title: 9-Oxidophenalenone: a noninnocent β-diketonate ligand?
abstract: The redox systems [Ru(L)(bpy)(2)](k), [Ru(L)(2)(bpy)](m), and [Ru(L)(3)](n) containing the potentially redox-active ligand 9-oxidophenalenone = L(-) were investigated by spectroelectrochemistry (UV-vis-near-IR and electron paramagnetic resonance) in conjunction with density functional theory (DFT) calculations. Compounds [Ru(L(-))(bpy)(2)]ClO(4) ([1]ClO(4)) and [Ru(L(-))(2)(bpy)]ClO(4) ([2]ClO(4)) were structurally characterized. In addition to establishing electron-transfer processes involving the Ru(II)/Ru(III)/Ru(IV) and bpy(0)/bpy(•-) couples, evidence for the noninnocent behavior of L(-) was obtained from [Ru(IV)(L(•))(L(-))(bpy)](3+), which exhibits strong near-IR absorption due to ligand-to-ligand charge transfer. In contrast, the lability of the electrogenerated anion [Ru(L)(2)(bpy)](-) is attributed to a resonance situation [Ru(II)(L(•2-))(L(-))(bpy)](-)/[Ru(II)(L(-))(2) (bpy(•-))](-), as suggested by DFT calculations.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Das
authors.forename: Thomas Michael
authors.initials: TM
authors.lastname: Scherer
authors.forename: Shaikh M
authors.initials: SM
authors.lastname: Mobin
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
authors.forename: Goutam Kumar
authors.initials: GK
authors.lastname: Lahiri