Selective C–F and C–H Activation of Fluoroarenes by Fe(PMe₃)₄ and Catalytic Performance of Iron Hydride in Hydrosilylation of Carbonyl Compounds

Abstract

The reactions of perfluorinated toluene (CF3C6F5), pentafluoropyridine (C5NF5), and hexafluorobenzene (C6F6) with the iron(0) complex Fe­(PMe3)4 were investigated. The Fe­(I) complexes (4-CF3C6F4)­Fe­(PMe3)4 (1), (4-C5NF4)­Fe­(PMe3)4 (2), and (C6F5)­Fe­(PMe3)4 (3) were obtained by selective activation of the C–F bonds. However, under similar reaction conditions, the reaction of Fe­(PMe3)4 with perfluoronaphthalene (C10F8) afforded a π-coordinated Fe(0) complex, (η4-1,2,3,4-C10F8)­Fe­(PMe3)3 (4), and the expected C–F bond activation reaction was not observed. The expected iron hydride (C6F5)­FeH­(PMe3)4 (6) could be obtained in a yield of 80% by the reaction of bromopentafluorobenzene with Fe­(PMe3)4 and subsequent reduction with NaBH4. The molecular structures of complexes 2, 4, and 6 were determined by single-crystal X-ray diffraction. Complexes 1–4 and 6 could be used as catalysts for the hydrosilylation of carbonyl compounds. Among them, complex 6 is the best catalyst. The selective reduction of carbonyl groups of α,β-unsaturated aldehydes and ketones was also realized with 6 as catalyst