title: Synthesis of bis(phosphinoferrocenyl) copper complexes from zwitterionic quinonoid ligands and their structural and redox properties.
abstract: Reactions of N,N'-di-n-butyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium L(1), or N,N'-diisopropyl-2-amino-5-alcoholate-1,4-benzoquinonemonoiminium L(2) with [{(dppf)Cu}(2)(mu-Cl)(2)] (dppf = 1,1'-bis(diphenylphosphino)ferrocene) or [{(dispf)Cu}(2)(mu-Cl)(2)] (dispf = 1,1'-bis(diisopropylphosphino)ferrocene) led to the formation of the heterodinuclear complexes [(dppf)(CuL(1)(-H))] (2), [(dppf)(CuL(2)(-H))] (3), [(dispf)(CuL(1)(-H))] (4), and [(dispf)(CuL(2)(-H))] (5). The crystal structure of L(2) was determined by X-ray diffraction and shows that the molecule exists in a 6pi + 6pi zwitterionic form, with two chemically connected but electronically nonconjugated pi-subunits. The crystal structures of complexes 2-4 show a distorted tetrahedral coordination environment for the Cu(I) center and a more localized pi-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.
authors.affiliation: Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Université de Strasbourg, 4 rue Blaise Pascal, F-67070 Strasbourg Cédex, France. braunstein@chimie.u-strasbg.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Braunstein
authors.forename: Denis
authors.initials: D
authors.lastname: Bubrin
authors.forename: Biprajit
authors.initials: B
authors.lastname: Sarkar