Single-molecule magnets: [Mn 12O 12(O 2CCF 2Cl) 16(H 2O) 4] 0

• Published in: Polyhedron 2005-11, Vol.24 (16), p.2205-2214
• Main Authors: Tsai, Hui-Lien, Shiao, Hong-Ann, Jwo, Tyn-Yih, Yang, Chen-I, Wur, Ching-Shuei, Lee, Gene-Hsiang
• Format: Article
• Language: English
• Subjects: Crystal structure; Magnetic quantum tunneling; Single-molecule magnet; Step-like hysteresis loop
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2005.03.106

The syntheses, X-ray crystal structures and magnetic properties of [Mn 12O 12(O 2CCF 2Cl) 16(H 2O) 4] ( 1) and [PPh 4][Mn 12O 12 (O 2CCF 2Cl) 16(H 2O) 4] ( 2) are reported. The results of DC and AC magnetic susceptibility studies are described. Complexes 1 and 2 exhibit two out-of-phase component of the AC magnetic susceptibility with frequency dependent maxima. The anisotropic energies U/ k B are 82.7, 64.8, 56.4 and 32.4 K for complexes 1(HT), 2(HT), 1(LT) and 2(LT), respectively. Step-like features are seen on hysteresis loops of complex 1. DC decay relaxation of complex 1 shows quantum tunneling behavior below 2.1 K. The syntheses, X-ray crystal structures and magnetic properties of [Mn 12O 12(O 2CCF 2Cl) 16(H 2O) 4] ( 1) and [PPh 4][Mn 12O 12(O 2CCF 2Cl) 16(H 2O) 4] ( 2) are reported. Complex 1 · 4H 2O crystallizes in the tetragonal space group I 4 ¯ at 150(1) K with a = 18.6838(1) Å, c = 13.3829(5) Å, and Z = 2. Reduction of complex 1 with PPh 4I in CH 2Cl 2 leads to isolation of complex 2 · 2H 2O · CH 2Cl 2, it crystallizes in the monoclinic space group P2 1/ c at 150(1) K with a = 18.6623(7) Å, b = 13.3626(5) Å, c = 45.4482(17) Å, β = 97.204°, and Z = 4. The results of DC and AC magnetic susceptibility studies are described. DC studies of complexes 1 and 2 in a 1.0 kG field show maxima of the χ M T versus T plot in the 5–10 K range at 47.63 and 54.27 emu K mol −1, respectively. Complexes 1 and 2 exhibit out-of-phase component of the AC magnetic susceptibility with frequency dependent maxima. Step-like features are seen on hysteresis loops of complex 1. DC decay relaxation of complex 1 shows quantum tunneling behavior below 2.1 K.