Stereochemistry and properties of the M(II)N(py) coordination bond in the low-spin dipyridinated iron(II) and cobalt(II) phthalocyanines
Stereochemistry and properties of the M(II)N(py) coordination bond in the low-spin dipyridinated iron(II) and cobalt(II) phthalocyanines
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DOI：
10.1016/s0020-1693(02)01060-5
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发表时间：
2003-01
影响因子：
2.8
通讯作者：
J. Janczak;R. Kubiak
中科院分区：
文献类型：
--
作者：
J. Janczak;R. Kubiak
用单晶X-射线衍射法和振动光谱法研究了联吡啶化铁(II)和钴(II)的配合物FePc(Py)2和CoPc(Py)2(Pc=C32H16N8，Py=C5H5N)的配位键M(II)N(Py)与振动性质和立体化学的关系。将β-FePc或β-CoPc在160℃的吡啶溶液中加热，得到了晶态的联吡啶配合物，晶体是在缓慢冷却过程中形成的。FePc(Py)2和CoPc(Py)2晶体是等结构的。它们在单斜晶系的P21/c空间群中结晶，每个晶胞有两个分子。这些络合物的结构结果与配位键性质密切相关。Fe~(2+)和Co~(2+)离子与大环上的4个N-异吲哚原子配位，轴向配位于吡啶分子上的2个氮原子，形成四方吡喃。Co和Fe电子结构的不同对振动M尼索吲哚参数的影响比相应的结构参数大得多。M(II)N(Py)键的轴向长度强烈依赖于中心金属的电子构型。M(II)N(Py)键长在FePc(Py)2中为2.039(2)ä，在CoPc(Py)2中为2.340(2)ä，这清楚地证明了未成对电子在钴络合物中Co的dz2轨道上的局域化。电子顺磁共振(EPR)谱和磁化率测量也发现了CoPc(Py)2分子中的未成对电子。对FePc(Py)2固体样品进行的EPR和磁化率测量显示了其抗磁性。D(π)→π*(Pc)回馈的重要性体现在Pc大环的C-尼索吲哚和C--NaZAME键长之间的差异。
A comparison between the coordination bond M(II)N(py) and vibrational properties and stereochemistry of the dipyridinated iron(II) and cobalt(II) phthalocyaninato complexes, FePc(py)2and CoPc(py)2(Pc=C32H16N8, py=C5H5N), is carried out using the single crystal X-ray diffraction and the vibrational spectroscopy. Both dipyridinated complexes have been synthesized in crystalline form by heating of the β-FePc or β-CoPc in pyridine at 160°C. The crystals are formed during the slowly cooling process. The crystal of FePc(py)2and CoPc(py)2are isostructural. They crystallize in the space group P21/c of the monoclinic system with two molecules per unit cell. The structural results and coordination bond properties are strictly related in these complexes. The Fe2+and Co2+cations are coordinated by four N-isoindole atoms of the phthalocyaninato(2-) macrocycle and axially by two nitrogen atoms of pyridine molecules to form a tetragonal bypyramid. The vibrational MNisoindoleparameters are much more affected than the corresponding structural parameters by the difference in the electronic structure of the Co and Fe. The axial M(II)N(py) bond length depends strongly on the electron configuration of the central metal. The value of the M(II)N(py) bond length of 2.039(2) Å in FePc(py)2and 2.340(2) Å in CoPc(py)2clearly evidences on the localization of the unpaired electron on the dz2orbital of the Co in the cobalt complex. The electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility measurements have also detected the unpaired electron in the molecule of CoPc(py)2. EPR and magnetic susceptibility measurements performed on a solid sample of FePc(py)2shown on its diamagnetic character. The importance of the d(π)→π*(Pc) back donation is manifested in the difference between the values of the CNisoindoleand CNazamethinebond lengths of the Pc macrocycle.