The Chemistry of Group X Transitions Metels and their reactivity with C60 and Maleonitriledithiolates, /

Abstract

In the early 1990's, Drs. Fagan and Calabrese synthesized and characterized several nickel, palladium and platinum C60 complexes. Their work played a major role in defining the chemistry ofC60. Electrochemical techniques allowed them to propose a suitable mechanism and establish trends for the pattern of exohedral substitution to the C60 cage. The goal of this research is to extend Fagan and Calabrese's studies by bonding spectroscopically and spectroelectrochemically active ligands exohedrally to the C60 cage. This should enable the extent of communication between the phosphine ligand, the metal and the C6o. The synthesis of a series of maleonitriledithiolate complexes of nickel, palladium and platinum phosphines having the formulae (dppe)M(mnt) and (PPh3) M(mnt) (where dppe = PhzPCHzCHzPPhz, mnt = 1,2-dicyanoethene-l,2-dithiolate and M = Ni, Pd or Pt) from the reaction ofNaz(mnt) and the appropriate (phosphine) MClz is reported. These complexes were characterized by a combination ofmass spectrometry, IR, UV-Visible and IH, B C and 31p NMR. X-ray diffraction analysis of all three congeners revealed them to be isomorphous. Analysis of the diffraction data reveals that the metal centers are all square planar. In addition, characterization of the dppe complexes by single crystal X-ray diffraction reveals that the planar mnt ligands are tilted slightly away from the metal square planes. A series of (C6o)M(dppf) complexes (where dppf = 1-1'bis(diphenylphosphino) ferrocene and M = Ni, Pd or Pt) were synthesized and characterized using IR, UVVisible and B C and 31p NMR spectroscopy. The synthesis of these complexes are novel because the metal is reduced in-situ. These complexes are stable in air. The 31p NMR revealed that the phosphorus is coordinated with the respective metal center and the B C NMR demonstrated the substitution of the C60 cage. Cyclic voltammetry was also performed on these complexes. The dppfligand is irreversible chemically and electrochemically. The cathodic electrochemistry correlates well with that ofFagan and Calabrese's complexes. There are two cathodic waves which are chemically reversible, electrochemically quasi-reversible and are shifted with respect to EO.