This study investigates the relationship between energy metals and precious metals to assess their suitability as safe haven assets in clean energy investment portfolios. This study aims to conduct ...an effect analysis of the events that occurred during the years 2020 and 2022, characterized by substantial investments in the field of clean energy. The analysed period encompasses the period from 13 July 2018 to 11 July 2023. The study is carried out in multiple stages with the aim of investigating a highly tumultuous period in the global economy. To assess long-term relationships, the econometric methodology proposed by Gregory and Hansen will be employed. The research shows a positive association between energy metals (excluding nickel futures) and clean energy indexes, suggesting their potential as secure investments for green investors diversifying their portfolios. Additionally, the study confirms the reliability of precious metals, such as gold, silver, and platinum as safe havens for clean energy stock indexes. These findings highlight the stability that both energy and precious metals can offer within clean energy portfolios during market volatility, emphasizing their value in such investment strategies. In brief, this study affirms that energy and precious metals are invaluable pillars in the structure of clean energy portfolios, offering unwavering support during market turbulence.
Neste artigo, apresentamos uma análise preliminar do Libro de cirugía, de 1725, um manuscrito anônimo de medicina e farmácia, que se encontra na Biblioteca do convento da ordem franciscana de ...Catamarca, Argentina, e se mantém inédito até hoje. Sua transcrição e análise contribuem significativamente para a reconstituição da cultura científica vigente na América platina do Setecentos, principalmente, no que concerne aos saberes e às práticas medicinais que circulavam na região e eram empregados nas reduções jesuíticas. Além de discutirmos o título dado ao manuscrito e as hipóteses levantadas pelos historiadores Felix Garzón Maceda (1916) e Guillermo Furlong (1947) sobre sua procedência e autoria, nos detemos, também, nas evidências de intertextualidade que o texto nos oferece e compartilhamos algumas breves análises dos conteúdos dos capítulos que compõem o Libro.
Constituiu objetivo da pesquisa em identificar e caracterizar abordagens em livros didáticos de História do Brasil em relação à presença brasileira na região platina, na segunda metade do século XIX. ...Foi selecionado um total de 13 livros didáticos de diferentes temporalidades, compreendendo o período de 1886 a 1999. A seleção dos livros observou critérios como possuir inúmeras edições, ter sido adotado por escolas das redes de ensino da educação básica e o lugar socioinstitucional dos autores. A análise das fontes se fez por meio da técnica da análise de conteúdo. Caracterizamos três conjuntos de autores com concepções diversas. Apesar disso, foram observadas permanências nas narrativas dos livros analisados, como a do Império brasileiro como garantidor da independência do Uruguai.
D'Elia offers a compelling, surprising story that reveals a Renaissance world that witnessed the rebirth of interest in the classics, a thriving homoerotic culture, the clash of Christian and pagan ...values, the contest between republicanism and a papal monarchy, and tensions separating Christian Europeans and Muslim Turks.
The reaction of the dinuclear platina-β-diketone Pt2{(COMe)2H}2(μ-Cl)2 (1) with two equivalents of adenine and its methylated derivatives N6-R,9-R′Ade–H resulted in adenine-based aminocarbene ...platinum(II) complexes Pt(COMe)Cl{CMe(N6-R,9-R′Ade–H)-κC,κN} (R/R′ = Me/Me, 2; H/Me, 3; H/H, 4) whose identities were confirmed by NMR and IR spectroscopies as well as by high-resolution mass spectrometric investigations. Single-crystal X-ray diffraction analyses of complexes 2 and 4·THF revealed relatively short Pt–C and N–C bonds in the aminocarbene–platinum units, which is in accord with a substantial double bond character of these bonds. The electronic structure of these complexes will be further confirmed by DFT calculations as also the course of reaction.
Reactions of the dinuclear platina-β-diketone 1 with adenine and its methylated derivatives resulted in formation of adenine-based aminocarbene platinum(II) complexes 2–4 (R, R′ = H, Me). These reactions belong to the few ones where a nucleophile (here the N6 atoms of adenines) attacks the hydroxycarbene C atom of platina-β-diketones. Display omitted
•Adenines were found to attack the hydroxycarbene C atom of platina-β-diketones.•Adenine-based aminocarbene complexes of platinum are prepared and characterized.•A substantial pπ–pπ bonding character in the aminocarbene–platinum units was found.•DFT calculations give insight into the course of aminocarbene Pt complex formation.
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.
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