Crossing Bridges: Synthetic and Charge Transfer Studies of Linear and Cross-Conjugated Systems

Abstract

This thesis sets out to explore the electronic structure and properties of organometallic complexes. The mixed valence states generated on one-electron oxidation are investigated based on the theory developed in Chapter 1, which provides an introduction to the general area and electron transfer.

Further Chapters in this thesis set out to explore the communication between redox states spanning linear and branched architectures and draw on the ideas presented in Chapter 1 to draw conclusions as to the degree of communication between the sites. To this extent a series of platinum-acetylide complexes bearing the unusual triarylamine ligand, containing one to four redox centres, were prepared and the electronic properties probed with IR and UV-vis NIR spectroelectrochemistry. The results show that there is only very weak communication between the centres. In Chapter 3 the work looks at symmetrical analogues of these compounds and builds on previously published work to explore in more detail the electronic structure of a series of trans-[Pt(C≡CC6H4NAr’2)2(PR3)2] complexes to explore the effect of the triarylamine and ancillary phosphine ligands. The results show modest communication between the centres and little effect of the phosphine ligand.

The later chapters in this thesis focus on developing synthetic routes and analyses of branched-conjugated materials. Chapter 4 develops the synthesis of a range of compounds based on the FcCH=C(CCR)2 with organic R groups. The results show that, despite proposals of such systems being able to act as transistors, the ferrocene moiety is electronically isolated. Chapter 5 builds on this work and develops the synthesis of FcCH=C(CCC6H4CCMLn)2, MLn= Ru(PPh3)2Cp or Ru(dppe)Cp*. Spectroelectrochemical analysis has shown weak communication between the –Ru-(CC)- centres. Finally, Chapter 6 addresses the interactions within multi-ferrocenyl compounds. Analysis by IR SEC studies have shown that in compounds bearing either 2, 3 or 4 ferrocene groups that each centre is essentially electronically isolated despite electrochemical studies highlighting that in the right conditions a degree of through-space communication can be observed.