Search results for "vetysidokset"
showing 10 items of 25 documents
Host-guest complexes of C-propyl-2-bromoresorcinarene with aromatic N-oxides*
2018
The host-guest complexes of C-propyl-2-bromoresorcinarene with pyridine N-oxide, 3-methylpyridine N-oxide, quinoline N-oxide and isoquinoline N-oxide are studied using single crystal X-ray crystallography and 1H NMR spectroscopy. The C-propyl-2-bromoresorcinarene forms endo-complexes with the aromatic N-oxides in the solid-state when crystallised from either methanol or acetone. In solution, the endo-complexes were observed only in methanol-d4. In DMSO the solvent itself is a good guest, and crystallisation provides only solvate endo-complexes. The C-propyl-2-bromoresorcinarene shows remarkable flexibility when crystallised from either methanol or acetone, and packs into one-dimensional sel…
Experimental FTIR-MI and Theoretical Studies of Isocyanic Acid Aggregates
2023
Homoaggregates of isocyanic acid (HNCO) were studied using FTIR spectroscopy combined with a low-temperature matrix isolation technique and quantum chemical calculations. Computationally, the structures of the HNCO dimers and trimers were optimized at the MP2, B3LYPD3 and B2PLYPD3 levels of theory employing the 6-311++G(3df,3pd) basis set. Topological analysis of the electron density (AIM) was used to identify the type of non-covalent interactions in the studied aggregates. Five stable minima were located on the potential energy surface for (HNCO)2, and nine were located on the potential energy surface for (HNCO)3. The most stable dimer (D1) involves a weak, almost linear N-H⋯N hydrog…
Matrix Isolation FTIR and Theoretical Study of Weakly Bound Complexes of Isocyanic Acid with Nitrogen.
2021
Weak complexes of isocyanic acid (HNCO) with nitrogen were studied computationally employing MP2, B2PLYPD3 and B3LYPD3 methods and experimentally by FTIR matrix isolation technique. The results show that HNCO interacts specifically with N2. For the 1:1 stoichiometry, three stable minima were located on the potential energy surface. The most stable of them involves a weak, almost linear hydrogen bond from the NH group of the acid molecule to nitrogen molecule lone pair. Two other structures are bound by van der Waals interactions of N⋯N and C⋯N types. The 1:2 and 2:1 HNCO complexes with nitrogen were computationally tracked as well. Similar types of interactions as in the 1:1 complexes were …
Structure and IR Spectroscopic Properties of HNCO Complexes with SO
2021
FTIR spectroscopy was combined with the matrix isolation technique and quantum chemical calculations with the aim of studying complexes of isocyanic acid with sulfur dioxide. The structures of the HNCO⋯SO2 complexes of 1:1, 1:2 and 2:1 stoichiometry were optimized at the MP2, B3LYPD3, B2PLYPD3 levels of theory with the 6-311++G(3df,3pd) basis set. Five stable 1:1 HNCO⋯SO2 complexes were found. Three of them contain a weak N-H⋯O hydrogen bond, whereas two other structures are stabilized by van der Waals interactions. The analysis of the HNCO/SO2/Ar spectra after deposition indicates that mostly the 1:1 hydrogen-bonded complexes are present in argon matrices, with a small amount of the van de…
Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II : Vibrational Overtone Excitations
2019
Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N2 complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra. Both position and intensity of new absorptions appeared to be highly sensitive on the wavelength of radiation used, as well as on the annealing of the matrix. Based on theoretical calculations a…
Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. I : Structures and Thermal Effects
2019
Molecular complexes between glycolic acid and nitrogen were studied in a low-temperature argon matrix with FTIR spectroscopy, and supported by MP2 and BLYPD3 calculations. The calculations indicate 11 and 10 stable complex structures at the MP2 and BLYPD3 levels of theories, respectively. However, only one hydrogen-bonded complex structure involving the most stable SSC conformer of glycolic acid was found experimentally, where the nitrogen molecule is bound with the carboxylic OH group of the SSC conformer. The complex shows a rich site structure variation upon deposition of the matrix in different temperatures and upon annealing experiments, which provide interesting prospects for site-sel…
Cocrystal trimorphism as a consequence of the orthogonality of halogen- and hydrogen-bonds synthons.
2019
True trimorphic cocrystals, i.e. multi-component molecular crystals of identical composition that exhibit three polymorphic structures, are exceedingly rare and so far no halogen-bonded cocrystal system has been reported to exhibit trimorphism. Here we describe a unique example of a trimorphic cocrystal exhibiting both hydrogen and halogen bonds in which the differences between polymorphs reveal their orthogonality, evident by the apparently independent variation of well-defined hydrogen- and halogen-bonded motifs. peerReviewed
Dimeric iodine(i) and silver(i) cages from tripodal N-donor ligands via the [N–Ag–N]+ to [N–I–N]+ cation exchange reaction
2022
The directionality of the [N–I–N]+ halogen bond makes iodine(I) ions impeccable tools in the design and construction of [N–I–N]+ halogen-bonded assemblies. The synthesis of dimeric iodine(I) cages with imidazole-derived N-donor tripodal ligands is described, as well as their corresponding silver(I) precursors. The addition of elemental iodine to the parent two-coordinate Ag(I) complexes produces iodine(I) complexes with three-center four-electron (3c–4e) [N–I–N]+ bonds. Complex formation via this cation exchange was confirmed by 1H and 1H–15N HMBC NMR studies in solution, and additionally by electrospray ionisation and ion mobility mass spectrometry analysis (MS) in the gas phase. The struc…
The solid-state hierarchy and iodination potential of [bis(3-acetaminopyridine)iodine(I)]PF6
2022
The first iodine(I) complex bearing hydrogen-bond donor and acceptor groups, [bis(3-acetaminopyridine)iodine(I)]PF6 (3), was synthesised, which exhibited two temperature-dependent solid-state connectivities of the hydrogen bonding. Upon reaction of 3 with tBuOMe, unprecedented iodination of a tBu methyl group proceeded under exceptionally mild conditions in good yield. peerReviewed
FTIR matrix isolation and theoretical studies of glycolic acid dimers
2018
Glycolic acid (GA) dimers were studied in low temperature argon matrices by means of FTIR spectroscopy. Experimentally, the dimers were produced when monomeric glycolic acid molecules were thermally mobilized upon annealing of argon matrices at 25–35 K. The experimental spectra observed upon annealing indicate the presence of three different dimer structures. Computationally, MP2 and DFT calculations were used to study the potential dimer species in order to scrutinize the possible dimer structures, their energetics and their spectral features. Altogether 27 local minima were found for dimer structures for the three lowest conformers of glycolic acid considered based on previous studies on …