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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]

DFT calculations were performed for a series of N-triflyl substituted amidines, their dimers, and hydrogen-bonded complexes with hexafluoroisopropanol (HFIP) and DMSO, as well as transition states of tautomeric interconversion RNH−C(Me)=NTf ⇆ RN=C(Me)–NHTf (R = Me). The free energy barrier ΔG‡ for the equilibrium gradually decreases in going from monomers to H-complexes with DMSO, cyclic dimers, and H-complexes with HFIP. The X-ray analysis of crystals and FT-IR analysis of neat compounds and their solutions in the temperature range of 298–190 K was performed in comparison with the computed vibrational frequencies. The predominance of the E-syn and E-anti conformational isomers of the studied compounds and their cyclic and linear dimers is shown. For R = 2-norbornyl, the above tautomeric equilibrium in HFIP solution is shifted towards the NHTf form with lowering the temperature. [ABSTRACT FROM AUTHOR]