Compound 8 was crystallized from toluene in the presence of 18-crown-6 as 8-crown (Figure , top, and Figure ). The geometry is distorted from square planar, with τ4 = 0.20. The Fe-SAr bond distance is 2.2448(8) Å, which is shorter than the Fe-SAr bond in 7-crown (Table ). Unlike the structure of the THF adduct 7-crown, one mesityl group of THF-free 8-crown is twisted to cover an axial iron site; however, the long 3.06 Å distance between iron and the arene centroid is inconsistent with a direct electronic interaction. We previously observed a similar orientation of this thiolate ligand in another SCS iron complex and ascribed this phenomenon to crystal packing effects. We were unable to crystallize four-coordinate thiolate 8 without crown ether. The 1 H NMR spectrum of 8 in THF-d8 has ten broad peaks between 15 and -63 ppm (Figure ). Upon dissolution in THF-d8, the color of 8 changes from dark brown to red, indicating that the THFadduct 7 is likely formed. The number and integration of the signals suggests C2v symmetry, which implies that the crystallographically observed lack of symmetry caused by the bulky aryl thiolate is not preserved in THF-d8 solution.