A magnesium complex containing a reduced 2,2′-bipyridyl ligand: Synthesis, structure, reactivity, and computational studies

An Isolable Magnesium(II)-Radical Dianion Complex

“…Very recently, Ren et al , and Gilliard et al reported the magnesium-bipyridine and -diazo complexes D – G . Analyses of the electronic structures reveal that the bipyridine and diazo ligands are in a radical anion state due to the redox-active properties, and the magnesium center is essentially in the +2 oxidation state.…”

Reduction of a 1,4-diazabutadiene and 2,2’-bipyridine using magnesium(I) compounds

“…We believed that the unique combination of properties that magnesium(I) reagents hold could lend them to the selective oneelectron reduction of 1,4-diazabutadienes (DAB) and 2,2'-bipyridine (bipy). Indeed, the radical products of these reductions could themselves be synthetically useful, as has previously shown to been the case for related radical systems (Ren et al, 2017). Here, we describe the synthesis and structural characterization of three such magnesium complexes of DAB and bipy radicals.…”

“…While the one and two-electron reductions of such compounds have previously been achieved by a number of methods (e.g. reaction with activated elemental magnesium, and alkali metal reductions of magnesium halides in the presence of the unsaturate), product selectivity can be a problem (Freeman et al, 2019;Gao et al, 2011;Gardiner et al, 1994;Liu et al, 2009;Ren et al, 2017). We believed that the unique combination of properties that magnesium(I) reagents hold could lend them to the selective oneelectron reduction of 1,4-diazabutadienes (DAB) and 2,2'-bipyridine (bipy).…”

“…Similarly, treating [{( Mes Nacnac)Mg} 2 ] with 2,2'-bipyridine gave rise to a low isolated yield of the purple crystalline compound, 3, which incorporates one singly reduced and one neutral bipy ligand. It should be noted that the closely related radical complex, [( Dip Nacnac)Mg(bipy•)], has been reported to arise from the reduction of [( Dip Nacnac)MgBr], using KC 8 in the presence of bipy (Ren et al, 2017). It is possible that only one bipy ligand coordinates the Mg center in that complex because of its sterically bulkier β-diketiminate, relative to that in 3.…”

“…This becomes apparent when those distances are compared to those in unreduced and singly reduced bipy ligands in related complexes, e.g. C-C 1.487(3) Å and N-C 1.349 Å (mean) in [( Dip Nacnac)Mg(SePh)(bipy)]; and C-C 1.425(3) Å and 1.392 Å (mean) in [( Dip Nacnac)Mg(bipy•)] (Ren et al, 2017).…”