Crystal structures of two (5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) complexes

Reported in this contribution are the synthesis and crystal structures of two new FeIII complexes of 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane (HMC), namely, dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) chloride, [FeCl2(C16H36N4)]Cl or cis‐[FeCl2(rac‐HMC)]Cl (1), and dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) tetrachloridoferrate, [FeCl2(C16H36N4)][FeCl4] or trans‐[FeCl2(meso‐HMC)][FeCl4] (2). Single‐crystal X‐ray diffraction studies revealed that both 1 and 2 adopt a pseudo‐octahedral geometry, where the macrocycles adopt folded and planar geometries, respectively. The chloride ligands in 1 are cis to each other, while those in 2 have a trans configuration. The relevant bond angles in 1 deviate substantially from an ideal octahedral coordination geometry, with the angles between the cis substituents varying from 81.55 (5) to 107.56 (4)°, and those between the trans‐ligating atoms varying from 157.76 (8) to 170.88 (3)°. In contrast, 2 adopts a less strained configuration, in which the N—Fe—N angles vary from 84.61 (8) to 95.39 (8)° and the N—Fe—Cl angles vary from 86.02 (5) to 93.98 (5)°. The crystal structures presented herein consist of two positively charged FeIII–HMC complexes, each of which was prepared from the pure meso‐ or rac‐HMC ligand and which adopt trans or cis configurations, respectively.