The long and the short of it - ruthenium alkynyl complexes / by Benjamin George Ellis.

This Thesis continues the study into the syntheses and reactivity of transition metal yndiyl and polyyndiyl complexes.These molecules show promise as models for molecular wires.Chapter One gives a general overview of modern electronics and introduces the need for molecule based technology.The three most promising classes of molecular wires are described before the four available methods of evaluation are individually addressed.Chapter Two describes the syntheses of the diyndiyl complexes {Ru(PP)Cp*}2(C=CC=C) (PP : dpp-, dppe), prepared by four-step procedures.Starting from the chloro-ruthenium precursors RuCl(PP)Cp*, treatment with TMSC=CH gave the vinylidenes [Ru(:C:CH2)@P)Cp*]*, which were deprotonated to the ethynyls Ru(C=CH)(PP)Cp*, before being oxidatively coupled ([FeCp2][PF6]) to give the bis-vinylidenes [{Ru(PP)Cp*}z(:C:CHCH:C:)]2*.Deprotonation of these with dbu or KOBur gave the corresponding diyndiyls in excellent yield (90%).Electrochemistry of the diyndiyl complexes revealed the expected sequence of four one-electron redox steps, which occurred at significantly lower -82 values than found for the Ru(PPh¡)zCp analogue.Single-crystal X-ray structure determinations are reported for all complexes, together with the structures of the monoand dications of the diyndiyl complex in the dppe series.Chapter Three summarises a collection of reactions that detail the reactivity of bis- vinylidenes [{Ru(dppm)Cp*}r(:C:CRCR:C:)]'* (R : H, Me) towards the strong base, KOBu/.Under these conditions, deprotonation of a single dppligand and cyclisation, followed by the removal of one of the pendant R groups occurred, giving complexes of the general formula {Cp*(dppm)Ru}-C=CC(R):C-{Ru(Ph2PCHPPhz)Cp*}.This Chapter also describes the protonation (HOTf) of the diyndiyl complex {Ru(dppe)Cp*}2(C=CC=C) to give the corresponding bis-vinylidene, a reaction that previously has not been reported in the M(PP)Cp' (M: Fe, Ru, Os) series.Chapter Four includes a large number of reactions that demonstrate the reactivities of the diynyl complexes Ru(C=CC=CR)(dppe)Cp* (R: TMS, H).Together with the syntheses of these very versatile reagents, a number of other complexes are also reported that result from the reaction of the intermediate butatrienylidene [Ru(:Q:ç:C:CH2)(dppe)Cp*]* with a variety of nucleophiles (NH3, HzO and MeOH).Also reported is the synthesis of an 1l asymmetric ruthenium diyndiyl complex featuring Ru(dppe)Cpx and Ru(PPh¡)zCp endgroups.An electrochemical study of this complex revealed the expected sequence of four one-electron redox steps, which occurred at values intermediate to those found for the corresponding symmetric diyndiyls.Other complexes reported include mixed rutheniumgold diyndiyls and trinuclear copper(I) clusters, Cu3(p-dppm)3, capped by either one or two Ru(C=CC=C)(dppe)Cpx units.The redox properties for all the isolated complexes are also reported.Chapter Five details reactions of Ru(C=CC=CHXdppe)Cp* with FeCl(PP)Cpt in the presence of Na[BPfu] and dbu in THFA{Et3 solvents, which gave the mixed ruthenium-iron diyndiyls {Cp*(dppe)Ru}(C=CC=C){Fe(PP)Cp*} (PP : dppe, dppp).Cyclic voltammetry shows that these complexes undergo sequential loss of up to three electrons.Guided by these data, subsequent chemical oxidation with [FeCpz][PFo] gave the corresponding mono- and dicationic derivatives derived from the dppe series.Detailed studies of the IR, UV/VisA{IR spectra, coupled with NMR, ESR, magnetic and Mössbauer measurements have enabled some understanding of the electronic configurations of these compounds to be obtained.In particular, the relative stabilities of the singlet and triplet configurations of the dication were shown to be related to the electron-donating power of the two end-groups.Chapter Six describes the syntheses of a series of electron-rich binuclear ruthenium complexes of the general formula [Ru]-(C=C),-[Ru] (r: I,2,3,4,7 and 11).These complexes were prepared under a number of different reaction conditions, demonstrating how subtle variations can influence the outcome of a reaction.The electrochemical properties of these complexes are analysed and the effect of chain length on the electronic interaction between the two end-groups is examined.Of significant interest is the syntheses of complexes with n : I and n : lI repeating acetylene units.These complexes represent the shortest and longest yndiyl and polyyndiyl complexes isolated as pure complexes to date.Also described are a number of adducts that result from the treatment of the Co and Cs binuclear complexes with the reagents TCNE and Fe2(CO)e.The products from these reactions crystallise readily, allowing for structural characterisation that was used to confirm the structures of the parent complexes.

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