Unprecedented Variety of Outcomes in the Oxygenation of Dinuclear Alkylzinc Derivatives of an N,N‐Coupled Bis(β‐diketimine)

Abstract

Reactions between O 2 and organometallics with non-redox-active metal centers have received continuous interest foro ver1 50 years, althoughs ignificant uncertainties concerningt he character and details of the actual mechanism of these reactions persist. Harnessingd inuclear threecoordinate alkylzinc derivatives of an N,N-coupled bis(b-diketimine) proligand (LH 2 )a sam odel system, we demonstrate for the first time that as light modification of the reaction conditions might have ad ramatic influence on the oxygenation reaction outcomes, leading to an unprecedented variety of products originating from as ingle reaction system,t hat is, partially and fully oxygenated zinc alkoxides,zinc alkylperoxides, and zinc hydroxide compounds. Our studies indicate that accessibility of the three-coordinate zinc center by the O 2 molecule, coupled with the lower reactivity of Zn-Me vs.

Reaching Milestones in the Oxygenation Chemistry of Magnesium Alkyls: towards Intimate States of O2 Activation and the First Monomeric Well‐Defined Magnesium Alkylperoxide

“…Undoubtedly, a remarkable observation of these studies is the stabilization of the magnesium alkylperoxide 4 by thf. Thus, these studies along with our earlier results for zinc alkylperoxide unambiguously prove that stabilization of the most unstable oxygenation products is due to the increased electron density on the metal centre.…”

“…Towards the role of the coordination state of the magnesium centre in the oxygenation of magnesium alkyls : As mentioned, our previous results emphasized the essential role of the coordination state of the metal centre in the oxygenation reaction. For example, the four‐coordinate zinc alkyl species do not display reactivity towards dioxygen, in contrast to the three‐coordinate species, which react smoothly (Scheme A) . Remarkably, the similar issue has not yet been resolved for alkylmagnesium complexes .…”

“…Furthermore, we have provided compelling evidence that a variety of oxygenation products result from the decomposition of (L)ZnOOR species mediated by the O−O bond scission. Recently, we demonstrated that the observed diversity of the reaction outcomes may be a distinguishing feature of a single reaction system based on dinuclear alkylzinc complexes incorporating a sterically encumbered bis( β ‐diketiminate) ligand . In their entirety, our results provided a basis for a new mechanism for the oxygenation of organometallics with non‐redox‐active metal centres, an inner‐sphere electron‐transfer mechanism (ISET) .…”

“…Moreover, despite the structural diversity of isolated metal alkylperoxides with non‐redox‐active centres, knowledge of their modes of further transformation still appears to be fragmentary. Our group's systematic studies on the reactivity of zinc alkyls towards O 2 have demonstrated that not only zinc alkylperoxides and alkoxides, but also zinc peroxide, hydroxide, oxo and even carboxylate species can be isolated from the controlled oxygenation of organozincs. Furthermore, we have provided compelling evidence that a variety of oxygenation products result from the decomposition of (L)ZnOOR species mediated by the O−O bond scission.…”

Ligands with Two Monoanionic N,N‐Binding Sites: Synthesis and Coordination Chemistry

“…Heteroleptic dinuclear complexes of type C are known for transition metals (Cu, Y, Zn) as well as for rare‐earth (Yb) and main‐group elements (Al, Ca, In, Mg, Na, Tl). Notably, calcium and magnesium complexes of type C show a dynamic behavior and undergo rapid ligand exchange in accordance with the Schlenk equilibrium yielding homoleptic complexes of type D .…”