Dissertations / Theses: 'Osmium'

1

Lee, Yui-bing, and 李蕊冰. "The chemistry of osmium-silver and osmium-iridium mixed-metalclusters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40987632.

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Lee, Yui-bing. "The chemistry of osmium-silver and osmium-iridium mixed-metal clusters." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40987632.

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3

Rijt, Sabine H. van. "Osmium arene anticancer complexes." Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/3213/.

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Drawbacks associated with anticancer chemotherapeutic cisplatin include tumour drug resistance, non-effectiveness against all tumours and lack of tumour-specificity resulting in severe side-effects (e.g. nausea, hair loss and kidney toxicity). The use of other metals such as transition metals rutheniumandosmium, may address the problems associated with platinum drugs and have received increased interest over the years. In this thesis the biological activity and aqueous solution chemistry of half-sandwichosmium (II) compounds of the type [(arene)OsII(X)(YZ)] n+ is explored. Chelating ligands containing nitrogen or nitrogen and oxygen donor atoms (N, NandN, O-chelatingligands) are investigated. It is shown that the chelating ligand has a large effect on the aqueous reactivity of the complexes. The introduction of functional groups on the chelate allowed for the ‘fine-tuning’ of the aqueous reactivity and nucleobase binding of the complexes. Also the nature of the coordinating arene was found to have an important effect on their biological activity. This could be rationalised by increased hydrophobicity with more extended arenes such as biphenylandtetrahydroanthracene, resulting in increased cellular uptake and increased cytotoxicity. Conjugating cell penetrating peptides to the complexes resulted in improved biological properties and opened a new way for functionalisation of the compounds. Several compounds reported in this thesis exhibit promising activity in the ovarian, colon and lung cancer cell lines and some could overcome cisplatin resistance in ovarian cisplatin resistant cell lines. Initial studies revealed cell death via apoptosis and the possible involvement of mitochondria in the apoptotic pathway. These results point to a novel pathway of activation for these complexes which is advantageous for addressing chemoresistance and effectiveness to oher types of cancers. This work shows that the biological properties of these compounds can be tuned by choice of ligands and also provides initial evidence for a novel pathway of activation.

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4

Black, Steven J. "Reactions of osmium clusters." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/14084.

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Previous studies of the ligand properties of primary, secondary and tertiary phosphines on metal monomers have been carried out. These studies investigated the properties of the phosphines in terms of the effects of their basicity and Tolman's cone angle on the metal substrate. The reactions of [Os3(CO)10(MeCN)2] with a series of primary, secondary and tertiary phosphines (PRxH3-x) where R = Me, Et, i-Pr, Ph, were studied by variable temperature 31P{1H}, and 31P nmr. The reactions were monitored by nmr firstly after 24 hours at ambient temperature, the tubes were then heated to 60°C for 1 hour and the products studied by nmr, ir and mass spectroscopy. The products present included mono and disubstituted clusters. Also identified were inter- and intramolecular phosphinidene bridged species. The cluster bound products were initially identified on the basis of the 1JPH coupling constants - approximately 400Hz as opposed to approximately 200Hz for the free phosphines. Stability studies were carried out on the triosmium benzene cluster system [Os3(CO)9(η2η2η2C6H6)]. The cluster was reacted with a series of tertiary phosphines initially with heating and later uv irradiation to attempt to displace the benzene ligand. The ligand has proven to be strongly bound to the cluster as there was no displacement observed, though CO displacement occurs affording mono-, bis- and tris-phosphine cluster derivatives. The benzene ligand attached to the cluster also proved resistant to displacement via high vacuum pyrolysis. Study of the mechanism for the thermal conversion of the raft cluster [Os6(CO)21] with the species [Os6(CO)18] under vacuum has been carried out via pressure monitoring, showing the loss of CO to be a stepwise process. During this reaction the formation of a novel ketenylidene species, [Os3(CO)11CCO] has been observed. This species has been characterised by high resolution FAB mass spectroscopy.

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5

Gosby, Katherine M. P. "Osmium mediated formation of heterocycles." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496899.

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6

Drake, S. R. "High nuclearity clusters of osmium." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233876.

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The work described in this Thesis is a study of the synthesis and reactivity of some giant osmium carbonyl clusters and an investigation into their magnetic and electronic properties. Chapter One contains an overview of the concept of the chemical bond from Dalton to the present day ideas of Wade and Mingos, and their application to transition meial clusters. Chapter Two is an investigation into the fluxional and dynamic behaviour of mixed-metal clusters in solution using multinuclear N.M.R. (lH,iaC, and 3lP{1H}). The clusters [Os10C(CO)24MPR3]-(M = Cu, Ag or Au) and [Os1oC(CO)24(MPR3)(M>PR3)] (M = M'= Ag or Au, and M 5* M' Ag and Au) have been examined using these techniques. Chapter Three reports the synthesis of the dianion [Os11C(CO)27]2~, a cluster containing a trigonal prismatic geometry and its reaction with elec-trophiles such as H+, I2, [Cu(NCMe)4]PF6, AuPR3Cl and AgBF4. THe X-ray structure of [HOsnC(CO)27]~ is described, and the conversion of [OSllC(CO)27]2- to [Os10C(CO)24]2-. Chapter Four is concerned with the synthesis of giant osmium clusters using [Os10C(CO)24]2"~ as a precursor and reacting it with Hg(CF3COO)2 to form [Os20Hg(C)2(CO)42]2-, [Os30Hg2(C)3(CO)72]2-and [Os40Hg3(C)4(CO)oe] • The corresponding gold derivatives, [Os10C(CO)24AuBr]- and [Os20Au(C)2(CO)40]2~ have also been prepared and fully characterised by X-ray crystallography. Chapter Five describes the use of l87Os-1H satellites and Inversion-Recovery 1H n.m.r. as aids in the study of the dynamic behaviour of hydrido osmium carbonyl clusters in solution. In particular the work has focussed on differentiating between hydride ligands in tetrahedral or octahedral interstitial sites. The improved synthesis of [H4Osio(CO)24]3~ is reported and its reactions with electrophiles are discussed. The dianion reacts with H+ to form [H5Os10(CO)24]~ which has been characterised by an X-ray structural determination. Chapter Six presents UV/visible, magnetic and EPR measurements on a range of osmium carbonyl clusters prepared in Chapters Two to Five. A molecular orbital framework for understanding these results is presented. Finally Chapter Seven contains the experimental section and spectroscopic data.

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7

Cromhout, Natalie Lyn. "Aspects of osmium cluster chemistry." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627307.

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8

Fu, Ying. "Organometallic osmium arene anticancer complexes." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/52695/.

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The interest in the development of anticancer metal complexes for cancer therapy is growing spurred by the encouraging successful stories of platinum drugs. Osmium arene chlorido complexes had been found to show anticancer activity in vitro. In this thesis, the osmium arene iodido complexes were mainly explored and investigated. It is found that iodido OsII arene complexes with a general structure: [Os(η6- arene)(XY)I]PF6 (XY = p-hydroxy or p-dimethylamino phenylazopyridine, arene = p-cymene or biphenyl) are potently cytotoxic at nanomolar concentrations toward a panel of human cancer cell lines. In contrast to the chlorido osmium arene anticancer complexes, the iodido complexes are stable and inert toward aquation. More than thirty half sandwich azopyridine OsII arene complexes [Os(η6- arene)(azopyridine)X]+ (where X is chloride or iodide, the arene is p-cymene or biphenyl and the pyridine ring of azopyridine ligand bearing a variety of substituents) were synthesized and characterized. A preliminary structure activity relationships (SARs) were built up based on the anticancer activity towards A2780 human ovarian cancer cell line. In general, the introduction of an electronwithdrawing group (e.g. F, Cl, Br or I) at specific positions on the pyridine ring significantly increases cytotoxic activity and aqueous solubility. Changing the arene from p-cymene to biphenyl or the monodentate ligand (X) from chloride to iodide resulted in a significant increase in the anticancer activity. Studies in A2780 human ovarian cancer cells suggested that cellular uptake and targeting to cellular organelles play important roles in determining the anticancer activity. According to the 60 cancer cell lines screening results from National Cancer Institute (NCI), the anticancer activity achieved by the most potent OsII arene azopyridine complex is 100 times more than cisplatin; 1000 times activity was found in some cell lines. The mechanism of action may involve the inhibition of tubulin polymerization. One iodido osmium complex was selected for anticancer efficiency evaluation in vivo: [Os(η6-p-cym)(Azpy-NMe2)I]PF6 (FY026). This complex delayed the growth of HCT116 human colon cancer xenografts in mice, with negligible toxicity. It is the first example of in vivo antitumour activity for an organometallic osmium arene complex. Its activity appears to involve redox mechanisms. Its potency towards A2780 ovarian and A549 lung cancer cells is increased significantly when used in combination with L-buthionine-sulfoximine (L-BSO) indicating that L-BSO can be a good candidate for combination therapy treatment with iodido osmium complexes. Further study on the bioisosteres of FY026 was carried out by changing the azo bond (N=N) to imine bond (CH=N). Sixteen osmium arene iminopyridine complexes were synthesized, well characterized and showed good anticancer activity. Different structure-activity relationships comparing iminopyridine complexes with azopyridine complexes were identified which suggested a different anticancer mechanism. In contrast to FY026, [Os(η6-p-cym)(Impy- NMe2)I]PF6 (6) and [Os(η6-p-cym)(Impy-NMe2)Cl]PF6 (14) were found to undergo hydrolysis and the binding was observed between their hydrolyzed product (14A) and 9-ethylguanine. Moreover, a hydride transfer from NADH to form an osmium hydride intermediate which is involved in a catalytic process resulting in the formation of NAD+ was discovered. This process might be involved in the anticancer mechanism of action. A dual mechanism of action was proposed based in the interaction of these compounds with DNA nucleobase and catalytic oxidation of NADH.

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9

Lindsay-Scott, Peter J. "New osmium-catalysed routes to heterocycles." Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.509979.

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10

Birri, Anthony. "Thiopene complexes of ruthenium and osmium." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394242.

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11

Woodhouse, Oliver Brian. "Osmium in seawater : analysis and geochemistry." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284676.

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12

Peacock, Anna F. A. "Design of osmium arene anticancer complexes." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/15612.

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In this thesis the biological activity and aqueous solution chemistry of half-sandwich Os11 arene complexes of the type [(η6-arene)Os(XY)C1] is explored, and it is demonstrated that these properties can be tuned by careful choice of XY chelating ligand (N,N-, O,O- and N,O-chelates) to achieve cancer cytotoxicity comparable to carboplatin. The osmium complexes containing N,N-chelates hydrolyse more slowly than their ruthenium analogues and the pKa of the resulting water is more acidic. Efforts to increase the rates of hydrolysis and the resulting pKa led to replacement of the neutral N,N-chelating ligand by an anionic O,O-chelate. This was successful in that hydrolysis is more rapid and the pKa of the coordinated water has increased by ca 0.8 units. However, these complexes are deactivated by formation of the inert and thermodynamically stable hydroxo-bridged dimers. Attempts to tune the stability of complexes containing XY = O,O-chelate, by replacing the 6-membered O,O-chelate with 5-membered analogues, was partially successful for the development of active complexes, but was unsuccessful in preventing hydroxo-bridged dimer formation. Within the class of N,N- and N,O-chelated complexes the choice of donor group is important. Replacing amine N-donor groups with the Π-acceptor pyridine, reduced both the rate of hydrolysis and pKa or coordinated water, and increased the overall stability of the complex. This was especially the case for complexes containing N,O-chelates, which displayed aqueous chemistry in between that of the parent compounds containing neutral N,N-or anionic O,O-chelates. Within this group of osmium arene complexes, [(η6-arene)Os(N,O)C1], active cytotoxic complexes were obtained, and the first X-ray crystal structures of osmium bound to either G or A nucleobases is reported. This work shows that a wide range of reactivity can be obtained for complexes of the form [(η6-arene)Os(XY)C1]n+ by careful choice of the XY chelating ligand, and this knowledge has allowed complexes with cancer cell cytotoxicity to be designed.

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13

Cathey, Christopher. "Some studies in osmium cluster chemistry." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272644.

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14

Al-Mandhary, Muna R. A. "Aspects of the chemistry of some osmium-containing clusters." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272646.

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15

林漢華 and Hon-wah Lam. "Synthesis, reactivities and photochemistry of osmium-nitridocomplexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31232292.

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16

McQueen, A. Ewan D. "1,1-dithiolate complexes of ruthenium and osmium." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/28608.

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17

Nagra, Harpreet K. "Bromine derivatives of ruthenium and osmium carbonyls." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq24211.pdf.

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18

Lunniss, Julie Amanda. "Organometallic chemistry of some hydrido osmium cluster." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279819.

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19

Chughtai, Majid J. "Development of the osmium mediated aminohydroxylation reaction." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427891.

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20

陳雁菁 and Suzanna Chan. "The chemistry of osmium-palladium carbonyl clusters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31234628.

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21

Champness, Neil Robert. "Studies in ruthenium and osmium coordination chemistry." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239648.

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22

Prior, Neville D. "Some organometallic chemistry of osmium carbonyl clusters." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257045.

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23

Massey, Anju Deepali. "Some chemistry of ruthenium and osmium clusters." Thesis, University of Cambridge, 1990. https://www.repository.cam.ac.uk/handle/1810/273135.

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24

Lee, Hui Zhi Shirley. "Organometallic compounds of osmium for cancer therapy." Palaiseau, Ecole polytechnique, 2015. https://tel.archives-ouvertes.fr/tel-01232147/document.

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Cis-platin and its derivatives are the most currently used for cancer treatment. Inspired by these metallodrugs, organometallic compounds (Ti, Ru, Fe, Rh, Au…) have been developed over the years as potential candidates for anticancer drugs, some of these have entered clinical trials. Jaouen and co-workers have developed novel therapeutic agents based on ferrocene compounds analogous to tamoxifen, which show high anti-proliferative effects against two types of breast cancer cells, namely the ER+ breast carcinoma (MCF-7) and the ER- breast carcinoma (MDA-MB-231). Similarly, Leong’s group has found a series of triosmium carbonyl clusters that shows anticancer activity against these two breast cancer cells. Thus, it would be interesting to study osmocene compounds analogous to tamoxifen. Cytotoxic activity of these tamoxifen analogues, as well as that of triosmium clusters, were studied. This work aims to study the relationship between structure and activity of triosmium cluster Os3(CO)10(NCMe)2 compound with cytotoxic properties. The results show that the presence of a vacant coordination site and good solubility are important to have a good cytotoxic activity. The second part of the study was devoted to osmocene analogues (osmocifens), especially in the comparative study between the cytotoxic activity of three metallocene series: ferrocifen, ruthenocifen and osmocen. For osmium and ruthenium complexes, only compounds containing the amino chain are active while the phenolic compounds are almost inactive.

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25

Luther, Thomas Alan. "Dicationic dihydrogen complexes of osmium and ruthenium /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/11540.

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Chan, Suzanna. "The chemistry of osmium-palladium carbonyl clusters /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18061576.

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27

Geswindt, Theodore Earl. "The reactions of osmium (VIII) in hydroxide medium." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/960.

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Spectrophotometric techniques were used to elucidate the discrepancies surrounding the reduction of osmium tetroxide by several primary alcohols in a hydroxide matrix. In contrast to the documented literature, this reaction was observed to occur in two consecutive reaction steps. Geometrical and computational analysis of kinetic data revealed that the reaction proceeds by the following reaction model: Os(VIII) + RCH2OH Os(VI) + RCHO Os(VIII) + Os(VI) Os2(VII) k1 k+2 k-2 The conditional rate constants and molar extinction coefficients were calculated using custom written software. A hydride transfer mechanism, coupled with the synchronous removal of the hydroxyl proton of the alcohol, was postulated. The complexation between osmium(VIII) and osmium(VI) was investigated. Mole ratio titrations and mole fraction plots show that at pH 14.3 a 1:1 complexation occurs between osmium(VIII) and osmium(VI). The equilibrium constants and molar extinction coefficients calculated by these methods were found to be consistent with the parameters obtained from the reduction of osmium tetroxide by primary alcohols at pH 14.3. The formation of a mixed oxidation state dimeric osmium complex (denoted Os2(VII)) has been proposed. Key words: Spectrophotometric techniques, osmium tetroxide, osmium(VIII), primary alcohols, osmium(VI).

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28

Lam, Hon-wah. "Synthesis, reactivities and photochemistry of osmium-nitrido complexes /." [Hong Kong : University of Hong Kong], 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12922444.

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29

Kandala, Srikanth. "Synthesis and characterization of diphosphine ligand substituted osmium and ruthenium clusters." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3955/.

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The kinetics for the bridge-to-chelate isomerization of the dppe ligand in H4Ru4(CO)10(dppe) have been investigated by UV-vis and NMR spectroscopies over the temperature range of 308-328 K. The isomerization of the ligand-bridged cluster 1,2-H4Ru4(CO)10(dppe) was found to be reversible by 31P NMR spectroscopy, affording a Keq = 15.7 at 323 K in favor of the chelating dppe isomer. The forward (k1) and reverse (k-1) first-order rate constants for the reaction have been measured in different solvents and in the presence of ligand trapping agents (CO and PPh3). On the basis of the activation parameters and reaction rates that are unaffected by added CO and PPh3, a sequence involving the nondissociative migration of a phosphine moiety and two CO groups between basal ruthenium centers is proposed and discussed. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligands dppbz proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(dppbz) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C4H4]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(dppbz) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(dppbz), molecular structure of both the isomers have been determined by X-ray crystallography. The kinetics for the ligand isomerization has been investigated by UV-vis and 1H NMR spectroscopy in toluene solution over the temperature range of 318-343 K. On the basis of kinetic data conducted in the presence of added CO and the Eyring activation parameters, a non-dissociative phosphine migration across one of the Os-Os bonds is proposed. Ortho metalation of one of the phenyl groups associated with the dppbz ligand is triggered by near-UV photolysis of the chelating cluster 1,1-Os3(CO)10(dppbz). The triosmium cluster 1,2-Os3(CO)10(MeCN)2 reacts with the diphosphine ligand 3,4bis(diphenylphosphino)-5-methoxy-2(5)H-furanone (bmf) at 25 ºC to give the bmf-bridged cluster 1,2-Os3(CO)10(bmf). Heating 1,2-Os3(CO)10(bmf) leads to an equilibrium with the chelating isomer 1,1-Os3(CO)10(bmf). The molecular structure of each isomer has been crystallographically determined, and the kinetics for the isomerization has been investigated by UV-vis and 1H NMR spectroscopy. The reversible nature of the diphosphine isomerization has been confirmed by NMR measurements, and the forward (k1) and reverse (k-1) first-order rate constants for the bridge-to-chelate isomerization have been determined. Thermolysis of the SEQ CHAPTER h r 11,1-Os3(CO)10(bmf) cluster (>110 ºC) leads to regiospecific activation of C-H and P-C bonds, producing the hydrido clusters HOs3(CO)9[µ-PPh2C=C{PPh(C6H4)} CH(OMe)OC(O)] and the benzyne clusters HOs3(CO)8(μ3-C6H4)[µ-PPhC=C(PPh2)CH(OMe)OC(O)]. The hydride and benzyne clusters, which exist as a pair of diastereomers, have been fully characterized in solution by IR and NMR spectroscopy, and the molecular structure of one benzyne cluster (major diastereomer) has been determined by X-ray crystallography.

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鍾偉祥 and Wai-cheung Chung. "Syntheses, characterization and reactivities of some high-valent osmium porphyrin complexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31230817.

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鄭永堅 and Wing-kin Cheng. "Synthesis, reactivities, and electrochemistry of osmium complexes withmacrocyclic tertiary amine and multianionic amide and schiff-baseligands." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31231512.

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Cheng, Wing-kin. "Synthesis, reactivities, and electrochemistry of osmium complexes with macrocyclic tertiary amine and multianionic amide and schiff-base ligands /." [Hong Kong : University of Hong Kong], 1989. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12374118.

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33

Khattar, Rajesh. "Aspects of organometallic chemistry of some osmium clusters." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328690.

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34

Clarke, L. P. "The chemistry of osmium and ruthenium diyne clusters." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597722.

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The work describes in this dissertation concerns the syntheses, reactivities and characterisation of some triosmium and tetraruthenium carbonyl clusters with conjugatively unsaturated diynes. While the alkyne chemistry of osmium and ruthenium carbonyl clusters has been explored extensively over the past 20 years, the analogous chemistry of diynes has been less thoroughly explored. Chapter 1 gives a general introduction to the area of carbonyl clusters and their alkyne derivatives in chapter 1, with an emphasis on the group 8 transition metals. Recent and related diyne work is also discussed. The addition reactions of a series of related diyne ligands to the hydridocarbonyl cluster, H2Os3(CO)10, are presented in Chapter 2. This results in hydrogenation of ligands containing simple aliphatic terminal groups. Cluster derivatives from diynes with terminal cyclic aromatic systems have been shown to undergo novel cyclisation reactions resulting in the formation of cluster coordinated fused ring systems. Their subsequent reactivities have been investigated and are the results presented herein. Chapter 3 describes the chemistry of Os3(CO)10(NCMe)2 with 1,3-diyne ligands. The utilisation of ligands with sterically undemanding terminal groups leads to the generation of a number of products exhibiting carbon-carbon bond formation, cyclisations and cluster linkage. Reactions with increasingly sterically demanding diyne ligands are more selective. The substitution chemistry associated with the above products has been investigated. Chapter 4 continues the study of diyne ligands with the hydridoruthenium cluster, H4Ru4(CO)12, leading to a range of tri- and tetraruthenium derivatives exhibiting novel coordination modes, unusual metal core geometries, ligand transformation and varying degrees of ligand hydrogenation. Chapter 5 is concerned with the reactions of Os3(CO)10(NCMe)2 with an alternative series of diyne ligands, in which the alkyne moieties are separated by an arene spacer group. Molecules in which one or both of the alkyne moieties coordinate a triosmium-decacarbonyl unit have been isolated.

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35

Alyoubi, A. R. O. "Nuclear magnetic resonance studies of some osmium complexes." Thesis, University of Essex, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373208.

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36

Osman, Robert. "Photochemistry of polyphosphine complexes of Ruthenium and Osmium." Thesis, University of York, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358621.

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37

Stavropoulos, P. "Oxo alkyls and aryls rhenium, tungsten and osmium." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37866.

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38

Martin, James Neville. "The chemistry of osmium clusters with unsaturated ligands." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620211.

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39

Brown, Alisdair James. "Functionalised transition metal clusters of cobalt and osmium." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/12847.

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In Chapter One, a review of the chemistry of the tricobalt nonacarbonyl methylidyne cluster is presented. The concept of organic polymeric species containing inorganic moieties is introduced and methods of synthesis and characterisation are discussed. The importance of these compounds as potentially homogenised heterogeneous catalysts is highlighted, and some examples of these species are given. Finally, the catalytic cross linking of alkyd polymers is considered. In the second chapter, the synthesis and characterisation of some tricobalt clusters and their derivatives is presented. Reaction of [(CO)9Co3(μ3-CCO)]+ [AlCl4-] with nucleophiles ROH produced the compounds [(CO)9Co3(μ3-CCOOR)], where R= CH2CH=CH2 (1) and CH2CH2O(CO)CH=CH2 (2). The crystal structure of (1) is presented, and whilst it does not undergo polymerisation, compound (2) is readily polymerised by free radical initiation in both solution and emulsion systems with acrylic comonomers. The polymeric systems were characterised by infrared and ultra violet spectroscopy, as well as by gel permeation chromatography. However, neither the polymeric or monomeric cluster systems were found to catalyse the cross linking of alkyd polymers as they exhibit no redox properties under the ambient conditions studied. Chapter Three describes the synthesis and characterisation of triosmium clusters which contain functionalised alkynes. The crystal structure of [Os3(CO)8(μ-CO)(HOCH2C=CCHOCCHCCH2) is reported. Attempts to make polymeric and multicluster derivatives of these functionalised compounds are described. Chapter Four details the synthesis and characterisation of a novel amide linked di-cluster. Reaction of [(CO)9Co3(μ3-CCO+)][PF6-] with [(CO)9Co3(μ3-C)(p-C6H4NH2)] produced the species [(CO)9Co3(μ3-CCON(H)-p-C6H4(μ3-CCo3(CO)9], which has been characterised by X Ray crystallography, as well as by IR, NMR, FABMS and electrochemical techniques.

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40

Bryce, Garry Thomas. "Palladium acylation catalysts and osmium cluster arene complexes." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/15491.

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The acyl palladium complex (bpy)Pd(COMe)(I) (bpy = 2,2'-bipyridyl) was synthesised, and reacted with a variety of different alkenes, cyclic alkenes and dienes, and arenes in an attempt to yield the inserted acyl complexes {(bpy)Pd(CxRYCOMe)}. The inserted complexes were the first stage in setting up a catalytic reaction with the Palladium complex acting as a catalyst in the synthesis of an acylated arene. The osmium cluster Os3(CO)10(NCMe)2, was reacted with a series of functionalised arenes of the type C6H4R1R2 (where R1 = H, R2 = F, Cl, Br, CHCH3, C(CH3)CH2 and Me; R1 = R2 = Me, R1 = R2 = C(CH3)CH2) yielding clusters of the type Os3(CO)9H2(C6H2R1R2). The crystallographic and spectroscopic data provides evidence of the different geometric forms that the complexes demonstrate with the different types of ligands. The osmium arene complexes were reacted further using a Friedel-Crafts acylation reaction to acylate the arene ring when it is attached to the cluster. The resultant complexes show a shifting of the IR bands in the IR to higher wavenumbers. The compound Os3(CO)9H2(C2H3F) reacted with 2-butyne yielding the complexes Os3(CO)8(H)(CH2CHCHCH3)(C6H3F) and Os3(CO)8H2(η2-2-butyne)(C6H3F) which were identified crystallographically and spectroscopically. These two complexes show two different bonding modes of the butyne ligand to metal centre.

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Needham, Russell James. "Organo-osmium anticancer complexes with novel azo-ligands." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/88273/.

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Piano-stool iodido Os(II) arene complexes containing AZPY (phenylazopyridine) π-acceptor bidentate ligands have been previously shown to exhibit potent anticancer activity and mechanisms of action that involve ROS generation, and differ greatly from early Os(II) arene complexes baring σ-donor bidentate ligands. The aim of this thesis was to explore Os(II) complexes containing other types of azo-ligands as well as continue our studies into AZPY complexes. Develop methods for improving the solubility of complexes, explore their intracellular activation, and further understand the mechanisms in which ROS levels are elevated inside cells. Firstly I explored Os(II) arene complexes with AZBTZ (phenylazobenzothiazole) bidentate liagnds. It was found that AZBTZ ligands can undergo unaided cyclometallation with Os(II) to form N,C-coordinated osmacycles as well as N,N-coordination. The amount of cyclo-metallation taking place seemed to be dependent on steric factors and occurred more for iodido complexes than chlorido and bromido analogues. The osmacycles were more stable than N,N-coordinated species and exhibited unique properties such as regio-specific deuteration of the aniline ring, but were too hydrophobic for biological evaluation. A total of 31 new Os(II) arene AZPY complexes were synthesised using the previously determined structure-activity relationships as a basis. The majority contained alkoxy and glycolic side chain substituents on the AZPY ligand, which was achieved via a novel synthesis protocol. Their trends in anti-cancer activity, solubility, lipophilicity and cell uptake were explored. It was found that varying the anion was the best method for improving aqueous solubility without affecting activity, lipophilicity or uptake. Key complexes were found to be very active against OE19 oesophageal cancer cells, were capable of inducing apoptosis and elevating ROS levels in A2780 cells, as well as causing cell cycle arrest in different phases of the cell cycle. Complexes [Os(ɳ6-p-cym)(5-EtO-AZPY)I]+ and [Os(ɳ6-p-cym)(AZPY-NMe2)I]+ were labelled with radioisotope 131I (β-/γ emitter, t½ 8.02 d) in Kings College London. They were relatively stable in human blood serum and cell culture medium over 24 h. However, in the presence of MCF-7 cells, rapid dissociation of the iodide monodentate ligand was observed in the supernatants. Cell uptake studies revealed a spike in 131I uptake after 5-10 min, which proceeds to steadily decline. The complexes seemed to undergo intracellular activation involving dissociation of the iodide ligand, and uptake of the complex is in competition with a rapid rate of iodide efflux, probably involving chloride transport channels. The aqua species, [Os(ɳ6-p-cym)(5-EtO-AZPY)H2O]2+, was synthesised and its pKa was determined as 4.55, meaning it exists predominantly as a +1 charged hydroxido species under physiological conditions. Using UV-Vis spectroscopy and EPR (DEPMPO spin trap), [Os(ɳ6-p-cym)(5-EtO-AZPY)OH]+, and its chlorido and iodido analogues were found to catabolise H2O2, generating HO· radicals in the process that were capable of cleaving lysozyme protein with effectiveness in the order OH > Cl > I. Interestingly it was discovered that iodide complexes are activated by iodide ligand dissociation in the presence of low concentrations of GSH (75 μM) to form the more active hydroxido species. However, in higher concentrations (7.5 mM), they formed Os-SG and Os-SOG adducts. Likewise, [Os(ɳ6-p-cym)(5-EtO-AZPY)OH]+ and its iodido analogue were both capable of oxidising NADH to NAD+ with effectiveness in the order OH > I. NADH was also capable of activating iodido species in a similar manner and generating the hydroxido species was required for NADH oxidation to proceed.

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42

Amoroso, Angelo James. "The synthesis and reactivity of osmium carbonyl clusters." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/272544.

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43

Morewood, Catherine Alexandra. "π-complexes of osmium and ruthenium organometallic clusters". Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/272792.

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44

Buntem, Radchada. "Synthetic studies in carbonyl cluster compounds of osmium." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/271933.

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45

Mathur, Ryan Dilip. "Rhenium-osmium isotopes of base metal porphyry deposits." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289216.

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This study uses Re-Os isotopes from sulfide minerals (molybdenite, pyrite, chalcopyrite, bornite, sphalerite, arsenopyrite, and galena) and magnetite from high (400-500°C) and low and low ( < 300°C) temperature mineralization assemblages associated with the intrusion of igneous rocks to trace the source of Os and by inference the other metals. The source of Os is used as a proxy for the source of copper and gold in these systems. Concentrations of Re-Os for all sulfides except molybdenite in various deposit types vary from 0.005-2 ppb Os and 0.120-500 ppb Re. Initial ¹⁸⁷Os/¹⁸⁸Os ratios derived from isochron plots ranges from 0.15-50. These data show interesting relationships among deposits of different styles within the district, region, and worldwide scales. On the district-deposit scale, Re-Os isotopes illustrate a complex behavior for the source of Os and by inference other transition and noble metals. The source of Os can be linked to one intrusive event, multiple intrusive events, and the sedimentary rocks into which the magmas intersect. On a regional scale, in the Andean Cordillera, Re-Os isotopes reveal a correspondence between the initial ¹⁸⁷Os/¹⁸⁸Os ratios from sulfides of the ore deposit and amount of copper present in porphyry copper deposits. Eleven deposits sampled from different crustal blocks and different mineralization ages form a trend in which deposits that contain large amounts of copper have less radiogenic ¹⁸⁷Os/¹⁸⁸Os initial ratios, suggesting a greater mantle component. Smaller deposits have more radiogenic Os suggesting greater crustal components. On a global scale, the significant observation for the deposits that form in arc environments is that all of the calculated initial ¹⁸⁷Os/¹⁸⁸Os ratios are greater then the chondritic mantle. This indicates that there must be a crustal source (recycled in a metasomatized mantle, lower/upper continental crust, or subducting slab) that contributes Os and by inference other metals present in porphyry coppers. Another feature of the data set is that gold-bearing systems in arc environments associated with porphyry intrusions have crustal signatures (0.5-2.5) regardless of the style of the related ore body. For instance, the low/high sulfidation epithermal gold systems in Bucaramanga Columbia (¹⁸⁷Os/¹⁸⁸Os initial 1.2), the massive sulfide ores of the Grasberg, Irian Jaya (¹⁸⁷Os/¹⁸⁸Os initial 0.7--1.2), and Cu-Au skarns in the Hedley District, British Columbia (¹⁸⁷Os/¹⁸⁸Os initial 1.7-2.5) all have large crustal components.

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梁士賢 and Sze-yin Leung. "The chemistry of hexa- and hepta- osmium carbonyl clusters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238877.

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Leung, Sze-yin. "The chemistry of hexa- and hepta- osmium carbonyl clusters /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20978765.

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48

Mace, J. M. "Nitrosyl, nitrido and sulphido clusters of ruthenium and osmium." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354344.

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49

洪若華 and Yeuk-wah Hung. "The chemistry of Osmium-Rhodium mixed-metal carbonyl clusters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B3121535X.

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LaPointe, Anne Marie. "Alkyl, alkylidene, and alkylidyne complexes of rhenium and osmium." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11762.

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Dissertations / Theses on the topic 'Osmium'

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