187 research outputs found
The Russian-Mongolian relations and Chinese factor: modern transformations
The article highlights modern Russian-Mongolian and Mongolian-Chinese relations in the period 2013- 2022, including political, diplomatic, trade, economic, transport, energy and humanitarian spheres, as well as the impact of the Chinese Belt and Road Initiative on the interaction in the triangle “Russia – Mongolia – China”. The processes of transformation of the Russian-Mongolian relations are investigated, both before the launch of the Initiative in 2013 and after it. The author analyzes Mongolian public opinion on the Russian special military operation (SMO) in Ukraine and highlights the main reactions of its population, as well as the possibilities of transformation of Ulaanbaatar’s official position on the Ukrainian events, objective obstacles for Mongolia to dismantle friendly relations with the Russian Federation and connect to anti-Russian sanctions
Bumblebees (Bombidae) along pollution gradient - heavy metal accumulation, species diversity, and nosema bombi infection level
Substrate-Selective C-H Functionalization for the Preparation of Organosulfur Compounds from Crude Oil-Derived Components
The
direct utilization of a natural feedstock in organic synthesis
is an utmost challenge because the selective production of one product
from a mixture of starting materials requires unprecedented substrate
selectivity. In the present study, a simple and convenient procedure
is evaluated for the substrate-selective alkenylation of a single
component in a mixture of organosulfur compounds. Pd-catalyzed alkenylation
of two-, three-, four-, and five-component mixtures of crude oil-derived
sulfur species led to the exclusive C–H functionalization of
only one compound. The observed remarkable substrate selectivity opens
new opportunities for sustainable organic synthesis
Фауна пчел (Hymenoptera, Apoidea: Apiformes) реликтового липового острова Горной Шории
Подведены промежуточные итоги изучения фауны пчел реликтовых лесов с участием липы сибирской, расположенных в Горной Шории (Кемеровская область). Обнаружено 74 вида пчел из 15 родов и 6 семейств, из которых 8 видов впервые указаны для Кемеровской области. По числу видов преобладает семейство Apidae (за счёт шмелей), по числу особей (без учёта шмелей) – Colletidae (род Hylaeus). Наиболее богаты видами роды Bombus (15) и Andrena (14). Население пчел существенно меняется в ходе летнего сезона. Большая часть обнаруженных видов пчел имеет обширные ареалы, эндемики и новые виды выявлены не были
A novel samarium(II) complex bearing a dianionic bis(phenolate) cyclam ligand: synthesis, structure and electron-transfer reactions
A novel divalent samarium complex anchored on a dianionic bis(phenolate) ligand is reported and reactivity studies demonstrate that it is highly effective in inducing single-electron transfer processes.</p
Pd-II-mediated integration of isocyanides and azide ions might proceed via formal 1,3-dipolar cycloaddition between RNC ligands and uncomplexed azide
The generation of (tetrazolate)PdII complexes via the integration of (isocyanide)PdII precursors with uncomplexed azides and the verification of plausible reaction mechanisms.</p
Palladium(II)-Mediated Addition of Benzenediamines to Isocyanides: Generation of Three Types of Diaminocarbene Ligands Depending on the Isomeric Structure of the Nucleophile
Coupling
of the palladium-bis(isocyanide) complexes <i>cis</i>-[PdCl<sub>2</sub>(CNR)<sub>2</sub>] (R = 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub> <b>1</b>, 2-Cl-6-MeC<sub>6</sub>H<sub>3</sub> <b>2</b>) with benzene-1,3-diamine (<b>BDA1</b>) leads to the
diaminocarbene species <i>cis</i>-[PdCl<sub>2</sub>(CNR){C(NHR)NH(1,3-C<sub>6</sub>H<sub>4</sub>NH<sub>2</sub>)}] (<b>5</b> and <b>6</b>, respectively). In this reaction, <b>BDA1</b> behaves as a
monofunctional nucleophile that adds to one of the RNC ligands by
one amino group. By contrast, the reaction of <b>1</b> and <b>2</b> with benzene-1,4-diamine (<b>BDA2</b>) involves both
amino functionalities of the diamine and leads to the binuclear species
[<i>cis</i>-PdCl<sub>2</sub>(CNR){μ-<u>C</u>(NHR)NH(1,4-C<sub>6</sub>H<sub>4</sub>)NH<u>C</u>(NHR)}<i>-</i>(<i>cis</i>)-PdCl<sub>2</sub>(CNR)] (<b>6</b> and <b>7</b>) featuring two 1,4-bifunctional
diaminocarbene ligands. The reaction of <i>cis</i>-[PdCl<sub>2</sub>(CNR)<sub>2</sub>] (R = cyclohexyl <b>3</b>) with either <b>BDA1</b> or <b>BDA2</b> does not afford any isolable carbene
derivatives. The most versatile chemistry was observed when <b>1</b>–<b>3</b> were treated with benzene-1,2-diamine
(<b>BDA3</b>) and the relevant substituted 1,2-diamines, viz.,
4,5-dimethylbenzene-1,2-diamine (<b>BDA4</b>) and 4,5-dichlorobenzene-1,2-diamine
(<b>BDA5</b>). The addition of these diamines brings about the
formation of the monocarbene cationic complexes <i>cis</i>-[PdCl(CNR){<u>C</u>(NHR)NHC<sub>6</sub>H<sub>2</sub>X<sub>2</sub><u>N</u>H<sub>2</sub>}]Cl (X
= H, Me, Cl) (<b>8</b>–<b>16</b>), the Chugaev-type <i>C,C</i>-bound bis-carbenes <i>cis</i>-[PdCl<sub>2</sub>{<u>C</u>(NHR)NHC<sub>6</sub>H<sub>2</sub>X<sub>2</sub>NH<u>C</u>(NHR)}] (<b>17</b>, <b>18</b>), and the bis(<i>C,N</i>-chelated)carbene
complexes <i>cis</i>-[Pd{<u>C</u>(NHR)NHC<sub>6</sub>H<sub>2</sub>X<sub>2</sub><u>N</u>H<sub>2</sub>}<sub>2</sub>]Cl<sub>2</sub> (<b>19</b>–<b>24</b>). All prepared complexes (with the exception of <b>17</b> and <b>18</b>) were isolated as colorless or pale yellow solids and characterized
by elemental analyses (C, H, N), HRESI<sup>±</sup>-MS, IR, <sup>1</sup>H and <sup>13</sup>C{<sup>1</sup>H} NMR spectroscopies, and <b>4</b>, <b>7</b>, <b>13</b>, <b>16</b>, and <b>24</b> by X-ray diffraction. Complexes <b>17</b> and <b>18</b> were characterized by HRESI<sup>±</sup>-MS and IR
spectroscopy, and their structures were established by X-ray crystallography
Reactivity of bulky tris(Phenylpyrazolyl) methanesulfonate copper(I) complexes towards small unsaturated molecules
Reaction of the tris(3-phenylpyrazolyl)methane sulfonate species (Tpms(Ph))Li with the copper(I) complex [Cu(MeCN)(4)][PF6] affords [Cu(Tpms(Ph))(MeCN)] 1. The latter, upon reaction with equimolar amounts of cyclohexyl-(CyNC) or 2,6-dimethylphenyl (XylNC) isocyanides, or excess CO, furnishes the corresponding Cu(I)complexes [Cu(Tpms(Ph))(CNR)] (R = Cy 2, Xyl 3) or [Cu(Tpms(Ph))(CO)] 4. The ligated isocyanide in 2 or 3 (or the acetonitrile ligand in 1)is displaced by 3-iminoisoindolin-1-one to afford 5, the first copper(I) complex containing an 3-iminoisoindolin-1-one ligand. The ligated acetonitrile in 1 undergoes nucleophilic attack by methylamine to give the amidine complex [Cu(Tpms(Ph)){MeC(NH)NHMe}] 6, whereas only the starting materials were recovered from the attempted corresponding reactions of 2 and 3 with methylamine. Complexes 1 or 6 form the trinuclear hydroxo-copper(II)species [(mu-Cu){Cu(mu-OH) (2)(Tpms(Ph))}(2)] 7 upon air oxidation in moist methanol. In all the complexes the scorpionate ligand facially caps the metal in the N,N,O-coordination mode
Application of palladium complexes bearing acyclic amino(hydrazido)carbene ligands as catalysts for copper-free Sonogashira cross-coupling
Metal-mediated coupling of one isocyanide in cis-[PdCl2(CNR1)2] (R1 = C6H11 (Cy) 1, tBu 2, 2,6-Me2C6H3 (Xyl) 3, 2-Cl-6-MeC6H34) and various carbohydrazides R2CONHNH2 [R2 = Ph 5, 4-ClC6H46, 3-NO2C6H47, 4-NO2C6H48, 4-CH3C6H49, 3,4-(MeO)2C6H310, naphth-1-yl 11, fur-2-yl 12, 4-NO2C6H4CH213, Cy 14, 1-(4-fluorophenyl)-5-oxopyrrolidine-3-yl 15, (pyrrolidin-1-yl)C(O) 16, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propane-1-yl 17, EtNHC(O) 18] or sulfohydrazides R3SO2NHNH2 [R3 = Ph 19, 4-MeC6H420] led to a series of (hydrazido)(amino)carbene complexes cis-[PdCl2{C(NHNHX)double bond; length as m-dashN(H)R1}(CNR1)]; X = COR2, SO2R3 (21–48, isolated yields 60–96%). All prepared species were characterized by elemental analyses (C, H, N), HR ESI+-MS, IR, 1H and 13C{1H} NMR spectroscopy, and by a single-crystal X-ray diffraction for 38. Complexes 21–48 demonstrated excellent activity as catalysts in copper-free Sonogashira coupling of aryl iodides and a variety of aromatic terminal alkynes. Catalytic system runs in environmentally benign EtOH ensuring product yields of up to 75–96% and TONs of up to 104. Mechanism of the copper-free Sonogashira catalytic cycle involving 21–48 as catalysts was proposed upon identification of key intermediates using HRESI-mass
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