Redox and structural properties of transition metal dithioacetylacetonates and related complexes

Abstract

CHAPTER 1 provides a brief summary of the previously reported electrochemical behaviour of metal bisdithiochelate complexes (X = Ai,Pd,Pt) and a general outline of the topics discussed in each chapter of this thesis.CHAPTER 2 initially describes the preparative routes to the parent systems [M(S₂C₃RHR')₂] and [M(S₂CNR'₂)₂], followed by a detailed account of the syntheses of the hybrid complexes [M(S₂C₃RHR')(S₂CNR"₂)] (M = Ni, Pd,Pt,R,R' = CH₃, Ph, CF₃; R' = CH₃, C₂H₅, i-C₃H₇, C₄H₉; but not all possible combinations). Infra-red, nmr, electronic and mass spectroscopic studies of these 1,1-dithio-1,3- dithio complexes are also extensively reported.CHAPTER 3 is concerned with X-ray crystallographic studies of [Ni (S₂C₉CH₃HCH3) (S₂CN (C₂H₅)₂)] and [Ni (S₂C₃CF₃HCH₃)(S₂CN(i-C₃H₇)₂)]. These structural results suggest that with the exception of the MS₄ core, the geometric parameters of the (S₂C₃RHR') and (S₂CNR'₂) hybrid moieties are relatively unaltered from those found in the respective parent complexes [Ni(S₂C₃RHR")₂] and [Ni (S₂CNR"₂)₂] .CHAPTER 4 discusses the voltammetric behaviour of the hybrid systems [M(S₂C₃RHR')(S₂CNR"₂)], which all display one isolated reversible reduction. Our electrochemical data strongly supports predominant 1,3-dithio-ß-diketonate character in the redox-active orbital involved in this reduction.CHAPTER 5 describes the syntheses and spectroscopic characterisations of the asymmetrically-substituted systems [M(S₂C₃CF₃HCH₃)(S₂C₃CH₃HCH₃)] (M = Ni, Pd,Pt). Voltammtric investigations, in conjunction with our [M(S₂C₃RHR') (S₂CHR"₂) ]⁰/¹⁻ data, suggest that the two observed one-electron ligand-mediated reductions of the mixed complexes are, at least, consistent with localised electron -acceptance.