title: Controlled Interconversion of a Dinuclear Au Species Supported by a Redox-Active Bridging PNP Ligand Facilitates Ligand-to-Gold Electron Transfer.
abstract: Redox non-innocent ligands have recently emerged as interesting tools to obtain new reactivity with a wide variety of metals. However, gold has almost been neglected in this respect. Here, we report mechanistic investigations related to a rare example of ligand-based redox chemistry in the coordination sphere of gold. The dinuclear metal-centered mixed-valent AuI-AuIIIcomplex 1, supported by monoanionic diarylamido-diphosphine ligand PNPPrand with three chlorido ligands overall, undergoes a complex series of reactions upon halide abstraction by silver salt or Lewis acids such as gallium trichloride. Formation of the ultimate AuI-AuIcomplex 2 requires the intermediacy of AuI-AuIdimers 5 and 7 as well as the unique AuIII-AuIIIcomplex 6, both of which are interconverted in a feedback loop. Finally, unprecedented ortho-selective C-H activation of the redox-active PNP ligand results in the carbazolyldiphosphine derivative PN*PPrvia ligand-to-metal two-electron transfer. This work demonstrates that the redox-chemistry of gold may be significantly expanded and modified when using a reactive ligand scaffold.
authors.affiliation: Homogeneous, Supramolecular & Bio-inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Vincent
authors.initials: V
authors.lastname: Vreeken
authors.affiliation: Department of Chemistry, John Hopkins University, Baltimore, MD, USA.
authors.forename: Maxime A
authors.initials: MA
authors.lastname: Siegler
authors.affiliation: Homogeneous, Supramolecular & Bio-inspired Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands.
authors.forename: Jarl Ivar
authors.identifier: http://orcid.org/0000-0003-0665-9239
authors.initials: JI
authors.lastname: van der Vlugt
keywords: C−H activation; bimetallic systems; bridging ligand; gold; reactive ligand