The unanti-cipated oxidation of a tertiary amine in a tetra-cyclic glyoxal-cyclam condensate yielding zinc(II) coordinated to a sterically hindered amine oxide.

The complex, tri-chlorido-(1,4,11-tri-aza-8-azonia-tetra-cyclo-[6.6.2.0 4,16 .0 11,15 ]hexa-decane 1-oxide-κ O )zinc(II) monohydrate, [ZnCl 3 (C 12 H 23 N 4 O)]·H 2 O, ( I ), has monoclinic symmetry (space group P 2 1 / n ) at 120 K. The zinc(II) center adopts a slightly distorted tetra-hedral coordination geometry and is coordinated by three chlorine atoms and the oxygen atom of the oxidized tertiary amine of the tetra-cycle. The amine nitro-gen atom, inside the ligand cleft, is protonated and forms a hydrogen bond to the oxygen of the amine oxide. Additional hydrogen-bonding inter-actions involve the protonated amine, the water solvate oxygen atom, and one of the chloro ligands.