The development of a new class of phosphine-alkene and thio-phosphine-alkene ligands based on a chalcone ferrocene framework, represents the primary focus of this study. The synthesis and characterisation of novel ligands, ferrochalcone 32 and thio-ferrochalcone 33, are described. The related alkene-phosphine ligands, the Lei ligand 17 and novel thio-Lei ligand 46, are further detailed. The coordination chemistry of four ligands (17, 32, 33 and 46) with various transition metals (Pt, Pd, Cu, Rh and Au) has been investigated in a comprehensive spectroscopis study. Single crystal X-ray analysis has been conducted at suitable junctures within the project. A surprising finding was that some solution-state structures were found to be different when studied in the solid state. The AuI complexes-containing the ligands have been successfully used in 1,5-enyne cycloisomerisation reactions. In addition to the coordination chemistry of the novel ligand systems, some interesting findings emerged For example, AuI complex of Lei ligand 17 and monodbaPHOS 74 undergoes an interesting solid-state [2+2] intramolecular cycloaddition transformation, giving cycloadduct, 72 and 77. An interesting finding includes the presence of impurity in commercially available Pd(OAc)2. Cyclopalladation of papaverine was carried out using pure and impure Pd(OAc)2, which resulted in the identification of novel Pd-dimer complex, 86. The result suggest that nitrite contaminants derive from impurities in Pd(OAc)2, and not from the oxidation of acetonitrile mediated by metallic Pd0, explain the formation of PdII-nitrito cyclopalladated products. Photocrystallographic metastable linkage isomerisation and complete conversion to an oxygen-bound nitrito complex 90 was also observed.

Ligand hybrid design is becoming an increasingly important area of the synthetic activity in organometallic chemistry. The coordination chemistry of diallylphosphines and phosphine-stabilized germylenes has been studied in this thesis. In particular, phosphine-stabilized germylenes have not only been studied by its potential use as ligands for transition metals, but also as possible synthetic tools in organic chemistry. Diallylphosphine behave as bidentate ligands to stabilize cationic rhodium species of type [Rh(COD){?3(P,C,C)RP(CH2CH=CH2)2}][BF4] [R= iPr2N, tBu and Ph]. Hemilabile properties of diallylphosphine ligands have been demonstrated by ligand exchange reactions. In solution, a dynamic equilibrium of exchange between the two allylic double bonds was detected by low temperature NMR analysis. In the same way, the reversible displacement of coordinated allylic double bond by acetonitrile could be observed. Theoretical calculations have been performed to explain the experimental results for the order of reactivity on removing the acetonitrile under vacuum. Germylenes stabilized by coordination of a phosphine ligand have been synthesized and fully characterized. Reactivity studies showed that phosphine-stabilized germylenes are unreactive toward unsaturated compounds, such as: alkyne, alkene and carbonyl derivatives, but reactive toward 2,3-dimethylbutadiene. The reactivity of phosphine-stabilized germylenes toward transition metal complexes have been studied by reaction with the dimer complex [Rh2(μ-Cl2)(COD)2], demonstrating that phosphine-stabilized germylenes are useful ligands with high potential in organometallic chemistry. The first isolable germanium analogue of alkynes, known as germyne, stabilized by coordination of a phosphine ligand has been synthesized and fully characterized. Synthesized germynes rearrange at RT affording a phosphaalkene and a new stable N-heterocyclic germylene. Keywords: Hybrid ligands, hemilabile properties, coordination chemistry, diallylphosphines, phosphine-stabilized germylene, germyne.