A Stable Aminyl Radical Coordinated to Cobalt

Abstract

A family of cobalt complexes bearing the trop NH [bis(5-H-dibenzo[a,d]cyclohepten-5-yl)-amine] and 2,2'-bpy (2,2'-bipyridine) chelate ligands were prepared and fully characterized. The compounds [Co(trop N)(bpy)], [Co(trop NH)(bpy)] , and [Co(trop N)(bpy)] are cobalt complexes interrelated by one-electron redox processes and/or proton transfer. Two limiting resonance structures can be used to describe the paramagnetic complex [Co(trop N)(bpy)] : [Co (trop N )(bpy)] (Co amido) and [Co (trop N )(bpy)] (Co -aminyl radical). Structural data, DFT calculations, and reactivity toward H-abstraction indicate a slightly higher contribution of the aminyl radical form to the ground state of [Co(trop N)(bpy)] . The results described here complete the series of Group 9 metal aminyl radical complexes bearing the diolefin amine ligand trop NH.

Electronic Structures and Reactivity Profiles of Aryl Nitrenoid-Bridged Dicopper Complexes

“…Chemical reduction of the imido complexes afforded dicopper iminyl products as determined by EPR, Cu/N XAS, crystallography, and computations. The iminyl ligand is distinct from previously reported subvalent nitrogen motifs which arise from radical delocalization following nitride, , imide, ,,, or amide − oxidation. , The iminyl complexes reported herein show modest disruption of the aryl units, arising from population of the NAr lowest-lying π* orbital. The iminyl density is predominantly localized on the N 2p x orbital, normal to the [Cu 2 (μ 2 -NAr)] plane, optimally located to aminate the benzylic C–H bonds of the ( Mes dmx) ligand but remain sterically occluded in the ( t Bu dmx) framework and are thus robust.…”

Gesellschaft Deutscher Chemiker Prizes and Honors

“…Grützmacher's research interests include phosphorus radicals, low‐coordinated phosphorus compounds and metal phosphides, photoinitiators based on main‐group elements, and transition‐metal complexes as catalysts for dehydrogenative coupling reactions. He has reported in Chemistry—A European Journal on a stable cobalt‐coordinated aminyl radical, and in Angewandte Chemie on phenylphosphinidene transfer reactions . Grützmacher has been on the Editorial Board of Angewandte Chemie since 2014.…”

Redox Communication between Two Diarylamido/Bis(phosphine) (PNP)M Moieties Bridged by Ynediyl Linkers (M = Ni, Pd, Pt)

“…15,16 The oxidation of diarylamido ligands can be related to those of other metalbound aminyl radicals. 41,42 We became interested in investigating the properties of group 10 bimetallic complexes, in which the two (PNP)M sites are connected by ynediyl linkers (Figure 1). We reasoned that such a design is an amalgam of the types of systems exemplified by compounds A−F in that the two intimately metal bound redox sites are connected by an organic and potentially conjugating linker but the metal centers themselves are not expected to undergo oxidation.…”