Spin-state switching: chemical modulation and the impact of intermolecular interactions in manganese(iii) complexes

Abstract

A series of mononuclear manganese(III) complexes [Mn(X-sal2-323)](ReO4) (X = 5 Cl, 1; X = 5 Br, 2; X = 3,5 Cl, 3; X = 3,5 Br, 4; and X =...

Realm of Spin State Switching Materials: Toward Realization of Molecular and Nanoscale Devices

“…As young research enthusiasts in this vast field, our group is exploring the fundamental and application realm of SCO materials. Ranging from monomeric manganese­(III)-based SCO systems − to multifunctional SCO-active iron­(II)-based luminescent polymers , and mononuclear, dinuclear, and 1D coordination polymers of cobalt­(II), − we are exploring the stimuli-responsive SCO systems. We are further taking a leap into addressing the lesser-known or unexplored areas in this vast field.…”

“…Additionally, we have reported for the first time the incorporation of a redox-active motif (EDOT) into the terpyridine system to investigate the SCO characteristics in the cobalt­(II) center (Figure a) . Similarly, several Mn­(III) complexes incorporating an azobenzene motif in the hexadentate Schiff base ligand and different counteranions to study the spin-state switching of the complexes (Figure b–d) − are a few milestones achieved in the SCO field.…”

Stimuli-responsive magnetic materials: impact of spin and electronic modulation

“…Accordingly, we ended up with a series of five mononuclear manganese( iii ) complexes [Mn(X-sal 2 -323)](ReO 4 ) (X = 5-Cl, ( 27 ); X = 5-Br, ( 28 ); X = 3,5-Cl, ( 29 ); X = 3,5-Br, ( 30 ); and X = 5-NO 2 , ( 31 )). 201 All the complexes have a crystal structure comprising the [Mn(X-sal 2 -323)] + cation and the ReO 4 − anion. To obtain better insight into the effect of cooperativity on the spin crossover properties, careful analysis of the intermolecular interactions between the cationic and anionic unit depicted strong interactions coming from the N–H⋯Z and C–X⋯Z moiety among the cationic unit [Mn(X-sal 2 -323)] + and the counter anion ( Z ).…”

“…32 was the first ever cyanide-bridged mixed valence [Fe 2 Fe 2 ] square with thermo- and photoinduced SCO, where iron( ii ) centres with an N 6 environment showed spin-state switching between the Fe II LS (S = 0) and Fe II HS (S = 2) state. 201 Although most of the [Fe 2 Co 2 ] squares, using a similar synthesis strategy, undergo MMET between iron and cobalt centres, whereas [Fe 2 Fe 2 ] square moieties in a similar environment prefer to exhibit spin-state switching. 201–212 Even before this ground-breaking work by Lescouëzec et al , Oshio et al and Real et al reported iron( ii ) based cyanide bridged molecular squares showing SCO behaviour using diamagnetic iron( ii ) building blocks.…”

“…201 Although most of the [Fe 2 Co 2 ] squares, using a similar synthesis strategy, undergo MMET between iron and cobalt centres, whereas [Fe 2 Fe 2 ] square moieties in a similar environment prefer to exhibit spin-state switching. 201–212 Even before this ground-breaking work by Lescouëzec et al , Oshio et al and Real et al reported iron( ii ) based cyanide bridged molecular squares showing SCO behaviour using diamagnetic iron( ii ) building blocks. 85,205 Later, by changing the counter anions from [Fe(Tp)(CN) 3 ] − in 32 to ClO 4 − and BF 4 − , Lescouëzec et al reported three different [Fe 2 Fe 2 ] square complexes with the general formula ({[Fe III (Tp)(CN) 3 ] 2 [Fe II (bik) 2 ] 2 }(ClO 4 ) 2 ·2CH 3 CN, 33 ) and ({[Fe III (Tp)(CN) 3 ] 2 [Fe II (bik) 2 ] 2 }(BF 4 ) 2 ·2CH 3 OH, 34 ), and the T 1/2 value shifted from 330 K to above 400 K for 33 and 34 respectively.…”