A Model of Spin Crossover in Manganese(III) Compounds: Effects of Intra- and Intercenter Interactions

Abstract

A microscopic approach to the problem of cooperative spin crossover in the [MnL2]NO3 crystal, which contains Mn(III) ions as structural units, is elaborated on, and the main mechanisms governing this effect are revealed. The proposed model also takes into account the splitting of the low-spin 3T1 (t(2)(4)) and high-spin 5E (t(2)(3)e) terms by the low-symmetry crystal field. The low-spin → high-spin transition has been considered as a cooperative phenomenon driven by interaction of the electronic shells of the Mn(III) ions with the all-around full-symmetric deformation that is extended over the crystal lattice via the acoustic phonon field. The model well explains the observed thermal dependencies of the magnetic susceptibility and the effective magnetic moment.

Determination of the molecular structure of the short-lived light-induced high-spin state in the spin-crossover compound [Fe(6-mepy)3tren](PF6)Chakraborty1, Tissot2, Peterhans3 et al. 2013Phys. Rev. B12290View full textAdd to dashboardCite

“…The long-range component is proportional to the average number of HS molecules per unit volume and is mediated by the lattice. 18,[36][37][38][39][40][41][42] In the present case, the shift in the thermal spin transition temperature as a function of Fe(II) concentration is relatively small. Simple thermodynamic considerations, detailed elsewhere, 36,37 on the basis of the classical model of Slichter and Drickamer 39 within the mean-field approximation lead to the expression of Eq.…”

Challenges in assignment of orbital populations in a high spin manganese(iii) complex

“…In reality only S=1 and S=2 spin states have been observed in small molecule complexes and a small subset of these show thermal switching between the high spin (HS) S=2 and the so-called low spin (LS) S=1 states. [30][31][32][33][34][35][36][37][38][39][40][41] As both the S = 1 and S = 2 states are Jahn-Teller active it is of interest to examine how the distortion is manifest in the HS form of spin crossover (SCO) complexes + cations, where R-Sal 2 323 is a hexadentate dianionic Schiff base ligand. 28,[30][31][32][33]38 To date an axial compression has been suggested for the HS forms of such complexes which has prompted some computational studies 40, 41 with the starting assumption that the magnetic orbital is d x 2 y 2 .…”

Microscopic Approach to the Problem of Cooperative Spin Crossover in Polynuclear Cluster Compounds: Application to Tetranuclear Iron(II) Square Complexes

“…Among the various macroscopic models used for the interpretation of experimental data there are the thermodynamic approach [24][25][26] , the Wainflasz and Pick model 27 and its extensions called "Ising-like models" [28][29][30][31][32][33][34][35][36][37][38] , atom-phonon coupling model [39][40][41][42] and mechano-elastic model. [43][44][45][46] In molecular crystals the elasticities of intra-and intermolecular spaces are different that has been taken into account in the model suggested in 47,48 and applied for the description of the SCO phenomena in mononuclear 49,50 and polynuclear [51][52][53] molecular crystals. The first microscopic approach to the description of cooperative SCO was proposed by Sasaki and Kambara.…”