Τίτλος:
Magnetic Properties and Electronic Structure of the S = 2 Complex [MnIII(OPPh2)2N3] Showing Field-Induced Slow Magnetization Relaxation
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
The high-spin S = 2 Mn(III) complex [Mn(OPPh2)2N3] (1Mn) exhibits field-induced slow relaxation of magnetization (Inorg. Chem. 2013, 52, 12869). Magnetic susceptibility and dual-mode X-band electron paramagnetic resonance (EPR) studies revealed a negative value of the zero-field-splitting (zfs) parameter D. In order to explore the magnetic and electronic properties of 1Mn in detail, a combination of experimental and computational studies is presented herein. Alternating-current magnetometry on magnetically diluted samples (1Mn/1Ga) of 1Mn in the diamagnetic gallium analogue, [Ga(OPPh2)2N3], indicates that the slow relaxation behavior of 1Mn is due to the intrinsic properties of the individual molecules of 1Mn. Investigation of the single-crystal magnetization of both 1Mn and 1Mn/1Ga by a micro-SQUID device reveals hysteresis loops below 1 K. Closed hysteresis loops at a zero direct-current magnetic field are observed and attributed to fast quantum tunneling of magnetization. High-frequency and-field EPR (HFEPR) spectroscopic studies reveal that, apart from the second-order zfs terms (D and E), fourth-order terms (B4m) are required in order to appropriately describe the magnetic properties of 1Mn. These studies provide accurate spin-Hamiltonian (sH) parameters of 1Mn, i.e., zfs parameters |D| = 3.917(5) cm-1, |E| = 0.018(4) cm-1, B04 = B42 = 0, and B44 = (3.6 ± 1.7) × 10-3 cm-1 and g = [1.994(5), 1.996(4), 1.985(4)], and confirm the negative sign of D. Parallel-mode X-band EPR studies on 1Mn/1Ga and CH2Cl2 solutions of 1Mn probe the electronic-nuclear hyperfine interactions in the solid state and solution. The electronic structure of 1Mn is investigated by quantum-chemical calculations by employing recently developed computational protocols that are grounded on ab initio wave function theory. From computational analysis, the contributions of spin-spin and spin-orbit coupling to the magnitude of D are obtained. The calculations provide also computed values of the fourth-order zfs terms B4m, as well as those of the g and hyperfine interaction tensor components. In all cases, a very good agreement between the computed and experimentally determined sH parameters is observed. The magnetization relaxation properties of 1Mn are rationalized on the basis of the composition of the ground-state wave functions in the absence or presence of an external magnetic field. © 2020 American Chemical Society.
Συγγραφείς:
Sanakis, Y.
Krzystek, J.
Maganas, D.
Grigoropoulos, A.
Ferentinos, E.
Kostakis, M.G.
Petroulea, V.
Pissas, M.
Thirunavukkuarasu, K.
Wernsdorfer, W.
Neese, F.
Kyritsis, P.
Περιοδικό:
ISRN Inorganic Chemistry
Εκδότης:
American Chemical Society
Λέξεις-κλειδιά:
Calculations; Chlorine compounds; Computation theory; Electron spin resonance spectroscopy; Electronic properties; Electronic structure; Gallium compounds; Ground state; Hysteresis; Hysteresis loops; Magnetic fields; Magnetic materials; Magnetic susceptibility; Magnetization; Paramagnetic resonance; Quantum chemistry; Relaxation processes; Single crystals; Spectroscopic analysis; Spin orbit coupling; SQUIDs; Wave functions, Electron paramagnetic resonances (EPR); External magnetic field; Ground state wavefunctions; Magnetic and electronic properties; Magnetization relaxation; Quantum chemical calculations; Quantum tunneling of magnetization; Spin Hamiltonian parameters, Manganese compounds
DOI:
10.1021/acs.inorgchem.0c01636
