14,390 research outputs found
C–H Amination Mediated by Cobalt Organoazide Adducts and the Corresponding Cobalt Nitrenoid Intermediates
No full textTreatment of ((Ar)L)CoBr ((Ar)L = 5-mesityl-1,9-(2,4,6-Ph(3)C(6)H(2))dipyrrin) with a stoichiometric amount of 1-azido-4-(tert-butyl)benzene N(3)(C(6)H(4)-p-(t)Bu) furnished the corresponding four-coordinate organoazide-bound complex ((Ar)L)CoBr(N(3)(C(6)H(4)-p-(t)Bu)). Spectroscopic and structural characterization of the complex indicated redox innocent ligation of the organoazide. Slow expulsion of dinitrogen (N(2)) was observed at room temperature to afford a ligand functionalized product via a [3+2] annulation, which can be mediated by a high-valent nitrene intermediate such as a Co(III) iminyl ((Ar)L)CoBr((·)N(C(6)H(4)-p-(t)Bu)) or Co(IV) imido ((Ar)L)CoBr(N(C(6)H(4)-p-(t)Bu)) complex. The presence of the proposed intermediate and its viability as a nitrene group transfer reagent are supported by intermolecular C–H amination and aziridination reactivities. Unlike ((Ar)L)CoBr(N(3)(C(6)H(4)-p-(t)Bu)), a series of alkyl azide-bound Co(II) analogues expel N(2) only above 60 °C, affording paramagnetic intermediates that convert to the corresponding Co-imine complexes via α–H–atom abstraction. The corresponding N(2)-released structures were observed via single-crystal-to-crystal transformation, suggesting formation of a Co-nitrenoid intermediate in solid-state. Alternatively, the alkyl azide-bound congeners supported by a more sterically accessible dipyrrinato scaffold (tBu)L ((tBu)L = 5-mesityl-(1,9-di-tert-butyl)dipyrrin) facilitate intramolecular 1,3-dipolar cycloaddition as well as C–H amination to furnish 1,2,3-dihydrotriazole and substituted pyrrolidine products, respectively. For the C–H amination, we observe that the temperature required for azide activation varies depending on the presence of weak C–H bonds, suggesting that the alkyl azide adducts serve as viable species for C–H amination when the C–H bonds are (1) proximal to the azide moiety and (2) sufficiently weak to be activated
Paul and the powers in relation to Christ's supremacy:: re-visiting the Pauline concept of "supernatural powers" from an African worldview perspective.
Full text linkThe Pauline concept of "supernatural powers" underlines the supremacy of Christ over "supernatural powers". They were created in him, through him and for him (Col 1: 16-20). Christ's death was not only their defeat, but also their humiliation (Col 2: 15). Christ's resurrection and exaltation clearly speaks of his supremacy (Eph 1: 20f; Phil 2: 9-11). Christ is also supreme since "supernatural powers" cannot separate believers from the love of God (Rom 8: 38f) or thwart the existence of the church, through which the manifold wisdom of God is made known to them (Eph 3: 10). Paul's teachings about the "powers" in relation to Christ's supremacy do not seem to have had much sway in the African context. This happens due to two opposite but related errors: that of believing "supernatural powers" exist and allowing them to determine human existence and that of denying they exist. Yet the Pauline concept neither denies the existence of "supernatural powers" nor allows them to be given allegiance or worship as if they are equal to Christ. Due to these two errors, which also represent the missionary legacy and the African response to it, most African believers hold a dual religious heritage that causes pastoral problems for the African church. Rather than engaging the dual religious heritage, most of the studies on "supernatural powers" seem to have complicated it. The trend among anthropologists has been to deny that "supernatural powers" exists and/or to reduce them to psychological or social or political or religious functions. Several biblical scholars, who deal with "supernatural powers" from the perspective of myth, maintain that "supernatural powers" were marginal in Paul's thinking and irrelevant for modern Christians. They maintain that Paul demythologised "supernatural powers" so as to refer to existential realities such as sin and death or to the structures of human existence. As a result, most of the anthropological and biblical treatises on "supernatural powers" do not seem to engage the full measure of the African beliefs in "supernatural powers". This is largely because their interpretations of "supernatural powers" are shaped by the Western worldview and are mainly from a Western worldview perspective. But the interpretation of reality as people perceives it is usually shaped by their worldview. For that reason, it is vital to re-visit the Pauline concept of "supernatural powers" from an African worldview perspective, taking into consideration that Paul initially spoke to a context similar to the African context with regard to the beliefs in, and fear of "supernatural powers"
Empire, Hegemony, and Leadership: Developing a Research Framework for the Study of Regional Powers
Full text linkRegional powers are often conceived of as “regional leading powers,” states which adopt a cooperative and benevolent attitude in their international relations with their neighbors. The paper argues that regional powers can follow a much wider range of foreign policy strategies in their region. Three ideal-typical regional strategies are identified: empire, hegemony, and leadership. The paper is devoted to a theory-led distinction and clarification of these three terms, which are often used interchangeably in the field of international relations. According to the goals pursued, to the means employed, and to other discriminating features such as the degree of legitimation and the type of self-representation by the dominant state, the paper outlines the essential traits of imperial, hegemonic, and leading strategies and identifies subtypes for better classifying hegemony and leadership.regional powers, empire, hegemony, leadership, strategy
The agential fork : the hidden consequences of agency for plenitude in David Lewis' thesis of genuine modal realism
No full textIn this dissertation, I argue that David Lewis' abductive argument for Genuine Modal Realism (GMR) has the unwelcome, and hidden, implication of being unable to
accommodate agent causation theories of free will. This is because of his formulation of plenitude, which basically says that every way that a world or a part of a world could be is the way that some world, or part of some world is. This formulation tacitly assumes
that chance and nomological principles are sufficient to account for everything that happens at worlds. However, agent causation theories argue that free will is neither reducible to chance nor determined by physics. My argument recasts a fork argument made by Andrew Beedle. I proceed by arguing that chance-based principles evince an ontologically distinct kind of modality than agent causation principles. However,
plenitude only accounts for the physics/chance-based kind of modality. There is no similar principle of plenitude that can be given for agential modality that does not
collapse into the chance-based principle. But even if such a principle could be found, it would violate the doctrine in GMR that claims worlds are causally isolated. If no agential plenitude principle can be found and there is agential modality, then plenitude fails. If there is no agency at our world, and Lewis’ original formulation of plenitude is correct, then GMR implies no agency at any
world. This is the fork: If there is agency and GMR holds, then either plenitude fails, or isolation fails. But if there is no agency, and GMR holds, then there is no agency at any possible world. The latter prong is too strong a claim for an abductive argument like GMR. The
former proves that GMR cannot accommodate agent-causation theories. GMR loses its neutrality either way, to its detriment
The burgeoning constitutional requirement of rationality and separation of powers has rationality review gone too far?
No full textThis thesis presents an analysis of three recent judgments of our apex courts which collectively illustrate a maximising of the 'minimum threshold requirement' of rationality through the seemingly inexhaustible constitutional principle of legality. The question sought to be addressed is whether, in extending this baseline requirement to cover procedural fairness, reason-giving and something akin to proportionality, in the context of non-administrative action and in the absence of any meaningful engagement with the doctrine of separation of powers, the courts are going too far
Decomposing symmetric powers of certain modular representations of cyclic groups
Full text linkFor a prime number p, we construct a generating set for the ring of invariants for the p+1 dimensional indecomposable modular representation of a cyclic group of order p^2. We then use the constructed invariants to describe the decomposition of the symmetric algebra as a module over the group ring, confirming the Periodicity Conjecture of Ian Hughes and Gregor Kemper for this case
Nitrogen Atom Transfer Catalysis by Metallonitrene C–H Insertion: Photocatalytic Amidation of Aldehydes
No full textC−H amination and amidation by catalytic nitrene transfer are well-established and typically proceed via electrophilic attack of nitrenoid intermediates. In contrast, the insertion of (formal) terminal nitride ligands into C−H bonds is much less developed and catalytic nitrogen atom transfer remains unknown. We here report the synthesis of a formal terminal nitride complex of palladium. Photocrystallographic, magnetic, and computational characterization support the assignment as an authentic metallonitrene (Pd−N) with a diradical nitrogen ligand that is singly bonded to PdII. Despite the subvalent nitrene character, selective C−H insertion with aldehydes follows nucleophilic selectivity. Transamidation of the benzamide product is enabled by reaction with N3SiMe3. Based on these results, a photocatalytic protocol for aldehyde C−H trimethylsilylamidation was developed that exhibits inverted, nucleophilic selectivity as compared to typical nitrene transfer catalysis. This first example of catalytic C−H nitrogen atom transfer offers facile access to primary amides after deprotection.European Research Council http://dx.doi.org/10.13039/100010663Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659U.S. Department of Energy http://dx.doi.org/10.13039/100000015Welch Foundation http://dx.doi.org/10.13039/100000928National Science Foundation http://dx.doi.org/10.13039/10000000
Responding to Indo-Pacific rivalry: Australia, India and middle power coalitions
Full text linkIn this Analysis, Lowy Institute International Security Program Director Rory Medcalf and Nonresident Fellow C. Raja Mohan argue that Chinese assertiveness and uncertainties about America’s role in Indo-Pacific Asia are causing middle powers to look for alternative approaches to regional security. The Analysis argues that enhanced security cooperation between Indo-Pacific middle powers should be extended to the creation of “middle-power coalitions” in the region.
Key findings
China’s assertiveness and uncertainties about America’s response are causing middle powers in Indo-Pacific Asia to looking beyond traditional approaches to security
Cooperation between Indo-Pacific middle power coalitions would build regional resilience against the vagaries of US-China relations
India and Australia are well placed to form the core of middle power coalition buildin
The Evolution of Reciprocity, Trust, and the Separation of Powers
Full text linkThis dissertation is composed of three self-contained essays on strategic interactions under incomplete contracting. Chapter 1 considers the evolution of reciprocal preferences in a setting where individuals live in separate groups. Chapter 2 analyzes the costs and benefits of a separation of powers in an incomplete contracts framework. Chapter 3 finally shows that, even when important parts of a relationship could be arranged perfectly by a complete contract, contractual incompleteness can arise endogenously if the proposal of a complete contract is perceived as a signal of distrust.Evolution of Reciprocity; Trust; Incomplete Contracts; Separation of Powers
Predictions of helical twisting powers and molecular chirality
Full text linkWhen chiral molecules are added to an achiral nematic liquid crystalline solvent, they can transmit their molecular chirality to the whole system over distances many times their molecular length. The helical twisting power, βm, is a measure of the degree of twist a chiral molecule can induce in a nematic liquid crystal. The work in this thesis is primarily concerned with calculating helical twisting powers for a variety of chiral molecules using computational and theoretical methods. The first technique used to calculate βm employed Monte Carlo simulations of an atomistic chiral dopant molecule in a chiral liquid crystal phase composed of generic liquid crystalline molecules. The method was found to be computationally expensive, but provided reasonable predictions of when compared with experimental results. Prior to these calculations, a liquid crystal solvent for use in this method was studied. Computer simulations of L/D = 4 soft repulsive spherocylinder (SRS) molecules were performed and two liquid crystalline phases were found in the SRS phase diagram. The scaled chiral index and the chirality order parameter are quantitative measures of molecular chirality. Both of these methods have been found to show a good correlation with experimentally determined helical twisting powers of relatively rigidchiral molecules. The chiral measures have also been incorporated in Monte Carlo simulations of flexible chiral molecules. This method has been successful in predicting βm for flexible chiral dopants, in predicting the temperature dependence of βm, has demonstrated a temperature induced helical twist inversion, and has been used in a predictive study to aid in future synthetic strategies. The final part of the thesis uses Monte Carlo simulations of a chiral molecule in an achiral liquid crystal phase. These simulations have shown that it is possible to relate the torque the chiral molecule induces in the solvent to βm
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