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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- 作者：Hongmei Wang ; Zhiliang Liu ; Caiming Liu ; Deqing Zhang ; Zhengliang Lü ; Hua Geng ; Zhigang Shuai ; and Daoben Zhu
- 刊名：Inorganic Chemistry
- 出版年：2004
- 出版时间：June 28, 2004
- 年：2004
- 卷：43
- 期：13
- 页码：4091 - 4098
- 全文大小：208K
- 年卷期：v.43,no.13(June 28, 2004)
- ISSN：1520-510X
文摘
Three new complexes of the formula M2L2 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]2·2H2O (2), and (4-QNNN)2·Cu(hfac)2·Cu'(hfac)2 (3), were synthesized and characterized structurally as well as magnetically. Complexes 1 and2 are four-spin complexes with quadrangle geometry, in which both the nitrogen atoms of quinoline rings andoxygen 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 furtherlinked to another molecule of Cu(hfac)2 (referred to as Cu'(hfac)2) to form a 1D alternating chain. The magneticbehaviors of the three complexes were investigated. For complex 1, as the nitronyl nitroxides and Mn(II) ions arestrongly antiferromagnetically coupled, consequently its temperature dependence of magnetic susceptibility wasfitted to the model of spin-dimer with S = 2, yielding the intradimer magnetic exchange constant of J = -0.82cm-1. For complex 2, the temperature dependence of the magnetic susceptibility in the T > 50 K region wassimulated with the model of two-spin unit with S1 = 3/2 and S2 = 1/2, leading to J = -321.9 cm-1 for themagnetic 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 throughquinoline rings and those between nitronyl nitroxides due to the short O···O short contacts. The temperaturedependence of magnetic susceptibility of 3 was approximately fitted to a model described previously affording J1= -6.52 cm-1 and J2 = 3.64 cm-1 for the magnetic interaction between nitronyl nitroxides and Cu(II) ions throughthe quinoline unit via spin polarization mechanism and the weak O···Cu coordination bonding, respectively.