SF₆ as a Selective and Reactive Fluorinating Agent for Low-Valent Transition Metal Complexes^#

SF6 has been found to react readily with vanadocene, yielding V(C5H5)2F, while reactions with decamethylchromocene can lead to a number of products, depending on conditions. Among the products can be included Cr(C5Me5)F2(dmap) (dmap = p-dimethylaminopyridine), Cr(C5Me5)2+[Cr2(C5Me5)2F5]-, and Cr8(C5Me5)6F18. Each of these reactions is likely to occur via the equivalent of an inner-sphere electron-transfer process. An even more rapid reaction was observed with the 19-electron Fe(C5H5)[1,3,5-C6H3(t-C4H9)3] complex, leading to various salts of the expected 18-electron cation. In these cases, the reactions are likely to be analogous to an outer-sphere electron transfer, presumably leading initially to a “naked” fluoride ion. Structural characterization of each of these species has been obtained through X-ray diffraction studies.