Redox behavior of novel nickel and palladium complexes supported by trianionic non-innocent ligand containing β-diketiminate and phenol groups

Abstract

A new type of nickel and palladium complexes with non-innocent β-diketiminate ligand having redox active phenol groups, 2,4-di-tert-butyl-6-(((1E,2E)-3-((3,5-di-tert-butyl-2-hydroxyphenyl)amino)-2-nitroallylidene)amino)phenol ( L H 3, fully protonated form) have been developed, and the structure, physical properties, and reactivity of their one-electron and two-electron oxidized complexes, [MII(L•2-)] and [MII(L-)]+ ( M = Ni II or Pd II ) have been examined in detail. The two-electron oxidized forms of both complexes, [MII(L-)]+, exhibited hydrogen atom abstraction ability from 1,4-cyclohexadiene (CHD) comparable to its copper analog [ Cu II ( L -)]+ (Dalton Trans. 2013; 42: 2438-2444). The one-electron oxidized form of palladium complex, [ Pd II ( L •2-)], was also found to oxidize CHD, whereas the nickel analog, [ Ni II ( L •2-)], exhibited photo-induced oxidation ability of CHD.