Synthesis, characterization, and crystal structure of an iron(II) 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane macrocyclic complex

The synthesis and detailed characterization of the macrocyclic complex [Fe(meso)(CH3CN)2](ClO4)2·2CH3CN (meso: 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) based on analytical, spectrometric, spectroscopic and X-ray diffraction methods are reported herein. This is the first single crystal structure of an iron-meso complex ever reported in the literature. The molecular structure revealed a tetragonally distorted octahedral geometry with the iron(II) bound to four amine nitrogens in the equatorial plane, while the apical positions are occupied by acetonitrile molecules. The macrocycle adopts the most stable conformation with the six-membered rings in chair form, while the gauche conformation is seen for the five-membered rings. The compound crystallizes in the space group P21/n, with cell parameters a=10.139(1), b=12.237(1), c=13.311(1) Å, β=99.542(2)° and Z=2.