Tripositive Mercury. Low Temperature Electrochemical Oxidation of 1,4,8,11-Tetraazacyclotetradecanemercury(II) Tetrafluoroborate

Abstract

A complex of mercury(III) has been synthesized by electrochemical oxidation of [Hg(Cyclam)] [BF4]2 (Cyclam = [14]aneN4 or 1,4,8,11-tetraazacyclotetradecane) in propionitrile at -78°. Accessibility to mercury in a formally tripositive state is consistent with its ionization potentials and with known oxidation states and oxidation potentials of neighboring elements. Measurements by cyclic voltammetry, electron spin resonance, and visible spectroscopy establish that the half-life of [Flg([14]aneN4)]3+ is 5 s at -78°. The oxidation potential of [Hg([14]aneN4)]2+ shifts markedly as the temperature is lowered and becomes appreciably lower than the ligand oxidation potential. For [Hg([14]aneN4)]3+, the g factor is 2.014, the hyperfine coupling constant is 2124 MHz for 199Hg, and 14N hyperfine coupling is not observed, consistent with a d9 configuration for mercury. © 1976, American Chemical Society. All rights reserved.