Three lanthanide-based complexes involving a tetrathiafulvalene deriv. (L) in which the lanthanide ion has a pseudo-D4d symmetry have been reported. One is a dinuclear compd. of formula [Dy(hfac)3(L)]2 (1) while the two others are isostructural and described as mononuclear complexes of formulas [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 mol. magnets, while 2 does not. The crystal field splitting of the ground multiplet state has been theor. detd. as well as the orientation of the easy axis of the ground MJ state. The results of ab initio calcns. are in agreement with the exptl. detns. of the anisotropy axis. Irradn. of the lowest-energy charge transfer bands of 3 led to an intense and resolved Yb-centered emission which can be correlated to the magnetic data. Thus 3 can be described as a redox-active luminescent field-induced single-mol. magnet.