A theoretical study of 1:1 and 1:2 complexes of acetylene with nitrosyl hydride

Ab initio calculations at MP2 computational level using aug-cc-pVTZ basis set were used to analyze the interactions between 1:1 and 1:2 complexes of acetylene and nitrosyl hydride. The structures obtained have been analyzed with the atoms in molecules and the density functional theory–symmetry adapted perturbation theory methodologies. Four minima were located on the potential energy surface of the 1:1 complex. Twenty-four different structures have been obtained for the 1:2 complexes. Five types of interactions are observed, CH···O, CH···N, NH···π hydrogen bonds and orthogonal interactions between the π clouds of triple bond, or the lone pair of oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of the 1:1 and 1:2 clusters including basis set superposition error and ZPE are in the range 3–8 and 6–17 kJ mol⁻¹ at MP2/aug-cc-pVTZ computational level, respectively. Blue shift of NH bond upon complex formation in the ranges between 18–30 and 20–96 cm⁻¹ is predicted for 1:1 and 1:2 clusters, respectively. The total nonadditive energy in the 1:2 cluster, calculated as the sum of the supermolecular nonadditive MP2 energy and the three-body dispersion energy, presents values between −1.48 and 1.20 kJ mol⁻¹.     

1:1 alternating copolymers of 1-bicyclobutanecarbonitrile with styrene

High molecular weight, 1:1 alternating copolymers of 1-bicyclobutanecarbonitrile with styrene were prepared in tetramethylenesulfone solution by complexing the electron-poor bicyclobutane monomer with zinc chloride. Methyl 1-bicyclobutanecarboxylate under these conditions gave copolymers containing a slight excess of styrene units (ratio 1:1.3 to 1:1.8). High molecular weight homopolymers of 1-bicyclobutanecarbonitrile and of methyl 1-bicyclobutanecarboxylate were prepared similarly. The tendency of the bicyclobutane nitrile to form 1:1 alternating copolymers is as great as that of its vinyl analog, acrylonitrile, and the synthesis of other alternating copolymers from this monomer should be possible.     

Structure of 1 : 1 and 2 : 1 complexes of 3,5-dimethylpyrazole with HCl and HO3SCF3

3,5-Dimethylpyrazole complexes with HCl (an 1 : 1 complex) and trifluoromethanesulfonic acid (1 : 1 and 2 : 1 complexes) were structurally studied using X-ray crystallography.     

SIT Parameters for 1:1 Electrolytes and Correlation with Pitzer Coefficients

The empirical parameters of a two-parameter SIT equation were determined for some 1:1 electrolytes: chlorides, bromides, iodides, nitrates, perchlorates and carboxylates of alkali metals, inorganic acids and bases, and tetralkylammonium halides. A wide range of ionic strengths were considered. Canonical correlation analysis identified correlations between the SIT and Pitzer interaction coefficients for different classes of 1:1 type electrolytes.Calculation of SIT parameters: Part II. Part I, ref. [1].     

A 1:1 cocrystal of baicalein with nicotinamide

Cocrystallization of baicalein with nicotinamide yields a 1:1 cocrystal [systematic name: pyridine‐3‐carboxamide–5,6,7‐trihydroxy‐2‐phenyl‐4H‐chromen‐4‐one (1/1)], C₆H₆N₂O·C₁₅H₁₀O₅. The asymmetric unit contains one baicalein and one nicotinamide molecule, both in neutral forms. Molecules in the cocrystal form column motifs stabilized by an array of intermolecular hydrogen bonds.     

1:2 Complexes of chloranilic acid with pyrazole and imidazole,and the aceto­nitrile solvate of a 1:1 complex with imidazole

2,5‐Di­chloro‐3,6‐di­hydroxy‐1,4‐benzo­quinone (chloranilic acid) forms X—H?Y (X, Y = N or O) and C—H?Cl hydrogen bonds with pyrazole and imidazole to afford bis­(pyrazolium) di­chloro­anilate and bis­(imidazolium) di­chloro­anilate, (I) and (II), both 2C₃H₅N₂⁺·C₆Cl₂O₄^2?, and imidazolium chloro­anilate aceto­nitrile solvate, C₃H₅N₂⁺·­C₆HCl₂O₄^?·C₂H₃N, (III). Their crystal structures demonstrate three novel supramolecular architectures based on supramolecular synthons to build a ladder, (I), a two‐dimensional network, (II), and a flat ribbon, (III).     

混合二烃基二氯化锡与水杨醛缩苯胺类Schiff碱1∶1配合物的合成和表征

由混合二烃基二氯化锡（ＲＲ＇ＳｎＣｌ＿２）与水杨醛缩苯胺类Ｓｃｈｉｆｆ碱（２－ＨＯＣ＿６Ｈ＿４ＣＨ＝ＮＡｒ）反应，合成了１４种新的有机锡配合物。经元素分析、ＩＲ、ＮＭＲ和ＴＧ－ＤＳＣ测定，确定配合物的组成是有机锡与Ｓｃｈｉｆｆ碱的１：１配合物，配体以酚羟基氧原子与锡原子配位，摩尔电导率测定表明配合物均为非电解质。     

5:1 and 2:1 cocrystals of 2,3,4,5,6‐pentafluorophenol with phenazine

2,3,4,5,6‐Pentafluorophenol (pFp), unlike phenol, forms cocrystals with the weak heteroaromatic base phenazine (phz). Two types of cocrystals were prepared, (I) with a high content of pFp, 2,3,4,5,6‐pentafluorophenol–phenazine (5/1), 5C₆HF₅O·C₁₂H₈N₂, and (II) with a 2:1 pFp–phz molar ratio, 2,3,4,5,6‐pentafluorophenol–phenazine (2/1), 2C₆HF₅O·C₁₂H₈N₂. In both forms, homostacks are formed by the heterocyclic base and phenol molecules and no aryl–perfluoroaryl stacking interactions occur. The arrangement of the molecules in the crystal of (I) is determined by strong O—H...N and O—H...O hydrogen bonds, weak O—H...F, C—H...F and C—H...O interactions, π–π stacking interactions between the phz molecules and C—F...π_F interactions within the pFp stacks. Among the specific interactions in (II) are a strong O—H...N hydrogen bond, weak C—H...F interactions and π–π stacking interactions between the phz molecules. In (I) and (II), the heterocyclic molecules are located around inversion centres and one of the symmetry‐independent pFp molecules in (I) is disordered about an inversion centre. Remarkably, similar structural fragments consisting of six pFp stacks can be identified in cocrystal (I) and in the known orthorhombic polymorph of pFp with Z′ = 3 [Gdaniec (2007). CrystEngComm, 9 , 286–288].     

1-Bromo-3,3,3-trifluoro-1-nitropropene: Synthesis and reaction with phenyl azide

An improved procedure was developed for the synthesis of 3,3,3-trifluoro-1-nitropropene, and a new representative of gem-bromonitroalkenes, 1-bromo-3,3,3-trifluoro-1-nitropropene, was synthesized therefrom. Its reaction with phenyl azide gave a mixture of two regioisomeric 1,2,3-triazoles, from which pure 5-nitro-1-phenyl-4-(trifluoromethyl)-1H-1,2,3-triazole was isolated.     

New helical foldamers: heterogeneous backbones with 1:2 and 2:1 alpha:beta-amino acid residue patterns

Foldamers, oligomers with strong folding propensities, are subjects of growing interest because such compounds offer unique scaffolds for the development of molecular function. We report two new foldamer classes, oligopeptides with regular 1:2 or 2:1 patterns of alpha- and beta-amino acid residues. Two distinct helical conformations are detected via 2D NMR in methanol for each backbone. One of the helices for each backbone is characterized via X-ray crystallography.     

Complexes of 1-boraadamantane and its derivatives with 1-azaadamantanes: Synthesis and molecular structure

The reactions of 1-boraadamantane and 2-methyl-, 2-ethyl-, 2,2-dimethyl-, and 3,5-dimethyl-substituted 1-boraadamantanes with their 1-azaadamantane analogs afforded a series of 1:1 adducts, which are stable to atmospheric air and moisture.^IH,¹³C, and³¹B NMR spectra as well as mass spectra of the compounds synthesized were investigated. Only the adduct of 2,2-dimethyl-1-boraadamantane with 2,2-dimethyl-1-azaadamantane readily dissociates into the initial components due to steric hindrances that prevent strong B→N coordination. The structure and geometric parameters of the 1-boraadamantane complex with 3,5-dimethyl 1-azaadamantane were established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1818–1824, September, 1998.     

A 1:1 cocrystal of fluconazole with salicylic acid

The interaction of the antifungal pharmaceutical agent fluconazole with salicylic acid in acetonitrile solution yields the 1:1 cocrystal 2‐(2,4‐difluorophenyl)‐1,3‐bis(1H‐1,2,4‐triazol‐1‐yl)propan‐2‐ol–2‐hydroxybenzoic acid (1/1), C₁₃H₁₂F₂N₆O·C₇H₆O₃. The asymmetric unit consists of one molecule of fluconazole and one molecule of salicylic acid, both in their neutral forms. Both crystal agents form head‐to‐tail hydrogen‐bonded dimers, which are further connected into hydrogen‐bonded extended zigzag tapes propagating along the ac diagonal.     

Dynamic, electrooptical and energetic nonequivalency of NH bonds in 1:1 and 1:2 complexes of aminopyridines with proton acceptors

The influence of the –NH₂ group position in the pyridine ring on the proton donor ability of N–H groups in hydrogen bonding as well as on the spectral behaviour of stretching and bending vibrations of aminopyridines has been studied. The proton donor ability was shown to increase in the row: meta-, ortho-, and para-aminopyridines. It was established tha N–H bonds in ortho-aminopyridine were not equivalent, and the evaluation of their dynamic nonequivalence was made.

The influence of temperature on the spectral characteristics of the absorption bands of the stretching vibrations of amine groups in the free and hydrogen bonded molecules in CCl₄ has been studied (in temperature range 290–330 K), the formation constants of the complexes have been determined, enthalpy of the 1:1 complexes formation (−ΔH₁) between ortho- and meta-aminopyridines with dimethylformamide, dimethylsulphoxide and hexamethylphosphoramide has been calculated in temperature range 290–330 K. The 1:2 complexes of ortho-, meta- and para-aminopyridines with acetonitrile, tetrahydrofurane, dimethylsulphoxide, hexamethylphosphoramide were studied at the indoor temperature. Enthalpy of the 1:2 complex (−ΔH₂) was estimated on the basis of ‘intensity rule’; −ΔH₁=ΔB^1/2 assuming that parameter does not depend on the composition of a complex.

The vibrational and electrooptical tasks were solved for the free and H-bounded molecules of aminopyridines as well as its complexes of the 1:1 and 1:2 compositions. Dynamic, electrooptical and energetic nonequivalency of NH bonds of aminogroups in aminopyridines was studied quantitatively. The independent calculations of dynamic constants proved mentioned above nonequivalency of NH bonds.

Correlations between spectral characteristics of the absorption bands, geometric, dynamic and electrooptical parameters of –NH₂ group in aminopyridines in the free and hydrogen bonded molecules have been established. Those correlations allow to determine the most important molecular characteristics obtained on the basis of spectral measurements in the range of the absorption bands of the stretching vibrations of aminogroup.     

Solution Phase Chemistry of Lanthanide Complexes. 12. 1:1 and 1:2 Lanthanide Complexes with s-Carboxymethoxysuccinic Acid

Abstract

The solution phase coordination chemistry associated with 1:1 and 1:2 complexes of lanthanide ions with S-carboxymethoxysuccinic acid (CMOS) has been studied by spectroscopic means. The Tb(III) luminescence intensities and lifetimes were found to be sensitive towards the solution phase properties, as were the circularly polarized luminescence spectra of these complexes. It was found that below pH 6, Ln(CMOS) complexes were monomeric in nature and contained an average of 6 molecules of coordinated water. Above neutral pH, the Ln(CMOS)₂ complexes became self-associated into hydroxy-bridged, oligomeric species. The Ln(CMOS)₂ complexes were found to be oligomeric at all pH values, with ligand bridging taking place below neutral pH and hydroxy bridging taking place above neutral pH.     

1:1 Complexes of octafluoronaphthalene with trans-stilbene and trans-azobenzene

Co-crystallisation of octafluoronaphthalene (OFN) with trans-stilbene or trans-azobenzene from solutions yielded 1:1 molecular complexes, shown by single-crystal X-ray diffraction to contain infinite stacks of near-parallel and planar, alternating OFN and trans-stilbene or trans-azobenzene molecules.     

Corannulene and its penta-tert-butyl derivative co-crystallize 1:1 with pristine C60-fullerene

The first X-ray structural determinations of pristine fullerene C(60), cocrystallized 1:1 with corannulene and with its pentaalkyl-substituted derivative, 1,3,5,7,9-penta-tert-butyl-corannulene, have now been achieved.