AbstractPentalenides are dianionic ligands that can be thought of as two fused cyclopentadienides. They have drawn attention due to the interesting structural and electronic properties of pentalenide complexes of s, p, d and f block elements. However, exploration of the organometallic chemistry of these ligands has been limited by the difficulties associated with synthesising the precursors for these species. In Chapter 1 the current literature regarding pentalenide synthesis is reviewed. Pyrolytic and solution phase routes to the ligand precursors, typically dihydropentalenes, are discussed, as well as their conversion into mono- and dianionic derivatives. Select examples of synthesising organometallic pentalenide compounds from these precursors are also discussed.
In Chapter 2 the synthesis of phenyl-substituted dihydropentalenes is described. Attempts to synthesise di-, tri-, penta- and hexa-phenyl dihydropentalenes are detailed, and a straightforward, high-yielding synthesis of 1,3,4,6-tetraphenyldihydropentalene is reported, with a variety of reagents being shown to facilitate its formation. Chapter 3 details the conversion of 1,3,4,6-tetraphenyldihydropentalene into its mono- and dianionic derivatives, and the characterisation of these anions by NMR and XRD. This chapter includes the first pentalenide to be characterised with different alkali metals. Solubility issues with the dilithium, disodium and dipotassium salts of tetraphenyldihydropentalenide were overcome by synthesising hetero-bimetallic alkali metal salts, the first such pentalenide species to be described.
In Chapter 4 the synthesis of dihydropentalenes bearing both methyl and phenyl substituents is documented. The deprotonation of these dihydropentalenes, which leads to formation of the first vinyl-dihydropentalenide anions, is also described.
|Date of Award||2019|
|Supervisor||Michael Whittlesey (Supervisor) & Ulrich Hintermair (Supervisor)|