1,3‐Benzothia­zole‐6‐carboxamidinium chloride dihydrate

The title compound, C₈H₈N₃S⁺·Cl⁻·2H₂O, has been synthesized and characterized both spectroscopically and structurally. The structure consists of 1,3‐benzothia­zole‐6‐carboxamidinium cations, chloride anions and water mol­ecules, all interconnected by hydrogen bonds into a three‐dimensional network. The 1,3‐benzo­thia­zole moiety is inclined to the 6‐­amidine group by 36.71 (9)°.     

A comparison of the Cope rearrangements of cis-1,2-divinylcyclopropane, cis-2,3-divinylaziridine, cis-2,3-divinyloxirane, cis-2,3-divinylphosphirane, and cis-2,3-divinylthiirane: a DFT study

Transition structures, energetics, and nucleus-independent chemical shifts (NICS) for Cope rearrangements of cis-2,3-divinylaziridine (1N), cis-2,3-divinyloxirane (1O), cis-2,3-divinylphosphirane (1P), and cis-2,3-divinylthiirane (1S), leading to 4,5-dihydro-1H-azepine (3N), 4,5-dihydrooxepine (3O), 4,5-dihydro-1H-phosphepine (3P), and 4,5-dihydrothiepine (3S), respectively, are reported at the (U)B3LYP/6-31G level and compared to those of cis-1,2-divinylcyclopropane (1C). The minimum energy path for all rearrangements proceeds through an endo-boatlike, aromatic transition structure. The predicted activation barriers increase in the order of 1C < 1N < 1O < 1P < 1S, which agrees qualitatively with the decreasing ring strain order of reference compounds (cyclopropane > aziridine > oxirane > phosphirane > thiirane). The exothermicities for these rearrangements decrease in the order of 1N > 1O > 1C > 1P > 1S. If the place of 1C in this sequence is ignored, the decreasing reaction exothermicity order correlates well with the increasing activation barrier order and with decreasing strain order of reference compounds. NICS values calculated for transition structures are typical of highly aromatic transition structures of thermally allowed pericyclic reactions.     

Structure-acidity-IR spectra correlations for p-substituted N-phenylsulfonylbenzamides

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same.     

Bis{1‐[N‐(2‐methoxy­phenyl)imino­methyl]naphthalen‐2(1H)‐onato‐κ3O,N,O′}zinc(II) ethanol solvate

In the crystal structure of the title compound, [Zn(C₁₈H₁₄NO₂)₂]·C₂H₆O, the Zn atom displays a highly distorted octa­hedral coordination involving the O and N atoms of two mol­ecules of the Schiff base 1‐[N‐(2‐methoxy­phenyl)imino­methyl]naphthalen‐2(1H)‐one, which acts as an O,N,O′‐tridentate ligand. The ethanol mol­ecule is bound to the methoxy group of one ligand mol­ecule via a hydrogen bond.     

The concentrations and exposure doses of radon and thoron in residences of the rural areas of Kosovo and Metohija

This paper deals with the results of indoor radon and thoron concentrations and exposure doses obtained for 63 dwellings out of the 14 rural communities of Central Kosovo, North Kosovo and Prizren region. These research activities are part of overall radiological research that has systematically been carried out since 1986, particularly in Kosovo and Metohija regions. Passive radon/thoron discriminative detectors, exposed for three months, were used. The arithmetic mean concentrations of indoor radon and thoron are C_Rn = 429 Bq m^?3 C_Tn = 85 Bq m^?3.     

Differential Equations Invariant Under Conditional Symmetries

Nonlinear PDE’s having given conditional symmetries are constructed. They are obtained starting from the invariants of the conditional symmetry generator and imposing the extra condition given by the characteristic of the symmetry. Series of examples starting from the Boussinesq and including non-autonomous Korteweg–de Vries like equations are given to show and clarify the methodology introduced.     

Association of copper(II) isonicotinamide moieties via different anionic bridging ligands: Two paths of ferromagnetic interaction in the azide coordination compound

Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of [Cu₂(μ-1,1-N₃)₂(μ-1,3-N₃)₂(isn)₂]_n (1) is composed of binuclear species, Cu₂(μ-1,1-N₃)₂(isn)₂, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN₄N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN₄S₂ is present in [Cu(μ-N,S-NCS)₂(isn)₂]_n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)₂ moieties. The third anionic ligand, i.e. sulfate, in {[Cu(μ-O,O’-SO₄)(H₂O)(isn)₂]·2H₂O}_n (3) completes the CuO₂N₂O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H₂O)(isn)₂ moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J₁) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J₂) to the whole FM interaction seen herein (J₁ = 18.5 cm^–1, J₂ = 4.9 cm^–1).     

Supramolecular Architecture via Self-Complementary Amide Hydrogen Bonding in [Ag(pia)<Subscript>2</Subscript>](NO<Subscript>3</Subscript>)·H<Subscript>2</Subscript>O: Synthesis,Thermal and Structural Studies

Abstract  

The synthesis, thermal and spectral characterization and crystal structure of silver(I) complex with picolinamide, [Ag(C₆H₆N₂O)₂](NO₃)·H₂O, are reported. The silver(I) atom is chelated by two picolinamide (pia) ligands in approximately square planar geometry. The distortion within the coordination environment is mainly imposed by formation of the chelate rings, but it is also observed in two longer (Ag–O) and two shorter (Ag–N) bond lengths. The compound crystallizes in the triclinic space group P[`1]P\bar{1} with a = 7.1265(2) ?, b = 8.9157(4) ?, c = 12.9527(4) ?, α = 83.934(3)°, β = 86.094(2)°, γ = 67.023(3)° and Z = 2. Cationic complexes are linked through amide–amide hydrogen bonds of ‘head-to-head’ R ₂²(8) motif leading to infinite chains, while nitrate anions and H₂O molecules act only as a cross-link between such four symmetry related cationic chains via hydrogen bonds forming 2D supramolecular double sheets. Therefore, the ‘head-to-head’ amide interactions in [Ag(C₆H₆N₂O)₂](NO₃)·H₂O are robust enough to accommodate the usually disruptive NO₃ ⁻ anion and H₂O molecule and could be regarded as a tool for controlling the assembly of this silver complex.