The reaction of dilithionaphthalene with R
2NPCl
2 (R
=
i
Pr and Et) gave dialkylamino-naphtho1,8-
bcphosphete (phosphorus versions of single-atom peri-bridged naphthalene), the strained ...four-membered ring of which was retained upon formation of Lewis-acid adducts with BH
3, S, Me
+, and W(CO)
5.
The reaction of dilithionaphthalene with R
2NPCl
2 (R
=
i
Pr and Et) gave diisopropylamino-naphtho1,8-
bcphosphete
3a and its diethyl analog
3b (phosphorus versions of single-atom peri-bridged naphthalene). The nature of the strained four-membered ring thus formed was examined by treating
3a with four types of electrophiles, BH
3, elemental sulfur, methyltriflate, and a metal fragment W(CO)
5, all of which gave the corresponding electrophile adducts with the strained ring retained. X-ray analysis was performed for
3b and all of the above adducts, showing that the trigonal plane of the amino group was commonly oriented almost perpendicular to the naphthalene plane, which was rationally understood on the basis of the favorable overlap between the lone pair orbital of the sp
2 nitrogen center and the σ
∗ orbital(s) of the two P–C bonds. In addition, when the W(CO)
5 adduct, W(
3a)(CO)
5, was treated with Pt(PPh
3)
4 and then with a CO gas, its four-membered ring was expanded to give a tungsten–platinum heterodinuclear complex having a five-membered platina–phospha heterocycle.
Since the fifteenth century, scholars have wondered about the authorship of the anonymous series of papal biographies from St. Peter onwards, now known as the Liber pontificalis. Bartolomeo Platina ...(ca. 1421-81) and Onofrio Panvinio (1530-68) were responsible for the false notion that "Anastasius the Librarian" was the book's principal author. This article reconsiders why the myth of Anastasius was created and how it was passed on. It rejects the thesis by Girolamo Arnaldi that Platina created this myth on purpose, with the intention of furthering his own career. Rather, Platina produced the myth more or less accidentally. Yet this myth proved so powerful that it was not completely dispelled until the late nineteenth century.
Platina-β-diketones were found to catalyze the hydrosilylation of alkynes and alkenes such as hexynes, hex-1-ene, styrene and trimethylvinylsilane showing up to twice as high activities in comparison ...with the well-established catalysts from Speier and Karstedt. To get insight into the mechanism of the hydrosilylation, Si–H oxidative addition reactions towards the dinuclear platina-β-diketone Pt
2{(COMe)
2H}
2(μ-Cl)
2 have been explored resulting with an 8-quinolyl substituted silane under loss of H
2 in the formation of a diacetyl(silyl)platinum(IV) complex Pt(COMe)
2Cl-(N
▪SiMe
▪N-κ
2
N,
N′,κ
Si).
The platina-β-diketones Pt
2{(COMe)
2H}
2(μ-Cl)
2 (
1), PPh
4Pt{(COMe)
2H}Cl
2 (
2) and Pt{(COMe)
2H}-(acac) (
3) were found to catalyze the hydrosilylation of alkynes (hex-1-yne, hex-2-yne, hex-3-yne) and alkenes (hex-1-ene, styrene, trimethylvinylsilane) with methyldiphenylsilane (
n
silane:
n
substrate:
n
Pt
=
3000:3000:1,
T
=
27
°C, in C
6D
6). The comparison with the well-established catalysts from Speier (
4) and Karstedt (
5) exhibited up to twice as high activities for catalyst
1 and comparable regioselectivities. To get insight into the mechanism of the hydrosilylation, Si–H oxidative addition reactions towards the dinuclear platina-β-diketone
1 have been explored. Reactions of
1 with 2-picolyl substituted hydrosilanes of the type N
▪SiMe
2H and N
▪SiMeH
▪N resulted in decomposition with the formation of platinum black, only. On the other hand, the analogous reaction with the 8-quinolyl substituted silane of the type N
▪SiMeH
▪N was found to proceed under loss of H
2 with the formation of a diacetyl(silyl)platinum(IV) complex Pt(COMe)
2Cl(N
▪SiMe
▪N-κ
2
N,
N′,κ
Si) (
23). DFT calculations gave insight into the reason for this different reactivity and into the course of reaction. For comparison, the reaction of
1 with bis(2-picolyl)amine was performed resulting under proton shift in the sense of an oxidative addition reaction in the formation of the diacetyl(hydrido)platinum(IV) complex Pt(COMe)
2Cl(N
▪NH
▪N-κ
3
N,
N′,
N′′) (
25). The complexes
23 and
25 were fully characterized spectroscopically (
1H,
13C,
195Pt,
29Si NMR, IR) and by single-crystal X-ray structure determinations.
Neste artigo, é feito um levantamento sobre o número de projetos registrados no âmbito do Centro de Artes e Letras (CAL), da Universidade Federal de Santa Maria (UFSM), no período 1992/2008, com ...temáticas referentes à região Platina e/ou ao Mercado Comum do Sul (MERCOSUL). Para esse levantamento, utilizou-se relatório solicitado e emitido pelo Centro de Processamento de Dados (CPD), através do Sistema de Informações para o Ensino (SIE). Foram levantados os números em relação aos tipos de projetos, situações e sua origem – se de graduação, ou de pós-graduação, além de outras informações pertinentes a projetos. A análise dessas informações foi feita a partir de uma abordagem quantitativa e tratou-se o tema sob enfoque do banco de dados como patrimônio documental. Enfatiza-se que o referido banco de dados deve ser administrado de forma a garantir a autenticidade e a fidedignidade dos documentos, assim como viabilizar o acesso deles à sociedade.
N-alkylplatina(II)azetidines (alkyl = Me,
tert-Bu) were prepared from chloro di(2-pyridyl)methanesulfonate ethylene platinum(II) complex and corresponding alkylamine. These complexes react with O
2 ...to form the corresponding N-alkylplatina(IV)azetidines in water at 20
°C; the latter complexes undergo C-O reductive elimination in acidic aqueous solutions to produce 2-(N-alkylamino)ethanols in high yield.
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► Stoichiometric aminohydroxylation of coordinated ethylene in the presence of primary amines and dioxygen as a direct oxidant is achieved using di(2-pyridyl)methanesulfonate Pt(II) complexes in acidic aqueous solutions ► Di(2-pyridyl)methanesulfonate ligand enables aerobic oxidation of N-alkylplatina(II)azetidines to N-alkylplatina(IV)azetidines in acidic aqueous media. ► N-alkylplatina(IV)azetidines undergo C–O reductive elimination in acidic aqueous solutions to form 2-(N-alkylamino)ethanol-derived salts. ► C–N reductive elimination of N-alkylplatina(IV)azetidines is not observed in either aprotic or protic solvents.
Chloro di(2-pyridyl)methanesulfonate ethylene platinum(II) complex was converted to corresponding N-alkylplatina(II)azetidines by reacting the former with primary amines, MeNH
2 and
tert-BuNH
2, to produce 2-ammonioethyl chloro platinum(II) species and their subsequent cyclization in the presence of NaOH in methanol. The N-alkylplatina(II)azetidines are oxidized under air or the atmosphere of pure O
2 to the corresponding N-alkylplatina(IV)azetidines in water or in methanol solution in the presence of one equivalent of a strong acid under ambient pressure at 22
°C. The resulting N-alkylplatina(IV)azetidines undergo C–O reductive elimination in acidic aqueous solutions to produce 2-(N-alkylamino)ethanols.
In this article, I examine friendship as a subject of political theory rather than as a social practice relevant to political life. As suggested by Francesco d'Altobianco Alberti in the poem recited ...at the first certame coronario, two ideas of political friendship existed side by side in Medicean Florence. They appeared in full in Palmieri's Vita civile and in Platina's De optimo cive. As I will show, the Ciceronian language of friendship is used in these works to resolve two key problems of Renaissance political thought: the need for political unity and the just way of appointing the governing elite. Palmieri placed friendship in the political sphere of concord: he was a republican imperialist who believed that civic friendship protected the political unity of the city, without which Florence would not have been able to expand. Platina, on the other hand, situated friendship in the political sphere of counsel: his concern was to support the selection of the most virtuous and knowledgeable citizens, worthy of access to public office. While Palmieri looked back to the city's medieval past, Platina cast light on the politics of friendship that allowed the Medici to stay in power.
Analisam-se as posições de Pedro Arata, Moisés Santiago Bertoni, Carlos Leonhardt e Guillermo Furlong no debate sobre o papel da Companhia de Jesus na introdução e no desenvolvimento das ciências na ...América platina. Escritas entre 1890 e fins de 1950, as obras desses autores tanto analisam o conhecimento médico, farmacêutico e botânico dos missionários jesuítas nos séculos XVII e XVIII quanto avaliam a contribuição da Companhia para o pensamento científico nos países de colonização ibérica. Suas posições antecipam o debate historiográfico sobre o reacionarismo da ordem jesuíta e as reflexões sobre a contribuição dos saberes indígenas sobre a farmacopeia americana para o conhecimento que os missionários levaram aos continentes em que atuaram.
Em várias regiões do mundo, os múltiplos usos de águas compartilhadas apresentam-se como um componente importante no jogo de poder regional. Essa situação explica por que a gestão de recursos ...hídricos se encontra vinculada a preocupações de ordem estratégica ou outras questões de alta política em muitos desses casos. Mas em que intensidade? Em busca de respostas para essa questão, o presente estudo analisa o caso da Bacia do Prata, empregando, para tanto, conceitos como securitização, atores securitizadores, objetos de referência, Complexos Regionais de Segurança (CRS) e, também, a ideia dos Complexos Hidropolíticos, originalmente desenvolvida por Michael Schulz como uma forma distinta de CRS aplicável em áreas onde as questões relacionadas aos recursos hídricos se destacam como uma característica proeminente nas dinâmicas políticas regionais.In many regions of the world, the multiple uses of transboundary fresh water have been seen as a critically important component for regional stability. This situation explains why, in many cases, water management has commonly become linked to national security concerns or other issues of a "high politics" nature. But, at what intensity? In search of answers for this question, this research analyzes the case of the River Plate Basin employing Barry Buzan's central concepts of securitization, securitizing actors, referent objects, Regional Security Complex (RSC) and the related concept of Hydropolitical Complex (HC) developed by Michael Schulz as a distinct form of RSC applicable on areas where water-related issues stand out as a salient feature in regional political dynamics.
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