Fluorinated dienes in transition-metal chemistry - the rich chemistry of electron-poor ligands.

The coordination chemistry of alkenes is among the fundamentals of organometallic chemistry. However, despite the beneficial effects of fluorination to organic molecules, their fluorinated counterparts are rarely found in transition-metal complexes and most examples are limited to simple monoalkenes like tetrafluoroethene. The paucity of fluorodiene complexes is contrasted by their structural diversity. Seemingly similar dienes containing conjugated, isolated or cumulated double bonds exhibit largely different ligand properties. While the most prominent group, the conjugated fluorodienes, is very flexible in hapticity, their analogues bearing isolated double bonds behave more like monoalkenes. Fluorinated cumulenes in contrast are thermally labile, their chemistry is dominated by the stabilising effect of metal coordination. This review outlines the synthesis, structure and reactivity of transition-metal complexes derived from fluorinated dienes.