New publication of CIEL team : “Spin Cross-Over (SCO) complex based on unsymmetrical functionalized triazacyclononane ligand: structural characterization and magnetic properties”
M. Halit, M. Roger, V. Patinec, S. Yefsah, C. J. Gómez-García, S. Triki
Magnetochemistry 2019, 5, 19 – DOI : 10.3390/magnetochemistry5010019
The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7- triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1) which was characterized as the first Fe(II) complex based on unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K as shown by thermogravimetric and DSC measurements.