Stress‐Induced Domain Wall Motion in a Ferroelastic Mn³⁺ Spin Crossover Complex

Abstract

Domain wall motion is detected for the first time during the transition to af erroelastic and spin state ordered phase of as pin crossover complex. Single-crystal X-ray diffraction and resonant ultrasound spectroscopy(RUS) revealed two distinct symmetry-breaking phase transitions in the mononuclear Mn 3+ compound [Mn(3,5-diBr-sal 2-(323))]BPh 4 ,1 .T he first at 250 K, involves the space group change Cc!Pc and is thermodynamically continuous,w hile the second, Pc!P1 at 85 K, is discontinuous and related to spin crossover and spin state ordering. Stress-induced domain wall mobility was interpreted on the basis of asteep increase in acoustic loss immediately belowt he the Pc-P1 transition

Abrupt Spin‐State Switching in Mn(III) Complexes with BPh4 Anion: Effect of Halide Substituents on Crystal Structure and Magnetic Properties.

“…À units, where N⋯C distances lie in the range of 3.31(3.36)-3.44(3.49) Å for 100 (250) K. As well known, that the cation-anion non-covalent intermolecular interactions, particularly NÀ H⋯X interactions between the Mn(III) cationic complex and counter anions, can play a significant role in determining the spin-state switching behavior. [4,16] Unlike previously reported isostructural complexes [Mn(5-Cl/Br-sal-N-1,5,8,12)]BPh 4 , [18,20] the formation of various new CÀ H⋯Hal interactions in crystal structure 1 at decreasing the temperature to 100 K does not observed due to the smaller size and vdW radii of F atom. On the other hand, molecular and crystal structure of complex 1 are different from another 5-Fsubstituted complex [Mn(5-F-salk-N-1,5,8,12] + with identical BPh 4…”

“…In contrast to our syntheses, sodium tetraphenylborate and manganese(II) chloride or nitrate tetrahydrates were used in the procedures described in works. [18][19][20] Crystals of complex 1 were obtained by slow evaporation of the mother liquor, while crystals of 2 and 3 were formed within week at standing solutions. It is noteworthy that the complexes 1-3 do not contain co-crystallized solvent molecules, which, firstly, increases their stability, since solvate solvents are often lost during storage of the SCO complexes, and secondly, it allows one to study the effects of ligand substitution on the magneto-structural relationships in SCO complexes without any additional influence associated with the co-crystallized solvent.…”

“…The compound 1 crystallizes at 100 and 250 K in the same monoclinic space group P2 1 /n (see Experimental Section). 1 is isostructural to the [Mn(5-Cl-sal-N-1,5,8,12)]BPh 4 [18] and [Mn(5-Br-sal-N-1,5,8,12)]BPh 4 [20] complexes. The crystal structure of 1 consists of a mononuclear cationic [Mn(5-F-sal-N-1,5,8,12)] + complex and a BPh 4 À counter anion (Figure S2).…”

“…For complex 1, upon decreasing the temperature from 250 to 100 K, the values of the octahedral distortion parameters decrease significantly, and the distortion parameters at 250 and 100 K correspond to the HS and close to LS manganese(III) complexes, respectively. [4] As in the case of isostructural complexes [Mn(5-Cl-sal-N-1,5,8,12)]BPh 4 [18] (4) and [Mn(5-Br-sal-N-1,5,8,12)]BPh 4 [20] (5), in complex 1 (Figure 2) the main intermolecular interactions are cation-anion non-covalent NÀ H⋯π Ph ⋯ HÀ N interactions between [Mn(5-F-sal-N-1,5,8,12)] + and BPh 4…”

“…[16] More recently, advanced results in the SCO research of Mn(III) complexes have been achieved by two groups at once. [18][19][20] The tetraphenylborates of cation Mn(III) complexes with 5-Cl-, 5-Br-and 3,5-diBr-derivatives of sal-N-1,5,8,12 ligand were synthesized and showed an abrupt spin transitions. Moreover, the study of the magnetic properties, crystal structure and spectra of resonant ultrasound spectroscopy of the SCO complex [Mn(3,5-diBr-sal-N-1,5,8,12)]BPh 4 in a wide temperature range showed the coexistence of ferroelastic and spin state ordered phase.…”