HUG and SQUEEZE: using CRYSTALS to incorporate resonant scattering in the SQUEEZE structure-factor contributions to determine absolute structure

Structure factors representing disordered regions of a crystal structure can be modified to account for resonant scattering, improving the chances of successful absolute structure determination.

Structural diversity of polynuclear Mg_xO_y cores in magnesium phenoxide complexes

2,6-Di-tert-butyl-4-methyl­phenoxide (BHT) magnesium complexes exhibit a variety of crystal structure motifs. The X-ray structures of the bi-, tri- and tetranuclear BHT–Mg complexes have been established, viz. [(BHT)(DME)Mg(μ-OBn)₂Mg(THF)(BHT)], {[(BHT)(THF)Mg]₂Mg(μ-OC₆H₄-2-Me)₄} and Mg₄(BHT)₂(OCH₂CH₂NH₂)₆ (DME is 1,2-di­meth­oxy­ethane and THF is tetrahydrofuran), respectively. The various types of polynuclear Mg_xO_y cores for known ArO–Mg complexes are discussed.

Cation tautomerism, twinning and disorder in the triclinic and monoclinic forms of 4-amino-5-chloro-2,6-di­methyl­pyrimidinium 5-chloro-2-hy­droxy­benzoate and a new disordered refinement of 2-amino-4,6-di­meth­oxy­pyrimidin-1-ium thio­phene-2-carboxyl­ate

Two forms, i.e. triclinic and monoclinic, of 4-amino-5-chloro-2,6-di­methyl­pyrimidinium 5-chloro-2-hy­droxy­benzoate contain tautomeric forms of the cation, both of which exhibit quinonoid-type bond fixation, and the monoclinic form also exhibits both merohedral twinning and disorder. The ionic components in the triclinic form are linked by hydrogen bonds into finite four-ion aggregates, but those in the monoclinic form are linked into a three-dimensional framework structure.

A three-dimensional supra­molecular framework based on the inter­linkage of an inter­penetrating diamondoid coordination network

A three-dimensional cadmium(II) supra­molecular framework was prepared by the hydro­thermal reaction between Cd(NO₃)₂·4H₂O, 1,4-bis­(pyridin-4-yl)buta-1,3-diene and adipic acid. This supra­molecular architecture is formed by the inter­linkage of a threefold inter­penetrating diamondoid coordination network through O—H⋯O hydrogen-bonding inter­actions.

Halogen bonding in a series of Br(CF₂)_nBr–DABCO adducts (n = 4, 6, 8)

Each of three adducts of a series of di­bromo­perfluoro­alkyl compounds, BrCF₂(CF₂)_nCF₂Br (n = 2, 4, 6), and 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO) displays a one-dimensional halogen-bonded network. All three adducts exhibit N⋯Br distances less than the sum of the van der Waals radii, with one adduct showing the shortest N⋯Br halogen-bond distances yet reported between a bromo­perfluoro­carbon and a nitro­gen base.

A hybrid imidazolyl­idene/imidazolium nickel NHC complex: an isolated inter­mediate

The crystal structure of a hybrid imidazolyl­idene/imidazolium nickel N-heterocyclic carbene (NHC) complex is reported, which can be understood as a rare example of an isolated inter­mediate.

A new two-dimensional polymeric cadmium(II) complex containing dicyanamide bridging ligands

In a new cadmium–dicyanamide (dca) complex, each Cd^II cation is coordinated by six nitrile N atoms from six anionic dca ligands to furnish a slightly distorted octa­hedral geometry. Neighbouring Cd^II cations are linked by dicyanamide bridges to construct a two-dimensional anionic layer coordination polymer.

Synthon preference in the cocrystal of 3,4,5-tri­fluoro­phenyl­boronic acid with urea

A novel cocrystal of 3,4,5-trifluoro­phenyl­boronic acid with urea has been synthesized and structurally characterized. The preference of formation of possible supra­molecular synthons has been verified by DFT calculations.

An arsenate with the α-CrPO₄ structure type, NaCa_1–xNi_3–2xAl_2x(AsO₄)₃ (x = 0.23): crystal structure, charge-distribution and bond-valence-sum analyses

A new arsenate, NaCa_0.77Ni_2.54Al_0.46(AsO₄)₃, was synthesized using a flux method and it appears closely related to the α-CrPO₄-structure type. The proposed structural model was validated by bond-valence-sum and charge-distribution analyses.

Copper(II)- and gold(III)-mediated cyclization of a thio­urea to a substituted 2-amino­benzo­thia­zole

The copper(II)- and gold(III)-mediated cyclizations of thio­urea derivatives to substituted 2-amino­benzo­thia­zoles are reported. The study provides mechanistic insight into the role of the metal cations in these transformations.

Novel modification of anhydrous transition metal oxalates from powder diffraction

The crystal structures of the novel γ-modification of anhydrous oxalates have been determined from powder diffraction data for MnC₂O₄ and CdC₂O₄ obtained during thermal decomposition of the corresponding hydrates. The distinctive features of this modification are loose packing and low densities compared with the known α- and β-modifications of anhydrous transition metal oxalates.

Synthesis and coordination chemistry of the PPN ligand 2-[bis­(diiso­propyl­phosphanyl)methyl]-6-methyl­pyridine

In the isostructural tetra­hedral Fe and Co complexes of the multidentate PPN ligand 2-[bis­(diiso­propyl­phosphanyl)methyl]-6-methyl­pyridine, the ligand adopts a bidentate P,N-coordination, whereas in the case of the octa­hedral Mn complex, the ligand coordinates via both P atoms to the metal centre.

Synthesis and structures of photoactive rhenium carbonyl complexes derived from 2-(pyridin-2-yl)-1,3-benzo­thia­zole, 2-(quinolin-2-yl)-1,3-benzo­thiazole and 1,10-phenanthroline

Three rhenium(I) carbonyl-based photoCORMs have been synthesized and structurally characterized. All three complexes are highly luminescent and exhibit variable apparent CO release rates upon expousre to low-power UV light.

Side-chain conformations in the isomorphous polyfluorinated {4,4′-bis­[(2,2-di­fluoro­eth­oxy)meth­yl]-2,2′-bi­pyridine-κ²N,N′}di­chlorido­palladium and -platinum complexes

The structures of the palladium and platinum complexes of 4,4′-bis­[(2,2-di­fluoro­eth­oxy)meth­yl]-2,2′-bi­pyridine are isomorphous and have –C(H_α)₂OC(H_β)₂CF₂H side chains with H-atom donors at the α and β sites. Mol­ecules are associated into dimers and the dimers form columns, with alternating dimers reinforced by C—H⋯Cl hydrogen bonds and C—H_β⋯F(—C) inter­actions.

Adipo­nitrile at 100 K

In the structure of adipo­nitrile, a key inter­mediate in the synthesis of the polyamide Nylon 66, at 100 K, the mol­ecule adopts an exact C_i-symmetric gauche–anti–gauche conformation of the C—C—C—C skeleton about an inversion centre. The mol­ecules are densely packed, with short contacts between the α-H and nitrile N atoms.

The synthesis, crystal structure and thermal properties of an energetic compound: the hydrated azanium salt of 3,6-bis­[(1H-1,2,3,4-tetra­zol-5-yl)amino]-1,2,4,5-tetra­zine

The energetic ionic salt bis­(1-amino­guanidin-2-ium) 5,5′-[1,2,4,5-tetra­zine-3,6-diylbis(aza­nedi­yl)]bis­(1H-1,2,3,4-tetra­zol-1-ide) dihydrate has a high nitro­gen content and exhibits good thermal stability. The crystal structure reveals a three-dimensional network of N—H⋯N, N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds.

Cs₃LiZn₂(WO₄)₄ and Rb₃Li₂Ga(MoO₄)₄: different filled derivatives of the cation-deficient Cs₆Zn₅(MoO₄)₈ structure

Cs₃LiZn₂(WO₄)₄ and Rb₃Li₂Ga(MoO₄)₄ represent two distinct series of filled derivatives of the cation-deficient Cs₆Zn₅(MoO₄)₈ structure with three-dimensional tetra­hedral frameworks related to that of mayenite 12CaO·7Al₂O₃. The series of tetra­gonal A₃Li₂R(MoO₄)₄ compounds exhibits second harmonic generation effects compatible with that of β′-Gd₂(MoO₄)₃.

Crystallographic studies of cinnamamide derivatives as a means of searching for anti­convulsant activity

Three new crystal structures of N-substituted cinnamamide derivatives, which were screened for anti­convulsant activity, are stabilized by inter­molecular O—H⋯O hydrogen bonds and additionally by N—H⋯O hydrogen bonds in two of the structures. The compounds possess fragments that are considered as beneficial for anti­convulsant activity. The conformations of these compounds were analyzed in comparison with the characteristic features of the proposed pharmacophore model of the anti­convulsants active in the maximal electroshock test.

Copper(II) bis­(4,4,4-tri­fluoro-1-phenyl­butane-1,3-dionate) complexes with pyridin-2-one, 3-hy­droxy­pyridine and 3-hy­droxy­pyridin-2-one ligands: mol­ecular structures and hydrogen-bonded networks

The influence of tautomeric forms and different coordination modes has been studied with respect to the formation of hydrogen-bonded networks in (4,4,4-tri­fluoro-1-phenyl­butane-1,3-dionato)copper(II) moieties in the presence of pyridin-2-one, 3-hy­droxy­pyridine and 3-hy­droxy­pyridin-2-one.

A novel tetra­zolate- and cyanide-bridged three-dimensional heterometallic coordination polymer: crystal structure, thermal stability and magnetic properties

A tetra­zolate- and cyanide-bridged Cu^II–Co^III bimetallic coordination polymer is the first example of a trinodal (6,8,8)-connected three-dimensional network and is constructed from anionic [Co(CN)₆]³⁻ and cationic [(Cu1)₂(tta)₂]²⁺ and [(Cu2Cu3)(tta)₃]⁺ units. A magnetic investigation shows anti­ferromagnetic inter­actions between the paramagnetic Cu^II ions.

Asymmetric structure of cis-[N-(9-an­thra­cenyl­meth­yl)-1,2-ethanedi­amine]di­pyridineplatinum(II) dinitrate

In many cases, complexes of platinum and other metals have a symmetrical structure. In contrast, in the platinum(II) complex with pyridine and N-(9-anthracenylmeth­yl)-1,2-ethanedi­amine as ligands, the molecular structure is asymmetric. Only one of the two pyridine rings is π-stacked with the anthracene ligand enhancing the asymmetry.

Two-dimensional coordination polymeric structures in the sodium, potassium and rubidium complex salts with (4-fluoro­phen­oxy)acetic acid

An extension of the study of the coordination capability of the (4-fluoro­phen­oxy)acetate ligand in the generation of metal complexes and, in particular, coordination polymeric supra­molecular structures with the alkali metal complex salts.

LiBC₃: a new borocarbide based on graphene and heterographene networks

The crystal structure of the hexgonal ternary borocarbide LiBC₃ has been determined by the single-crystal method. LiBC₃ represents the stucture family based on the graphene and heterographene networks.

A new polymorph of 2,6-di­amino­pyridine

Sublimation yielded a new polymorph of 2,6-di­amino­pyridine, a common ingredient in and a synthetic precursor to many colorants.

Deciphering composition and connectivity of a natural product with the assistance of MS and 2D NMR

The structure of a three-component cocrystal of natural products contained extensive positional disorder in one of the mol­ecules. The identity of the disordered mol­ecule was established by 2D NMR and MS thereby making disorder modelling and structural refinement possible.

Synthesis, crystal structure and activity evaluation of novel 3,4-di­hydro-1-benzoxepin-5(2H)-one derivatives as protein–tyrosine kinase (PTK) inhibitors

Four 3,4-di­hydro-1-benzoxepin-5(2H)-one derivatives have been synthesized and the structure of 4-[3-(5-bromo-2-hy­droxy­phen­yl)allylidene]-3,4-di­hydro-1-benzoxepin-5(2H)-one was confirmed by single-crystal X-ray analysis. The inhibitory activities of these compounds against protein–tyrosine kinases (PTKs) were evaluated.

Complexes of nickel(II) and copper(II) with 1,2,4-triazole-3-carb­oxy­lic acid and of cobalt(III) with 3-amino-1,2,4-triazole-5-carb­oxy­lic acid

The structures of a dimeric nickel(II) complex and a polymeric copper(II) complex supported by 1,2,4-triazole-3-carboxylate ligands, and a dimeric cobalt(III) complex supported by 3-amino-1,2,4-triazole-5-carboxylate ligands are reported.

Construction and photocatalytic properties of two metal-mediated coordination polymers based on benzene-1,3,5-tri­carb­oxy­lic acid and trans-1-(pyridin-3-yl)-2-(pyridin-4-yl)ethene

Two coordination polymers with distinct structures have been prepared under hydro­thermal conditions, based on mixtures of benzene-1,3,5-tri­carb­oxy­lic acid and trans-1-(pyridin-3-yl)-2-(pyridin-4-yl)ethene, together with two different d¹⁰ metal ions. Both compounds exhibit good photocatalytic properties in the decomposition of the organic dye contaminant of rhodamine B.

Mono- and dinuclear Cu^II complexes of the benzyl­dipicolyl­amine (BDPA) ligand: crystal structure, synthesis and characterization

Copper complexes ligated by benzyl­dipicolyl­amine (BDPA) are described. Inter­molecular O—H⋯O(tri­flate), O—H⋯O(tetrahydrofuran), C—H⋯F(tri­flate) and C—H⋯O(tri­flate) hydrogen bonds stabilize the crystal lattice of both structures.

Synthesis, structure and in vitro cytotoxicity of platinum(II) complexes containing eugenol and a quinolin-8-ol-derived chelator

Three new platinum(II) complexes of the type [PtCl(R-OQ)(Eug)], containing eugenol (Eug) and a quinolin-8-ol derivative (R-OQ), show promising in vitro cytotoxicity on four human cancer cell lines.