Clusters containing fluorocarbons

Abstract

Nonacarbonylbis(μ 3-fluoromethylidyne)triiron, Fe 3(CO) 9(μ 3-CF) 2, and tetrafluoroferrole, (CO) 3(Fe FeCFCFCFC F(CO) 3, are obtained by the reaction of Fe(CO) 5 with CFBr 3. Fe 3(CO) 9(μ 3-CF) 2 was found to be a versatile starting material for the synthesis of other new clusters. Clusters containing a diferra-allyligand are formed by regioselective attack of alkynes on one μ 3-CF ligand of Fe 3(CO) 9(μ 3-CF) 2 from the sterically less-hindered side. Replacement of fluorine by chlorine in Fe 3(CO) 9(μ 3-CF) 2 using aluminium chloride yields nonacarbonylbis(μ 3-chloromethylidyne)triiron at ambient temperature. At elevated temperature or with aluminium bromide further attack of the cluster and substitution of three carbonyl ligands by benzene occurs, forming a cationic cluster, which reacts with nucleophiles such as alcohols, forming Fe 3(CO) 6(η 6-C 6H 6)(μ 3-CX)(μ 3-CCOOR). The reaction of Fe 3(CO) 9(μ 3-CF) 2 with the phosphaalkyne t-C 4H 6CP results in the formation of a pentagonal bipyramidal cluster Fe 2(CO) 8[ FeCFC(C 4H 9)PC F], that contains a perfect planar FeCPCC five-membered ring system. In the cluster expansion reaction of Fe 3(CO) 9(μ 3-CF) 2 with Cp*Co(CO) 2, carboncarbond bond formation with formation of a coordinated difluoroethyne ligand occurs. To our knowledge Cp*CoFe 3(CO) 9(μ 4-η 2-FCCF) is the first example of a coordinated difluoroethyne ligand.