Magnetic Properties of 1:2 Mixed Cobalt(II) Salicylaldehyde Schiff-Base Complexes with Pyridine Ligands Carrying High-Spin Carbenes (Scar = 2/2, 4/2, 6/2, and 8/2) in Dilute Frozen S
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- 作者：Satoru Karasawa ; Kimihiro Nakano ; Daisuke Yoshihara ; Noriko Yamamoto ; Jun-ichi Tanokashira ; Takahito Yoshizaki ; Yuji Inagaki ; Noboru Koga
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：June 2, 2014
- 年：2014
- 卷：53
- 期：11
- 页码：5447-5457
- 全文大小：599K
- 年卷期：v.53,no.11(June 2, 2014)
- ISSN：1520-510X
文摘
The 1:2 mixtures of Co(p-tolsal)2, p-tolsal = N-p-tolylsalicylideniminato, and diazo-pyridine ligands, DXpy; X = 1, 2, 3l, 3b, and 4, in MTHF solutions were irradiated at cryogenic temperature to form the corresponding 1:2 cobalt鈥揷arbene complexes Co(p-tolsal)2(CXpy)2, with Stotal = 5/2, 9/2, 13/2, 13/2, and 17/2, respectively. The resulting Co(p-tolsal)2(CXpy)2, X = 1, 2, 3l, 3b, and 4, showed magnetic behaviors characteristic of heterospin single-molecule magnets with effective activation barriers, Ueff/kB, of 40, 65, 73, 72, and 74 K, for reorientation of the magnetic moment and temperature-dependent hysteresis loops with a coercive force, Hc, of 0, 6.2, 10, 6.5, and 9.0 kOe at 1.9 K, respectively. The relaxation times, 蟿Q, due to a quantum tunneling of magnetization (QTM) were estimated to be 1.6 s for Co(p-tolsal)2(C1py)2, 2.0 脳 103 s for Co(p-tolsal)2(C2py)2, and >105 s for Co(p-tolsal)2(CXpy)2; X = 3b, 3l, and 4. In heterospin complexes, organic spins, carbenes interacted with the cobalt ion to suppress the QTM pathway, and the 蟿Q value increased with increasing the Stotal values.