N—H⋯S and C—H⋯S hydrogen bonds in two tetra­alkyl­ammonium di­thio­biurea(1–) inclusion compounds

In two inclusion compounds of di­thio­biurea and tetra­propyl­ammonium and tetra­butyl­ammonium, the dithiobiurea anions, which form dimers via N—H⋯N hydrogen bonds in one, are linked via N—H⋯S interactions to produce one-dimensional chains.

Reversible phase transition of 2-carb­oxy­pyridinium perchlorate–pyridinium-2-carboxyl­ate (1/1)

Differential scanning calorimetry (DSC) measurements show that 2-carb­oxy­pyridinium perchlorate–pyridinium-2-carboxyl­ate (1/1) undergoes a reversible phase transition at about 261.7 K, with a wide heat hysteresis of 21.9 K. The lower-temperature polymorph (223 K) crystallizes in the space group C2/c, while the higher-temperature polymorph (T = 296 K) crystallizes in the space group P2/c. The relationship between these two phases can be described as: 2a_RT = a_LT; 2b_RT = b_LT; c_RT = c_LT.

Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O′)bis­(5,5′-di­methyl-2,2′-bi­pyridine-κ²N,N′)nickel(II) perchlorate mono­hydrate

In crystals of the new ionic complex [Ni(ac)(5,5′-dmbpy)₂]ClO₄·H₂O (where 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bi­pyridine and ac is acetate), neighbouring complex cations are linked by π–π inter­actions forming zigzag chains. The magnetism of the complex at low temperature is dominated by single-ion anisotropy.

A two-dimensional silver(I) coordination polymer constructed from 4-amino­phenyl­arsonate and tri­phenyl­phosphane: poly[[(μ₃-4-amino­phenyl­arsonato-κ³N:O:O)(tri­phenylphosphane-κP)silver(I)] monohydrate]

A new silver(I) coordination polymer has been prepared by the reaction of AgNO₃ with 4-amino­phenyl­arsonic acid and tri­phenyl­phosphane. The compound possesses a two-dimensional (4,4)-network, with a dinuclear [Ag₂O₂N₂P₂] unit as a four-connected node and 4-amino­phenyl­arsonate as a linker.

Tetra­hydro­berberine, a pharmacologically active naturally occurring alkaloid

The crystal structure of racemic tetra­hydro­berberine, a pharmacologically active alkaloid, shows inter­molecular 1,3-benzodioxole –CH₂⋯OCH₃ and –OCH₃⋯OCH₃ inter­actions.

Inversion twinning in a second polymorph of the hydro­chloride salt of the recreational drug ethyl­one

A second polymorph of the hydro­chloride salt of the recreational drug ethyl­one appears in crystallizations performed above 308 K. The ions are linked into enanti­opure chains by N—H⋯Cl hydrogen bonds. A lack of discrimination between enanti­omorphs in the packing of adjacent chains leads to inversion twinning.

Unexpected proline coordination in the copper chain polymer [Cu(μ-Cl)₂(μ-DL-proline-κ²O:O′)]¹_∞

The coordination of proline to Cu^II leads to unexpected carboxyl­ate bridging and a chain polymer, rather than the much more common N,O-chelation adopted by amino acids.

Three cocrystals and a cocrystal salt of pyrimidin-2-amine and glutaric acid

The conformational flexibility of the glutaric acid mol­ecule results in the formation of two polymorphs of the 1:1 cocrystal of pyrimidin-2-amine and glutaric acid and is also responsible for the colouring of the cocrystals. The crystallization of cocrystals and a cocrystal–salt from the same solvent mixture supports the idea of a cocrystal–salt continuum in the liquid state.

Evidence for stereoelectronic effects in the N—C—N group of 8,10,12-tri­aza-1-azonia­tetra­cyclo[8.3.1.1^8,12.0^2,7]penta­decane 4-nitro­phenolate 4-nitro­phenol monosolvate from the protonation of aminal (2R,7R)-1,8,10,12-tetra­aza­tetra­cyclo[8.3.1.1^8,12.0^2,7]penta­decane: X-ray and natural bond orbital analysis

The cocrystalline adduct of 1,8,10,12-tetra­aza­tetra­cyclo[8.3.1.1^8,12.0^2,7]penta­decane and 4-nitro­phenol crystallizes via proton transfer and strong inter­molecular hydrogen bonds. This is the first example of a proton-transfer adduct containing anionic 4-nitro­phenolate and aza­adamantane structures.

A three-dimensional cadmium(II) coordination polymer with unequal homochiral double-stranded concentric helical chains

A homochiral helical three-dimensional coordination polymer was synthesized by the reaction of cadmium acetate and N-(1H-tetra­zol-5-yl)isonicotinamide. The most striking feature of the structure is the presence of two different homochiral metal–tetra­zole helices with a coaxial 6₁ screw axis.

A monoclinic form of dendocarbin A: a borderline case of one-dimensional isostructural polymorphism

A monoclinic polymorph of dendocarbin A has been isolated from Drimys winteri and displays an identical mol­ecular structure to the previously reported ortho­rhom­bic phase, while varying significantly in chain pitch, and can thus be considered as a borderline case of one-dimensional isostructural polymorphism.

A square-planar hydrated cationic tetra­kis­(methimazole)gold(III) complex

The Au^III atoms in the cationic pseudo-square-planar complex tetra­kis­(1-methyl-2,3-di­hydro-1H-imidazole-2-thione-κS)gold(III) trichloride sesquihydrate reside at the corners of the unit cell on an inversion center and are bound by the S atoms of four methimazole ligands in a planar arrangement, with S—Au—S bond angles of approximately 90°.

Three isotypic polymeric complexes with rare earth cations, but-2-enoate anions and 4,4′-(ethane-1,2-di­yl)di­pyridine and 4,4′-(ethene-1,2-di­yl)di­pyridine bridging ligands

The crystal structures of three isotypic one-dimensional polymeric complexes with Y and Gd cations, but-2-enoate anions, and 4,4′-(ethane-1,2-di­yl)di­pyridine and 4,4′-(ethene-1,2-di­yl)di­pyridine bridging ligands are analysed. There are intra-chain and inter-chain hydrogen bonds in the structures, the former providing cohesion of the linear arrays and the latter promoting the formation of broad planes parallel to (010).

A one-dimensional zinc(II) coordination polymer based on mixed multidentate N- and O-donor ligands

A novel inorganic–organic coordination polymer based on Zn^II cations with mixed multidentate N-donor 1-[(1H-benzoimidazol-2-yl)meth­yl]-1H-tetra­zole and μ₄-bridging O-donor glutarate ligands has been prepared and structurally characterized. Two Zn^II ions are linked by four bridging glutarate carboxyl­ate groups to generate a dinuclear [Zn₂(CO₂)₄] paddle-wheel unit. The dinuclear units are further connected into a one-dimensional chain via the glutarate ligands.

One- and two-dimensional polymers from proline and calcium bromide

Calcium bromide and proline assemble into two extended solids of very different topologies. Chirality matters as reaction with racemic proline leads to a chain polymer, whereas the enanti­opure amino acid gives a two-dimensional layer structure with unusual CaBr₂ dumbbells.

A new two-dimensional anionic cadmium(II) polymer constructed through thio­cyanate coordination bridges

In a new one-dimensional cadmium–thio­cyanate complex, the thio­cyanate ligands play different roles in the build up of the structure; one role results in the formation of [Cd₂(NCS)₂] building blocks, while the other links the building blocks and cations via N—H⋯S hydrogen bonds.

Four oxo­indole-linked α-alk­oxy-β-amino acid derivatives

The diastereo­selectivity of the chemical reaction involving α-diazoesters and isatin imines in the presence of benzyl alcohol is confirmed through the relative configuration of the two stereo­genic centres. The diastereo­selectivity is possibly aided by intramolecular N—H⋯O hydrogen bonding and possible π–π inter­actions.

An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs₂O₇ and BaCuAs₂O₇

The structures of two isostructural diarsenates, SrZnAs₂O₇ and BaCuAs₂O₇, consist of corner-sharing M2O₅ (M2 = Zn or Cu) square pyramids and diarsenate (As₂O₇) groups forming a three-dimensional open framework, which contains two types of tunnels filled with large divalent M1 (M1 = Sr or Ba) cations. Geometrical characteristics of the coordination polyhedra and the conformation of the As₂O₇ groups for a family of isostructural diarsenates, viz. M1^IIM2^IIAs₂O₇ (M1^II = Sr, Ba, Pb; M2^II = Mg, Co, Cu, Zn), which crystallize in the space group P2₁/n, are presented.

A new phosphoro­thioic tri­amide structure: P(S)[NHCH₂C₆H₅]₃

The bond-angle sums at the N atoms are analysed for structures with a P(S)[N]₃ skeleton having the N atom in a [P]N[X][Y] environment, considering a new structure and also structures deposited in the Cambridge Structural Database.