We next investigated the feasibility of removing the phosphine ligands. When iron(III) species 4 was treated with a slight excess of triphenylborane in THF, the color of the reaction mixture changed from green to orange, and precipitation of Me3P-BPh3 was observed (Scheme 3). Crystallization from Et2O gave 5-Et2O in 58% yield (Figure ). Dissolving 5-Et2O in THF and removing solvent under vacuum several times led to the formation of 5-THF (Figure ). We refer to these compounds collectively as 5-Solv because of their similarity and ability to interconvert as a function of solvent. ). Mössbauer spectra of 5-THF differ, however, between the solid state and a frozen THF solution. Specifically, there is a higher isomer shift of 0.45 mm/s for the frozensolution spectrum, which may suggest that the dimer is broken up with THF replacing the bridging sulfur (Figure ). The frozen solution also shows an increased quadrupole splitting and marked doublet asymmetry (|ΔEQ| = 4.26 mm/s, ΓL = 0.73 mm/s, ΓR = 0.49 mm/s). The 1 H NMR spectrum of 5-Et2O in THF-d8 shows six broad signals between 12 and -81 ppm (Figure ). The number and integration of the peaks is consistent with C2v symmetry; a seventh expected peak integrating to 4H was not resolved, likely due to broadening. This is also consistent with the dimer breaking up, although it is also possible that there is some other dynamic phenomenon. The 1 H NMR spectra of 5-Solv in C6D6 have at least 12 peaks with considerable broadness, which prevented further analysis but points to a lowered symmetry in the dimer.