Irina V. Sterkhova

Structure and intramolecular hydrogen bonds in bis(trifluoromethylsulfonylamino)methane and N-[(trifluoromethylsulfonyl)aminomethyl]acetamide

Bis(trifluoromethylsulfonylamino)methane in an inert medium exists as an equilibrium mixture of monomeric forms with various types of intramolecular hydrogen bonds, whose population depends on the polarity of the medium. The energetically most favorable form is a symmetrical form containing two N-H...O=S bonds. Less stable are the isomer with two N-H...F-C bonds and the unsymmetrical isomer with two different hydrogen bonds. N-[(Trifluoromethylsulfonyl)aminomethyl]acetamide contains one intramolecular intramolecular N-H...O=C hydrogen bond and preserves ability for self-association.

Structure of bis(trifluoromethanesulfonyl)imide in inert and protophilic media

According to the data of IR spectroscopy, dielectrometry, and HF/6-31G**, B3LYP/6-311G** quantum chemical calculations bis(trifluoromethanesulfonyl)imide (CF3SO2)2NH in nonpolar medium (CCl4) exists as an H-complex formed by its molecules in two tautomeric (NH and OH) forms. In a polar medium (CH2C12) linear chain polyassociates with a bifurcate hydrogen bond are formed similar to those existing in the crystal. In the presence of protophilic solvents ion pairs consisting of the protonated molecule of the base and dimeric anion of bis(trifluoromethanesulfonyl)imide are formed.

Molecular Structure and Photoinduced Intramolecular Hydrogen Bonding in 2-Pyrrolylmethylidene Cycloalkanones

The structures of pyrrolylmethylidene derivatives of 2,3-dihydro-1H-inden-1-one (3), 3,4-dihydro-naphthalen-1(2H)-one (4), and cycloalkanones (5-7) were studied for the first time in the solid state and solution by NMR, IR, and UV spectroscopies supported by DFT quantum mechanical calculations. It was shown that all studied compounds except cycloheptanone derivative 7 both in crystal and in solution exist in the form of dimers where single E or E,E configuration with respect to the exocyclic C═C bond is stabilized by intermolecular hydrogen bonds N-H···O═C. UV irradiation at a wavelength of 365 nm of MeCN or DMSO solutions of 3-6 results, depending on the exposition time and solvent, partial to complete isomerization to the Z or Z,E isomers (in the case of 6, also the Z,Z isomer). The NMR and IR spectroscopy data show the existence of a strong intramolecular hydrogen bond N-H···O═C in the Z moieties of isomerized compounds. The studied compounds are protonated by trifluoroacetic acid at the carbonyl oxygen, in spite of the reverse order of basicity and nucleophilicity of the carbonyl group and the pyrrole ring. Investigation of the behavior of compound 6 with respect to acetate and fluoride anions allows one to consider it as a potential fluoride sensor.

Effect of the state of a melt on the glass-forming ability, structure, and properties of a melt-quenched bulk amorphous nickel-based alloy

The glass-forming ability, viscosity, phase composition, and microhardness of a melt-quenched Ni64.4Fe4Cr4.9Mn2B16.2C0.5Si8 bulk amorphous alloy quenched from various melt temperatures at near-critical rates are studied. The melt-quenching temperature ensuring the maximum glass-forming ability and microhardness (HV= 13 GPa) of the alloy is found to be 1200–1230°C. The melt viscosity is shown to behave anomalously near the solidification temperature, and the related factors favoring this anomalous behavior are detected.

Conformations and Self-association of Trifluoro-N-(3-formylcyclohept-2-en-1-yl)methanesulfonamide

The structure of trifluoro-N-(3-formylcyclohept-2-en-1-yl)methanesulfonamide and its self-association in solution have been studied by IR spectroscopy and quantum chemical methods [B3LYP/6-311G(d,p), AIM]; proton affinities of basic centers in its molecule have been evaluated. Trifluoro-N-(3-formylcyclohept-2-en-1-yl)methanesulfonamide in inert solvents forms cyclic dimers, whereas in crystal chain associates are more likely to be formed via hydrogen bonding between the NH and C=O groups of neighboring molecules. The carbonyl group in the title compound undergoes protonation only by the action of very strong trifluoromethanesulfonic acid. Weaker acids give rise to solvate H-complexes at the NH, C=O, and S=O groups. The topology of hydrogen bonds in dimers of different types has been analyzed in terms of the AIM theory.

Experimental and theoretical investigation of self-association in inert environment of new triflamide derivatives

According to the data of IR spectroscopy and quantum chemical calculations N-(2-phenylethyl) trifluoromethanesulfonamide exists in an inert solvent CCl4 as an equilibrium mixture of the monomer and chain associates; in contrast, N-(5-iodocyclopentenyl)-1,1,1-trifluoromethanesulfonamide under the same conditions is prone to the formation of cyclic self-associates. The behavior of N,N′-(cyclohexenediyl)-bis(1,1,1-trifluoromethane sulfonamide) in the same medium is far more complicated: apart from the monomer with intramolecular hydrogen bonds (HB), it forms only cyclic self-associates with eight-membered and eleven-membered rings.

Solvatochromism of heteroaromatic compounds: XXX. N-Methyltrifluoromethanesulfonamide as hydrogen-bond donor

In two-centered H-complexes with protophilic solvents, the monomer of N-methyltrifluoromethanesulfonamide I behaves as a strong H-bond donor, stronger than 4-fluorophenol and ranking second after 4-nitrophenol. In protophilic media, amide I exists as monomeric H-complexes with a two-centered H-bond and 1:2 H-complexes of the open-chair dimer with a bifurcated (three-centered) hydrogen bond. The formation of a strong bifurcated H-bond weaken the bridging N-H.‥O=S bond.

Solvatochromism of heteroaromatic compounds: XXXI. Energetics of hydrogen bonding between N-methyltrifluoromethanesulfonamide and ethers

For a series of H-complexes of ethers with N-methyltrifluoromethanesulfonamide CF3SO2NHMe, a proportionality between the spectral shift (ΔvNH) and the enthalpy of complex formation (ΔH) was found. Comparison with hydroxyl-containing H-bond donors revealed the following contradiction: ΔH increases in the order CF3SO2NHMe < MeOH < PhOH, whereas ΔvXH increases in the order MeOH < CF3SO2NHMe ∼ PhOH. The absence of a single Badger-Bauer relationship ΔvXH ∼ f(ΔH) is due to the contribution of universal interactions into the enthalpy of H-complex formation. The account for these interactions allowed calculation of the energy of an intermolecular hydrogen bond, which varies in parallel with the spectral shift: MeOH < CF3SO2NHMe ∼ PhOH.

Oxidative cycloaddition of electron-deficient arenesulfonamides to hexa-1,5-diene

The reaction of electron-deficient arenesulfonamides 4-XC6H4SO2NH2 (X = Cl, NO2) with hexa-1,5-diene in the oxidative system t-BuOCl-NaI afforded cis- and trans-isomeric 1-(arenesulfonyl)-2,5-bis(iodomethyl)pyrrolidines. The diastereoisomers were separated, and their structure was determined by NMR spectroscopy and X-ray analysis. No further cyclization of these compounds into 3,8-diazabicyclo[3.2.1]-octanes was observed.

Microwave-assisted synthesis of 2,5-diarylthiazolo[5,4-d]thiazoles from benzaldehydes and dithiooxamide

One-pot condensation of dithiooxamide with aromatic aldehydes and subsequent oxidation of intermediate 2,5-dihydro[1,3]thiazolo[5,4-d][1,3]thiazoles with selenium dioxide afforded 2,6-diaryl[1,3]thiazolo-[5,4-d][1,3]thiazoles which were characterized by 1H and 13C NMR, IR, and X-ray diffraction data.