title: Localized Mixed-Valence and Redox Activity within a Triazole-Bridged Dinucleating Ligand upon Coordination to Palladium.
abstract: The new dinucleating redox-active ligand (LH4), bearing two redox-active NNO-binding pockets linked by a 1,2,3-triazole unit, is synthetically readily accessible. Coordination to two equivalents of PdIIresulted in the formation of paramagnetic (S=1/2 ) dinuclear Pd complexes with a κ2-N,N'-bridging triazole and a single bridging chlorido or azido ligand. A combined spectroscopic, spectroelectrochemical, and computational study confirmed Robin-Day Class II mixed-valence within the redox-active ligand, with little influence of the secondary bridging anionic ligand. Intervalence charge transfer was observed between the two ligand binding pockets. Selective one-electron oxidation allowed for isolation of the corresponding cationic ligand-based diradical species. SQUID (super-conducting quantum interference device) measurements of these compounds revealed weak anti-ferromagnetic spin coupling between the two ligand-centered radicals and an overall singlet ground state in the solid state, which is supported by DFT calculations. The rigid and conjugated dinucleating redox-active ligand framework thus allows for efficient electronic communication between the two binding pockets.
authors.affiliation: Homogeneous, Bioinspired and Supramolecular Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Daniël L J
authors.initials: DL
authors.lastname: Broere
authors.affiliation: Homogeneous, Bioinspired and Supramolecular Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Raoul
authors.initials: R
authors.lastname: Plessius
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
authors.forename: Joanne
authors.initials: J
authors.lastname: Tory
authors.affiliation: Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammanstrasse 4, 37077, Göttingen, Germany.
authors.forename: Serhiy
authors.initials: S
authors.lastname: Demeshko
authors.affiliation: Homogeneous, Bioinspired and Supramolecular Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: de Bruin
authors.affiliation: Department of Chemistry, John Hopkins University, 3400 N. Charles St., Baltimore, MD, 21218, USA.
authors.forename: Maxime A
authors.initials: MA
authors.lastname: Siegler
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
authors.forename: Frantisek
authors.initials: F
authors.lastname: Hartl
authors.affiliation: Homogeneous, Bioinspired and Supramolecular Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands. j.i.vandervlugt@uva.nl.
authors.forename: Jarl Ivar
authors.initials: JI
authors.lastname: van der Vlugt
keywords: dinucleating ligand; intervalence charge transfer; mixed-valence; palladium; redox-active ligands