First aminoacetone chelate: [Co(tren){NH2CH2C(O)CH3}]3+—a substrate binding and activation model for zinc(ii)-dependent 5-aminolaevulinic acid dehydratase

Abstract

The complex p-[Co(tren){NH₂CH₂C(O)CH₃}](ClO₄)₃·H₂O (4) was produced stereoselectively from [Co(tren)(O₃SCF₃)₂]O₃SCF₃ (1) and 2-(aminomethyl)-2-methyl-1,3-dioxolane (2). The structure of 4 was determined by X-ray crystallography. The complex is the first aminoacetone chelate to be reported and the first structurally characterized example of a non-conjugated ketone moiety coordinated to cobalt(III). The robust complex was stable to aquation in strong acid and behaved as an acid with pK_a = 4.99(1) indicative of a strong activation of the aminoacetone ligand towards deprotonation. The complex constitutes a structural model for a proposed substrate binding mode relevant for substrate activation of the zinc(II)-dependent enzyme 5-aminolaevulinic acid dehydratase.