Ganguly Sumit, Giles Logan J, Thomas Kolle E, Sarangi Ritimukta, Ghosh Abhik
Department of Chemistry and Center for Theoretical and Computational Chemistry, UiT-, The Arctic University of Norway, 9037, Tromsø, Norway.
Structural Molecular Biology, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, 94306, USA.
Chemistry. 2017 Oct 26;23(60):15098-15106. doi: 10.1002/chem.201702621. Epub 2017 Oct 6.
Two new series of iron meso-tris(para-X-phenyl)corrole (TpXPC) complexes, Fe[TpXPC]Ph and Fe[TpXPC]Tol, in which X=CF , H, Me, and OMe, and Tol=p-methylphenyl (p-tolyl), have been synthesized, allowing a multitechnique electronic-structural comparison with the corresponding FeCl, FeNO, and Fe (μ-O) TpXPC derivatives. Optical spectroscopy revealed that the Soret maxima of the FePh and FeTol series are insensitive to the phenyl para substituent, consistent with the presumed innocence of the corrole ligand in these compounds. Accordingly, we may be increasingly confident in the ability of the substituent effect criterion to serve as a probe of corrole noninnocence. Furthermore, four complexes-Fe[TPC]Cl, FeTPC, {Fe[TPC]} O, and Fe[TPC]Ph-were selected for a detailed XANES investigation of the question of ligand noninnocence. The intensity-weighted average energy (IWAE) positions were found to exhibit rather modest variations (0.8 eV over the series of corroles). The integrated Fe-K pre-edge intensities, on the other hand, vary considerably, with a 2.5 fold increase for Fe[TPC]Ph relative to Fe[TPC]Cl and FeTPC. Given the approximately C local symmetry of the Fe in all the complexes, the large increase in intensity for Fe[TPC]Ph may be attributed to a higher number of 3d holes, consistent with an expected Fe -like description, in contrast to Fe[TPC]Cl and FeTPC, in which the Fe is thought to be Fe -like. These results afford strong validation of XANES as a probe of ligand noninnocence in metallocorroles. Electrochemical redox potentials, on the other hand, were found not to afford a simple probe of ligand noninnocence in Fe corroles.
已合成了两个新系列的铁中-三（对-X-苯基）卟啉（TpXPC）配合物，即Fe[TpXPC]Ph和Fe[TpXPC]Tol，其中X = CF、H、Me和OMe，且Tol = 对甲基苯基（对甲苯基），从而能够与相应的FeCl、FeNO和Fe(μ-O)TpXPC衍生物进行多技术电子结构比较。光谱学表明，FePh和FeTol系列的Soret最大值对苯基对位取代基不敏感，这与这些化合物中卟啉配体的假定非活性一致。因此，我们可能会越来越相信取代基效应标准作为卟啉非活性探针的能力。此外，选择了四种配合物——Fe[TPC]Cl、FeTPC、{Fe[TPC]}₂O和Fe[TPC]Ph——对配体非活性问题进行详细的X射线吸收近边结构（XANES）研究。发现强度加权平均能量（IWAE）位置表现出相当适度的变化（在一系列卟啉中变化0.8 eV）。另一方面，Fe-K边前积分强度变化很大，相对于Fe[TPC]Cl和FeTPC，Fe[TPC]Ph增加了2.5倍。鉴于所有配合物中Fe的局部对称性近似为C，Fe[TPC]Ph强度的大幅增加可能归因于更多的3d空穴，这与预期的类似Fe³⁺的描述一致，与Fe[TPC]Cl和FeTPC相反，其中Fe被认为是类似Fe²⁺的。这些结果有力地验证了XANES作为金属卟啉中配体非活性探针的有效性。另一方面，发现电化学氧化还原电位并不能简单地作为Fe卟啉中配体非活性的探针。
