Halide abstraction competes with oxidative addition in the reactions of aryl halides with [Ni(PMenPh(3-n))4]

Density functional theory (DFT) calculations have been used to study the oxidative addition of aryl halides to complexes of the type [Ni(PMenPh(3-n))4], revealing the crucial role of an open shell singlet transition state for halide abstraction. The formation of NiI versus NiII has been rationalised through the study of three different pathways: (i) halide abstraction by [Ni(PMenPh(3-n))3], via an open shell singlet transition state; (ii) SN2-type oxidative addition to [Ni(PMenPh(3-n))3], followed by phosphine dissociation; and (iii) oxidative addition to [Ni(PMenPh(3-n))2]. For the case of [Ni(PMe3)4], a microkinetic model was used to show that these data are consistent with the experimentally-observed ratios of NiI and NiII. Importantly, [Ni(PMenPh(3-n))2] complexes often have little if any role in the oxidative addition reaction because they are relatively high in energy. The behaviour of [Ni(PR3)4] complexes in catalysis is therefore likely to differ considerably from those based on diphosphine ligands in which two coordinate Ni0 complexes are the key species undergoing oxidative addition

A computational journey in organoboron chemistry: from photochemistry to cross-coupling catalysis

Organoboron chemistry is one of the most powerful tools in organic synthesis to achieve chemical complexity. In the recent years, boron substituents have been used to modulate the selectivity of chemical reactions. However, the understanding or boron effects is usually a challenging task and requires intensive mechanistic investigations.Along the last years, our group have focused on the computational investigation of different reactions where boron plays a key role in controlling the overall reactivity of the system. Herein, we provide a comprehensive scenario of those effects using four different examples where boron controlsthe outcome of the process. First, we will discuss the chemoselective reduction of carboxylic acids over ketones due to a highly activate organoboron species that is formed by hidden borane chemistry (Figure 1A).[1] Then, a modular access to the counter-thermodynamic disubstituted cyclohexanes will be rationalized based on a cascade reaction where boron plays a key role to revert the thermodynamic driving force (Figure 1B).[2] Finally, the mechanism of two different light-mediated reactions, where boron plays a key role in both the activation and the stability of the resulting radicals (Figure 1C-D), will be briefly introduced to show the amazing potential of boron in radical based photochemistry to modulate the selectivity and the reactivity of metalloid radicals.[3,4

Present-Day Social Problem and its Solution by Buddhism

departmental bulletin pape

IoT マルウェアの画像分類手法への難読化による攻撃と対処の研究

指導教員：稲村 浩thesi

「教育効率」と「教育効果」との関係をめぐる理論的考察 ―「学習形態論」から把握し直す「教育実践」の意味―

text紀要論文 / Departmental Bulletin Paperdepartmental bulletin pape

Energy Transfer (EnT) Catalysis of Non-Symmetrical Borylated Dienes: Origin of Reaction Selectivity in Competing EnT Processes

Energy transfer catalysis (EnT) has had a profound impact on contemporary organic synthesis enabling the construction of higher in energy, complex molecules, via efficient access to the triplet excited state. Despite this, intermolecular reactivity, and the unique possibility to access several reaction pathways via a central triplet diradical has rendered control over reaction outcomes, an intractable challenge. Extended chromophores such as non-symmetrical dienes have the potential to undergo [2+2] cycloaddition, [4+2] cycloaddition or geometric isomerisation, which, in combination with other mechanistic considerations (site- and regioselectivity), results in chemical reactions that are challenging to regulate. Herein, we utilise boron as a tool to probe reactivity of non-symmetrical dienes under EnT catalysis, paying particular attention to the impact of boron hybridisation effects on the target reactivity. Through this, a highly site- and regioselective [2+2] cycloaddition was realised with the employed boron motif effecting reaction efficiency. Subtle modifications to the core scaffold enabled a [4+2] cycloaddition, while a counterintuitive regiodivergence was observed in geometric isomerisation versus [2+2] cycloaddition. The observed reactivity was validated via a mechanistic investigation, determining the origin of regiodivergence and reaction selectivity in competing EnT processes

「ソビエト社会主義共和国連邦における社会保障(公的資料集)」（二）

application/pdfСоциальное обеспечение в СССР. 翻訳資料社會問題研究. 1965, 15(2), p.72-102departmental bulletin pape