Synthesis and Properties of Iron(III) and Iron(II) Porphyrinates with Novel Electron Configuration and Magnetic Characteristics

卟啉环的非平面变形使某些特定的金属-卟啉相互作用成为可能。因此，非平面卟啉配合物可以表现出一些在相应的平面配合物中无法观察到的特征电子和磁性能。在本研究中，我们制备了一系列高度变形的中-四烷基卟啉（TRP）和八乙基四苯基卟啉（OETPP）配合物，并对其电子结构和磁性行为进行了研究。弱场强轴向配体稳定了铁（III）卟啉配合物的中间自旋（S=3/2）态。因此，我们可以根据吡咯-氢的化学位移对弱轴配体的场强度进行排序，因为吡咯-氢的上场位移与中间自旋配合物的居数直接相关。根据一系列平面卟啉复合物的吡咯-氢化学位移，我们已经确定了各种氧配体的弱点，如下所示。根据各种铁（III）卟啉配合物的^1H和^ 13>C化学位移，我们还证实了两种具有不同电子构型的中间自旋配合物的存在，（d_<xy>）^2(d_<xz>,d_<yz>)^2(d_z2))^1和（d_<xz>,d_<yz>）^3(d_<xy>)^1(d_z2)^1。铁（III）卟啉配合物的磁性能受晶体填充的影响。通过在OMTPP的中苯基的3,5位上引入庞大的基团，我们能够制备出每个分子应该松散堆积的晶体。SQUID和穆斯堡尔测量表明，这些配合物在固态中实际上表现出自旋交叉现象。我们还发现了前所未有的例子，显示了五坐标高鞍配合物在极低温度下S=5/2和S=3/2之间的自旋交叉过程。携带烷基异氰化物的铁（III）卟啉酸酯总是采用低自旋态，电子构型为（d_<xz>,d_<yz>）^4(d_<xy>)^1。本研究首次发现重氮卟啉的烷基异氰化物配合物具有（d_<xy>）^2(d_<xz>,d_<yz>)^3电子构型的低自旋态。由于烷基异辛酸配体经常被用作揭示天然血红素蛋白电子结构的探针，因此本研究结果对揭示血红素蛋白的功能非常有用。少

Nonplanar deformation of porphyrin ring makes some specific metal-porphyrin interactions possible. As a result, the nonplanar porphyrin complexes could exhibit some characteristic electronic and magnetic properties that can not be observed in the corresponding planar complexes. In the present study, we have prepared a series of highly deformed meso-tetraalkylporphyrins(TRP) and octaethyltetraphenylporphyrin(OETPP) complexes and have examined the electronic structures and magnetic behaviors.The intermediate-spin(S=3/2) state of iron(III) porphyrin complexes are stabilized by the axial ligands with weak field strength. Thus, we can rank the field-strength of the weak axial ligands on the basis of the pyrrole-H chemical shifts, since the upfield shift of the pyrrole-H directly correlates with the population of the intermediate-spin complex. We have determined the weakness of a wide variety of oxygen ligands as given below on the basis of the pyrrole-H chemical shifts of a series of planar … More , ruffled, and saddled porphyrin complexes.4-MePyNO,3,5-Me_2PyNO>PyNO>4-ClPyNO>DMSO>DMF>MeOH>THF>DioxaneWe have also confirmed the presence of two types of intermediate-spin complexes with different electron configurations, (d_<xy>)^2(d_<xz>,d_<yz>)^2(d_z2))^1 and (d_<xz>,d_<yz>)^3(d_<xy>)^1(d_z2)^1, on the basis of the ^1H and ^<13>C chemical shifts of a wide variety of iron(III) porphyrin complexes.Magnetic behaviors of iron(III) porphyrin complexes could be affected by the crystal packing. By the introduction of bulky groups at the 3,5-positions of meso-phenyl groups of OMTPP, we were able to prepare the crystals where each molecule is supposed to be loosely packed. The SQUID and Mossbauer measurements have revealed that these complexes actually exhibit spin-crossover phenomena in the solid state. We have also found the unprecedented example showing the spin-crossover process between S=5/2 and S=3/2 in five-coordinate highly saddled complexes at extremely low temperature.The iron(III) porphyrinates carrying alkyl isocyanide always adopt the low-spin state with the (d_<xz>,d_<yz>)^4(d_<xy>)^1 electron configuration. In the present study, we have found for the first time that the alkyl isocyanide complexes of diazaporphyrin exhibit the low-spin state with the (d_<xy>)^2(d_<xz>,d_<yz>)^3 electron configuration. Since the alkyl isocynide ligands are frequently used as probes to reveal the electronic structures of naturally occurring heme proteins, the present results are quite useful to reveal the functions of heme proteins. Less