Ancillary ligand electro-activity effects towards phenyl acetylene homocoupling reaction by a nickel(ii) complex of a non-innocent O-amino phenol ligand: a mechanistic insight

Abstract

A new Ni(ii) complex, was synthesized from the reaction of a non-innocent o-aminophenol ligand, and Ni(OAc)2.

Comparing the Electronic Structure of Iron, Cobalt, and Nickel Compounds That Feature a Phosphine-Substituted Bis(imino)pyridine Chelate

“…Interestingly, 5 was found to exhibit a solution magnetic moment of 1.23 μ B at 25 °C, which is lower than the spin-only value expected for a single unpaired electron. The magnetic susceptibility of crystalline 5 was found to be even lower (0.33 μ B at 25 °C, magnetic susceptibility balance), a value that is within the error expected for a diamagnetic complex …”

Biradical o-iminobenzosemiquinonato(1−) complexes of nickel(ii): catalytic activity in three-component coupling of aldehydes, amines and alkynes

“…The electrochemical behavior of the complex Ni II L 2 BIS is similar to the previously studied o -iminobenzoquinone based complexes of Ni( ii ), 1 owing to the presence of three one-electron ligand-centered redox transitions on the voltammogram ( Fig. 5 and Table 4 ).…”

“…Then the catalytic activity of this complex, NiL 2 BIS , and the previously reported complex, NiL 2 NIS 1 in three-component coupling of aldehydes, amines and alkynes (A 3 -coupling) was investigated and the four-coordinated NiL 2 NIS complex was found to be significantly more efficient catalyst due to the non-innocent o -aminophenol ligand that acts as an “electron reservoir” and can accept and donate electrons in the C–H activation stage of catalytic cycle resulting a high reactivity in A 3 -coupling reaction. This procedure is also environmentally friendly and is done under solvent-free conditions as it does not require any organic solvents.…”

“…All catalytic reactions were monitored by TLC (thin layer chromatography) and all yields refer to isolated products. 1 H NMR spectra were recorded in CDCl 3 on a Bruker DRX-400 AVANCE (400 MHz for 1 H and 100 MHz for 13 C) spectrometer.…”

“…As a part of our ongoing effort we try to investigate the catalytic activity of NiL 2 BIS complex and the previously reported four-coordinated bis- o -iminosemiquinone of NiL 2 NIS 1 (in which L NIS is the bidentate o -iminosemiquinone 1-electron oxidized by 2-amino-4,6-di- tert -butyl-phenol ligand of L NAP ), ( Scheme 3 ), and the comparison between these two Ni( ii ) iminosemiquinone complexes in synthesis of propargylamines from three-component coupling of aldehydes, amines and alkynes, A 3 -coupling reactions ( Scheme 4 ).…”