Heterospin complexes of fluorinated dinuclear CuII and MnII triketonates with nitroxides

Abstract

Dinuclear heterospin complexes of CuII and MnII 1,1,1,7,7,7-hexafluoroheptane-2,4,6-trionates ([Cu2L2] and [Mn2L2], respectively) with nitronyl nitroxides 2-R-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide 1-oxyls (NIT-R, R = H, Me, Et, m-C5H4N, m-NCC6H4, p-NCC6H4, PzMe) and the diradical NIT-Pz-(CH2)4-Pz-NIT (Pz is 1,4-pyrazolylene) were synthesized and structurally characterized. In the complexes under study, the CuII atom tends to have the square-pyramidal coordination environment, and the MnII atom is in an octahedral environment. The magnetochemical investigation of the compounds in the temperature range of 2–300 K showed that the antiferromagnetic exchange coupling dominates in the [Cu2L2] molecules, whereas this coupling in [Mn2L2] is manifested in the experimental plot μeff(T) at T < 100 K. The magnetic properties of the heterospin complexes of [Cu2L2] with NIT-R are also determined by the intramatrix antiferromagnetic exchange coupling. For the complexes of [Mn2L2] with NIT-R, the coordination mode of the nitroxide plays a decisive role.