Stabilization of Copper Dioxygen Compounds: Design, Synthesis, and Characterization

Bispidine Coordination Chemistry

“…For example, the bispidine-cobalt(II) complexes usually are air stable and oxidation only occurs with strong oxidants (e.g., H 2 O 2 ; see Section III.D.3) (166,167). However, due to the high complementarity for copper(II) (see, however, Section III.D.1) the corresponding copper(I) complexes are, as expected, highly air sensitive (70,81,168,169). Oxidation of the iron(II) complexes to hydroperoxo-and peroxo-iron(III) and to oxo-iron(IV) complexes is generally easily accomplished (170)(171)(172), however, other simple iron(III) complexes (e.g., aqua, chloro, hydroxo) have not yet been isolated or spectroscopically characterized.…”

“…The stability of this, for copper(II) unusual structure, enforced by the (tetradentate) bispidine ligands, has been qualitatively assumed to be due to a high complementarity (42,81) and is the reason for the relatively high complex stabilities (Section III.D.2), the strong bonds to substrates (Section III.D.2, III.D.3), and the interesting biomimetic copper chemistry (Section III.D.3; see, however, the discussion of other structural forms and of the bonding properties below) (81,169,192,196,213).…”

“…The copper coordination chemistry of bispidine ligands has been studied extensively, and this has been particularly rewarding (70,71,81,82,168,169,192,194,196,199,201,213,214). The main reasons are that (1.)…”

“…that lead to the isolation and characterization of novel model complexes with hemocyanine-and catechol oxidase activities properties (81,192,196,213). In the latter case, it was possible to isolate and structurally characterize complexes with coordinated catechol model substrates with structural features, which have been proposed to be of relevance in the enzyme catalysis cycle, but have not been observed before in low molecular weight complexes (192,213).…”

Reactivity of Copper(I) Complexes Towards Dioxygen

“…[69] This group investigated the reaction of dioxygen with a mononuclear copper(I) complex {with the ligand methyl 2,4-bis(2-pyridinyl)-3,7-diazabicyclo[3.3.1]nonane-9-diol-1,5-dicarboxylate} and detected a quite stable peroxo compound. In order to further increase the stability of the oxygenation product, a linker for two of the mononuclear units had to be designed.…”