Photo- and thermo-induced spin crossover in a cyanide-bridged {Mo^V₂Fe^II₂} rhombus molecule

Abstract

The self-assembly of [Mo(V)(CN)8](3-) and [Fe(II)(bik)2(S)2](2+) affords a cyanide-bridged {Mo(V)2Fe(II)2} rhombus molecule that shows photomagnetic effect under laser light irradiation at low temperature and exhibits thermo-induced spin crossover near ambient temperature.

Thermally-Induced Spin Crossover and LIESST Effect in the Neutral [FeII(Mebik)2(NCX)2] Complexes: Variable-Temperature Structural, Magnetic, and Optical Studies (X = S, Se; Mebik = bis(1-methylimidazol-2-yl)ketone)

“…These features match to the trends generally observed in this class of spin-crossover complexes. (Mondal et al, 2014; De et al, 2018) In fact, the larger metal-ligand bond lengths in the high-spin Fe II complexes result in a weaker overlap between metal-centered and ligand-centered orbitals as compared to the low-spin state. Therefore, the intensity of the MLCT band strongly decreases upon converting the LS into HS species.…”

“…When the N- donors are the metallo-ligands, [Mo(CN) 8 ] 3− or [Fe(Tp)(CN) 3 ] − (in the cyanide-bridged rhombus molecules of formula {[Mo(CN) 8 ] 2 [Fe( Me bik) 2 ] 2 }( H MeIm) 2 ·5H 2 O·CH 3 CN, where Me ImH + = N-methyl-imidazolium cation, and {[Fe III (Tp)(CN) 3 ] 2 [Fe II ( Me bik) 2 ] 2 }. [Fe III (Tp)(CN) 3 ] 2 ·18H 2 O·4CH 3 OH), the most efficient effect are observed at 405 and 808 nm, respectively (Mondal et al, 2013, 2014) These differences should be related to the different electronic structures of the compounds and the nature of the accessible excited-states involved in the LIESST effect. The occurrence of reverse LIESST effect in some of these compounds was also proposed to account for a partial decrease of the photomagnetic response (Moussa et al, 2007).…”

“…Taking advantage of such feature, we synthesized and studied [Fe( R bik) 2 (NC-) 2 ] SCO systems, where one of the R bik ligand is replaced by two cyanido metallo-ligand, abbreviated (NC-). For example, we investigated two tetranuclear rhombus {Fe 2 M 2 } (M = Fe, Mo) switchable complexes containing the {Fe II ( R bik) 2 (NC-) 2 } subunit (NC- represents cyanido metallo ligand: [Fe III (Tp)(CN) 3 ] − or [Mo V (CN) 8 ] 3− ) (Mondal et al, 2012, 2014). Both complexes show gradual thermally-induced spin transition on the Fe(II) centers and photomagnetic effect (LIESST) at low temperature.…”

Switching Magnetic Properties by a Mechanical Motion

“…In this case, an increase of the magnetization is observed upon irradiation at low temperature, indicating the population of the metastable HS state. However, by increasing the temperature, a drop in the magnetization is observed at temperatures where the thermal energy is enough to allow for a relaxation to the stable LS state [24]. Apart from temperature and light, chemical [25], electrical [26], or pressure [27] stimuli have also been used to induce a spin crossover.…”

Tuning the Spin States of Two Apical Iron(II) Ions in a Pentanuclear Iron(II) Cluster Helicate through the Choice of Anions

“…In addition, in a multi-nuclear compound system, we can probably capture a phenomenon combining SCO behavior and magnetic exchange; the latter may be good for enhancing the signals [16] of spin and obtaining spin transition materials with more prominent performance, helping us to understand spintronics. However, restricted by compounding means, there are few reports in this field [17][18][19][20][21].…”