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 Solutions: Role of Organic Spin in Heterospin Single-Molecule Magnets
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 Solutions: Role of Organic Spin in Heterospin Single-Molecule Magnets
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1:2 混合钴 (II) 水杨醛希夫碱配合物与携带高自旋卡宾（疤痕 = 2/2、4/2、6/2 和 8/2）的吡啶配体在稀冷冻溶液中的磁性：作用
DOI：
10.1021/ic403074d
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Noboru Koga
中科院分区：
文献类型：
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作者：
Satoru Karasawa; Kimihiro Nakano;Daisuke Yoshihara;Noriko Yamamoto;Jun-ichi Tanokashira;Takahito Yoshizaki;Yuji Inagaki;Noboru Koga
Co(p-tolsal)2,p-tolsal =N-p-tolylsalicylideniminato 和重氮吡啶配体 DXpy;X=1,2,3l,3b, and4 在 MTHF 溶液中的 1:2 混合物在低温下辐照形成相应的 1:2 钴-卡宾配合物 Co(p-tolsal)2(CXpy)2，其中Stotal=分别为 5/2、9/2、13/2、13/2 和 17/2。所得的 Co(p-tolsal)2(CXpy)2,X=1,2,3l,3b 和 4, 显示出异旋单分子磁体的磁性行为特征，有效激活势垒 Ueff/kB 为 40、65、73、72 和 74 K，用于磁矩的重新定向和矫顽力 Hc 为 ∼0 的温度依赖性磁滞回线， 1.9 K 时分别为 6.2、10、6.5 和 9.0 kOe。由于磁化量子隧道效应 (QTM)，Co(p-tolsal)2(C1py)2 的弛豫时间 τQ 估计为 1.6 s，Co(p-tolsal)2(C2py)2 的 ∼2.0 × 103s，Co(p-tolsal)2(CXpy)2 的 >105s；X=3b、3l 和 4。在异自旋配合物中，有机自旋、卡宾与钴离子相互作用抑制QTM途径，并且τQ值随着Stotal值的增加而增加。
The 1:2 mixtures of Co(p-tolsal)2,p-tolsal =N-p-tolylsalicylideniminato, and diazo-pyridine ligands,DXpy;X=1,2,3l,3b, and4, in MTHF solutions were irradiated at cryogenic temperature to form the corresponding 1:2 cobalt–carbene complexes Co(p-tolsal)2(CXpy)2, withStotal= 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, and4, 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, τQ, due to a quantum tunneling of magnetization (QTM) were estimated to be 1.6 s for Co(p-tolsal)2(C1py)2, ∼2.0 × 103s for Co(p-tolsal)2(C2py)2, and >105s for Co(p-tolsal)2(CXpy)2;X=3b,3l, and4. In heterospin complexes, organic spins, carbenes interacted with the cobalt ion to suppress the QTM pathway, and the τQvalue increased with increasing theStotalvalues.