Vanadium [dicyanoperfluorostilbene]2·yTHF: a molecule-based magnet with Tc ca. 205 K

Abstract

A new radical anionic bridging ligand, derived from the in situ reduction of a,aA-dicyanoperfluorostilbene, is reported to support ferrimagnetic ordering below 205 K in a threedimensional vanadium-based coordination polymer.

A Methyl Tricyanoethylenecarboxylate‐Based Room‐Temperature Magnet

“…MeTCEC underwent a reversible one-electron reduction at -0.05 V (vs. saturated calomel electrode (SCE) in MeCN), [12] that is ca. 0.3 V harder to reduce than TCNE, but easier to reduce than tetracyanopyrazine (-0.31 V), [13] and a reaction with V(CO) 6 (Fig. 1).…”

“…[TCNB] 2 ·0.05(CH 2 Cl 2 ); [9] however, reaction with V(CO) 6 (CO) 6 ] 1/2 ·zS (4>x > 3.5; S = CH 2 Cl 2 , PhCF 3 ) composition that orders above room temperature at 50°C (323 K). [9] A mild electronic acceptor methyl tricyanoethylenecarboxylate (MeTCEC; Scheme 1) has recently been used to synthesize isostructural decamethylmetallocene electron-transfer salt magnets of [MCp* 2 ][MeTCEC] (M = Cr, Mn, Fe) composition from which only Mn salt orders ferromagnetically below 7 K. [10] This is a little attenuated with respect to that observed for [MCp* 2 ][TCNE] (T c = 8.8 K).…”

“…These include a,a′-dicyanoperfluorostilbene, (T c = 205 K), [6] tetracyanopyrazine (T c = 200 K), [7] and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ; T c = 52 K). (CO) 6 ] 1/2 ·zS (4>x > 3.5; S = CH 2 Cl 2 , PhCF 3 ) composition that orders above room temperature at 50°C (323 K).…”

“…Herein, we report a new organicbased magnet prepared from the reaction of V(CO) 6 and MeTCEC with T c close to room temperature. MeTCEC underwent a reversible one-electron reduction at -0.05 V (vs. saturated calomel electrode (SCE) in MeCN), [12] that is ca.…”

“…[4] Magnetotransport studies reveal that the electrons in valence and conducting bands of V [TCNE] x films are spin polarized, suggesting potential spin-dependent transport applications. [5] With the goal of finding new organic-based magnets the reaction of V(CO) 6 with numerous polynitrile electron acceptors led to the discovery of several new V-based magnets with T c below room temperature. These include a,a′-dicyanoperfluorostilbene, (T c = 205 K), [6] tetracyanopyrazine (T c = 200 K), [7] and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ; T c = 52 K).…”