Syntheses of hydrido selenophenolato iron(II) complexes and their catalytic application in hydrosilylation of aldehydes and ketones

Three novel selenophenolato hydrido iron(II) complexes [cis-(H)(SeAr)Fe(PMe3)(4)] (4-6) (Ar = C6H5 (4), p-MeOC6H4 (5) and o-MeC6H4 (6)) were prepared through the reaction of Fe(PMe3)(4) with selenophenols ArSeH (1-3) via Se-H activation. The iron hydrido complexes 4,5 and 6 could catalyze the hydrosilylation of aldehydes and ketones. Among them complex 5 is the best catalyst for this process. Furthermore, alpha,beta-unsaturated alcohols could be obtained from the selective reduction reactions of the corresponding alpha,beta-unsaturated carbonyls catalyzed by hydrido iron(II) complex 5. This catalytic system has good tolerance for some common groups but it is easy to reduce the nitro group to an amino group. The experiments indicate that the chemoselectivity for this catalytic system is -CHO > -NO2 > -C(=O)CH3. The crystal structure of 6 was determined by X-ray diffraction.