The reaction of the ligand HL ´(HCl) 2 (HL = 2,6di(aminomethyl)-4-tert-butyl-thiophenol) with MCl 2 in methanol in the presence of sodium methanolate and air affords the dinuclear complexes [L 3 M 2 ][ClO 4 ] 3 (M = Fe: 2, Co: 3) in 85% and 68% yield, respectively. Both complexes were characterized by infrared spectroscopy, magnetic susceptibility measurements, and 1 H NMR spectroscopy. By temperature-variable 57 Fe Mo È ssbauer spectroscopy diamagnetic 2 is shown to exhibit a gradual spin transition between the species [L 3 (low-spin-Fe) 2 ] 3+ ((ls,ls)-2) and [L 3 (high-spin-Fe) 2 ] 3+ ((hs,hs)-2). At room temperature the relative concentrations of both species are nearly equal. Well resolved quadrupole doublets at all temperatures for both (ls,ls)-2 (C in the range 0.22(1)±0.28(1) mm s ±1 ) and (hs,hs)-2 (C in the range 0.48(1)±0.53(2) mm s ±1 ) are indicative of a spin conversion time longer than the half-life of the I = 3 / 2 state of 57 Fe. Cyclic voltammetry and square wave voltammetry of 2 in CH 3 CN solution reveal four quasi-reversible one-electron transfer processes. The first two processes were assigned to metal-centered reductions of (hs,hs)-2 and (ls,ls)-2, respectively, to yield the mixed-valent species [L 3 Fe II Fe III ] 3+ .