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Studies into the effects of hexa-hapto spectator ligands on the chemistry of ruthenium.

Steed, Jonathan W.; (1993) Studies into the effects of hexa-hapto spectator ligands on the chemistry of ruthenium. Doctoral thesis (Ph.D.), University College London. Green open access

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Abstract

This thesis describes the results of investigations into the chemistry of ruthenium complexes of hexa-hapto spectator ligands. Two specific systems have been examined. Chapters 2-5 describe aspects of the chemistry of the ruthenium(IV) chloride bridged compound [{Ru(η3:η3-C10H16)Cl(µ-Cl)}2] which contains the n3:n3-bis(allyl) ligand 2,7-dimethylocta-2,6-diene-1,8-diyl, derived from the ruthenium trichloride mediated dimerisation of isoprene. In Chapters 6 and 7 the reactivity of arenes and cyclohexadienes is examined in ruthenium complexes of the polyaromatic η6-spectator [2.2]paracyclophane. Chapter 1 offers a general introduction to arene and allyl transition metal chemistry and attempts to place the results reported herein into a wider context. In Chapter 2 the reactions of the bis(allyl)ruthenium(IV) chloride bridged dimer [{Ru(η3:η3-C10H16)Cl(µ-Cl)}2] with amines and polypyridines are examined. Bridge cleaved amine adducts of formulae [Ru(η3:η3-C10H16)Cl2L] or [{Ru(η3:η3-C10H16)Cl2}2(?-L)] (L = PhNH2, o-pda, p-pda) are reported and the diastereoisomerism of the binuclear compounds examined. The mononuclear chelate compounds [Ru(η3:η3-C10H16)Cl(L- L)][Bp4] (L-L = 2,2'-diaminodiphenyl, 2,2'-bipyridyl, 1,10-phenanthroline) and [Ru(?3-?3-C10H16)(terpy)][BF4]2 are formed from treatment of the starting material with Ag[BF4] and the appropriate ligand. Chapter 3 reports a number of carboxylato compounds of ruthenium(IV). These products occur as either 1 : 1 bidentate chelates [RU(η3:η3-C10H16)CLO2CR)] (R = Me, CH2F, CH2Cl) or 1 : 2, monodentate carboxylato aqua complexes [Ru(η3:η3-C10H16)(O2CR)2(OH2)] (R = CH2CI, CH2F, CHCl2, CHF2, CCl3, CF3). The electronic properties of the carboxylato ligand are found to be crucial to the product stoichiometry. The analogous thiocarboxylato compounds [Ru(η3:η3-C10H16)]Cl(OSCR)] (R = Me, Ph, tBu) exhibit bidentate coordination and exist as two alternative geometric isomers with the sulphur located either axially or equatorially. In the case where R = Me coordination is found to proceed via a two step process involving the monodentate thioacetic acid adduct [Ru(η3:η3-C10H16)]Cl2(S(OH)CMe}]. The related nitrato compounds [Ru(η3:η3-C10H16)Cl(NO3)] and [Ru(η3:η3-C10H16)](NO3)2] are also reported. In the latter case the "semi-chelating" nitrato ligands readily become monodentate in the presence of two electron ligands to give adducts [Ru(η3:η3-C10H16)(NO3)2L] (L = CO, py). Chapter 4 reports a range of 2-pyridinol and pyridine-2-thiol compounds of ruthenium(IV) of form [Ru(η3:η3-C10H16))Cl(pyrX)] (X = O, S) and related species. These compounds all exhibit axial and equatorial geometrical isomerism and a method based on 1H NMR spectroscopy is described for distinguishing between the two forms. In Chapter 5 a range of bi- and trinuclear compounds of ruthenium(IV) are described and their inherent diastereoisomerism studied. The bridge-cleaved adducts [{Ru(η3:n3-C10H16)Cl2}2(µ-pyz)] and [{Ru(η3:η3-C10H16)Cl2}n(µ-tra)] (n = 1, 2, 3) are reported along with the thiocyanato, carboxylato and nicotinato bridged compounds [{Ru(η3:η3-C10H16)C1(µ-SCN)}2], [{Ru(η3:η3-C10H16)Cl}2(µ-O4R)] (R = C2, C3,H2) and [RU2(η3:η3-C10H16)2CL3(µ-NC5H4CO2)]. In Chapter 6 the single nucleophilic addition reactions of simple anions N- (N = H, CN, OMe, Me) to unsymmetrical bis(arene)ruthenium(II) compounds [Ru(η6-arene)(η6-[2.2]paracyclophane)]2+ (arene = C6H6, p-MeC6H4CHMe2, l,4-(CHMe2)2C6H4, C6Me6, C16H16) are examined. It is found that the cyclophane acts as a non-innocent spectator ligand, directing nucleophiles onto other arenes coordinated to the same metal centre to give the cyclohexadienyl compounds [Ru(η6-[2.2]paracyclophane)(η5-C6R6N)]+. Chapter 7 describes the extension of the work reported in Chapter 6 to double nucleophilic addition reactions to give ruthenium(0) compounds of general form [Ru(η6-[2.2]paracyclophane)(η4-diene)]. The reactivity of these Ru(0) species towards H[BF4] is examined resulting in a range of novel agostic compounds. Mechanistic aspects are investigated by a range of deuteriation studies. Finally, Chapter 8 offers some conclusions on what has been learned about the effects the two spectator ligands studied have on the chemistry of ruthenium.

Type: Thesis (Doctoral)
Qualification: Ph.D.
Title: Studies into the effects of hexa-hapto spectator ligands on the chemistry of ruthenium.
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
URI: https://discovery.ucl.ac.uk/id/eprint/10104042
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