-substituted planar porphyrin based electron transfer salt, octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(iii) tetracyanoethanide

Abstract

The direct redox reaction between tetracyanoethylene (TCNE) and a planar porphyrinatomanganese(II), octakis(2,3,7,8,12,13,17,18-methylthio)porphyrinatomanganese(II), MnIIOMTP, produced a polymeric electron transfer salt (ETS), that has been structurally and magnetically characterized. The ETS belongs to the orthorhombic Cmca space group. The ETS has an extended one-dimensional linear chain coordination polymer motif comprised of S = 2 [MnIIIOMTP]+ and bridging S = 1/2 [TCNE]−˙ with an Mn–NTCNE distance of 2.330(5) A, and lacks solvent. The [TCNE]−˙ is disordered over two orientations in a 1 ∶ 1 ratio. The interchain Mn⋯Mn distance, 9.205 A, is shorter than the intrachain distance, 9.350 A (≡a-axis). The 2 to 300 K temperature dependence of the magnetic susceptibility can be fit to a Curie–Weiss expression with an effective θ value of +40 K. Intrachain coupling was modelled to a Seiden expression (H = −2Sa·Sb) with a Jintra of −125 K, and 10 Hz ac magnetic susceptibility indicates an ordering temperature, Tc, of 9.6 K. The frequency dependence of the ac susceptibility displays spin glass behaviour.