Magnetic and photo-physical investigations into DyIII and YbIII complexes involving tetrathiafulvalene ligand†
Three lanthanide-based complexes involving a tetrathiafulvalene derivative (L) in which the lanthanide ion has a pseudo-D4d symmetry have been reported. One is a dinuclear compound of formula [Dy(hfac)3(L)]2 (1) while the two others are isostructural and described as mononuclear complexes of formulae [Ln(tta)3(L)]·xCH2Cl2 (LnIII = Dy and x = 1.41 (2); Yb and x = 2 (3)). The nuclearity of the species is driven by the nature of the ancillary ligands. Magnetic properties revealed that 1 and 3 behave as single molecule magnets, while 2 does not. The crystal field splitting of the ground multiplet state has been theoretically determined as well as the orientation of the easy axis of the ground MJ state. The results of ab initio calculations are in agreement with the experimental determinations of the anisotropy axis. Irradiation of the lowest-energy charge transfer bands of 3 led to an intense and resolved Yb-centred emission which can be correlated to the magnetic data. Thus 3 can be described as a redox-active luminescent field-induced single-molecule magnet.
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