Synthesis of new ferrocenyl amine sulfide and selenide complexes of group 10 metals and their catalytic activities toward selective hydrogenation, isomerization, and asymmetric Grignard cross-coupling reactions

Two series of previously unknown ferrocenyl amine sulfide and selenide ligands (S,R)-[ER]C₅H₄FeC₅H₃[CHMeNMe₂] [ER] and [ER]C₅H₄FeC₅H₃[CH₂NMe₂]-[ER], where E = S and Se; R = Me, Ph, Bz, 4-tolyl, and 4-ClPh, have been prepared. Lithiation of (S)-[1-(dimethylamino)ethyl]ferrocene and [(dimethylamino)methyl] ferrocene first in the presence of ether and then TMEDA followed by treatment with different diselenides and disulfides resulted in the synthesis of these new ligands. Palladium and platinum dichloride adducts of these compounds have been prepared from a benzene solution of (PhCN)₂MCl₂ where M = Pd and Pt. The palladium complexes are active catalysts for selective hydrogenation of dienes to monoenes both under homogeneous and heterogeneous conditions. In the case of hydrogenation of 2,3-dimethyl-1,3-butadiene, isomerization has been observed. Nickel complexes of the new sulfide ligands were prepared in situ and used as catalysts for the asymmetric Grignard cross-coupling reactions. The possible structures of Pd and Pt complexes are discussed. The X-ray crystal structure was determined for [SMe]C₅H₄FeC₅H₃[CH₂NMe₂][SMe][PdCl₂]; it reveals that the Pd atom is coordinated to the S and N atoms of the same cyclopentadienyl ring.