Ferrimagnetic ordering of one-dimensional N,N′-dicyanoquinone diimine (DCNQI) electron transfer salts with porphyrinatomanganese(II)

Abstract

The redox reaction between N,N′-dicyanoquinone diimines (DCNQIs) and porphyrinatomanganese(II) produced electron transfer salts (ETSs), [MnIIITMesP]+[DMeO-DCNQI]−˙ 1 (MnIIITMesP = meso-tetrakis(2,4,6-trimethylphenyl)porphyrinatomanganese(III), DMeO-DCNQI = 2,5-dimethoxy-N,N′-dicyanoquinone diimine) and [MnTIIIMesP]+[DMe-DCNQI]−˙ 2 (DMe-DCNQI = 2,5-dimethyl-N,N′-dicyanoquinone diimine), having uniform chain structures that have been structurally and magnetically characterised. The salts have infinite one-dimensional linear chains comprised of S = 2 [MnIIITMesP]+ and bridging S = ½ [DCNQIs]−˙ with Mn–NDCNQIs distances of 2.249(2) and 2.261(4) Å for 1 and 2, respectively. The temperature dependence of the magnetic susceptibility from 2 to 300 K can be fitted to a Curie–Weiss expression with an effective θ value of +41 and +23 K for 1 and 2, respectively. Intrachain coupling was modelled to a Seiden expression (H = −2JijSi·Sj) with a Jintra of −90 (1) and −50 K (2), and the 10 Hz ac magnetic susceptibility indicates an ordering temperature, Tc, of 6.2 and 6.0 K for 1 and 2, respectively. The frequency dependencies of the ac susceptibility indicate spin glass behaviour.