Phosphine-Triggered Co-catenation of:BR and CO on an Iron Atom

摘要

Since the early 19th century, carbon monoxide CO has been known to undergo reductive coupling reactions when exposed to molten potassium, affording potassium salts of croconate [C5O5]~(2-) and rhodizonate [C6O6]~(2-). At the end of the 20th century, the scope of CO coupling reactions was extended to intramolecular C-C bond formation between two metal-coordinated CO ligands. To stabilize the final product, Lewis acids were introduced to form strong bonds with oxygen. Thus, the otherwise unstable acetylenes with the general formula of ROC≡COR (R = H, trialkylsilyl, BF3) were generated in the coordination sphere of transition metals. More recently, a handful of U~(III) complexes turned out to be able to couple CO, leading to [U]OC≡CO[U] as well as cyclic (C_nO_n) (n = 3, 4) moieties that are stabilized by two uranium(IV) fragments.