Mn(II) complexes of three [2 + 2] macrocyclic Schiff base ligands. Synthesis and X-ray crystal structure of the first binuclear–di(binuclear) cocrystal

The [2 + 2] cyclocondensation reactions of N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane (L22py), N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane (L23py) and N-(2-pyridylmethyl)-N-(3-aminopropyl)-1,3-diaminopropane (L33py) with 2,6-diformyl-4-methylphenol (dfp) in the presence of MnCl2 4H2O in equimolar ratios are reported. The resulting compounds, (1), (2) and (3), respectively, were characterized by IR spectroscopy, elemental analysis and mass spectrometry. The X-ray crystal structure analysis of (3) showed that it contains a novel cocrystal of a binuclear Mn(II) macrocyclic cation and a di(binuclear) one. The Mn(II) ions in the latter binuclear and di(binuclear) cations are five and six-coordinate respectively. The two binuclear parts in the di(binuclear) cation are bonded through two bridging chloride ions. The macrocyclic ligand in the above cations also has two different conformational structures, but in both cases it catches a proton. The analytical data show that compounds (1) and (2) probably have similar structures to (3).

Graphical abstractThree binuclear–di(binuclear) Mn(II) complexes were prepared by the reaction of three previously known tetraamine ligands bearing a pyridyl group with 2,6-diformyl-4-methylphenol and Mn(II) chloride in equimolar ratios. The resulting compounds were characterized by elemental analysis, IR and mass spectroscopy in all cases and by single crystal X-ray diffraction for one of them.Figure optionsDownload full-size imageDownload as PowerPoint slide