Crystal environments probed by EPR spectroscopy.: Variations in the EPR spectra of CoII(octaethylporphyrin) doped in crystalline diamagnetic hosts and a reassessment of the electronic structure of four-coordinate cobalt(II)
Crystal environments probed by EPR spectroscopy.: Variations in the EPR spectra of CoII(octaethylporphyrin) doped in crystalline diamagnetic hosts and a reassessment of the electronic structure of four-coordinate cobalt(II)
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DOI：
10.1021/ja030221f
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发表时间：
2003-10-15
影响因子：
15
通讯作者：
Balch, AL
中科院分区：
文献类型：
--
作者：
Ozarowski, A;Lee, HM;Balch, AL
Co-II（OEP）的粉末和单晶EPR光谱（OEP是辛乙基卟啉的离子）掺杂到一系列抗磁晶体中，包括简单的四坐标主体，H-2(OEP)，三斜B型Ni-II(OEP)，四方型Ni-II（OEP）和Zn-II(OEP)；五坐标宿主，（mu-二氧六烷）-{Zn-II(OEP)}(2)和（py）Zn-II(OEP)；六坐标宿主，（py）(2)Zn-II（OEP）和（py）(2)Mg-II(OEP)；含富勒烯的寄主C-60.2Zn(II)（OEP）。CHCl3, c - 70. - ni - ii (OEP) .C6H6。CHCl3和C-60.Ni-II（OEP）。得到并分析了2C(6)H(6)。用一个程序模拟了光谱，该程序采用了16 × 16复自旋哈密顿矩阵的精确对角化。这些掺杂样品的EPR光谱对每个晶体内的环境非常敏感，晶体位置的对称性决定了是否观察到轴向或菱形共振模式。对于Co-II（OEP）掺杂到四角形Ni-II（OEP）晶体中（其显示出非常大的g（垂直）为3.405，非常小的g（平行）为1.544）和其他几种含有四坐标金属位的晶体中，g分量不能用现有理论与通常的z(2)基态假设进行拟合。然而，假设未配对电子位于四坐标配合物的xy轨道上，所观察到的EPR参数可以得到合理的一致性。
The powder and single-crystal EPR spectra of Co-II(OEP) (OEP is the dianion of octaethylporphyrin) doped into a range of diamagnetic crystals including simple four-coordinate hosts, H-2(OEP), the triclinic B form of Ni-II(OEP), the tetragonal form of Ni-II(OEP) and Zn-II(OEP); five-coordinate hosts, (mu-dioxane)-{Zn-II(OEP)}(2) and (py)Zn-II(OEP); six-coordinate hosts, (py)(2)Zn-II(OEP) and (py)(2)Mg-II(OEP); and hosts containing fullerenes, C-60.2Zn(II)(OEP).CHCl3, C-70.Ni-II(OEP).C6H6.CHCl3, and C-60.Ni-II(OEP).2C(6)H(6) have been obtained and analyzed. Spectra were simulated using a program that employed the exact diagonalization of the 16 x 16 complex spin Hamiltonian matrix. The EPR spectra of these doped samples are very sensitive to the environment within each crystal with the crystallographic site symmetry determining whether axial or rhombic resonance patterns are observed. For Co-II(OEP) doped into tetragonal Ni-II(OEP) (which displays a very large g(perpendicular to) of 3.405 and a very small g(parallel to) of 1.544) and several other crystals containing four-coordinate metal sites, the g components could not be fit using existing theory with the assumption of the usual z(2) ground state. However, reasonable agreement of the observed EPR parameters could be obtained by assuming that the unpaired electron resides in an xy orbital in the four-coordinate complexes.