2‐Bromo‐5‐hydroxy­benz­aldehyde

The mol­ecules of the title compound, C₇H₅BrO₂, form zigzag chains running along the b axis and are stacked in layers perpendicular to the a axis. Intermolecular bonding occurs through hydrogen bonds linking the hydroxyl and carbonyl groups, with an O?O distance of 2.804 (4) Å. The Br atom deviates significantly from the plane of the ring and the aldehyde group is twisted by 7.1 (5)° around the Csp²—C_aryl bond. The geometry of the mol­ecule in the crystal is compared to that given by ab initio quantum mechanical calculations for the isolated mol­ecule, using a molecular orbital Hartree–Fock method and density functional theory.     

Sarcosinium tri­fluoro­acetate

The title compound, C₃H₈NO₂⁺·C₂F₃O₂^?, crystallizes in space group C2/c. The main N—C—COOH skeleton of the protonated sarcosine mol­ecule is almost perfectly planar. The tri­fluoro­acetate anion has a staggered conformation and typical bond distances and angles. The CF₃ group is probably slightly disordered. The structure is stabilized by an extensive network of strong O—H?O hydrogen bonds and weaker N—H?O bonds.     

Two anilinium salts: anilinium hydrogenphosphite and anilinium hydrogenoxalate hemihydrate

In the title compounds, C₆H₅NH₃⁺·H₂PO₃^? and C₆H₅NH₃⁺·C₂HO₄^?·0.5H₂O, the NH₃⁺ groups of the anilinium ion are ordered at room temperature. The rotation of these groups along the N—C_aryl bond, which is often observed at room temperature in other anilinium compounds, is prevented by hydrogen bonds between the NH₃⁺ group and the anions. In both compounds, the geometry of the cation is significantly distorted from D_6h to a symmetry close to C_2v. The angle ipso to the substituent is significantly larger than 120°, as expected from the σ‐electron‐withdrawing character of the NH₃⁺ group.     

Glycinium trichloro­acetate

The title compound, C₂H₆NO₂⁺·C₂Cl₃O₂⁻, crystallizes in the P4₁ space group with two glycinium cations and two trichloro­acetate anions in the asymmetric unit. The glycinium cations have nearly C_s point‐group symmetry which is only broken by the H atoms of the amine group. The trichloro­acetate anions show typical bond lengths and angles, one of the trichloro­methyl groups being disordered. Chains of alternating anions and cations run along the c axis. Within these chains, consecutive anion–cation pairs are bound via strong hydrogen bonds involving the carboxyl­ate anions and the carboxyl or amine groups of the cations. Weaker hydrogen bonds bind neighbouring chains together.     

R(30) rectangular rings in 2,5‐dioxopiperazine‐1,4‐di­acetic acid

Molecules of the title 2,5‐dioxopiperazinedione derivative, C₈H₁₀N₂O₆, occupy centres of symmetry in the crystal structure. The six‐membered ring has an almost planar conformation, with the substituent on nitrogen nearly perpendicular to the ring. The ideal geometry of the isolated mol­ecule, as determined by ab initio HF–LCAO quantum‐mechanical calculations, is slightly more puckered than that observed in the solid state. In the crystal structure, a strong hydrogen bond joins neighbouring mol­ecules, thus forming a network of rectangular (30) rings.     

An oxo‐centred trinuclear FeIII complex: tri­aqua­hexakis(μ2‐betaine‐O:O′)‐μ3‐oxo‐triiron(III) bis­(tetra­chloro­manganate) trichloride ­hexahydrate

The title compound, [Fe₃(C₅H₁₁NO₂)₆O(H₂O)₃](MnCl₄)₂Cl₃·6H₂O, contains a triiron core linked by a μ₃‐bridging oxide ion. Each of the iron(III) ions has a distorted octahedral environment, being coordinated, in addition to the oxide ion, by four neutral betaine mol­ecules and one water mol­ecule. The N‐alkyl­ated α‐amino acid betaine is present in the dipolar zwitterionic form and chelates pairs of Fe atoms at the vertices of the triangular [Fe₃O]⁷⁺ ionic core. The Fe complex has a crystallographically imposed D3 symmetry. The water mol­ecules fully exhaust their potential as hydrogen donors, forming a two‐dimensional hydrogen‐bond network in planes parallel to (001).     

Dimer Formation in 4-Benzyl-5-Methoxymethyl-3-Methyl-1<Emphasis Type="Italic">H</Emphasis>-Pyrrole-2-Carboxylic Acid Benzyl Ester

Abstract A new substituted pyrrole, a precursor of meso-free-porphyrins, has been synthesised and characterised by single-crystal X-ray diffraction: monoclinic, P2₁/c with a = 14.607(9) ?, b = 5.136(2) ?, c = 25.832(17) ?, β = 108.14(5)°, Mr = 349.41, V = 1841.6(18) ?³, Z = 4. The molecules are assembled in centrosymmetric dimers via strong N–H...O hydrogen bonds. The dimers are gathered into chains via C–H...π intermolecular interactions. Graphical abstract The molecules in 4-benzyl-5-methoxymethyl-3-methyl-1H-pyrrole-2-carboxylic acid benzyl ester are joined in dimmers by strong hydrogen bonds. The dimmers are aggregated in chains running along the b axis through C-H...?€ intermoleculear interactions. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.