The application of microwave dielectric heating to the synthesis of arene-metal complexes. Synthesis of [(η-arene)(CO) 3Mn]PF 6 complexes and [(η-arene)(η-cyclopentadienyl)Fe][PF 6] complexes with triphenylphosphine, tert-butylbenzenes and a sterically hindered phenol as arene ligands

Abstract

Microwave-mediated synthesis of [(η-arene)(CO) 3Mn](PF 6) 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, [((η-C 6H 5)(η-Cp)Fe] 2 PC 6H 5][PF 6] 2 is reported from AlCl 3-catalysed ligand exchange reactions between ferrocene and M(CO) 4(PPh 3) 2 complexes (M  Cr, Mo, W). Sterically hindered [(η-arene)(η-Cp)Fe][PF 6] 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.