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 convent ional methods to a few minutes using an unmodified domestic microwave oven. The synthesis of a bis complexed triphenylphosphine iron sandwic h 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 pre pared in moderate to excellent yields using the above microwave techni que. Attempts to synthesise the methyl cyclopentadienyl analogues resu lted 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 e xample of a phenol complex prepared via ligand exchange reactions in i ron sandwich chemistry. (C) 1997 Elsevier Science S.A.