A steric approach to metal-phosphine chemistry.

摘要

The research presented in this thesis involves the design and synthesis of sterically encumbered phosphine ligands and their metal complexes. In order to study the effects of coordinate unsaturation on transition metals, bulky substituents groups such as 2,6-dicyclohexyl benzene were incorporated into monodentate and chelating phosphine ligands. The phosphines and their metal complexes were characterized by single-crystal X-ray diffraction, 1H and 31P NMR. The Tolman Cone Angle was calculated from crystallographic data for the monodentate phosphine tris(2,5-dicyclohexylphenyl)phosphine and for the phosphite tris(2,6-diphenylphenyl)phosphite. The Tolman Cone Angle values for these compounds are the highest of any metal-complexed, crystallographically characterized monodentate phosphines to date, ranging from Θ = 225–238°.; Bulky ligands possessing thiolate groups were explored for their use in the synthesis of model compounds for [Ni-Fe] and [Fe-Fe] hydrogenases. Toward this end, the reactivity with BDAFe(CO)₃ and cyanide was investigated, yielding a series of biologically relevant complexes that were characterized crystallographically and by FT-IR.