The Syntheses of [M(C₅Ph₅)₂]ⁿ⁺ (N=0,1) Complexes of Nickel, Iron and Chromium. The Structures of the Decaphenylmetallocenium Cations of Nickel and Iron

Abstract

Decaphenylnickelocene is isolated from the reaction between [Ni(CO)₂(PPh₃)₂], 5-bromo-1,2,3,4,5-pentaphenylcyclopenta-1,3-diene and zinc dust. Decaphenylnickelocene is obtained as air-stable crystals, insoluble in most common solvents. It can be oxidized by bromine or by nitronium tetrafluoroborate to the decaphenylnickelocenium cation, which can be chemically reduced to decaphenylnickelocene. The decaphenylnickelocenium cation is characterized spectroscopically and its crystal structure, as its tribromide and tetrafluoroborate salts, is reported. The structures are compared with that of decaphenylferrocenium tribromide, which is formed by bromine oxidation of decaphenylferrocene. Decaphenylchromocenium tribromide is prepared by bromine oxidation of decaphenylchromocene, which is prepared from [Cr(MeCN)₃(CO)₃], pentaphenylcyclopentadienyl bromide and zinc dust.