Introdução: As alterações anatômicas do fêmur proximal ou do acetábulo, como as decorrentes das sequelas da epifisiólise do fêmur proximal, da displasia do quadril da doença de Legg-Perthes-Calvé, podem levar ao desenvolvimento da artrose do quadril. No entanto, em torno de 80% dos indivíduos que desenvolvem essa doença têm uma anatomia óssea considerada normal. Ainda assim, surgiu a hipótese que alterações sutis do fêmur proximal ou do acetábulo, denominadas, respectivamente, cam e pincer, poderiam gerar um contato anormal entre essas estruturas ósseas, desencadear lesão condral e, como consequência, a artrose do quadril. Esse mecanismo foi denominado impacto fêmoro-acetabular. No entanto, a comprovação da relação entre o impacto e a artrose do quadril depende da uniformização dos critérios diagnósticos do cam e do pincer, ainda escassa e variável na literatura. Dessa forma, será possível a definição da prevalência e história natura do impacto fêmoro-acetabular e da sua relação com a artrose do quadril. Objetivo: Avaliar a prevalência do impacto fêmoro-acetabular tipo cam e tipo pincer em uma amostra de indivíduos assintomáticos. Pacientes e Métodos: Foram estudados 106 indivíduos assintomáticos (65 homens e 41 mulheres), com idade entre 20 e 40 anos. A condição determinante para a inclusão no estudo foi à ausência de história de dor no quadril ao longo da vida. Foram obtidas radiografias em ântero-posterior e Dünn 45°. A presença de cam foi determinada por um ângulo alfa, arbitrado, de 55° e a presença de pincer, quando observado o sinal da parede posterior e/ou o sinal de crossover. Resultados: Foi observada prevalência de cam de 29%; o sinal do crossover e da parede posterior ocorreram, respectivamente, em 20% e 29% dos indivíduos estudados. Pelo menos uma das imagens de impacto fêmoro-acetabular estava presente em 65% dos indivíduos da amostra. Conclusão: A prevalência encontrada das imagens de impacto fêmoro-acetabular (65%) está acima daquelas relatadas na literatura. É necessária a ampliação do estudo para confirmar os resultados encontrados e a realização de estudos prospectivos bem controlados para avaliar o papel do cam e do pincer no desenvolvimento da artrose do quadril. / Background: Anatomical abnormalities of the proximal femur or the acetabulum, such as those resulting from the consequences of slipped epiphyses of the proximal femur, the hip dysplasia of Legg-Calve-Perthes disease, could lead to the development of hip osteoarthrosis. Nevertheless, around 80% of individuals who develop this condition have a bone anatomy considered normal. Still, the hypothesis arose that subtle alterations of the proximal femur or the acetabulum, called, respectively, cam and pincer, could generate an abnormal contact between these bony structures, triggering chondral lesion and as a consequence, arthritis of the hip. This mechanism has been named femoroacetabular impingement. Nevertheless, evidence of the relationship between the impact and osteoarthritis of the hip depends on the standardization of diagnostic criteria of cam and pincer, still scarce and variable in the literature. Thus it will be possible to define the prevalence and natural history of femoroacetabular impingement and its relationship with hip osteoarthrosis. Aim: To determine the prevalence of cam-type and pincer-type femoroacetabular impingements in asymptomatic subjects. Patients and Methods: Were studied 106 asymptomatic subjects (65 males and 41 females) aged between 20 and 40 years. The determining condition for inclusion in the study was the absence of history of hip pain throughout life. Radiographs were obtained in anteroposterior pelvic view and Dunn 45° view. The presence of cam was determined by an angle alpha, arbitrated, 55 ° and the presence of pincer when the observed the posterior wall and / or crossover signs. Results: A prevalence of 29% of cam, and 20% and 29% of crossover sign and posterior wall sign respectively was found. At least, one of those radiographic signs of femoroacetabular impingement was found in 65% (68) of the cases. Conclusion: In conclusion, the prevalence of images of femoroacetabular impingement (65%) is above those reported in the literature. Increase of the study is necessary to verify the results found, and the performance of well-controlled prospective studies to evaluate the role of the cam and pincer in the development of osteoarthritis of the hip.

Introdução: As alterações anatômicas do fêmur proximal ou do acetábulo, como as decorrentes das sequelas da epifisiólise do fêmur proximal, da displasia do quadril da doença de Legg-Perthes-Calvé, podem levar ao desenvolvimento da artrose do quadril. No entanto, em torno de 80% dos indivíduos que desenvolvem essa doença têm uma anatomia óssea considerada normal. Ainda assim, surgiu a hipótese que alterações sutis do fêmur proximal ou do acetábulo, denominadas, respectivamente, cam e pincer, poderiam gerar um contato anormal entre essas estruturas ósseas, desencadear lesão condral e, como consequência, a artrose do quadril. Esse mecanismo foi denominado impacto fêmoro-acetabular. No entanto, a comprovação da relação entre o impacto e a artrose do quadril depende da uniformização dos critérios diagnósticos do cam e do pincer, ainda escassa e variável na literatura. Dessa forma, será possível a definição da prevalência e história natura do impacto fêmoro-acetabular e da sua relação com a artrose do quadril. Objetivo: Avaliar a prevalência do impacto fêmoro-acetabular tipo cam e tipo pincer em uma amostra de indivíduos assintomáticos. Pacientes e Métodos: Foram estudados 106 indivíduos assintomáticos (65 homens e 41 mulheres), com idade entre 20 e 40 anos. A condição determinante para a inclusão no estudo foi à ausência de história de dor no quadril ao longo da vida. Foram obtidas radiografias em ântero-posterior e Dünn 45°. A presença de cam foi determinada por um ângulo alfa, arbitrado, de 55° e a presença de pincer, quando observado o sinal da parede posterior e/ou o sinal de crossover. Resultados: Foi observada prevalência de cam de 29%; o sinal do crossover e da parede posterior ocorreram, respectivamente, em 20% e 29% dos indivíduos estudados. Pelo menos uma das imagens de impacto fêmoro-acetabular estava presente em 65% dos indivíduos da amostra. Conclusão: A prevalência encontrada das imagens de impacto fêmoro-acetabular (65%) está acima daquelas relatadas na literatura. É necessária a ampliação do estudo para confirmar os resultados encontrados e a realização de estudos prospectivos bem controlados para avaliar o papel do cam e do pincer no desenvolvimento da artrose do quadril. / Background: Anatomical abnormalities of the proximal femur or the acetabulum, such as those resulting from the consequences of slipped epiphyses of the proximal femur, the hip dysplasia of Legg-Calve-Perthes disease, could lead to the development of hip osteoarthrosis. Nevertheless, around 80% of individuals who develop this condition have a bone anatomy considered normal. Still, the hypothesis arose that subtle alterations of the proximal femur or the acetabulum, called, respectively, cam and pincer, could generate an abnormal contact between these bony structures, triggering chondral lesion and as a consequence, arthritis of the hip. This mechanism has been named femoroacetabular impingement. Nevertheless, evidence of the relationship between the impact and osteoarthritis of the hip depends on the standardization of diagnostic criteria of cam and pincer, still scarce and variable in the literature. Thus it will be possible to define the prevalence and natural history of femoroacetabular impingement and its relationship with hip osteoarthrosis. Aim: To determine the prevalence of cam-type and pincer-type femoroacetabular impingements in asymptomatic subjects. Patients and Methods: Were studied 106 asymptomatic subjects (65 males and 41 females) aged between 20 and 40 years. The determining condition for inclusion in the study was the absence of history of hip pain throughout life. Radiographs were obtained in anteroposterior pelvic view and Dunn 45° view. The presence of cam was determined by an angle alpha, arbitrated, 55 ° and the presence of pincer when the observed the posterior wall and / or crossover signs. Results: A prevalence of 29% of cam, and 20% and 29% of crossover sign and posterior wall sign respectively was found. At least, one of those radiographic signs of femoroacetabular impingement was found in 65% (68) of the cases. Conclusion: In conclusion, the prevalence of images of femoroacetabular impingement (65%) is above those reported in the literature. Increase of the study is necessary to verify the results found, and the performance of well-controlled prospective studies to evaluate the role of the cam and pincer in the development of osteoarthritis of the hip.

Complexes with pincer ligand moieties have garnered much attention in the past few decades. They have been shown to be highly active catalysts in several known transition metal-catalyzed organic reactions as well as some unprecedented organic transformations. At the same time, the use of computational organometallic chemistry to aid in the understanding of the mechanisms in organometallic catalysis for the development of improved catalysts is on the rise. While it was common in earlier studies to reduce computational cost by truncating donor group substituents on complexes such as tertbutyl or isopropyl groups to hydrogen or methyl groups, recent advancements in the processing capabilities of computer clusters and codes have streamlined the time required for calculations. As the full modeling of complexes become increasingly popular, a commonly overlooked aspect, especially in the case of complexes bearing isopropyl substituents, is the conformational analysis of complexes. Isopropyl groups generate a different conformer with each 120 ° rotation (rotamer), and it has been found that each rotamer typically resides in its own potential energy well in density functional theory studies. As a result, it can be challenging to select the most appropriate structure for a theoretical study, as the adjustment of isopropyl substituents from a higher-energy rotamer to the lowest-energy rotamer usually does not occur during structure optimization. In this report, the influence of the arrangement of isopropyl substituents in pincer complexes on calculated complex structure energies as well as a case study on the mechanism of the isomerization of an iPrPCP-Fe complex is covered. It was found that as many as 324 rotamers can be generated for a single complex, as in the case of an iPrPCP-Ni formato complex, with the energy difference between the global minimum and the highest local minimum being as large as 16.5 kcalmol-1. In the isomerization of a iPrPCP-Fe complex, it was found that the isopropyl substituents not only influence the calculated structure energies, but they dictate the mechanism of isomerization with the rotation of isopropyl substituents from the arrangement in the starting material complex to the arrangement in the product complex being the rate-determining step.

No description available.

Abstract: Pincer compounds are organometallic complexes with intriguing tunable reactivities. In this work we explore their unique properties and reactivities through spectroscopic and computational investigations, with a focus on the PN3P pincer platform. First, we conducted a computational study on five pincer complexes with stereogenic phosphine arms that have multiple well-defined rotamers. Significant energy differences could be found between the lowest and highest energy rotamer in each set of pincer complexes. All rotamers for reactant, transition state, and product, were evaluated in a reaction energy profile of a CO2 reduction by a pincer nickel hydride, and we found that this reaction could be found either favorable or unfavorable, depending on the choice of rotamer. A software to generate rotamers has been developed and applied to the work presented in this part. The zwitterionic aromatic resonance form has a large contribution in the dearomatized PN3P* nickel pincer complexes, which is demonstrated by the imine arm's ability to act as an organic σ-donor, similar to NHC catalysts. Related to this property, as well as the pincer compound's ability to undergo metal-ligand cooperation catalysis, is the basicity (or acidity) of pincer ligand spacer arms. Therefore, we have determined the Brønsted basicity of the imine arm in three PN3P* nickel pincer complexes in THF. The relative basicity was found to be strongly influenced by the X ligand trans to the PN3P* ligand, and less by alkyl groups on phosphine donor arms. Finally, we explored the reactivity between a PN3P* rhodium carbonyl pincer complex and dioxygen at room temperature in solution, and at elevated temperature in the solid state. Intriguingly, the singlet PN3P* rhodium carbonyl complex reacts with the triplet dioxygen both in solution and in the solid state to afford oxidation on the ligand backbone. This is possible due to the ligands ability to do a single-electron transfer to dioxygen. The solid state reaction was studied with in situ rhodium K-edge X-ray absorption spectroscopy under dioxygen flow, where an isobestic point was observed, and simulation studies support formation of a Rh-O2 adduct. In situ FTIR studies in a static dioxygen environment revealed that the PN3P* rhodium carbonyl complex is able to facilitate the incorporation of O2 into CO and CO2.

No description available.

No description available.

L’objectif de cette thèse était la synthèse de nouveaux pro-ligands NHC et de leurs complexes métalliques correspondants, en particulier de l’iridium. La tentative de trouver de nouvelles voies de synthèse de complexes NHC à partir des imidazole-2-thiones correspondants n’a pas donné les résultats attendus.Cependant, il a été possible de préparer des composés de coordination intéressants de ces imidazole-2-thiones : ainsi, un complexe de Bi a été préparé et a pu servir d’agent de transmétallation vers le Pd. De nouveaux proligands NHC de type « pince » et plusieurs de leurs complexes d’iridium ont été préparés. Plusieurs complexes de mercure portant ces ligands ont été synthétisés. De plus, une série de sels d’imidazolium portant des fonctionnalités potentiellement hémilables a été préparée et leur réactivité vis-à-vis de l’iridium étudiée. / The purpose of this thesis was the synthesis of novel pro-ligands to NHCs and their corresponding metal complexes, notably of iridium. While the attempt to find a new pathway to obtain NHC complexes starting from the corresponding imidazole-2-thiones did not yield the expected result, it was possible to obtain interesting coordination compounds from those imidazole-2-thiones themselves:A dinuclear Bi complex was prepared that served as an effective transmetallation agent toward Pd. Novel pincer-type NHC pro-ligands were obtained, and several iridium complexes of their corresponding NHC ligands were prepared. Furthermore, several mercury complexes of these ligands were synthesized. Finally, a series of imidazolium salts bearing potentially hemilabile functionalities were prepared and their reactivity toward Ir was studied.

No description available.

No description available.