Slight pyramidalization at the four N atoms leads to a twist boat conformation for the tetrazinane ring of the title compound, C₄H₈N₄O₂. In the crystal structure, the tetrazinane-3,6-dione mol­ecules are disordered over two conform­ations with opposite ring puckerings, and are linked into two-dimensional sheets by N—HO hydrogen bonding.

In the cation of the title compound, C₇H₁₃N₆O⁺·Cl⁻, the presence of an sp³-hybridized C atom at the point of attachment of the imidazolyl substituent leads to a conformation for the tetr­aza­ne ring that is intermediate between a screw boat and an envelope. The crystal structure of (I) consists of a three-dimensional network of N—HO and N—HCl hydrogen-bonded cations and anions that is perforated by channels filled with disordered methanol solvent mol­ecules.

In the title compound, C₁₄H₂₂N₄S₂, a diethyl di­sulfide bridge containing an S—S bond of 2.0396 (6) Å connects two 3,5-di­methyl­pyrazole rings via the N1 atoms. The di­sulfide mol­ecules are linked by weak C—Hπ(pyrazole) interactions into chains that propagate along the b direction.

The distorted square-planar coordination environment of the palladium(II) centre in [Pd(NCN)I]·2I₂ {NCN is 2,6-bis­[(di­methyl­amino)­methyl]­phenyl, C₁₂H₁₉N₂} is defined by the monoanionic terdentate NCN ligand and one iodide anion. Two neutral I₂ mol­ecules interact with the coordinated iodide anion at distances of ∼3.3 Å, suggesting an alternative description of the title compound as a palladium pentaiodide complex, i.e. [Pd(NCN)I₅]. Weaker interactions of ∼3.6 Å between the I₅⁻ anions link the complexes into a two-dimensional network.

In the title complex, [Cu(BF₄)₂(1tpc)₄] [1tpc is 1-(3-chloro­propyl)-1,2,4-triazole, C₅H₈ClN₃], the copper(II) centres reside in a tetragonally distorted octahedral coordination environment. Four 1tpc ligands are coordinated to the metal atom via the N4 atom of the triazole rings in a square-planar arrangement, with Cu—N bond lengths in the range 2.002 (2)–2.019 (2) Å. Two tetra­fluoro­borate anions, in the axial positions above and below the square plane, are weakly coordinated to the copper(II) centre, with Cu—F distances of 2.4009 (18) and 2.5096 (18) Å.

The palladium(II) centre in the title compound, [PdCl₂(C₂₁H₁₈N₂OS)], is coordinated to the pyridyl N atom and to the thia­zolidinone S atom of the 5-benzyl-3-phenyl-2-(2-pyridyl)­thia­zolidin-4-one ligand, resulting in a five-membered chelate ring. Two cis-chloro ligands complete the square-planar coordination environment of the metal. Although the geometry at the Pd centre is essentially planar, the N—Pd—S bite angle of 85.20 (8)° causes deviations in the cis angles from the ideal value of 90°. Opposite enantiomers form one-dimensional chains in the cell via a short SO intermolecular interaction.

Third-generation hard-X-ray synchrotron radiation sources simultaneously provide both a need and an opportunity for the development of new short-wavelength optical components. The high power and power densities of the insertion-device-produced X-ray beams have forced researchers to consider what may seem like exotic approaches, such as cryogenically cooled silicon and highly perfect diamond crystals, to mitigate thermal distortions in the first optical components. Once the power has been successfully filtered while maintaining the high beam brilliance, additional specialized optical components can be inserted into the monochromatic beam that take advantage of that brilliance. This paper reviews the performance of such optical components that have been designed, fabricated and tested at the Advanced Photon Source, starting with high-heat-load components and followed by examples of several specialized devices, such as an meV resolution (in-line) monochromator, a high-energy X-ray phase retarder and a phase-zone plate with submicrometer focusing capability.