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Svetlana Pylaeva was awarded “The Best Start” prize at the VII National conference on chemistry and nanomaterials of young scientists, PhD and students with the international participation «Mendeleev-2013», held at the St. Petersburg State University on April 2-5, 2013.

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Elena Kurenkova has attended the course in the Immanuel Kant Baltic Federal University and got the certificate.

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Anastasia Kultaeva has completed the course devoted to the FT-EPR and Elexsys instruments in Bruker Biospin and got the certificate.

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Andreii S. Kritchenkov, Konstantin V. Luzyanin, Nadezhda A. Bokach, Maxim L. Kuznetsov, Vladislav V. Gurzhiy, Vadim Yu. Kukushkin

«Selective Nucleophilic Oxygenation of Palladium-Bound Isocyanide Ligands: Route to Imine Complexes That Serve as Efficient Catalysts for Copper-/Phosphine-Free Sonogashira Reactions»

Organometallics 2013, accepted.

Metal-mediated reactions between cis-[PdCl2(CNR)2] (R = Xy (1), Cy (2), tBu (3), C6H3(Cl-2), Me-6 (4)) and the ketonitrones Ph2C=N(O)C6H4R′ (R′ = Me (5), Cl (6)) proceed in a 1:1 molar ratio as selective nucleophilic oxygenations and provide the imine−isocyanide complexes [PdCl2{N(C6H4R′)=CPh2}(CNR)] (7−14: R′ = Me, R = Xy (7), Cy (8), tBu (9), C6H3(Cl-2)Me-6 (10); R′ = Cl, R = Xy (11), Cy (12), tBu (13), C6H3(Cl-2)Me-6 (14)) in excellent yields (90−94%), while the reaction of the cis-[PdCl2(CNR)2] complexes withaldonitrones proceeds as 1,3-dipolar cycloaddition, giving carbene adducts which then convert to the imine complexes. Theoretical calculations at the DFT level indicate that, in the case of aldonitrones, formation of the imine complexes occurs preferably via a cycloaddition/splitting pathway, including the generation of a cycloadduct, while, in the case of ketonitrones, both the cycloaddition/splitting route and the direct oxygen atom transfer pathway are equally plausible from a kinetic viewpoint. Complexes 7−14 were characterized by elemental analyses (C, H, N), by high-resolution ESI⁺-MS, IR, and ¹H and¹³C{¹H} NMR spectroscopy, and also by X-ray diffraction (for 8). The catalytic activity study conducted for 7−14, taken as the catalysts in the Cu-/phosphine-free Sonogashira reaction, was evaluated for a typical model system comprising 4-methoxyiodobenzene and phenylacetylene and affording 1-methoxy-4-(phenylethynyl)benzene. The obtained data indicate that 7−14 exhibit a high catalytic activity (yields up to 95%, TONs up to 9500), and these catalysts are among the best studied so far.

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Gleb A. Silantyev, Oleg A. Filippov, Peter M. Tolstoy, Natalia V. Belkova, Lina M. Epstein, Klaus Weisz, Elena S. Shubina

"Hydrogen bonding and proton transfer to ruthenium hydride complex CpRuH(dppe): metal and hydride dichotomy"

Inorganic Chemistry, 2013

Abstract:

The combination of variable temperature (190-297 K) IR and NMR spectroscopy studies with quantum-chemical calculations at the DFT/B3PW91 and AIM level had the aim to determine the mechanism of proton transfer to CpRuH(dppe) (1, dppe = Ph2P(CH2)2PPh2) and the structures of intermediates. Dihydrogen bond (DHB) formation was established in the case of interaction with weak proton donors like CF3CH2OH. Low-temperature protonation (at about 200 K) by stronger proton donors leads via DHB complex to cationic non-classical complex [CpRu(η2-H2)(dppe)]+ (2). Thermodynamic parameters of DHB formation (for CF3CH2OH:
deltaH° = -4.9 ± 0.2 kcal·mol-1,
deltaS° = -17.8 ± 0.7 cal·mol^-1·K^-1) and proton transfer (for (CF3)2CHOH: deltaH°PT = -5.2 ± 0.3 kcal·mol^-1, deltaS°PT = -23 ± 1 cal·mol^-1·K^-1) were determined. Above 240 K 2 transforms into trans-[CpRu(H)2(dppe)]+ (3) yielding a mixture of 2 and 3 in 1:2 ratio. Kinetic analysis and activation parameters for “[Ru(η2-H2)]+ → trans-[Ru(H)2]+” transformation indicate reversibility of this process in contrast to irreversible intramolecular isomerization of Cp* analogue. Calculations show that the driving force of this process is greater stability (by 1.5 kcal·mol^-1 in deltaE scale) of the dihydride cation in comparison with the dihydrogen complex. The calculations of the potential energy profile indicate the low barrier for deprotonation of 2 suggesting that the formation of trans-[CpRu(H)2(dppe)]+ proceeds via deprotonation of [Ru(η2-H2)]+ to DHB complex, formation of hydrogen bond with Ru atom and subsequent proton transfer to the metal site.