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 Fe III 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, [FeCl 2 (C 16 H 36 N 4 )]Cl or cis ‐[FeCl 2 ( rac ‐HMC)]Cl ( 1 ), and dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) tetrachloridoferrate, [FeCl 2 (C 16 H 36 N 4 )][FeCl 4 ] or trans ‐[FeCl 2 ( meso ‐HMC)][FeCl 4 ] ( 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)°.