Abstract
The reaction cavity of the nitro group in the crystal of the title compound, [CoCl(NO(2))(C(10)H(24)N(4))]Cl, (I), was investigated to confirm that it offers sufficient free space for linkage isomerization to occur in accordance with the observed photochemical reactivity. The complex cation has crystallographic 2/m symmetry and the nitro and chloro ligands at the trans positions are statistically disordered. The complete cyclam ligand is generated by symmetry from a quarter of the mol-ecule. In the crystal of (I), the complex cations and Cl(-) ions are linked into a three-dimensional network by N-H⋯Cl(counter-ion) hydrogen bonds.