Cupration of C2F5H: Isolation, Structure, and Synthetic Applications of [K(DMF)2][(t‑BuO)Cu(C2F5)]. Highly Efficient Pentafluoroethylation of Unactivated Aryl Bromides

Pentafluoroethane, C2F5H (HFC-125), is smoothly cuprated with preisolated or in situ-generated [K­(DMF)]­[(t-BuO)2Cu] to give [K­(DMF)2]­[(t-BuO)­Cu­(C2F5)] (1) in nearly quantitative yield. Complex 1 has been isolated, structurally characterized, and demonstrated to be an exceedingly versatile pentafluoroethylating reagent for a variety of substrates, including unactivated aryl bromides.