Superoxo, peroxo, and hydroperoxo complexes formed from reactions of rhodium porphyrins with dioxygen: thermodynamics and kinetics

Weihong Cui; Bradford B Wayland

doi:10.1021/ja0628755

Superoxo, peroxo, and hydroperoxo complexes formed from reactions of rhodium porphyrins with dioxygen: thermodynamics and kinetics

J Am Chem Soc. 2006 Aug 16;128(32):10350-1. doi: 10.1021/ja0628755.

Authors

Weihong Cui¹, Bradford B Wayland

Affiliation

¹ Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.

PMID: 16895384
DOI: 10.1021/ja0628755

Abstract

Rhodium(II) porphyrin complexes react with dioxygen to form terminal superoxo and bridged mu-peroxo complexes. Equilibrium constants for dioxygen complex formation with rhodium(II) tetramesitylporphyrin ((TMP)Rh*) and a m-xylyl-tethered dirhodium(II) diporphyrin complex (*Rh(m-xylyl)Rh*) are reported. (TMP)Rh-H reacts with oxygen to form a transient hydroperoxy complex ((TMP)Rh-OOH), which reacts on to form the rhodium(II) complex ((TMP)Rh*) and water. Kinetic studies for reactions of (TMP)Rh-H with O2 suggest a near concerted addition of dioxygen to the (TMP)Rh-H unit. Reactivity studies for mixtures of H2/O2 and CH4/O2 with the dirhodium(II) complex (*Rh(m-xylyl)Rh*) are reported.