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1, 4, 8, 11-tetraazacyclotetradecane(cyclam) gave two anodic waves (1:1) (E1/2=-0.35 and -0.52V) in acetonitrile containing 0.1mol dm-3 R4NClO4 (R=Et or Bu) or 0.05mol dm-3Me4NClO4 as the supporting electrolyte at 25°C. With 0.1mol dm-3 NaClO4, the potential difference between two waves became small (E1/2=-0.325 and -0.465V), and finally, with 0.1mol dm-3 LiClO4, the two waves were combined into a single anodic wave at E1/2=-0.225V. The anodic waves of cyclam (L) with R4NClO4 were based on successive mercury dissolution reactions: L+Hg_??_[HgL]+_??_[HgL]2+. The process was reversible: the [HgL]2+ complex gave two cathodic waves on the DME at the same potential as the anodic waves from cyclam. The single anodic wave from cyclam in the presence of Li+ ions was attributed to the reaction: [LiL]++Hg_??_[HgL]2++Li+. The formation constant of [LiL]+ was evaluated (Li++L_??_[LiL]+, log K=ca. 6.0) indirectly by the shift of the cathodic half-wave potential of [HgL]2+ to a positive direction with increasing concentration of Li+. Other voltammetric techniques, such as cyclic voltammetry or differential pulse polarography and coulometry, were also employed to elucidate the electrochemical process.

Polarographic Behavior of 1,4,8,11-Tetraazacyclo-tetradecane in Acetonitrile