Straightforward Synthesis of Substituted p‐Quinones: Isolation of a Key Intermediate and Use as a Bridging Ligand in a Diruthenium Complex

Energy‐Level Tailoring in a Series of Redox‐Rich Quinonoid‐Bridged Diruthenium Complexes Containing Tris(2‐pyridylmethyl)amine as a Co‐Ligand

“…and L 3 À2H with other substituents on the nitrogen atoms [8] and in the completely unsubstituted case. [16] The strongly donating acac ligand stabilizes the Ru III state in the starting complex, and reduction of the bridging ligand leads to the abovementioned three-spin system.…”

“…[16] The use of better donating co-ligands such as tmpa in the present case, or acetylacetonato (acac) as observed earlier, [8,16] gives access to higher oxidation states of the metal centers, such as Ru III or Ru…”

“…Substituting two of the [O] groups with the isoelectronic [NR] group leads to ligands with an [O,N,O,N] donor set, in which the steric as well as electronic properties can be readily varied with the substituents on the nitrogen atoms. [8][9][10] Such ligands have attracted attention recently because of their use in homogenous catalysis, [11,12] supramolecular chemistry, [13] magnetic materials, [14] and as bridging lig-A C H T U N G T R E N N U N G ands for "metal-metal" coupling. [8,[15][16][17] Research on mixed valency has primarily revolved around ruthenium complexes.…”

“…[8][9][10] Such ligands have attracted attention recently because of their use in homogenous catalysis, [11,12] supramolecular chemistry, [13] magnetic materials, [14] and as bridging lig-A C H T U N G T R E N N U N G ands for "metal-metal" coupling. [8,[15][16][17] Research on mixed valency has primarily revolved around ruthenium complexes. [18][19][20][21][22] Combining quinonoid ligands as bridges in such complexes raises ambiguities in metal-versus ligand-centered redox activities because of the close-lying ruthenium dp and quinonoid-based p* orbitals.…”

Radical ligand-containing single-molecule magnets

“…Efforts to generate benzosemiquinonoid-containing transition metal complexes with a nuclearity of greater than one have resulted in numerous dinuclear compounds, including those containing metal centers bridged by derivatives of 2,5-dihydroxy-1,4-benzoquinonoids [172][173][174][175][176][177][178][179][180][181][182][183][184][185][186][187][188][189], bis(pyrazolyl)benzoquinonoids [190][191][192][193], bis(phosphine)benzoquinonoids [194,195], bis(amino) benzoquinonoids [196][197][198][199][200][201][202], and bis(amino)diiminobenzoquinonoids [86,[203][204][205][206]. Indeed, the radical form of these ligands has shown enhanced magnetic coupling compared to their non-radical redox isomers [174,180,182].…”