Slow Magnetic Relaxation, Antiferromagnetic Ordering, and Metamagnetism in MnII(H2dapsc)‐FeIII(CN)6 Chain Complex with Highly Anisotropic Fe‐CN‐Mn Spin Coupling. Issue 64 (22nd October 2019)

• Record Type: Journal Article
• Authors: Zorina, Leokadiya V.; Simonov, Sergey V.; Sasnovskaya, Valentina D.; Talantsev, Artem D.; Morgunov, Roman B.; Mironov, Vladimir S.; Yagubskii, Eduard B.
• Is Part Of: Chemistry. Volume 25:Issue 64(2019)
• Page Start: 14583
• Page End: 14597
• Publication Date: 2019-10-22
• Subjects: coordination chemistry -- iron -- magnetic anisotropy -- manganese -- single-chain magnets -- slow magnetic relaxation; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201902551
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Reactions of [Mn(H2 dapsc)Cl2 ]⋅ H2 O (dapsc=2, 6‐ diacetylpyridine bis(semicarbazone)) with K3 [Fe(CN)6 ] and (PPh4 )3 [Fe(CN)6 ] lead to the formation of the chain polymeric complex {[Mn(H2 dapsc)][Fe(CN)6 ][K(H2 O)3.5 ]} n ⋅ 1.5 n H2 O (1 ) and the discrete pentanuclear complex {[Mn(H2 dapsc)]3 [Fe(CN)6 ]2 (H2 O)2 }⋅ 4 CH3 OH⋅ 3.4 H2 O (2 ), respectively. In the crystal structure of 1 the high‐spin [Mn II (H2 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 H2 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 (H2 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. Abstract : Chain gang : Two new cyano‐bridged complexes {[Mn(H2 dapsc)][Fe(CN)6 ][K(H2 O)3.5 ]} n ⋅ 1.5 n H2 O (1 ) and {[Mn(H2 dapsc)]3 [Fe(CN)6 ]2 (H2 O)2 }⋅ 4 CH3 OH⋅ 3.4 H2 O (2 ) (where dapsc=2, 6‐diacetylpyridine bis(semicarbazone)) are synthesized and characterized. Chain compound 1 reveals antiferromagnetic ground state, metamagnetism and single‐chain magnet behavior, which originates from highly anisotropic Fe III ‐CN‐Mn II intrachain spin coupling.