Synthesis, structure, electronic and magnetic properties of two new complexes obtained by coordination of Co(II) and Mn(II) phenyltrifluoroacetylacetonate with a nitronyl nitroxide radical

Two new magnetic compounds were obtained by using β-diketonate 1,3-butanedione, 4,4,4-trifluoro-1-phenyl (Phtfac) as ligand. The complexes with formula [M(Phtfac)2(NITpPy)2 [M = Co(II) 1, Mn(II) 2; NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] were characterized structurally and magnetically. Both structures consist of [M(II)(Phtfac)2(NITpPy)2] units, where the metal ion is in an octahedral environment bound to two NITpPy through the nitrogen atom of the pyridine ring. Compound 1 is the first case where a nitronyl nitroxide radical is coordinated to cobalt linked by the β-diketonate by the nitrogen atom of the pyridine ring. The magnetic behavior of this compound indicates that the cobalt ion and the NITpPy ligand are antiferromagnetically coupled with a coupling constant of −4.3 cm−1. The manganese derivative shows a ferromagnetic behavior with a coupling constant of 3.0 cm−1. The discussion of the electronic structure based on DFT calculations allows the rationalization of the ferromagnetic behavior.