Redox‐Active‐Ligand‐Mediated Formation of an Acyclic Trinuclear Ruthenium Complex with Bridging Nitrido Ligands

Abstract

Coordination of a redox-active pyridine aminophenol ligand to Ru(II) followed by aerobic oxidation generates two diamagnetic Ru(III) species [1 a (cis) and 1 b (trans)] with ligand-centered radicals. The reaction of 1 a/1 b with excess NaN3 under inert atmosphere resulted in the formation of a rare bis(nitrido)-bridged trinuclear ruthenium complex with two nonlinear asymmetrical Ru-N-Ru fragments. The spontaneous reduction of the ligand centered radical in the parent 1 a/1 b supports the oxidation of a nitride (N(3-) ) to half an equivalent of N2 . The trinuclear omplex is reactive toward TEMPO-H, tin hydrides, thiols, and dihydrogen.

Radical‐Type Reactivity and Catalysis by Single‐Electron Transfer to or from Redox‐Active Ligands

“…The group of van der Vlugt reported the reaction of NaN 3 with both cis ‐ and trans ‐Ru III (Cl) 2 (PPh 3 )( NNO ISQ ) X and Y , with NNO ISQ being the ligand‐radical version of a redox‐active pincer ligand NN H O H ligand L1 H2 . The final product after reaction in ambient light is a trinuclear complex Z featuring bridging nitrido ligands that originate from the sodium azide as well as three fully reduced NNO AP fragments (Scheme ).…”

“…[55] The group of van der Vlugt reported the reaction of NaN 3 with both cis-a nd trans-Ru III (Cl) 2 (PPh 3 )(NNO ISQ ) X and Y,w ith NNO ISQ being the ligand-radical version of ar edox-active pincer ligand NN H O H ligand L1 H2 . [56] The final product after reaction in ambient light is at rinuclear complex Z featuring bridging nitrido ligands that originate from the sodium azide as wella st hree fully reduced NNO AP fragments (Scheme 11). Isotopel abeled 15 N-azide studies coupled to GC analysis of the formed N 2 by-product strongly suggests multiple events of substrate-to-ligand single-electron transfer.T herea ppears to be much potential to extrapolate this concept of activating substrates by as ubstrate-to-ligand single-electron transfer to catalytic applications.…”

Controlled Interconversion of a Dinuclear Au Species Supported by a Redox‐Active Bridging PNP Ligand Facilitates Ligand‐to‐Gold Electron Transfer

“…The absolute configuration was established by anomalous-dispersion effects in diffraction measurements on the crystal, and the Flack parameter refines to À0.009 (4). (4), c = 17.6351 (5) , b = 112.891(3) o , V = 5078.7(2) 3 , Z = 4, T = 110(2) K, l = 0.71073 (Mo K-a), D x = 1.904 gcm À3 , m = 6.090 mm À1 .1 9707 Reflections were measured up to ar esolution of (sin q/l) max = 0.65 À1 .7 986 reflections were unique (R int = 0.0262), of which 7757 were observed [I > 2s(I)].6 52 Parameters were refined with 136 restraints. R1/wR2[ I > 2s(I)]: 0.0186/0.0358.…”

“…3 Redox-activel igandsh ave recently emerged as interesting tools to obtain new reactivity in homogeneous catalysis. [4,5] Various nitrogen-based ligands (ands ubstrates) have been de-scribeda sr edox non-innocent. [6] For example, tridentate diarylaminophosphino (PNP) ligands engage in reversible one-electron oxidation processes at nitrogen upon deprotonation and coordination of the central amido functionality to a( transition) metal.…”

Bond Activations Assisted by Redox Active Ligand Scaffolds

“…The group of van der Vlugt employs aminophenol NNO pincer in ruthenium complexes isolated in their cis ‐ and trans ‐ forms ( 32 and 33 ) (Figure ) . The electronic form of the complexes 32 and 33 was rather described by a median description as Ru II ‐NNO IBQ ↔ Ru III ‐NNO ISQ The redox active ligand acts as a sink on reaction of these complexes with sodium azide to yield an architypical trinuclear ruthenium complex 34 bridged by two nitrido groups.…”