Methylrhenium Oxides: Synthesis from R₂O₇ and Catalytic Activity in Olefin Metathesis

Rhenium-containing metathesis catalysts are formed selectively and in good yields from Re2O7 according to (a) and (b). In the presence of SnMe4, all four complexes are catalytically active, while in the absence of SnMe4 only 3, the methyl-richest compound, still catalyzes the metathesis. 2 is the only diamagnetic compound in the series R6–2nReOn; this can be attributed to spin-pairing in the ReRe bond.