Ni(ii) complexes of a new tetradentate NN′N′′O picolinoyl-1,2-phenylenediamide-phenolate redox-active ligand at different redox levels

Abstract

Using an asymmetric ligand [Ni(L2)]z (z = 0, 1+ and 1−) complexes have been synthesized and their molecular, electronic structures elucidated, supported by DFT calculations: [NiII{(L2)˙2−}], [NiII{(L2)−}]+ and [NiII{(L2)3−}]−.

Phenoxazinyl Zn(ii) diradical complex formed via redox-driven cyclization of a 2-aminophenol-based N3O ligand. Isolation of the modified N3 ligand radical and its Ni(ii) complex

“…S12, ESI ‡)). 3 The cathodic potential (E 1/2 = −0.80 V vs. Fc + /Fc) of the aminophenolate radical is ∼500 mV more positive compared to the Phz N • radical in 2. This is consistent with the fact that in the fully reduced state, Phz is more electron-rich than amidophenolate.…”

“…In addressing this issue, we employed an asymmetric AP-and PDA-based mono(phenol) redox-active ligand (H 3 L 1 ), previously reported by our group. 3 An aerobic reaction of Zn(ClO 4 ) 2 •6H 2 O with H 3 L 1 in the presence of Et Mg 2+ /Ca 2+ salts were also attempted; ESI ‡). The positive-ion ESI-MS spectrum of 1 in CH 3 CN showed a peak at m/z = 891.3571/891.3572 (calcd/found), corresponding to the species {Zn(L 1 *) 2 + H + } + , based on its simulated mass and isotopic distribution pattern (Fig.…”

“…Di- tert -butyl substituted N,O-donor 2-aminophenols (APs) and N,N-donor 1,2-phenylenediamines (PDAs) are widely explored prototypes of redox-active noninnocent ligands (NILs). 1 While extensive research has been done using such ligands separately, 1 only a few have been reported with both proradical components in symmetric 2 and asymmetric 3 ligand environments. Although radical congeners of these ligands are generally stable with a native ligand-backbone, 1–3 in some cases, intra-/inter-molecular oxidative cyclization reactions have been documented.…”

“…1 While extensive research has been done using such ligands separately, 1 only a few have been reported with both proradical components in symmetric 2 and asymmetric 3 ligand environments. Although radical congeners of these ligands are generally stable with a native ligand-backbone, 1–3 in some cases, intra-/inter-molecular oxidative cyclization reactions have been documented. 4 Intramolecular oxidative cyclization generating the phenoxazinylate (Phz) radical with the AP- and PDA-fused bis(phenol) ligand H 4 L [ N , N ′-bis(3,5-di- tert -butyl-2-hydroxy-phenyl)-1,2-phenylenediamine] 2 has been achieved.…”

Electronic Transition and Magnetic Coupling Regulation in Trimetallic Complexes Featuring a New Bridging Ligand Obtained by Oxidative Addition

“…There is currently considerable attention in the prediction of electronic configuration and reactivity of complexes with transition metals due to the diversity of electronic properties of auxiliary ligands and central metals. − In transition-metal complexes, the classical redox process only involves metal ions, and the oxidation states of the metal ions could be defined precisely. However, there are “noninnocent” ligands named by Jørgensen, which could also participate in redox process. − It has been well determined that the interaction of metals with noninnocent ligands is important to promote electron transfer processes in biological or chemical reactions. − In addition, the noninnocent ligands deeply offer more features in establishing “correct” electronic distribution . Hence, a profusion of noninnocent ligands with the N, O, and S atoms is utilized more frequently in the coordination, organometallic chemistry, and biochemistry, such as dithiolenes, , semiquinone (SQ) − or the hybrid o -aminophenol, − glyoxal-bis­(2-mercaptoanil) (H 2 gma), − etc.…”