Investigation of nitro-nitrito photoisomerization: Crystal structure of trans-chloridonitro(1,4,8,11-tetraazacyclotetradecane-κ⁴ N,N′,N′′,N′′′)cobalt(III) chloride

The reaction cavity of the nitro group in the crystal of the title compound, [CoCl(NO₂)(C₁₀H₂₄N₄)]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 molecule. 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.