Résumé 2,5-Bis(pyrrol-2-yl)phosphole derivatives were prepared using the reaction of titanacycles, generated in situ from a TiII reagent and pyrrole-capped 1,6-heptadiynes, with dichloro(phenyl)phosphine. The 2,5-bis(pyrrol-2-yl)phosphole derivatives were found to possess narrower optical HOMO–LUMO gaps and less positive oxidation potentials than those of previously reported 2,5-diarylphosphole analogs. This demonstrates that the intrinsic nature of the electron excessive pyrrole subunits as well as the effective π-conjugation over the coplanar heterole rings. The σ3-P type 2,5-bis(5-phenylpyrrol-2-yl)phosphole underwent complexation with AuCl(SMe2) and PtCl2 to yield the respective AuCl–monophosphine and PtCl2–bisphosphine complexes. In the square planar PtII complex, the pyrrolic NH protons were found to form intramolecular hydrogen bonds with the chlorine atoms that gave rise to symmetrically split, parallel π-chromophores linked by two Pt–P bonds. Density functional theory calculations on a PtII model complex suggested that this cooperative interaction induces a significant split of the original LUMOs of the symmetrical π-conjugated ligands.
摘要 利用由 TiII 试剂和
吡咯封端的 1,6-heptadiynes 原位生成的
钛环与二
氯(苯基)膦反应,制备了 2,5-双(
吡咯-2-基)膦孔衍
生物。与之前报道的 2,5-双(
吡咯-2-基)膦类似物相比,2,5-双(
吡咯-2-基)膦衍
生物具有更窄的光学 HOMO-LUMO 间隙和更低的正氧化电位。这表明电子过多的
吡咯亚基的内在性质以及共面杂环上有效的 π 共轭。σ3-P型 2,5-双(5-苯基
吡咯-2-基)膦孔与 AuCl(SMe2)和 PtCl2 发生络合反应,生成各自的 AuCl-一膦和 PtCl2-
二膦配合物。在方形 PtII 复合物中,发现
吡咯烷 NH 质子与
氯原子形成分子内氢键,从而产生对称分裂的平行 π 色基,并由两个 Pt-P 键连接。对一个 PtII 模型复合物进行的密度泛函理论计算表明,这种合作作用会导致对称的 π 共轭
配体的原始 LUMOs 发生显著分裂。