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N-propargylimidazole and N-propargyl-2-methylimidazole complexes of zinc(II) chloride and acetate were synthesized and studied by X-ray analysis, NMR, and FTIR spectroscopy. Molecular structures of compounds under study represent a configuration of the ZnN2O2 or ZnN2Cl2 type where the zinc(II) ion is coordinated by two nitrogen atoms from the N-propargylimidazole ligands and two atoms of the co-complexing agent. All complexes crystallize in the monoclinic system, the molecules of N-propargyl-2-methylimidazole complexes of zinc(II) chloride and acetate have the C2 symmetry axis passing through the zinc atom. The atoms in molecules (AIM) analysis method were used for investigation of the nature and energy of coordination bonding between metal and ligand and non-covalent interactions in the crystal. An evaluation of the antimicrobial activity of N-propargylimidazole complexes of zinc(II) chloride and acetate in relation to Enterococcus durans, Bacillus subtilis and Escherichia coli was carried out. The studied metal complexes were practically inactive against the test microorganisms. [ABSTRACT FROM AUTHOR]

X-ray molecular and supramolecular structure were analyzed for N-t-Bu-N′-(triflyl)acetamidine t-BuNHC(Me) = NTf 1 and compared to that of N-bromobicycloheptanyl-N′-(triflyl)acetamidine 2. Self-associates of amidines 1, 2 bound by NH···O = S bonds form lamellar structure with the layers linked by CH···O = S short contacts. DFT calculations were performed for the conformational isomers, tautomers RNHC(Me) = NTf (a) or RN = C(Me)NHTf (b), the solvate H-complexes, and self-associates. The calculations showed good agreement of the experimental and theoretical geometry for the associates of 1 in polar medium. The IR spectra of 1 were taken in different states at variable temperature and concentration and its conformational composition was analyzed using the results of calculations. The free energy barriers of 20–25 kcal/mol were calculated for the syn-anti rotation about the C–N bond. The barriers of the 1a ⇌1b tautomerization in the E-isomer and its complexes with dioxane and MeCN (37–45 kcal/mol) are too high to occur under usual conditions, whereas in the complex with hexafluoroisopropanol, it is much lower (< 17 kcal/mol) rendering the process kinetically more feasible. The C = N and C–N bonds are equalized or even invert due to conjugation in the amidine fragment, which is different in the conformational isomers, in dimers, and in different media. [ABSTRACT FROM AUTHOR]

Crystal and molecular structures of two silatranes, 1-iodomethyl-3-methyl- and 1-iodomethyl-3,7,10-trimethyl-2,8,9-trioxa-5-aza-1-silabicyclo[3.3.3]undecanes, were determined by X-ray analysis. Comparison of their structural and geometrical characteristics with those of other silatranes shows that the presence of methyl substituents β-positioned to nitrogen atoms increases the length of the dative Si←N bond, whereas the introduction of iodine into the axial position of the silatrane slightly decreases the length of the Si←N bond. [ABSTRACT FROM AUTHOR]

A simple one-step protocol for preparing N -trifluoromethylsulfonylamidines from N -sulfinyltrifluoromethanesulfonamide and N -formylated secondary amines is described. X-ray, NMR and potentiometric studies show strong conjugation in the amidine motif >N–CH N– and low basicity of the nitrogen atoms. [ABSTRACT FROM AUTHOR]

Conformational isomers of β-oxy-bis-acrylamides O(CH=CHCONR1R2) 2 and their dimers were calculated with DFT methods using NBO and QTAIM analysis. The low rotational barriers about the =С–С= and =C–O– bonds in monomers provide ease of their transitions and simultaneous participation in the formation of dimers. The calculated dissociation energies of dimers depend on the structural features of the conformers and PA values of the carbonyl oxygen. The cyclic dimers with three and two intermolecular N–H⋯O C bonds are the most stable. The influence of the orbital interaction of lone pair of nitrogen with carbonyl group on the proton affinity of the conformers was analyzed. The structures of compounds and their dimers were analyzed in solid state and in solutions at comparing of FTIR spectroscopy and calculated data. X-ray analysis of β-oxy-bis-N,N′-dimethylacrylamide was carry out. Image 1 • The rotational barriers of β-oxy-bis-acrylamide conformers were calculated by DFT methods. • According to IR spectra and calculated data more stable conformers participate in the formation of dimers. • The intermolecular NH⋯O = bonds in dimers are shorter than intramolecular. • The PA values of oxygen of carbonyl groups depend on n N.→π* C O orbital interaction energies. [ABSTRACT FROM AUTHOR]