Search results for "halogeenisidokset"
showing 10 items of 11 documents
Hydrogen and Halogen Bond Mediated Coordination Polymers of Chloro-Substituted Pyrazin-2-Amine Copper(I) Bromide Complexes
2020
A new class of six mono- (1
Dihypoiodites stabilised by 4-ethylpyridine through O–I–N halogen bonds
2021
Four bis(O–I–N) compounds have been synthesised from various dihypoiodites and 4-ethylpyridine. The compounds were characterised in both the solution and solid states by NMR spectroscopy (1H, 15N), X-ray diffraction, and computational calculations. peerReviewed
Halogen and Hydrogen Bonded Complexes of 5-Iodouracil
2013
Three derivatives of 5-iodouracil were prepared, and their complexation properties, supplemented by 5-iodouracil under the same conditions, were studied with and without halogen bond acceptors in N,N-dimethylformamide, N,N-diethylformamide, N-methylformamide, formamide, dimethylsulfoxide, and water. The intermolecular halogen and hydrogen bonding interactions observed in the solid state were investigated using single crystal X-ray diffraction and quantum chemical calculations, and the acquired data were contrasted with bonding interactions previously reported for 5-iodouracil in the Cambridge Structural Database. It was found that the polarized iodine atom and the amidic NH functionality ac…
Selective recognition of small hydrogen bond acceptors by a calix[6]arene-based molecular container
2019
Selective molecular recognition is of primary importance for applications such as sensing and separation of chemicals. This work describes the host-guest and crystallisation properties of a penta-carbamated calix[6]arene designed as a molecular container with a H-donating recognition group directed towards the heart of the cavity. As demonstrated by NMR spectroscopy and X-ray diffraction studies, this macrocyclic receptor can selectively recognise small H-bond acceptors through one or two hydrogen bonds, the guests nesting inside the polyaromatic cavity surrounded by eleven bulky tert-butyl groups.
Halogen bond preferences of thiocyanate ligand coordinated to Ru(II) via sulphur atom
2017
Halogen bonding between [Ru(bpy)(CO)2(S-SCN)2] (bpy = 2,2’-bipyridine), I2 was studied by co-crystallising the metal compound and diiodine from dichloromethane. The only observed crystalline product was found to be [Ru(bpy)(CO)2(S-SCN)2]⋅I2 with only one NCS⋅⋅⋅I2 halogen bond between I2 and the metal coordinated S atom of one of the thiocyanate ligand. The dangling nitrogen atoms were not involved in halogen bonding. However, computational analysis suggests that there are no major energetic differences between the NCS⋅⋅⋅I2 and SCN⋅⋅⋅I2 bonding modes. The reason for the observed NCS⋅⋅⋅I2 mode lies most probably in the more favourable packing effects rather than energetic preferences between …
Role of Weak Hydrogen Bonds and Halogen Bonds in 5-Halo-1,3-dimethyluracils and Their Cocrystals—A Combined Experimental and Computational Study
2016
Seven single crystals containing either N,N-dimethyluracil (DMHU) or one of its 5-halogenated derivatives (DMXU; X = F, Cl, Br, I) were prepared using N,N-dimethylformamide as the crystallization solvent. Single crystal X-ray diffraction and quantum chemical calculations carried out at the spin component scaled local MP2 level of theory were then used to study the intramolecular halogen and nonconventional hydrogen bonds present in the structures. The results were compared to and contrasted with the previously reported data for uracil and its halogenated derivatives. In particular, the intermolecular interactions in DMIU were compared to the halogen and hydrogen bonds in 5-iodouracil that, …
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…
Strong N−X···O−N Halogen Bonds: Comprehensive Study on N‐Halosaccharin Pyridine N‐oxide Complexes
2019
A detailed study of the strong N−X⋯−O−N+ (X = I, Br) halogen bonding interactions in solution and in the solid‐state reports 2×27 donor×acceptor complexes of N‐halosaccharins and pyridine N‐oxides (PyNO). Density Functional Theory (DFT) calculations were used to investigate the X···O halogen bond (XB) interaction energies in 54 complexes. The XB interaction energies were found to vary from –47.5 to –120.3 kJ mol–1, with the strongest N−I⋯−O−N+ XBs approaching those of 3‐center‐4‐electron [N–I–N]+ halogen‐bonded systems (∼160 kJ mol–1). Using a subset of 32 complexes, stabilized only through N−X···−O−N+ XB interactions, a simplified, computationally fast, electrostatic model to predict the X…
Halogen Bonds in 2,5-Dihalopyridine-Copper(I) Halide Coordination Polymers
2019
Two series of 2,5-dihalopyridine-Cu(I)A (A = I, Br) complexes based on 2-X-5-iodopyridine and 2-X-5-bromopyridine (X = F, Cl, Br and I) are characterized by using single-crystal X-ray diffraction analysis to examine the nature of C2&minus
The C–I･･･⁻O–N⁺ Halogen Bonds with Tetraiodoethylene and Aromatic N-oxides
2020
The nature of C–I⋯⁻O–N⁺ interactions, first of its kind, between non-fluorinated tetraiodoethylene XB-donor and pyridine N-oxides (PyNO) are studied by single-crystal X-ray diffraction (SCXRD) and Density Functional Theory (DFT) calculations. Despite the non-fluorinated nature of the C2I4, the I⋯O halogen bond distances are similar to well-known perfluorohaloalkane/-arene donor-PyNO analogues. With C2I4, oxygens of the N-oxides adopt exclusively 2-XB-coordination in contrast to the versatile bonding modes observed with perfluorinated XB-donors. The C2I4 as the XB donor forms with PyNO’s one-dimensional chain polymer structures in which the C2I4⋯(μ-PyNO)2⋯C2I4 segments manifesting two bondin…