A C₂-symmetric analogue of dppf : synthesis and characterization of indenyl-phosphines, phosphino-ferroindacenes and their coordination compounds
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The synthesis, isolation and characterisation of a series of indenyl phosphines: 3-diphenylphosphinoindene (ppinH), 1,3- bis(diphenylphosphino)indene (dppinH), bis(3-indenyl)phenylphosphine (pdinH₂) and tris(3-indenyl)phosphine (ptinH₃) is reported. Until now these compounds have been either uncharacterized or poorly characterized in the literature. The reactions of ppin-, dppin- and pdin²- with ferrous chloride were investigated. Fe(ppin)₂ exists in two isomeric forms: a racemic isomer with C₂ symmetry and a meso form with C₂ symmetry, these are analogues of dppf. Crystallographic investigations of the coordination compounds of Fe(ppin)₂ allowed isolation of both isomers of the Fe(ppin)₂Mo(CO)₄ complex, and the meso isomer of the Fe(ppin)₂PdCb complex. Solution NMR investigations of Fe(ppin)₂PdCl₂ and Fe(ppin)2PtCl₂ show two compounds in solution in each case, suggesting a dynamic process. The electrochemistry of the complexed and uncomplexed ferroindacene show reversible oxidation processes in dry dichloromethane at E½ = -140 mV (Fe(ppin)₂), +60 mV (Fe(ppin)₂Mo(CO)₄) and +260 mV (Fe(ppin)₂PdCl₂) vs. Fe/Fc+. The investigation of the tetraphosphinoferroindacene Fe(dppin)₂ showed it only to be stable in dilute solution and that the major decomposition product is Fe(ppin)₂. The decomposition mechanism is unknown. The synthesis of diferrocenobis(phenylphosphino)cyclophane, an eight membered diferrocenlycyclophane characterized by mass spec and NMR, is described and the investigation of the indenyl analogue of diferrocenobis(phenylphosphino)cyclophane Fe₂(pdin)₂ which proved to be very unstable, is also described.