Tetraethylammonium fluoride as a convenient source of hydroxide ions in acetonitrile solution. Its reaction with [Fe(eta-C5H5)(CO)(2)(L)](+) salts and [Fe(eta-C5H5)(CO)(2)X] complexes

In acetonitrile solution, [Et4N]F(.)2.5H(2)O acts as a convenient source of hydroxide ions for use in organometstllic chemistry. Within 20 min, at roo m temperature, it converts [Fe(eta -C5H5)(CO)(2)(L)](+) salts (molar ratio 1:1) to [Fe-2(eta -C5H5)(2)(CO)(3)(L)] (L = CO, CNMe and PPh3) complexes in good yields with the evolution of CO2 and, when L = CO, CO. Under the same conditions it converts [Fe(eta -C5H5)(CO)(2)Cl] (molar ratio 1:2 or, bette r, 1:3) to [Fe-2(eta -C5H5)(2)(CO)(3)(NCMe)]. Other [Fe(eta -C5H5)(CO)(2)X] (X = Br or I) react only slowly to give [Fe-2(eta -C5H5)(2)(CO)(4)]. Other routes to [Fe-2(eta -C5H5)(2)(CO)(3)(PPh3)] and [Fe-2(eta -C5H5)(2)(CO)(3) (NCMe)] involve prolonged photolysis and give impure or non-isolable produc ts. This route gives them as analytically pure solids in high yields. It is proposed that in acetonitrile solutions, the F- ions react with H2O to giv e HF and OH- in a reaction driven by the strength of the H-F bond and the l ack of anion solvation in acetonitrile. The OH- ions then attack the [Fe(et a -C5H5)(CO)(2)(L)](+) cafions at CO with, the evolution of CO2 to give the [Fe(eta -C5H5)(CO)(L)](-) which subsequently displaces L from the cations. (C) 2001 Elsevier Science B.V. All rights reserved.