Weak Ferromagnetic Ordering of the Li⁺[TCNE]^•– (TCNE = Tetracyanoethylene) Organic Magnet with an Interpenetrating Diamondoid Structure

Abstract

Li[TCNE] (TCNE = tetracyanoethylene) magnetically orders as a weak ferromagnet (canted antiferromagnet) below 21.0 ± 0.1 K, as observed from the bifurcation of the field-cooled and zero-field-cooled magnetizations, as well as remnant magnetization. The structure, determined ab initio from synchrotron X-ray powder diffraction data, consists of a planar μ4-[TCNE](•-) bound to four tetrahedral Li(+) ions. The structure consists of two interpenetrating diamondoid sublattices, with closest interlattice distances of 3.43 and 3.48 Å. At 5 K this magnetic state is characterized by a coercivity of ~30 Oe, a remnant magnetization of 10 emu·Oe/mol, and a canting angle of 0.5°.