Metathesis is a valuable reaction for the production of new alkenes. In the last 50 years, heterogeneous as well as homogeneous catalysts have been used for this reaction. In the homogeneous category are the very successful catalysts designed by the Grubbs group. The first generation Grubbs precatalyst (Gr1) bearing two phosphine ligands was followed after extensive studies by the more active second generation Grubbs precatalyst (Gr2). In Gr2, one of the phosphine ligands is replaced with an N-heterocyclic carbene. Grubbs type precatalysts bearing pyridynyl-alcoholato chelating ligands are pertinent to this study. Scheme 1: The synthesis of Grubbs type precatalysts bearing a pyridynyl-alcoholato ligand. In two previous studies, both supported by computational methods, Grubbs type precatalysts with N^O chelating ligands were synthesised. These investigations were motivated by the fact that chelating ligands bearing different donor atoms can display hemilability. The loosely bound donor atom can de-coordinate to make available a coordination site to an incoming substrate “on demand”, whilst occupying the site otherwise and hence preventing decomposition via open coordination sites. In the first investigation, the incorporation of an O,N-ligand with both R1 and R2 being phenyl groups into the Gr2 precatalyst, resulted in an increase in activity, selectivity and lifetime of the precatalyst in comparison to Gr2 in the metathesis reaction with 1- octene. In the second study, three synthesised complexes were found to be active for the metathesis of 1-octene. This computational study sought to better understand the structural differences and thermodynamic properties of these Grubbs type precatalysts with bidentate/hemilabile ligands. A large number of structures were constructed in Materials Studio by varying the R groups of the bidentate/hemilabile ligand attached to both the Gr1 and Gr2 catalysts. The majority of structures were Gr1-type complexes. For each ligand selected, a group of structures consisting of closed precatalyst, open precatalyst, and where applicable a precatalyst less PCy3, closed metallacycle, open metallacycle and where applicable a metallacycle less PCy3, was constructed and optimised using DMol3. Bond lengths, bond angles, HOMO and LUMO energies and Hirshveld charges of structures were compared with one another. PES scans were performed on the metallacycles of four groups. The purpose of the PES scans was to ascertain whether these bidentate ligands were hemilabile and to illuminate the preferred reaction mechanism for these types of precatalysts. The major finding of this study was that the possibility of an associative mechanism cannot be ruled out for some Gr2-type precatalysts with bidentate ligand. For some precatalysts hemilability is energetically expensive and possibly not viable. No evidence of a concerted mechanism was found. The dissociative mechanism was found to be the preferred mechanism for most of the structures that were subjected to PES scans. The HOMO-LUMO energies of a complex can be used, as a predictive tool, to assess the reactivity and stability of a complex, as well as its preference for substrates. / Thesis (MSc (Chemistry))--North-West University, Potchefstroom Campus, 2013.

A major driving force for development of new catalyst systems is the need for more efficient synthesis of chemical compounds essential to modern life. Catalysts having superior performance offer significant environmental and economic advantages, but their discovery is not trivial. Well-defined, homogeneous catalysts can offer unparalleled understanding of ligand effects, which proves invaluable in directing redesign strategies. This thesis work focuses on the design of ruthenium complexes for applications in dinitrogen activation and olefin metathesis. The complexes developed create new directions in small-molecule activation and asymmetric catalysis by late-metal complexes. Also examined are the dual challenges, ubiquitous in catalysis, of adequate interrogation of catalyst structure and performance. Insight into both is essential to enable correlation of ligand properties with catalyst activity and/or selectivity. Improved methods for accelerated assessment of catalyst performance are described, which expand high-throughput catalyst screening to encompass parallel acquisition of kinetic data. A final aspect focuses on direct examination of metal complexes, both as isolated species, and under catalytic conditions. Applications of charge-transfer MALDI mass spectrometry to structural elucidation in organometallic chemistry is described, and the technique is employed to gain insight into catalyst decomposition pathways under operating conditions.

In this study a number of cage alkenes were synthesised and tested for activity towards ringopening metathesis polymerisation (ROMP) with the commercially available catalysts 55 (Grubbs-I) and 56 (Grubbs-II). The first group of monomers are derivatives of tetracyclo[6.3.0.04,1105,9]undec-2-en-6-one (1). The synthesis of these cage alkenes are summarised in Scheme 7.1. The cage alkene 126b was synthesised by a Diels-Alder reaction between 1 and hexachlorocyclopentadiene (9, Scheme 7.2). The geometry of 126b was determined from XRD data. Knowledge of the geometry of 126b also established the geometry of 127 since conformational changes during the conversion from 126b to 127 are unlikely. Synthesis of the cage alkene 125 by the cycloaddition of 9 to 118 failed. The cage alkene exo-11- hydroxy-4,5,6,7,16,16-hexachlorohexacyclo[7.6.1.03,8.02,13.010,14]hexa-dec-5-ene (124, Scheme 7.3) could therefore not be prepared. Synthesis of 125 by reduction of 126b with various reduction systems was not successful. Theoretical aspects of these reactions were investigated with molecular modelling. A possible explanation for the unreactive nature of 126b towards reduction is presented, but the lack of reactivity of 118 towards 9 eluded clear explanations. The synthesis of cage alkenes from 4-isopropylidenepentacyclo[5.4.0.02,6.03,10.05,9]-undecane-8,11- dione (23) did not meet with much success (Scheme 7.4). Numerous synthetic methods were investigated to affect the transformation from 134a/134b to 135 (Scheme 7.5). These attempts evolved into theoretical investigations to uncover the reasons for the observed reactivity. Possible explanations were established by considering the differences and similarities between the geometries and electronic structures of reactive and unreactive cage alcohols. ROMP of cage monomers based on 1 were mostly unsuccessful. Only the cage monomer 127 showed some reactivity. Endocyclic cage monomers with a tetracycloundecane (TCU) framework showed no reactivity. The results from NMR experiments verified the experimental results. Hexacyclo[8.4.0.02,9.03,13.04,7.04,12]tetradec-5-en-11,14-dione (3) exhibited notable ROMP reactivity. Examination of the orbitals of the cage alkenes used in this study suggested that the reactivity of 1 and 3 could possibly be enhanced by removal of the carbonyl groups. Decarbonylation of 1 and 3 yielded the cage hydrocarbons 159 and 175, respectively. ROMP tests revealed that 175 is an excellent monomer, but 159 was unreactive. The results obtained for the ROMP reactions in this study was rationalised by considering aspects such as ring strain, energy profiles, steric constraints, and frontier orbital theory. The concept of ring strain is less useful when describing the reactivity of cage alkenes towards ROMP and therefore the concepts of fractional ring strain and fractional ring strain energy (RSEf) were developed. A possible link between RSEf and the ROMP reactivity of cage alkenes was also established. The following criteria were put forth to predict the reactivity or explain the lack of reactivity of cage alkenes towards ROMP reactions with Grubbs-I and Grubbs-II. The criteria for ROMP of cage monomers: 1. Sufficient fractional ring strain energy (RSEf). 2. A reasonable energy profile when compared to a reference compound such as cyclopentene. 3. Ability to form a metallacyclobutane intermediate with reasonable distances between different parts of the cage fragment. 4. Sufficient ability of the polymer fragment to take on a conformation that exposes the catalytic site. 5. Sufficient size, shape, orientation and energy of HOMO and/or NHOMO at the alkene functionality of the cage monomer and of the LUMO at the catalytic site. / Thesis (Ph.D. (Chemistry))--North-West University, Potchefstroom Campus, 2012

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Marie E. Krafft, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Sept. 19, 2005). Document formatted into pages; contains 147 pages. Includes bibliographical references.

La préparation efficace d’une nouvelle famille de sels de 1,3-bis(aryl)-4,5-dihydroimidazolium non symétriques comprenant un groupement encombrant hexafluoroisopropylmethoxy en position para- ou ortho- sur l’un des substituants N-aryle a été développée. De nouveaux sels d’imidazolium contenant un substituant fluoroalkyle en position ortho d’un des substituant aryle ont aussi été synthétisés. Ces sels sont d’excellents précurseurs de carbènes N-hétérocycliques qui ont permis l’accès efficace à une série de nouveaux complexes carbéniques du ruthénium à ligands NHC non symétriques. La méthode repose sur la génération in situ du carbène par traitement des sels d’imidazolium avec le potassium hexamethyldisilazide suivie d’un échange du ligand tricyclohexylphosphine à partir des complexes de Grubbs et Hoveyda de première génération. L’activité de ces nouveaux complexes a été étudiée sur des réactions modèles intra- et intermoléculaires de métathèse des oléfines. Il a été montré que la plupart des complexes synthétisés ont de bonnes activités catalytiques en fermeture de cycle à partir du diallylmalonate d’éthyle et en métathèse croisée de l’allylbenzène avec le 1,3-diacetoxybut-2-ene. Leurs performances sont comparables à celles des catalyseurs de Grubbs et Hoveyda de seconde génération, avec toutefois quelques différences dans les étapes d’initiation. Les effets structuraux et électroniques des ligands NHC non symétriques sur la réactivité des nouveaux complexes du ruthénium ont été étudiés. En particulier, il a été montré que les catalyseurs de type Hoveyda porteurs de ligands monosubstitués par un groupement fluoroalkyle en position ortho d’un des substituant N-aryle présentent une initiation très rapide dans les réactions de métathèse croisée. Au contraire, les complexes porteurs d’un groupement donneur alkyle ont montré une activité catalytique très faible, comme par exemple le complexe porteur d’un ligand (tert-butyl)NHC qui s’est révélé inerte à la fois en fermeture de cycle et métathèse croisée. Les complexes porteurs d’un ligand NHC symétrique avec deux groupes hexafluoroisopropylmethoxy ont des activités catalytiques nettement inférieures à leurs homologues non symétriques, révélant ainsi la forte influence de l’absence de symétrie du ligand carbène NHC dans l’activité catalytique des complexes. / An efficient approach to a new family of unsymmetrical 1,3-bis(aryl)-4,5-dihydroimidazolium salts comprising bulky hexafluoroisopropylmethoxy group in para- or ortho-position in one of the N-aryl substituents has been developed. New imidazolinium salts with fluoroalkyl-containing mono-ortho-aryl substituent at one of the nitrogen atom have also been synthesized. It was found that these imidazolinium salts are effective NHC precursors and provided an efficient access to a series of new ruthenium carbene complexes with unsymmetrical fluorinated NHC ligands. The method involves in situ generation of the carbene via treatment of the starting salts with potassium hexamethyldisilazide and subsequent ligand exchange reaction with PCy3-containing first generation Grubbs and Hoveyda complexes. The catalytic activity of the new complexes has been investigated on model reactions of intra- and intermolecular olefin metathesis. It was found that most of the synthesized complexes exhibited high activity in cyclization of diethyl diallylmalonate and in cross metathesis of allyl benzene with 1,3-diacetoxybut-2-ene. Their performance has proved to be comparable with commonly used second generation Grubbs and Hoveyda catalysts, with sometimes some differences in the initiation step. Structural and electronic impact of fluorinated unsymmetrical NHC on reactivity of new ruthenium complexes has been studied. In particular, it was revealed that Hoveyda type catalysts with mono-ortho-aryl substituted NHC ligands have demonstrated very high initiation rate in CM reactions. On the contrary, catalysts with more donating N-alkyl NHCs have displayed low activity; for instance, the N-tert-butyl substituted complex has proved to be absolutely inert both in RCM and CM reactions. Symmetrical ruthenium carbene complexes bearing NHC ligands with two hexafluoroisopropylmethoxy group in para-positions of N-aryl moieties are significantly inferior in reactivity with respect to their asymmetric counterparts showing the strong influence of the desymmetrization factor on catalytic activity.

Poly(lactic acid), PLA, is a viable replacement to petroleum derived polymers due to its renewable feedstock, biodegradability and bioassimilability, yet improvements in its physical, thermal and mechanical properties are required before it can fully enter all commodity markets. This thesis investigates olefin cross-metathesis (CM) as a synthetic strategy to modify the properties of PLA. The use of novel lanthanide and actinide catalysts on the microstructure control of PLA are also explored. The Tebbe reagent was used in a new synthetic strategy to produce a novel olefin derivative of lactide (MML). Olefin CM of MML with hex-1-ene was successful but polymerisation pre- and post-CM was unsuccessful due to monomer instability. CM of another olefin derivative of lactide, 3-methylenated lactide (3-ML) was successful with aliphatic alkenes; hex-1-ene to dodec-1-ene. To overcome competing alcoholysis of the functionalised monomers, which prevented polymerisation, hydrogenation was used to remove the olefin entity followed by successful ring-opening polymerisation (ROP) to produce polymers of low glass-transition temperatures (Tg). Post-polymerisation CM on an olefin containing polymer P(β-heptenolactone) P(β-HL), with methyl acrylate and an epoxide, generated functionalised homopolymers with increased Tg’s. Co-polymerisation of lactide with β-HL generated novel gradient-copolymers. Olefin CM with 15 different cross-partners produced functionalised copolymers with different thermal properties. Based on this route a new methodology was created to introduce two unique functionalities into the polymer backbone by manipulation of the olefin reactivities. Finally, in a collaborative project, uranium and cerium catalysts, Me3SiOU(OArP)3 and Me3SiOCe(OArP)3 - designed out-with the group- were tested and compared as ROP catalysts for lactide. Both catalysts were active in living polymerisations of L-lactide and under immortal conditions the activity and rates of the catalysts were switched, accounted for by a change in the coordination sphere due to ligand displacement. ROP of rac-lactide using the uranium analogue produced heterotactic-biased PLA with a Pr = 0.79.

In this master thesis 1,2-disubstituted cyclopentadienes were prepared by method composed of three transition metal catalysed reactions. Then, the cyclopentadienes were converted into cyclopentadienyl manganese, rhenium and iron complexes. A one-pot synthesis of the cyclopentadienyl metal complexes was developed without isolation of the intermediate cyclopentadienes. The second goal of this thesis was preparation of vinyl-substituted cyclopentadienes using ring closing enyne metathesis. The last part of thesis dealt with synthesis of a chiral cyclopentadiene and preparation of the corresponding metal complexes. The important part of this work was preparation of starting materials using palladium catalysed cross-coupling reactions. Key words: cyclopentadienes, carbometallation, cross-coupling, metathesis, metallocenes.

Os monômeros ligantes 3amdpy2oxaNBE (1), 3imdpyoxaNBE (2) e ácido âmico (3) foram sintetizados e caracterizado por analise elementar (CHN), infravermelho e RMN 1H e 13C. A partir do monômero 1 sintetizou-se compostos partindo de complexos do tipo [RuCl2(LL)], onde foi LL=bpy 37 (complexo 4), phen (complexo 6) ou 5-Cl-phen (complexo 7), e foram realizados estudos de fotoquímica e fotofísica. Os complexos 6 e 7 apresentaram uma eficiente fotofísica e não apresentaram fotoquímica, enquanto os complexos semelhante [Ru(bpy)2(3amnpy)2](PF6)2 (5) e [Ru(phen)2(3amnpy)2](PF6)2 (8) que possui a aminopiridina no lugar do monômero 1, apresentaram fotoquímica. Observou-se que as diferenças na rigidez dos ligantes phen e bpy podem causar diferentes propriedades fotoquímicas e fotofísicasem sistemas do tipo cis-[RuCl2(?-diimina)]. Todos os complexos exibiram absorções na região de 350 nm e entre 420 a 500 nm. Sendo que 5 e 8 apresentaram fotoquímica e os complexos 6 e 7 apresentaram fotofisica. Estes foram estudados em diferentes solventes (DMF, CH3CN, CH2Cl2, THF) e em diferentes comprimentos de onda de irradiação (340, 440 e 500 nm). A emissão dos complexos 6 (580 nm) e 7 (582 nm) em acetonitrila é atribuída a uma MLCT (Ru_phen). Sendo observada a independência do _irr, mas existe dependência da emissão quando a temperatura é abaixada. Além disso, suas propriedades fotocatalíticas são demonstradas pela supressão oxidativa através de íons receptores do metilviologenio. Ainda deve-se levar em conta que, o anel quelante do monômero ligante 1 contribui ainda mais para a estabilização destes complexos, ao contrario, 5 e 8 possuem uma fotolabilização . / The monomer ligands 3amdpy2oxaNBE (1), 3imdpyoxaNBE (2) and amic acid (3) were synthesized and characterized by elementar analysis (CHN), infrared and 1H e 13C NMR. Since monomer 1, it was synthesized complexes of type [RuCl2(LL)], where LL=bpy 37 (complex 4), phen (complex 6) or 5-Cl-phen (complexo 7), with which photophysics and photochemical studies were performed. The complexes 6 and 7 presented efficient photophysics and they do not presented photochemistry, while the similar complexes [Ru(bpy)2(3amnpy)2](PF6)2 (5) and [Ru(phen)2(3amnpy)2](PF6)2 (8), which possess the aminopyridine in place of monomer 1, presented photochemistry. It was observed that the difference in the rigidity of the ligands phen and bpy may cause different photochemical and photophysical properties in systems of type cis-[RuCl2(?- diimine)]. All complexes exhibited absorptions in region of 350 nm and between 420 and 500 nm, where 5 and 8 presented photochemistry and the complexes 6 and 7 presented photophysics. They were studied in different solvents (DMF, CH3CN, CH2Cl2, THF) and in different irradiation wavelength (340, 440 e 500 nm). The emission of the complexes 6 (580 nm) and 7 (582 nm) in acetonitrile is attributed to an MLCT (Ru_phen). It was observed independence of _irr, however there is dependence of emission when the temperature is lowered. Furthermore, their photocatalytic properties are demonstrated by oxidative quenching using methylviologen ion. One should consider that the chelating ring of monomer ligand 1 contributes even more to the stabilization of these complexes, unlike, 5 and 8 that possess photolabilization.

Orientador: Luiz Carlos Dias / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T21:30:59Z (GMT). No. of bitstreams: 1 Finelli_FernandaGadini_D.pdf: 6560101 bytes, checksum: 5eb9e7f25248bb940dd29d8af3e505ed (MD5) Previous issue date: 2009 / Resumo: O capítulo 1 relata as sínteses da macrolactona da migrastatina 11 e da macrolactona análoga 62a. A macrolactona da migrastatina é o composto que apresenta a maior atividade de inibição de migração de células tumorais in vitro dentre os compostos da família da migrastatina até hoje sintetizados. A macrolactona 62a, ainda inédita na literatura, é epímero em C8 da macrolactona 62b sintetizada pelo grupo do Professor Danishefsky em 2004 e apresenta atividade de inibição semelhante à macrolactona 11. Além disso, foram realizados estudos visando à síntese da macrolactona 124, epímero da macrolactona 11. Paralelamente, em colaboração com a Farmoquímica Cristália e o grupo do Professor Adriano Andricopulo, do IF/USP de São Carlos, foram realizados testes de avaliação biológica de diversos compostos sintetizados neste trabalho com o intuito de gerar novas substâncias químicas bioativas candidatas a novos fármacos no tratamento do câncer de mama. O capítulo 2 relata a síntese e aplicação de alguns substratos contendo grupos funcionais que ainda não haviam sido testados frente à reação de metátese de alcinos utilizando um novo catalisador de molibdênio. Este projeto foi desenvolvido no laboratório do Professor Alois Fürstner, no Instituto Max-Planck, em Mülheim an der Ruhr ¿ Alemanha. Além disso, um precursor do fragmento B das Latrunculinas A e B foi sintetizado em grande escala, fornecendo material para subsequentes estudos químicos e biológicos / Abstract: Chapter 1 describes the syntheses of macrolactones 11 and 62a. Macrolactone 11 presents the best tumor cell migration inhibitory effect among the compounds of the migrastatin family synthesized so far. Macrolactone 62a, not described in the literature, is the C8-epimer of macrolactone 62b, which was synthesized by Professor Danishefsky¿s group in 2004 and shows similar antitumor activities when compared to macrolactone 11. Studies aiming at the synthesis of macrolactone 124, epimer of macrolactone 11, were also performed. Besides, in collaboration with Farmoquímica Cristália and Professor Andricopulo¿s group (IF/USP, São Carlos), biological assays of several compounds synthesized in this work were carried out, with the purpose of developing new bioactive chemical substances which may soon be employed in the manufacturing of novel drugs in the treatment of breast cancer.Chapter 2 describes the syntheses of new substrates for applications in Mo-catalyzed RCAM. This project was carried out in Professor Fürstner¿s laboratory, at Max-Planck Institute, in Mülheim an der Ruhr ¿ Germany. In this part of the work, a Latrunculin A and B fragment precursor was also synthesized in large scale to provide further material for new biological and chemical studies / Doutorado / Quimica Organica / Doutor em Ciências

Os complexos do tipo [RuCl2(PPh3)2amina], amina = pip (1) ou pep (2), foram estudados como iniciadores catalíticos para reações de ROMP de NBE, NBD e oxaNBE-OMe e na ROMCP de NBE com NBD e oxaNBE-OMe com NBE. O complexo [RuCl2(PPh3)(pep)(isn)] (3) foi estudado na ROMP de NBE e NBD. Os complexos 2 e 3 são inéditos e suas caracterizações são discutidas e correlacionadas com o complexo com 1. As reações de catálises foram realizadas com variações de tempo, volume de solvente e temperatura, em atmosfera de Ar ou ar e na presença de EDA. <br />O rendimento foi quantitativo na ROMP de NBE com o complexo 1 em 2 mL de CHCl3, por 5 min a 25 &deg;C em Ar, com IPD de 1,9 e Mw na ordem de 106 g mol-1. Com o complexo 2, os rendimentos foram quantitativos (IPD ~ 3 e Mw na ordem de 104 g mol-1) e independentes do tempo (5 -120 min) e volume de solvente (2 - 8 mL). Com 3, os rendimentos diminuíram com o aumento do volume de solvente, mas com IPD ~ 2 e Mw na ordem de 104 g mol-1. Em todos os casos os rendimentos diminuíram em atmosfera de ar e com polímeros polimodais. <br />Rendimentos quantitativos de poliNBD foram obtidos com 1 a 40 &deg;C e com 2 a 25 &deg;C na faixa de volume de solvente estudada, por 60 e 120 min, em Ar. Os rendimentos com 3 foram inferiores a 35%. Foram também obtidos rendimentos quantitativos em atmosfera de ar em certas combinações de tempo e volume de solvente, indicando que os complexos são robustos para atividades em soluções contendo O2. Todos os polímeros de NBD foram insolúveis. <br />Obteve-se até 70% de poli(NBE-co-NBD) isolado a partir de reações com 1 e reações quantitativas com 2, dependendo da fração molar NBE:NBD usada, indicando as razões de reatividades do complexos. <br />A ROMP de oxaNBE-OMe com 1 ou com 2 formou 15 a 30% de rendimento, a 40 &deg;C por 24 h em Ar. Na ROMCP desse monômero com NBE obteve-se de 5 a 30% de rendimento, dependendo da fração molar. Os rendimentos são maiores nas frações molares com maior quantidade de NBE. Poli(oxaNBE-OMe) foi solúvel, enquanto que seus copolímeros foram pouco solúveis. <br />São realizadas discussões quantos às características eletrônicas e de impedimentos estéricos nos complexos estudados nas polimerizações via metátese, selecionando-se os ligantes ancilares frente às condições de reações para obtenções de bons rendimentos e características dos polímeros isolados. / The complexes of type [RuCl2(PPh3)2amina], amine = pip (1) or pep (2), were studied as catalytic initiators for ROMP of NBE, NBD and oxaNBE-OMe and for ROMCP of NBE with NBD and oxaNBE-OMe with NBE. The complex [RuCl2(PPh3)(pep)(isn)] (3) was studied for ROMP of NBE and NBD. The complexes 2 and 3 are novels and their characterizations are discussed and correlated with the complex 1. The catalysis reactions were performed with variations of time, volume of solvent and temperature, either in Ar or air atmosphere, in the presence of EDA. <br />The yield was quantitative for ROMP of NBE with complex 1 in 2 mL of CHCl3 for 5 min at 25 &deg;C in Ar, with PDI of 1.9 and Mw in the order of 106 g mol-1. With the complex 2, the yields were quantitatives (PDI ~ 3 and Mw in the order of 104 g mol-1) and independent of time (5 - 120 min) and volume of solvent (2 - 8 mL). With 3, the yields decreased when increasing the volume of solvent, but with PDI ~ 2 and Mw in the order of 104 g mol-1. In all the cases, the yields decreased in air atmosphere with polymodal polymers. <br />Quantitative yields of poliNBD were obtained with 1 at 40 &deg;C and with 2 at 25 &deg;C in the range of the studied volume of solvent, for 60 and 120 min, in Ar. The yields with 3 were less than 35%. Quantitative yields were also obtained in air atmosphere in some combinations of time and volume of solvent, indicating that the complexes are robust for activities in solutions containing O2. All polyNBD were insoluble. <br />It was obtained up to 70% of poly(NBE-co-NBD) isolated from reactions with 1 and quantitative reactions were obtained with 2, depending on the NBE:NBD molar fraction used, indicating the reactivity ratios for the complexes. <br />The ROMP of oxaNBE-OMe with 1 or with 2 yielded 15 to 30% at 40 &deg;C for 24h in Ar. In the ROMCP of this monomer with NBE, it was obtained from 5 to 30% yield, depending on the molar fraction. Yields are higher in molar fractions with higher amount of NBE. Poly(oxaNBE-OMe) was soluble, while its copolymers were poorly soluble. <br />Discussions are held on the electronic characteristics and steric hindrances in the studied complexes for the metathesis polymerization, selecting the ancillary ligands as a function of the reaction conditions to obtain good yields and to improve the characteristics of the isolated polymers.