Dinuclear Nickel Complexes in Five States of Oxidation Using a Redox-Active Ligand

Abstract

Redox-active nitrogen donor ligands have exhibited broad utility in stabilizing transition metal complexes in unusual formal oxidation states and enabling multielectron redox reactions. In this report, we extend these principles to dinuclear complexes using a naphthyridine-diimine (NDI) framework. Treatment of ((i-Pr)NDI) with Ni(COD)2 (2.0 equiv) yields a Ni(I)-Ni(I) complex in which the two metal centers form a single bond and the ((i-Pr)NDI) ligand is doubly reduced. A homologous series of ((i-Pr)NDI)Ni2 complexes in five oxidation states were synthesized and structurally characterized. Across this series, the ligand ranges from a neutral state in the most oxidized member to a dianionic state in the most reduced. The interplay between metal- and ligand-centered redox activity is interrogated using a variety of experimental techniques in combination with density functional theory models.

NiI Catalyzes the Regioselective Cross‐Coupling of Alkylzinc Halides and Propargyl Bromides to Allenes

“…However,N i I -alkyl complexes have been appointed as the active speciesf or Negishi, Kumada, and Suzuki cross-couplingst hat involve alkyl electrophiles. [19] This complex showsaNiÀNi bond length of 2.29 ,w hich indicates am etal-metal interaction (the Vand er Waals radius of Ni is 1.63 ). Interestingly,w ef ound that I may dimerize exothermically (À1.4 kcal mol À1 )t of ormadiamagnetic complex (Idim; Figure3).…”

Binuclear complexes of Ni(i) from 4-terphenyldithiophenol

“…One can differentiate between structural motifs in which electronic coupling of the Ni(I) ions either occurs through bonding to (i) bridging conjugated π-systems in both syn-and antarafacial fashion, [1][2][3][4][5][6][7][8] (ii) bridging amido, 9 phosphido, 10 thiolato, 11,12 sulfido, 13 halogenido, [14][15][16][17] and hydrido 18 ligands in the form of Ni 2 (μ-X) 2 cores, (iii) bridging diphosphine, 19,20 and biphenyldiyl 15,21,22 ligands, or in the form of unsupported Ni-Ni bonds. One can differentiate between structural motifs in which electronic coupling of the Ni(I) ions either occurs through bonding to (i) bridging conjugated π-systems in both syn-and antarafacial fashion, [1][2][3][4][5][6][7][8] (ii) bridging amido, 9 phosphido, 10 thiolato, 11,12 sulfido, 13 halogenido, [14][15][16][17] and hydrido 18 ligands in the form of Ni 2 (μ-X) 2 cores, (iii) bridging diphosphine, 19,…”

“…One can differentiate between structural motifs in which electronic coupling of the Ni(I) ions either occurs through bonding to (i) bridging conjugated π-systems in both syn-and antarafacial fashion, [1][2][3][4][5][6][7][8] (ii) bridging amido, 9 phosphido, 10 thiolato, 11,12 sulfido, 13 halogenido, [14][15][16][17] and hydrido 18 ligands in the form of Ni 2 (μ-X) 2 cores, (iii) bridging diphosphine, 19,20 and biphenyldiyl 15,21,22 ligands, or in the form of unsupported Ni-Ni bonds. 16 Based on solution reactivity and VT EPR studies on solid samples dinickel biradicals coexist in thermal equilibria with diamagnetic ground states. 16 Based on solution reactivity and VT EPR studies on solid samples dinickel biradicals coexist in thermal equilibria with diamagnetic ground states.…”

Reductive Cyclopropanations Catalyzed by Dinuclear Nickel Complexes

“…Herein, we report an entry into transition-metalcatalyzed reductive carbene transfer processes in the context of ac yclopropanation mediated by the dinuclear Ni complexes 1-3 ( Figure 2). [11] Thep rocedure allows CH 2 Cl 2 , [12] Figure 1. Noncatalytic and transition-metal-catalyzed alkene cyclopropanation reactions.…”