The synthesis,characterization and reactivity of diene and functionalized alkyl complexes of iron

Abstract

This thesis deals with the synthesis, characterisation and reactivity of a number of diene and functionalized alkyl complexes of iron. Iron alkenyl complexes of the type [(Cp)(C02)Fe{(CH2)nCH=CH2] (n = 2-4, 6), were used as precursors in the preparation of diene, heterobinuclear µ-alkanediyl and ro-hydroxyalkyl complexes of iron. Chapter 1 gives an overview of known hydrocarbyl complexes. Chapter 2 deals with the synthesis and characterisation of cationic diene complexes of iron of the type, [(175-C5H5)Fe(C0)2{r/-(a,ro-diene)}]PF6. These complexes were prepared by the reaction of the iron alkenyl complexes, [(Cp)(C02)Fe{(CH2)nCH=CH2] (n = 2-4, 6), with trityl salt, (Ph3CPF6) (􀀤-hydride elimination) to give a series of cationic diene complexes of iron of the type [(175 -C5H5)Fe(C0)2 { 172 -( a,ro­diene)} ]PF 6. The cationic diene complexes, [(175-C5Hs)Fe(C0)2{172-(a,ro­diene)} ]PF 6, were isolated as yellow air stable solids, which were fully characterized by microcroanalyses, FTIR, 1 H NMR, 13C NMR, 2D NMR (COSY) and MALDI-TOF mass spectrometry. Thermal analysis and thermal decomposition studies were also carried out on these compounds. Chapter 3 details the reactivity studies of these cationic diene complexes. We subjected these complexes to reactions with nucleophiles such as halides, hydrides, phosphines, amines and enolates. These reactions were found to proceed via four generalized pathways i.e. l) ligand substitution ( displacement) of the diene, 2) formation of the dimer, [CpFe(C0)2h 3) addition to the coordinated diene, 4) deprotonation of the diene using tertiary amines i.e. Et3N Where possible, the products of these reactions were fully characterized by microanalyses, FTIR, 1H NMR and 13C NMR spectroscopy. n Chapter 4 we subjected the iron alkenyl complexes, [(Cp)(C02)Fe{(CH2)nCH=CH2] (n = 2-4, 6), to hydrozirconation reactions using Cp2Zr(H)Cl to produce heterobinuclear µ-alkanediyl complexes of the type, [(Cp)(C02)FeCH2(CH2)nCH2Zr(Cp)2CI]. These complexes were isolated as yellow/brown oils which were found to decompose to the oxo-bridged dimer, [Cp2ZrC1]20 and the corresponding uon alkyl compounds, Cp(C0)2FeCH2(CH2)nCH3 In situ reactions of the heterobinuclear µ-alkanediyl complexes with various electrophiles were found to proceed in a similar fashion to those of the known mononuclear iron and zirconium alkyl complexes. Chapter 5 deals with the reactivity studies of c.o-hydroxyalkyl iron complexes of the type [(Cp)(C0)2Fe{(CH2)nCH20H}] (n = 3-5, 7) which were prepared by the oxidative hydroboration of the iron alkenyl complexes, The reactions of the c.o­hydroxyalkyl were found to take place at either the metal centre or at the hydroxy group. Where possible the products of these reactions were characterized by microanalyses, FTIR, spectrometry.