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Slow Magnetic Relaxation, Antiferromagnetic Ordering, and Metamagnetism in Mn II (H 2 dapsc)‐Fe III (CN) 6 Chain Complex with Highly Anisotropic Fe‐CN‐Mn Spin Coupling
Author(s) -
Zorina Leokadiya V.,
Simonov Sergey V.,
Sasnovskaya Valentina D.,
Talantsev Artem D.,
Morgunov Roman B.,
Mironov Vladimir S.,
Yagubskii Eduard B.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902551
Subject(s) - ferrimagnetism , metamagnetism , crystallography , chemistry , antiferromagnetism , magnetic anisotropy , magnetic susceptibility , anisotropy , ion , crystal structure , ligand (biochemistry) , magnetization , condensed matter physics , physics , magnetic field , biochemistry , receptor , organic chemistry , quantum mechanics
Reactions of [Mn(H 2 dapsc)Cl 2 ] ⋅ H 2 O (dapsc=2,6‐ diacetylpyridine bis(semicarbazone)) with K 3 [Fe(CN) 6 ] and (PPh 4 ) 3 [Fe(CN) 6 ] lead to the formation of the chain polymeric complex {[Mn(H 2 dapsc)][Fe(CN) 6 ][K(H 2 O) 3.5 ]} n ⋅ 1.5 n H 2 O ( 1 ) and the discrete pentanuclear complex {[Mn(H 2 dapsc)] 3 [Fe(CN) 6 ] 2 (H 2 O) 2 } ⋅ 4 CH 3 OH ⋅ 3.4 H 2 O ( 2 ), respectively. In the crystal structure of 1 the high‐spin [Mn II (H 2 dapsc)] 2+ cations and low‐spin hexacyanoferrate(III) anions are assembled into alternating heterometallic cyano‐bridged chains. The K + ions are located between the chains and are coordinated by oxygen atoms of the H 2 dapsc ligand and water molecules. The magnetic structure of 1 is built from ferrimagnetic chains, which are antiferromagnetically coupled. The complex exhibits metamagnetism and frequency‐dependent ac magnetic susceptibility, indicating single‐chain magnetic behavior with a Mydosh‐parameter φ =0.12 and an effective energy barrier ( U eff / k B ) of 36.0 K with τ 0 =2.34×10 −11 s for the spin relaxation. Detailed theoretical analysis showed highly anisotropic intra‐chain spin coupling between [Fe III (CN) 6 ] 3− and [Mn II (H 2 dapsc)] 2+ units resulting from orbital degeneracy and unquenched orbital momentum of [Fe III (CN) 6 ] 3− complexes. The origin of the metamagnetic transition is discussed in terms of strong magnetic anisotropy and weak AF interchain spin coupling.