Dioxygen-induced decarboxylation and hydroxylation of [NiII(glycyl-glycyl-L-histidine)] occurs via NiIII: X-ray crystal structure of [NiII(glycyl-glycyl-α-hydroxy-D,L-histamine)]·3H2O

Abstract

Electrochemical and EPR studies show that the dioxygen-induced decarboxylation and hydroxylation of [Ni^II(GGH-H_–2)]^–, where GGH is glycyl-glycyl-L-histidine (HL), in aqueous solution occurs via a Ni^III intermediate; the product [Ni^II(Gly-Gly-α-hydroxy-D,L-histamine-H₂)]·3H₂O is shown by X-ray crystallography to contain square-planar Ni^II coordinated to the terminal amino group [Ni–N, 1.932(3)Å], two deprotonated amide N's [1.884(3) and 1.831(3)Å] and imidazole δN [1.908(3)Å].