Hydrophosphination reactions with transition metal ferrocenylphosphine complexes

Abstract

The group 6 metal mono-, bis- and tris-ferrocenylphosphine complexes [M(CO)5(PH2Fc)] (1a, M = Cr; 1b, M = Mo; 1c, M = W), cis-[M(CO)4(PH2Fc)2] (2a, M = Cr; 2b, M = Mo; 2c, M = W) and fac-[M(CO)3(PH2Fc)3] (3a, M = Cr; 3b, M = Mo; 3c, M = W) [Fc = Fe(η5-C5H4)(η5-C5H5)] were prepared and fully characterised. IR and NMR spectroscopy and single-crystal X-ray diffraction analysis indicate that FcPH2 is as good a σ donor as PhPH2 but is easier to handle and furthermore has a redox-active ferrocenyl group. Complex 1c was employed in the hydrophosphination of acrylonitrile and methyl acrylate in the presence of catalytic amounts of KOtBu giving the secondary phosphine complexes [W(CO)5{PH(Fc)(CH2CH2CN)}] (4a) and [W(CO)5{PH(Fc)(CH2CH2C(O)OMe)}] (4b). In addition, FcP(CH2CH2CN)2 (5) was prepared by a similar method from FcPH2 and acrylonitrile. These hydrophosphination products represent a convenient method for the modification of phosphines.