Alkylation of [2,2′-([2,2′-bipyridine]-6,6′-diyl)bis[phenolato]-N,N′,O,O′]nickel(II) during catalytic reduction of 1-iodooctane

Stoichiometric reduction of primary alkyl monohalides with electrogenerated nickel(I) salen: Formation of aldehydes

“…However, in the presence of a proton donor, an alkane becomes a favorable product via reaction (7). These reaction pathways have been previously discussed in earlier research [58].…”

“…Recent work by Goken [46] has established that the mono-and dioctyl nickel salen species are formed when an excess of 1-bromooctane is catalytically reduced by electrogenerated nickel(I) salen, but no prior evidence for a hydroxonickel salen complex has been obtained. Modification (alkylation) of nickel(II) salen and other nickel-containing catalysts [58] by interactions with alkyl halides, as well as the regeneration of these catalyst precursors, is an ongoing area of research in our laboratory.…”

Reaction of Electrogenerated Ligand-Reduced Nickel Salen with Benzyl Bromide, 1-Bromomethylnaphthalene, and α-Bromodiphenylmethane: A Study of Steric Effects

“…On the basis of established mechanistic pathways [17][18][19][20]22 and our current findings, a possible mechanism for the nickel(I) salen-catalyzed reduction of the two aryl halides is proposed in Scheme 2. The electrogenerated metal-reduced nickel(I) (2) or the ligand-reduced radical−anion (3) can transfer one electron to the substrate, which undergoes reductive cleavage of the carbon−bromine bond to form the corresponding radical and regenerates nickel(II) salen (1) (reaction 1).…”

“…However, the S N 2 nucleophilic substitution could also take place between organic halides and species 3 as a side reaction, causing mono-or dialkylation of nickel(II) salen molecules at the ligand imino bonds (C=N) during the catalytic process. 17,19 Consequently, significant amount of substrate materials could be lost 10 and the nickel(II) salen catalysts would be ultimately deactivated. 9,21 Peters and his colleagues revealed that both monoalkylated and dialkylated nickel salens, which were identified by HPLC−ESI−MS and NMR, could be formed in this electrochemical catalysis.…”

Reaction Mechanism for the Formation of Dialkylated Nickel(II) Salen Involved in the Catalytic Reduction of (Bromomethyl)cyclopropane

“…We carried out cyclic voltammetry (CV) and controlled-potential electrolysis (CPE) for the initial investigations and the electrolyzed solution was subject to HPLC analysis. Following purification by preparative-scale HPLC, the dialkylated nickel(II) salen was examined by ESI-MS, 1 H NMR, COSY, and HECTOR NMR spectrometry. Its structure was resolved and found to be 4.…”