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In the title compound, C19H20N4, the dihedral angles formed by the planes of the triazine ring and the two phenyl substituents are 51.54 (1) and 49.27 (1)°. The phenyl rings form a dihedral angle of 80.81 (1)°. All bond lengths and angles are normal. The structure is stabilized by van der Waals interactions.

In the title compound, C15H14IN2+·I−, the C15H14IN2+ cations and I− anions are joined together via strong C—H⋯I hydrogen bonds. In the [010] direction, these cations form positively charged columns, between which the I− anions are included.

The new, non-linear, optically active crystal of the title compound, C14H13N2+·I−, has bond lengths and angles in the usual ranges, compared with similar structures retrieved from the literature. As in the case of the earlier known aza­aromatic halides and polyhalides, we have observed the same short H⋯X (X = Cl, I) distance for the C—H⋯X interaction.

Erbium dinickel disilicide, ErNi2Si2, crystallizes in the tetra­gonal ThCr2Si2 structure type, which is an ordered superstucture of the BaAl4 type. The coordination numbers are 22 for Er (2a site), 12 for Ni (4d site), and 9 for Si (4e site).

The asymmetric unit of the title compound, C19H20N+·BF4−, consists of an amino­diphenyl­cyclo­propenylium cation and a tetra­fluoro­borate anion. The crystal packing is stabilized by C—H⋯F hydrogen bonds.

In the solid state, the structure of the title compound, C10H8O2, is stabilized by both van der Waals interactions and O—H⋯O intermolecular hydrogen bonds with O⋯O distances of 2.714 (3) and 2.831 (4) A.

In the solid state, the centrosymmetric structure of 1-naphthalenol, C10H8O, is stabilized by both van der Waals interactions and intermolecular O—H⋯O hydrogen bonds. The mol­ecules are linked through hydrogen bonds, each of length 2.798 (1) A, into chains which are parallel to the symmetry axis.

The new terbium (lithium zinc) distannide, TbLi(1-x)Zn(x)Sn(2) (x = 0.2) crystallizes in the ortho-rhom-bic CeNiSi(2) structure type with space group Cmcm and Pearson symbol oS16. Of the four independent 4c atom positions (m2m site symmetry), three are fully occupied by individual atoms (two by Sn and one by Tb atoms) and the fourth is occupied by Li and Zn atoms with a statistical distribution. The Tb coordination polyhedron is a 21-vertex pseudo-Frank-Kasper polyhedron. One Sn atom is enclosed in a tricapped trigonal prism, the second Sn atom is in a cubocta-hedron and the statistically distributed (Li,Zn) site is in a tetra-gonal anti-prism with one added atom. Electronic structure calculations were used for the elucidation of reasons for and the ability of mutual substitution of lithium and transition metals. Positive charge density was observed around the rare earth atom and the Li and Zn atoms, the negative charge density in the proximity of the Sn atoms.

The title compound, C12H9N2+·Br−, crystallizes in the triclinic system (P\overline 1); it is not isostructural with its chloride analogue, which is monoclinic, P21/c. As in the case of the earlier known aza­aromatic chlorides and iodides, we also observed a short H⋯Br distance for the C—H⋯Br interaction.

The title compound (lanthanum dodecazinc), LaZn(12.37 (1)), is confirmed to be a nonstoichiometric (zinc-deficient) modification of the NaZn(13) structure type, in which one Zn atom (Wyckoff site 8b, site symmetry m[Formula: see text]) has a fractional site occupancy of 0.372 (11). The other Zn atom (96i, m) and the La atom (8a, 432) are fully occupied. The coordination polyhedra of the Zn atoms are distorted icosa-hedra, whereas the La atoms are surrounded by 24 Zn atoms, forming pseudo-Frank-Kasper polyhedra. Electronic structure calculations indicate that Zn-Zn bonding is much stronger than La-Zn bonding.

In the crystal structure of the title compound, C18H12N2OS, centrosymmetric dimers are stabilized both by van der Waals interactions and by two types of intermolecular O—H...N hydrogen bonds. In addition, an intramolecular C—H...S hydrogen bond is observed. The dihedral angles between the central ring and the two pendant phenyl rings are 7.4 (1) and 45.06 (9)°.

Single crystals of the MgZn2Ce alloy (magnesium dizinc cerium) were synthesized by a two-step method which couples the thermal treatment of pressed pellets of the pure elements with subsequent arc melting. The compound crystallizes in a Heusler-type (MnCu2Al) structure in the space group Fm\overline{3}m, with one Zn site (site symmetry \overline{4}3m), one Ce and one Mg site (both with m\overline{3}m site symmetry). All inter­atomic distances indicate metallic type bonding.