Synthesis of Bis(phosphinoferrocenyl) Copper Complexes from Zwitterionic Quinonoid Ligands and Their Structural and Redox Properties

Reactions of N,N′-di-n-butyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium L1, or N,N′-diisopropyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium L2 with [{(dppf)Cu}2(μ−Cl)2] (dppf = 1,1′-bis(diphenylphosphino)ferrocene) or [{(dispf)Cu}2(μ−Cl)2] (dispf = 1,1′-bis(diisopropylphosphino)ferrocene) led to the formation of the heterodinuclear complexes [(dppf)(CuL1−H)] (2), [(dppf)(CuL2−H)] (3), [(dispf)(CuL1−H)] (4), and [(dispf)(CuL2−H)] (5). The crystal structure of L2 was determined by X-ray diffraction and shows that the molecule exists in a 6π + 6π zwitterionic form, with two chemically connected but electronically nonconjugated π-subunits. The crystal structures of complexes 2−4 show a distorted tetrahedral coordination environment for the Cu(I) center and a more localized π-system for the ligands. Cyclic voltammetry on the ligands and complexes indicates various redox processes. The first oxidation of the complexes leads to an electron paramagnetic resonance supported formulation where the ligand radical is bound to Cu(I). UV−visible spectroscopy of the ligands and the complexes is also reported and discussed.

N,N'-二丁基-2-氨基-5-醇酸-1,4-苯醌单阳离子L1或N,N'-二异丙基-2-氨基-5-醇酸-1,4-苯醌单阳离子L2与[(dppf)Cu]2(μ-Cl)2（dppf = 1,1'-双(二苯基膦)铁卟啉）或[(dispf)Cu]2(μ-Cl)2（dispf = 1,1'-双(二异丙基膦)铁卟啉）反应，产生了异核配位化合物[(dppf)(CuL1-H)](2)、[(dppf)(CuL2-H)](3)、[(dispf)(CuL1-H)](4)和[(dispf)(CuL2-H)](5)。通过X射线衍射确定了L2的晶体结构，发现该分子以6π+6π的两性离子形式存在，其中两个化学上连接但电子上非共轭的π亚单元。化合物2-4的晶体结构展示了Cu(I)中心的扭曲四面体配位环境和配体更局域化的π系统。对配体和化合物的循环伏安法研究表明了多种氧化还原过程。复合物的首次氧化导致配体自由基与Cu(I)结合的电子顺磁共振支持的构型。此外，还报告并讨论了配体和化合物的紫外-可见光谱。