Direct Observation of Intermediates in the Reaction of Peroxynitrite with Carbon Dioxide

TLDR: In this paper, a weak ESR signal at g=2.013 was used to detect trioxocarbonate(1−) radicals (CO3.−) forming an adduct that absorbs with a maximum at 640 nm and an extinction coefficient of ca. 2 × 102 m−1 cm−1.

Abstract: Peroxynitrite (ONOO−, oxoperoxonitrate(1−)) reacts with carbon dioxide to form an adduct that absorbs with a maximum at 640 nm and an extinction coefficient of ca. 2 × 102 M−1 cm−1. Within 0.1 s at 4°, this absorption decreases while the maximum is shifted to lower wavelengths, which indicates that trioxocarbonate(1−) radicals (CO3.−) are formed. This interpretation is supported by the observation of a weak ESR signal at g=2.013.