Article Ten-Coordinate Lanthanide [Ln(HL)(L)] Complexes (Ln = Dy, Ho, Er, Tb) with Pentadentate N3O2-Type Schiff-Base Ligands: Synthesis, Structure and Magnetism

被引:12
作者
Bazhenova, Tamara A. [1 ]
Yakushev, Ilya A. [1 ,2 ,3 ]
Lyssenko, Konstantin A. [4 ]
Maximova, Olga V. [1 ,5 ,6 ]
Mironov, Vladimir S. [1 ,7 ]
Manakin, Yuriy V. [1 ]
Kornev, Alexey B. [1 ]
Vasiliev, Alexander N. [5 ,8 ]
Yagubskii, Eduard B. [1 ]
机构
[1] Inst Problems Chem Phys, Chernogolovka 142432, Russia
[2] Kurnakov Inst Gen & Inorgan Chem, Moscow 119991, Russia
[3] Natl Res Ctr Kurchatov Inst, Moscow 123182, Russia
[4] Lomonosov Moscow State Univ, Dept Chem, Moscow 119991, Russia
[5] Lomonosov Moscow State Univ, Fac Phys, Moscow 119991, Russia
[6] Natl Univ MISiS, Moscow 119049, Russia
[7] RAS, Shubnikov Inst Crystallog, Fed Sci Res Ctr Crystallog & Photon, Moscow 119333, Russia
[8] Natl Res South Ural State Univ, Chelyabinsk 454080, Russia
基金
俄罗斯科学基金会;
关键词
lanthanide complexes; single-molecule magnets; pentadentate Schiff-base ligands; magnetic relaxation; magnetic anisotropy; SINGLE-MOLECULE-MAGNET; CRYSTAL-FIELD ANALYSIS; X-RAY-STRUCTURE; ION-MAGNET; SLOW RELAXATION; 2-STEP RELAXATION; LOCAL SYMMETRY; ANISOTROPY; MAGNETIZATION; SERIES;
D O I
10.3390/magnetochemistry6040060
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
A series of five neutral mononuclear lanthanide complexes [Ln(HL)(L)] (Ln = Dy3+, Ho3+ Er3+ and Tb3+) with rigid pentadentate N3O2-type Schiff base ligands, H2LH (1-Dy, 3-Ho, 4-Er and 6-Tb complexes) or H2LOCH3, (2-Dy complex) has been synthesized by reaction of two equivalents of 1,1'-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))dibenzohydrazine (H2LH, [H(2)DAPBH]) or 1,1'-(pyridine-2,6-diyl)bis(ethan-1-yl-1-ylidene))di-4-methoxybenzohydrazine (H2LOCH3, [H(2)DAPMBH]) with common lanthanide salts. The terbium complex [Tb(L-H)(NO3)(H2O)(2)](DME)(2) (5-Tb) with one ligand H2LH was also obtained and characterized. Single crystal X-ray analysis shows that complexes 1-4 have the composition {[Ln(3+)(HL)(-)(L)(2-)] solv} and similar molecular structures. In all the compounds, the central Ln(3+) ion is chelated by two interlocked pentadentate ligands resulting in the coordination number of ten. Each lanthanide ion is coordinated by six nitrogen atoms and four oxygen atoms of the two N3O2 chelating groups forming together a distorted bicapped square antiprismatic polyhedron N6O4 with two capping pyridyl N atoms in the apical positions. The ac magnetic measurements reveal field-induced single-molecule magnet (SMM) behavior of the two dysprosium complexes (with barriers of U-eff = 29 K at 800 Oe in 1-Dy and U-eff = 70 K at 300 Oe in 2-Dy) and erbium complex (U-eff = 87 K at 1500 Oe in 4-Er); complex 3-Ho with a non-Kramers Ho3+ ion is SMM-silent. Although 2-Dy differs from 1-Dy only by a distant methoxy-group in the phenyl ring of the ligand, their dynamic magnetic properties are markedly different. This feature can be due to the difference in long-range contributions (beyond the first coordination sphere) to the crystal-field (CF) potential of 4f electrons of Dy3+ ion that affects magnetic characteristics of the ground and excited CF states. Magnetic behavior and the electronic structure of Ln(3+) ions of 1-4 complexes are analyzed in terms of CF calculations.
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页码:1 / 26
页数:26
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