O complexo [RuCl2(PPh2Bz)3] (1) é ativo em ROMP de norborneno. À 50 ºC na presença de EDA, observa-se prontamente precipitação de polímero. Obtendo-se cerca de 50% de rendimento tanto por 5 min como 30 min. O valor do IPD é alto quando aumenta-se o tempo de reação. Este complexo apresenta grandes rendimentos quando aumenta-se a razão [NBE]/[Ru], com quantitativo rendimento quando [NBE]/[Ru] = 15.000. Quando a razão [NBE]/[Ru] é 1.000, é obtido polímeros com cadeias polimodais. Trocando uma molécula de PPh2Bz em 1 por piperidina, o novo complexo [RuCl2(PPh2Bz)2pip] (2) é ativo a 25 ºC por 30 min com 92% de rendimento (PDI = 2.22). Observa-se rendimento quantitativo a 50 ºC por 30 min. O aumento da razão [NBE]/[Ru] diminui o rendimento para este complexo. Os complexos [RuCl2(PPh2Bz)2(nic)2] (3) e [RuCl2(PPh2Bz)2(isn)2] (4) não mostraram boa atividade a 25 ºC por 30 min. Obtém-se 7.2% de rendimento a 50 ºC por 5 min e 12.0% a 30 min com 5µL de EDA. / The complex [RuCl2(PPh2Bz)3] (1) is active in ROMP of norbornene. At 50 °C in presence of EDA, it is observed promptly precipitation of polymer. It is obtained c.a. 50% yield at 50 ºC for either 5 min or 30 min. The PDI value is larger when increasing the reaction time. This complex presents high yields when increasing the [NBE]/[Ru] ratio, with a quantitative reaction when [NBE]/[Ru] = 15,000. When the [NBE]/[Ru] ratio is 1,000, it is obtained polymodal polymer chains. Changing one PPh2Bz molecule in 1 for piperidine, the new complex [RuCl2(PPh2Bz)2pip] (2) is active at 25 ºC for 30 min with 92% yield (PDI = 2.22). Quantitative yield is obtained at 50 ºC for 30 min. The increase of [NBE]/[Ru] ratio affords the decrease in the yield when using this complex. The complexes [RuCl2(PPh2Bz)2(nic)2] (3) and [RuCl2(PPh2Bz)2(isn)2] (4) do not show good activity at 25 ºC up to 30 min. It is obtained 7.2% yield at 50 ºC for 5 min and 12.0% for 30 min with 5µL of EDA.

A molécula de 3-metilpiperidina (3-Mepip) foi investigada como ligante ancilar em um novo complexo do tipo [RuCl2(PPh3)2(amina)] em polimerização via metátese de olefinas ciclicas por abertura de anel (ROMP) de norborneno (NBE) e norbornadieno (NBD). A síntese do novo complexo foi realizada partindo-se do complexo precursor [RuCl2(PPh3)3], e foi caracterizado por: EPR, análise elementar de CHN, infravermelho (FTIR) e RMN de 31P. Com base nos resultados obtidos é possível propor um complexo pentacoordenado com geometria pirâmide de base quadrada (PBQ), estando os íons cloretos trans-posionados no plano equatorial da esfera de coordenação do metal, com a amina ocupando a posição apical da pirâmide devido ao seu forte caráter doador σ. As reações de ROMP dos monômeros NBE e NBD utilizando o novo complexo foram realizadas em atmosfera de argônio em função da razão molar de molar [monômero]/[Ru] (1000, 3000, 5000, 7000 e 10000), tempo (5, 30 e 60 min) e temperatura (25 e 50 °C). Com um volume de 5 µ de etildiazoacetato (EDA), 25 °C e uma razão molar de 5000 de monômero a 5 min, obteve-se 65 % de poliNBE com Mn = 0,8 x 105 e IPD igual a 1,9. Os polímeros obtidos com NBD apresentaram um rendimento em torno de 20% a 25 °C por 5 min. Reações de polimerização em atmosfera aberta resultaram em valores de rendimento próximos dos observados em atmosfera de argônio, sugerindo dessa forma que o novo complexo é resistente a processos oxidativos provocados pelo O2 da atmosfera ambiente. As reações de polimerização foram realizadas na presença de outros diazocompostos benzildiazoacetato (BDA) e tertbutildiazoacetato (TBDA) como fontes de carbenos, afim de avaliar a influência eletrônica e estérica provocada pelos diferentes grupo R desses diazocompostos. Foi observado que o etildiazoacetato (EDA) apresentou os melhores valores de rendimento dos polímeros isolados, provavelmente devido ao balanço nas características estéricas e eletrônicas desse diazo frente ao centro de Ru(II). / The 3-methylpiperidine (3-Mepip) molecule was investigated as ancillary ligand in a novel [RuCl2(PPh3)2(amine)] type complex for ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene (NBD). The synthesis of the new complex was performed from the precursor complex [RuCl2(PPh3)3], and it was characterized by: EPR, CHN elemental analysis, infrared (FTIR) and 31P NMR (1H). From the obtained results it was possible to propose a pentacoordenado complex with square-shaped pyramid geometry (PBQ), with chloride ions trans-positioned in the equatorial plane of the coordinating metal sphere, with the amine occupying the apical position of the pyramid due to its strong σ-donor character. The ROMP reactions of NBE and NBD monomers using the new complex were performed under argon atmosphere as a function of the [monomer]/[Ru] molar ratio (1000, 3000, 5000, 7000 and 10000), reaction time (5, 30 and 60 min) and temperature (25 and 50 ° C). With a volume of 5 µL of ethyldiazoacetate (EDA), at 25 °C and a 5000 molar ratio of monomer for 5 min, 65% polyNBE was obtained with Mn = 0.8 x 105 and IPD equal to 1.9. The polymers obtained with NBD showed 20% yield at 25 °C for 5 min. The polymers obtained with norbornadiene showed a yield of about 20% at 25 °C for 5 min. Polymerization reactions in air atmosphere resulted in values close to those observed in argon atmosphere, suggesting that the complex presents resistance to oxidative processes caused by O2 from the ambient atmosphere. The polymerization reactions were performed in the presence of other diazocompounds benzyldiazoacetate (BDA) and tert-butyldiazolacetate (TBDA) as sources of carbenes. In order to evaluate the electronic and steric influence caused by the different R groups of these diazocompounds, it was observed that ethyldiazoacetate EDA) presented the best yield values of the isolated polymers, probably due to the balance in the steric and electronic characteristics of this diazo in front of the Ru(II) center.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

Among the many ways in which sounds alternate in the world's languages, changes in the order of sounds (metathesis) are relatively rare. Mutsun, a Southern Costanoan language of California which was documented extensively before the death of its last speaker in 1930, displays three patterns of synchronic consonant-vowel (CV) metathesis. Two of these patterns appear to have remained productive while the language was actively spoken. In stem-deriving metathesis, many disyllabic noun stems ending in a VC string (as well as a few trisyllabic noun stems) alternate with semantically related verb stems ending in a CV string: e.g.,cayic ‘strength’ ~ cayci ‘to be strong’. In reflexive metathesis, a subset of verb stems, which are normally vowel-final in all environments, surface in consonant-final form in the presence of the reflexive suffix –pu and/or the reciprocal suffix -mu, as in kitro ‘to dress, to clothe’ ~ kitorpu ‘to get dressed, to dress oneself’. Finally, in suffix metathesis, the plural and locative suffixes (as well as the desiderative/irrealis enclitic) alternate between CCV and CVC forms depending on whether the preceding stem ends in a consonant or a vowel. Based on data from a large corpus of archival records of the language compiled over a span of more than a century, all three patterns of metathesis in Mutsun appear to defy the types of phonological analysis that have been proposed in the literature to account for metathesis in a variety of other languages. The phonetic and phonological factors claimed to motivate metathesis in other languages, such as misinterpretation of acoustic cues, stress attraction, sonority hierarchies, and positional restrictions, are absent in Mutsun. In this dissertation, I argue that prosodic analyses based on syllable weight and prosodic templates are required to account for Mutsun metathesis. Mutsun stem metathesis in particular has less in common, morphophonologically speaking, with metathesis in other languages than it does with reduplication or templatic morphology.

No description available.

This thesis describes a new catalytic activity of a commonly used metathesis catalyst and demonstrates the viability of directly coupling two powerful C-C bond forming strategies: cross-metathesis and ylide transformations, both proceeding via metal-catalysed carbene transfer. Catalytic C-C bond formation reactions are highly significant; my studies focus on such transformations involving metallocarbenes. Grubbs' 2^nd generation Ru catalyst is the most commonly used catalyst in olefin metathesis to generate thermodynamically preferred trans-olefms. During the course of my studies, I established that Grubbs 2^nd generation catalyst (0.5 mol%) can also dimerise diazoacetates to give cis-enediesters (maleates) in good to excellent yields (74-99%) with high stereoselectivity (Z:E>95:5). The reaction between two different diazoacetates, catalysed by Grubbs catalyst gave access to unsymmetrical cis-enediesters with high stereoselectivity (Z:E>95:5, generally 99:1). The catalyst was found to retain its alkene metathetical activity during diazo coupling; building on this latter observation a novel route to access dienyl dilactones by head-to-head dimerisation of unsaturated diazoacetates was developed. Cross-metathesis was found to be chemoselective in the presence of diazo functionality (when flanked by two carbonyl groups), allowing the functionalisation of tethered olefin. The elaborated diazocarbonyl olefms were subjected to Rh₂(OAc)₄ catalysed ylide formation and subsequent transformations. Significantly, one-pot cross-metathesis/ylide transformations (1,3-dipolar cycloaddition and [2,3]-simgatropic rearrangement) also proved to be viable, establishing that the spent Ru catalyst following metathesis does not affect the subsequent Rh(II)-catalysed transformation.

No description available.

The ever-worsening environmental crisis has stimulated development of less wasteful “green” technologies. To this end, tandem catalysis enables multiple catalytic cycles to be performed within a single reaction vessel, thereby eliminating intermediate processing steps and reducing solvent waste. Assisted tandem catalysis employs suitable chemical triggers to transform the initial catalyst into new species, thereby providing a mechanism for “switching on” secondary catalytic activity. This thesis demonstrates the importance of highly productive secondary catalysts through a comparative hydrogenation study involving prominent hydrogenation catalysts of tandem ring-opening metathesis polymerization (ROMP)-hydrogenation, of which hydridocarbonyl species were proved superior. This thesis illuminates optimal routes to hydridocarbonyls under conditions relevant to our ROMP-hydrogenation protocol, using Grubbs benzylidenes as isolable proxies for ROMP-propagating alkylidene species. Analogous studies of ruthenium methylidenes and ethoxylidenes illuminate optimal routes to hydridocarbonyls following ring-closing metathesis (RCM) and metathesis quenching, respectively. The formation of unexpected side products using aggressive chemical triggers is also discussed, and emphasizes the need for cautious design of the post-metathesis trigger phase.

This thesis describes the synthesis and characterisation of a variety of acetylide-bridged di- and trinuclear ruthenium acetylide complexes that were prepared in a controlled fashion, and the preparation and characterisation of the ruthenium(II) complexes required for these stepwise reactions. These precursor complexes, or building blocks, include dimethyl-, acetylidomethyl-, and bis(acetylido)ruthenium(II) complexes. An introduction to metal acetylide chemistry is presented in Chapter 1. The previous research in this area is briefly reviewed, and the potential applications of these complexes are highlighted. The primary aims of this course of work are outlined, namely, to develop a controlled synthetic approach to the synthesis of oligonuclear ruthenium acetylide complexes. The synthetic strategies for this aim are introduced in Chapter 2, and the synthetic routes to cis and trans-Ru(CH3)2(dmpe)2 (25/23) and cis and trans-Ru(CH3)2(depe)2 (26/24) are described. Characterisation of the novel, synthetically important trans-Ru(CH3)2(dmpe)2 (23) is completed by an examination of its X-Ray crystallographic structure. Chapter 3 describes the thermal and photochemical metathesis reactions of trans-Ru(CH3)2(dmpe)2 (23) with terminal acetylenes, and the preparation of a variety of acetylidomethylruthenium(II) complexes, trans-Ru(CH3)(C≡CR)(dmpe)2 (R = Ph (30), tBu (31), SiMe3 (32), C6H4-4-tBu (33), C6H3-3,5-tBu2 (34), C6H4-4-C≡CH (35), C6H4-4-OCH3 (36), C6H4-4-CH3 (37), C6H3-3,5-(CF3)2 (38)). The characterisation of these complexes by NMR spectroscopy, IR spectroscopy and X-Ray crystallography is presented. A clean and high yielding synthesis of the synthetically significant unsymmetrical bis(acetylido)ruthenium(II) complexes was developed via the reaction of an acetylidomethylruthenium(II) complex with an excess of a second terminal alkyne in a mixture of methanol and benzene. The characterisation of the novel complexes trans-Ru(C≡CR)(C≡CR′)(dmpe)2 (R = Ph, R′ = tBu (40), SiMe3 (41), C6H4-4-C≡CH (44); R = tBu, R′ = SiMe3 (42), C6H4-4-C≡CH (43), C6H4-4-tBu (45), C6H3-3,5-tBu2 (46)) by NMR and IR spectroscopy, mass spectrometry and X-Ray crystallography is described in Chapter 4. Additionally, Chapter 4 describes the synthesis and characterisation of symmetrical bis(acetylido)ruthenium(II) complexes, and a number of organic butenyne compounds, which were observed as by-products from the attempted synthesis of several of the bis(acetylido)ruthenium(II) complexes. Dinuclear ruthenium(II) complexes were prepared by the reaction of trans-Ru(C≡CR)(C≡CC6H4-4-C≡CH)(dmpe)2 (R = tBu (43) or Ph (44)) with an acetylidomethylruthenium(II) complex in toluene and methanol. Both symmetrical and unsymmetical dinuclear complexes could be prepared in this way, and were characterised by a range of techniques including NMR spectroscopy, IR spectroscopy, mass spectrometry and X-Ray crystallography, and are described in Chapter 5. In addition, an electrochemical study of one of the dinuclear complexes was undertaken using cyclic voltammetry. The symmetrical trinuclear ruthenium(II) complexes, trans,trans,trans- (RC≡C)Ru(dmpe)2(μ-C≡CC6H4C≡C)Ru(depe)2(μ-C≡CC6H4C≡C)Ru(dmpe)2(C≡CR) (R = Ph (80), tBu (81), SiMe3 (82)) was prepared by the reaction of two equivalents of an acetylidomethylruthenium(II) complex with the symmetrical bis(acetylido)ruthenium(II) complex, trans-Ru(C≡CC6H4-4-C≡CH)2(depe)2 (54), in toluene and methanol. These syntheses, and the subsequent characterisation of the products are also reported in Chapter 5. The primary aim of this thesis, viz. the synthesis and characterisation of acetylide bridged di- and trinuclear ruthenium acetylide complexes in a controlled fashion, was successfully achieved. Suggestions for future work are described in Chapter 6.

This thesis describes the synthesis and characterisation of a variety of acetylide-bridged di- and trinuclear ruthenium acetylide complexes that were prepared in a controlled fashion, and the preparation and characterisation of the ruthenium(II) complexes required for these stepwise reactions. These precursor complexes, or building blocks, include dimethyl-, acetylidomethyl-, and bis(acetylido)ruthenium(II) complexes. An introduction to metal acetylide chemistry is presented in Chapter 1. The previous research in this area is briefly reviewed, and the potential applications of these complexes are highlighted. The primary aims of this course of work are outlined, namely, to develop a controlled synthetic approach to the synthesis of oligonuclear ruthenium acetylide complexes. The synthetic strategies for this aim are introduced in Chapter 2, and the synthetic routes to cis and trans-Ru(CH3)2(dmpe)2 (25/23) and cis and trans-Ru(CH3)2(depe)2 (26/24) are described. Characterisation of the novel, synthetically important trans-Ru(CH3)2(dmpe)2 (23) is completed by an examination of its X-Ray crystallographic structure. Chapter 3 describes the thermal and photochemical metathesis reactions of trans-Ru(CH3)2(dmpe)2 (23) with terminal acetylenes, and the preparation of a variety of acetylidomethylruthenium(II) complexes, trans-Ru(CH3)(C≡CR)(dmpe)2 (R = Ph (30), tBu (31), SiMe3 (32), C6H4-4-tBu (33), C6H3-3,5-tBu2 (34), C6H4-4-C≡CH (35), C6H4-4-OCH3 (36), C6H4-4-CH3 (37), C6H3-3,5-(CF3)2 (38)). The characterisation of these complexes by NMR spectroscopy, IR spectroscopy and X-Ray crystallography is presented. A clean and high yielding synthesis of the synthetically significant unsymmetrical bis(acetylido)ruthenium(II) complexes was developed via the reaction of an acetylidomethylruthenium(II) complex with an excess of a second terminal alkyne in a mixture of methanol and benzene. The characterisation of the novel complexes trans-Ru(C≡CR)(C≡CR′)(dmpe)2 (R = Ph, R′ = tBu (40), SiMe3 (41), C6H4-4-C≡CH (44); R = tBu, R′ = SiMe3 (42), C6H4-4-C≡CH (43), C6H4-4-tBu (45), C6H3-3,5-tBu2 (46)) by NMR and IR spectroscopy, mass spectrometry and X-Ray crystallography is described in Chapter 4. Additionally, Chapter 4 describes the synthesis and characterisation of symmetrical bis(acetylido)ruthenium(II) complexes, and a number of organic butenyne compounds, which were observed as by-products from the attempted synthesis of several of the bis(acetylido)ruthenium(II) complexes. Dinuclear ruthenium(II) complexes were prepared by the reaction of trans-Ru(C≡CR)(C≡CC6H4-4-C≡CH)(dmpe)2 (R = tBu (43) or Ph (44)) with an acetylidomethylruthenium(II) complex in toluene and methanol. Both symmetrical and unsymmetical dinuclear complexes could be prepared in this way, and were characterised by a range of techniques including NMR spectroscopy, IR spectroscopy, mass spectrometry and X-Ray crystallography, and are described in Chapter 5. In addition, an electrochemical study of one of the dinuclear complexes was undertaken using cyclic voltammetry. The symmetrical trinuclear ruthenium(II) complexes, trans,trans,trans- (RC≡C)Ru(dmpe)2(μ-C≡CC6H4C≡C)Ru(depe)2(μ-C≡CC6H4C≡C)Ru(dmpe)2(C≡CR) (R = Ph (80), tBu (81), SiMe3 (82)) was prepared by the reaction of two equivalents of an acetylidomethylruthenium(II) complex with the symmetrical bis(acetylido)ruthenium(II) complex, trans-Ru(C≡CC6H4-4-C≡CH)2(depe)2 (54), in toluene and methanol. These syntheses, and the subsequent characterisation of the products are also reported in Chapter 5. The primary aim of this thesis, viz. the synthesis and characterisation of acetylide bridged di- and trinuclear ruthenium acetylide complexes in a controlled fashion, was successfully achieved. Suggestions for future work are described in Chapter 6.