A pseudo-merohedrally twinned rare-earth sulfate: K₆[Ce(HSO₄)₂(SO₄)₄]·H₂O, a novel structure type

This acidic ternary rare-earth sulfate is unique as it contains rare-earth monomers, [Ce(HSO₄)(SO₄)₄]^5-, and the structure is composed of these monomers, water mol­ecules, discrete hydrogensulfate ions and potassium ions held together by ionic inter­actions. There are two alternating layers in the structure, with the compositions [K₄Ce(HSO₄)(SO₄)₄]^- and [K₂(HSO₄)(H₂O)]⁺.

Stereoisomers of 1,2-diaryl-1,3-propanediols: erythro forms

Racemic erythro-1,2-diphenyl-1,3-propane­diol, C₁₅H₁₆O₂, is a model compound representative of erythro forms of structural elements of the 1,2-diaryl-1,3-propane­diol type in lignins. In the crystal structure, the torsion angle between the bulky phenyl groups is -62.26 (11)°. Strong hydrogen bonds take part in a directed co-operative O-H...O-H...O-H...O-H pattern that is assumed to have a decisive influence on the conformation. This is supported by comparisons with the geometries of related compounds.

2-(2-Oxazolin-2-yl)benzene-1,4-diol: X-ray and density functional theory studies

In the crystal structure of the title compound, C₉H₉NO₃, there are strong intra­molecular O—H...N and inter­molecular O—H...O hydrogen bonds which, together with weak inter­molecular C—H...O hydrogen bonds, lead to the formation of infinite chains of mol­ecules. The calculated inter­molecular hydrogen-bond energies are −11.3 and −2.7 kJ mol⁻¹, respectively, showing the dominant role of the O—H...O hydrogen bonding. A natural bond orbital analysis revealed the electron contribution of the lone pairs of the oxazoline N and O atoms, and of the two hydr­oxy O atoms, to the order of the relevant bonds.

4,4'-(Azinodimethyl­ene)dipyridinium bis­(tetra­fluoro­borate) and 4-[(4-pyri­dylmethyl­ene)hydrazonomethyl]­pyridinium perchlorate: two different hydrogen-bonding motifs

In the crystal structures of the title compounds, C₁₂H₁₂N₄²⁺·2BF₄^-, (I), and C₁₂H₁₁N₄⁺·ClO₄^-, (II), respectively, infinite two- and one-dimensional architectures are built up via N-H...F [in (I)] and conventional N-H...N [in (II)] hydrogen bonding. The N-N single bond in (I) lies on a crystallographic centre of symmetry; as a result, the two pyridinium rings are parallel. In (II), the pyridinium and pyridyl ring planes are inclined with a dihedral angle of 14.45 (3)°.

3-(4-Bromo­phen­yl)-5-(4-dimethyl­amino­phen­yl)-1-phenyl-2-pyrazoline: X-ray and density functional theory (DFT) studies

In the crystal structure of the title compound, C₂₃H₂₂BrN₃, a strong conjugation of the pyrazoline chromophore with the aromatic rings at positions 1 and 3 is observed, as well as a significant shift in the synclinal→synperiplanar direction. The absolute structure was unequivocally determined. In the absence of clasical hydrogen-bond donors, the structure is stabilized by weak C—H...π inter­actions. This paper also reports the electronic structure of the title compound using NBO (natural bond order) analysis. The contributions of lone pairs to the relevant bonds were revealed.

(E)-Methyl 2-anilinomethyl­ene-3-oxo­butanoate: X-ray and density functional theory studies

Mol­ecules of the title compound, C₁₂H₁₃NO₃, are not planar and are stabilized by electrostatic inter­actions, as the dipole moment of the mol­ecule is 3.76 D. They are also stabilized by intra­molecular hydrogen bonds of N...O and C...O types, and by a complicated network of weak inter­molecular hydrogen bonds of the C...O type. This paper also reports the theoretical investigation of the hydrogen bonding and electronic structure of the title compound using natural bond orbital (NBO) analysis.