An electrically conducting crystal composed of an octahedrally ligated porphyrin complex with high-spin iron(III)
An electrically conducting crystal composed of an octahedrally ligated porphyrin complex with high-spin iron(III)
复制标题
DOI：
10.1039/c7dt04649a
复制
发表时间：
2018-03-28
影响因子：
4
通讯作者：
Matsuda, Masaki
中科院分区：
文献类型：
--
作者：
Nishi, Miki;Ishii, Ryuta;Matsuda, Masaki
设计了一种基于卟啉的高自旋铁（III）八面体配合物，合成了导电晶体TPP[FeIII(tbp) Br-2](2) （TPP =四苯基磷，tbp =四苯并卟啉）。虽然TPP[Fe(tbp) Br-2](2)与报道的TPP[Fe(Mc) L-2](2)体系是同构的(Mc =大环配体，如酞菁（Pc）或tbp；当L = CN、Cl或Br)时，[Fe(tbp) Br2]单元中Fe与配体的键长明显大于其他单元，这是由于Fe的自旋状态不同：TPP[Fe(tbp) Br-2](2)为高自旋，其他为低自旋。当铁处于高自旋态时，在低自旋态观察到的磁各向异性消失。根据基于pc的系统的报告，TPP[Fe(tbp) Br-2](2)的负磁阻（MR）效应预计小于TPP[Fe(tbp)(CN)(2)](2)。然而，前者显示出与后者相似或更大的巨大负MR效应，这表明铁的性质是卟啉基材料电性能的关键因素。
A porphyrin-based octahedrally ligated complex with high-spin iron(III) was designed, and the resulting electrically conducting crystal TPP[FeIII(tbp) Br-2](2) (TPP = tetraphenylphosphonium and tbp = tetrabenzoporphyrin) was synthesised. Although TPP[Fe(tbp) Br-2](2) was isostructural to the reported TPP[Fe(Mc) L-2](2) systems (Mc = macrocyclic ligands such as phthalocyanine (Pc) or tbp; and L = CN, Cl, or Br), the bond lengths between Fe and ligands in the [Fe(tbp) Br2]unit were evidently longer than those in the other units, because of the different spin states of Fe: high-spin in TPP[Fe(tbp) Br-2](2) and low-spin in others. The magnetic anisotropy observed in the low-spin state vanished when the Fe is in the high-spin state. Based on reports for Pc-based systems, the negative magnetoresistance (MR) effect for TPP[Fe(tbp) Br-2](2) was expected to be smaller than that for TPP[Fe(tbp)(CN) (2)](2). However, the former showed a giant negative MR effect similar to or larger than the latter, suggesting that the nature of iron is a crucial factor for the electrical properties of porphyrin-based materials.