Coordination complexes of 2-(4-quinolyl)nitronyl nitroxide with M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)]: syntheses, crystal structures, and magnetic characterization.
Coordination complexes of 2-(4-quinolyl)nitronyl nitroxide with M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)]: syntheses, crystal structures, and magnetic characterization.
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DOI：
10.1021/ic049946q
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发表时间：
2004-06
影响因子：
4.6
通讯作者：
Hongmei Wang;Zhiliang Liu;Caiming Liu;Deqing Zhang;Zhengliang Lü;Hua Geng;Z. Shuai;Daoben Zhu
中科院分区：
文献类型：
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作者：
Hongmei Wang;Zhiliang Liu;Caiming Liu;Deqing Zhang;Zhengliang Lü;Hua Geng;Z. Shuai;Daoben Zhu
由2-（4-喹啉基）硝酰基氮氧自由基（4-QNNN）与M（hfac）（2）[M = Mn（II），Co（II），Cu（II）]，（4-QNNN）（2）合成了三个新的配合物M（2）L（2）. [Mn（hfac）（2）]（2）（1），（4-QNNN）（2）.合成了[Co（hfac）（2）]（2）·2 H（2）O（2）和（4-QNNN）（2）·Cu（hfac）（2）·Cu '（hfac）（2）（3），并对其结构和磁性进行了表征.配合物1和2均为四自旋配合物，喹啉环上的氮原子和硝酰基氮氧自由基上的氧原子都参与了配位键的形成。而配合物3中喹啉环上的氮原子与Cu（II）离子配位形成三自旋配合物，并进一步与另一分子Cu（hfac）（2）（简称Cu '（hfac）（2））连接形成一维交替链。研究了三种配合物的磁性。对于配合物1，由于硝酰基氮氧自由基与Mn（II）离子之间存在强反铁磁耦合，其磁化率随温度的变化符合S = 2的自旋二聚体模型，得到二聚体内磁交换常数J =-0.82cm（-1）。对于配合物2，在T > 50 K的温度范围内，用S（1）= 3/2和S（2）= 1/2的双自旋单元模型模拟了磁化率的温度依赖性，得到Co（II）.O配位键的磁相互作用J = -321.9 cm（-1），D = -16.3 cm（-1）（零场分裂参数），g = 2.26，zJ =-3.8cm（-1）。3的磁化率与温度的关系近似地符合前面所述的模型，得到硝基氮氧自由基与Cu（II）离子通过喹啉单元通过自旋极化机制的磁相互作用的J（1）= -6.52 cm（-1）和通过弱O·Cu配位键的磁相互作用的J（2）= 3.64 cm（-1）。
Three new complexes of the formula M(2)L(2) derived from 2-(4-quinolyl)nitronyl nitroxide (4-QNNN) and M(hfac)(2) [M = Mn(II), Co(II), and Cu(II)], (4-QNNN)(2).[Mn(hfac)(2)](2) (1), (4-QNNN)(2).[Co(hfac)(2)](2).2H(2)O (2), and (4-QNNN)(2).Cu(hfac)(2).Cu'(hfac)(2) (3), were synthesized and characterized structurally as well as magnetically. Complexes 1 and 2 are four-spin complexes with quadrangle geometry, in which both the nitrogen atoms of quinoline rings and oxygen atoms of nitronyl nitroxides are involved in the formation of coordination bonds. For complex 3, however, the nitrogen atoms of quinoline rings are coordinated with Cu(II) ion to afford a three-spin complex, which is further linked to another molecule of Cu(hfac)(2) (referred to as Cu'(hfac)(2)) to form a 1D alternating chain. The magnetic behaviors of the three complexes were investigated. For complex 1, as the nitronyl nitroxides and Mn(II) ions are strongly antiferromagnetically coupled, consequently its temperature dependence of magnetic susceptibility was fitted to the model of spin-dimer with S = 2, yielding the intradimer magnetic exchange constant of J = -0.82 cm(-1). For complex 2, the temperature dependence of the magnetic susceptibility in the T > 50 K region was simulated with the model of two-spin unit with S(1) = 3/2 and S(2) = 1/2, leading to J = -321.9 cm(-1) for the magnetic interaction due to Co(II).O coordination bonding, D = -16.3 cm(-1) (the zero-field splitting parameter), g = 2.26, and zJ = -3.8 cm(-1) for the magnetic interactions between Co(II) ions and nitronyl nitroxides through quinoline rings and those between nitronyl nitroxides due to the short O.O short contacts. The temperature dependence of magnetic susceptibility of 3 was approximately fitted to a model described previously affording J(1) = -6.52 cm(-1) and J(2) = 3.64 cm(-1) for the magnetic interaction between nitronyl nitroxides and Cu(II) ions through the quinoline unit via spin polarization mechanism and the weak O.Cu coordination bonding, respectively.