Vanadium[ethyl tricyanoethylene carboxylate]x: a new organic-based magnet

Abstract

We present the synthesis of a new high Curie temperature (T_c ∼ 145 K) organic-based magnet with composition V[ETCEC]_1.3·0.3 CH₂Cl₂ formed by the reaction of ethyl tricyanoethylenecarboxylate (ETCEC) with V(CO)₆ in CH₂Cl₂. Analysis of the IR spectrum indicates that all nitrile and carbonyl oxygen are coordinated to V(II) sites. Temperature-, field-, and frequency-dependent measurements of the magnetization reveal complex magnetic behavior with a magnetic transition into a more disordered state. Application of the random anisotropy model (RMA) shows that this disordered state is different from the correlated spin glass (CSG) phase observed in analogous organic-based magnets V[MeTCEC]_x and V[TCNE]_x synthesized in CH₂Cl₂. This suggests that V[ETCEC]_x is less disordered than its analogues, which can be attributed to the slower reaction rate. This result provides a new partner to MeTCEC and TCNE based materials for the exploration of all-organic magnetic heterostructures.