The application of microwave dielectric heating to the synthesis of arene-metal complexes. Synthesis of [(eta-arene)(CO)(3)Mn]PF6 complexes and [(eta-arene)(eta-cyclopentadienyl)Fe][PF6] complexes with triphenylphosphine, tert-butylbenzenes and a sterically hindered phenol as arene ligands

Microwave-mediated syntheses of [(eta-arene)(CO)(3)Mn](PF6) complexes are reported. Reaction times are reduced from several hours by conventional methods to a few minutes using an unmodified domestic microwave oven. The synthesis of a bis complexed triphenylphosphine iron sandwich complex, [((eta-C6H5)(eta-Cp)Fe)(2) PC6H5][PF6](2) is reported from AlCl3-catalysed ligand exchange reactions between ferrocene and M(CO)(4)(PPh3)(2) complexes (M = Cr, Mo, W). Sterically hindered [(eta-arene)(eta-Cp)Fe][PF6] complexes with tert-butyl substituents have been prepared in moderate to excellent yields using the above microwave technique. Attempts to synthesise the methyl cyclopentadienyl analogues resulted in appreciable de-alkylation. No evidence for restricted rotation was found in the latter complexes. The direct synthesis of the 1,3,5-trimethylphenol iron sandwich complex is reported. This is the first example of a phenol complex prepared via ligand exchange reactions in iron sandwich chemistry. (C) 1997 Elsevier Science S.A.