An introduction to the special issue on interplay of crystallography, spectroscopy and theoretical methods for solving chemical problems

Editorial

Building a two-dimensional network from mixed-valence copper units held together by acetone bridges

The co-deposition method was used for preparation of the mixed-valence supra­molecular compound {[Cu^I₄(O₂CCF₃)₄]₂–{μ₂-OC(CH₃)₂}₂–[Cu^II₂(O₂CCF₃)₄]}, which consists of copper(I) and copper(II) tri­fluoro­acetate units held together by acetone bridges and inter­molecular Cu⋯O inter­actions.

Ru^II–hydride–trop complexes: X-ray single-crystal determination and quantum-chemical calculations

Three Ru^II–hydride species have been synthesized and fully characterized, including X-ray single-crystal structures. Quantum chemical calculations predict very accurately the observed crystallographic data.

Bis(1,1,1,5,5,5-hexa­fluoro­pentane-2,4-dionato)tetra­kis­(μ₄-1,1,1,5,5,5-hexa­fluoro­pentane-2,2,4,4-tetra­olato)copper(II)octa­tin(II): a prospective precursor for Cu-doped SnO₂ films

The preparation and structure elucidation of a new tin-rich heterometallic complex [Sn₄(hfpt)₂–Cu(hfac)₂–Sn₄(hfpt)₂], which consists of a planar [Cu(hfac)₂] fragment sandwiched between two tetra­nuclear [Sn₄(hfpt)₂] units, are reported.

Powder diffraction: what's in a name?

The development of powder diffraction is briefly described; the extent of this development from studies of metals to protein crystal structures shows that powder diffraction is at the cutting edge of crystallography. A new name `polycrystallography' is proposed for these endeavours.

NMR diffusion: an update

NMR diffusion methods continue to attract increasing attention from practising chemists. This short article summarizes some of the more recent developments and highlights the areas in which these methods are finding application.

Structure, magnetism and colour in simple bis­(phosphine)nickel(II) dihalide complexes: an experimental and theoretical investigation

The complex (dtbpe-κ²P)NiI₂ is close to square planar in the solid state but is neither diamagnetic nor red in colour. Its structure and magnetism have been investigated by a combination of experiment and density functional theory. Comparisons have been made with analogous compounds bearing different halides and different phosphine ligands. Observed trends in structure and colour have been reproduced theoretically and rationalized.

Solid-state photochemistry of mol­ecular photo-switchable species: the role of photocrystallographic techniques

The analysis of the structures of metastable linkage isomers, generated photochemically, using single-crystal photocrystallographic techniques, is described. The factors that favour the formation of the metastable states are discussed.

On the possibility for Rb- and Eu-cation ordering in type-I clathrates: synthesis and homogeneity range of the novel compounds Rb_8–xEu_x(In,Ge)₄₆ (0.6 ≤ x ≤ 1.8)

Clathrates with the type-I structure are reported in the quaternary Rb–Eu–In–Ge system. Possible cation ordering is suggested.

Arrangement of Rh³⁺ ions in fac-triamminetri­chlorido­rhodium from powder data and in fac-triammine­trinitratorhodium crystals twinned by merohedry

The structure of fac-triamminetri­chlorido­rhodium consists of isolated octa­hedra and that of the fac-triammine­trinitratorhodium trigonal complex consists of octa­hedral columns with partially filled rhodium positions.

Distorted octa­hedral environments in tri­carbonyl­rhenium(I) complexes of 5-[2-(2,4,6-tri­methyl­phenyl)diazen-1-yl]quinolin-8-olate and 5,7-bis­[2-(2-methyl­phenyl)diazen-1-yl]quinolin-8-olate

The Re^I centres of the tri­carbonyl­rhenium(I) complexes of 5-[2-(2,4,6-tri­methyl­phenyl)diazen-1-yl]quinolin-8-olate and 5,7-bis­[2-(2-methyl­phenyl)diazen-1-yl]quinolin-8-olate are facially surrounded by the ligands in a slightly distorted octa­hedral environment. Both structures exhibit inter­molecular C—H⋯O inter­actions.

Coordination polymeric structures in the sodium salt of 4-chloro-3-nitro­benzoic acid and the sodium and potassium salts of 4-nitro­anthranilic acid

The hydrated sodium salt of 4-chloro-3-nitro­benzoic acid and the hydrated sodium and potassium salts of 2-amino-4-nitro­benzoic acid are stabilized by intra- and inter­molecular hydrogen bonding and strong π–π ring inter­actions. Na centres are linked through centrosymmetric four-membered duplex water bridges and through 18-membered duplex head-to-tail ligand bridges. Similar centrosymmetric bridges are found in the potassium salt.

A two-dimensional Cu^I framework incorporating the 1-phenyl-1H-1,2,3,4-tetra­zole-5-thiol ligand

The coordination polymer [Cu(ptt)]_n (ptt is 1-phenyl-1H-1,2,3,4-tetra­zole-5-thiol­ate) has been prepared under solvothermal conditions. Its structure features two-dimensional layers which lie parallel to the (100) plane.

(OC-6-13)-Di­fluorido­oxidobis(propan-2-ol)(propan-2-olato)vanadium(V)

The crystal structure and NMR data of the title compound are reported. It crystallizes in the space group P with Z′ = 2, the mol­ecules forming infinite chains via hydrogen bonds. The chains inter­act through dispersive aliphatic contacts.

A three-dimensional chiral crystal structure constructed from a chiral triazolate ligand showing an SrSi₂ topology: poly[bis­(μ₃-3,5-di­ethyl-1,2,4-triazolato-κ³N¹:N²:N⁴)tris­ilver nitrate]

A metal–organic framework (MOF) is reported in which an Ag^I cation is coordinated by two N atoms from two different 3,5-diethyl-1,2,4-triazolate ligands in a linear configuration. Each Ag^I cation is then connected to two adjacent Ag^I cations via a μ₃-N¹:N²:N⁴-triazolate ligand.

The coordination chemistry of two symmetric fluorene-based organic ligands with cuprous chloride

In two complexes, Cu^I atoms connect the symmetric 2,7-bis­(1H-imidazol-1-yl)-9,9-dimethyl-9H-fluorene and 2,7-bis­(1H-imidazol-1-yl)-9,9-dipropyl-9H-fluorene ligands into one-dimensional chains. In the former, a {[Cu^ICl₂]⁻} unit adheres to the one-dimensional chain through a weak Cu⋯Cu inter­action, while in the latter, a {[Cu^I₂Cl₄]²⁻} unit links two different chains into a one-dimensional rope-ladder-type chain.

Calcium and strontium salts of (glycinato-κ²N,O)oxidobis(peroxido-κ²O,O′)vanadate(V) tetra­hydrate

The calcium and strontium terahydrate salts of (glycinato)oxidobis(peroxido)vanadate(V) crystallized at pH ca 7.4 with similar lattice parameters. The glycinate anion acts as a bidentate N,O-chelating ligand, and the V atom has a penta­gonal bipyramidal geometry, with two η²-peroxide groups and the glycinate N atom in the equatorial plane, and one terminal oxo and a glycinate O atom at the axial positions.

Supra­molecular architecture of metal–organic frameworks involving dinuclear copper paddle-wheel complexes

In two dinuclear copper complexes, the two Cu^II ions are bridged by four syn,syn-η¹:η¹:μ carboxyl­ate groups, showing a paddle-wheel cage type structure with a square-pyramidal geometry. The three-dimensional supra­molecular metal–organic frameworks of one complex consist of three different (20) and an (36) ring motif, while the other complex simply packs as mol­ecular species.

Novel three-dimensional coordination polymers of lanthanides with sulfate and oxydi­acetic acid

Three-dimensional coordination polymers made up of lanthanides, oxydi­acetate and sulfate show novel structures in which the sulfate anion tends to reach saturation as a ligand.

A polymorphic form of 4,4-di­methyl-8-methyl­ene-3-aza­bicyclo­[3.3.1]non-2-en-2-yl 3-indolyl ketone, an indole alkaloid extracted from Aristotelia chilensis (maqui)

A polymorphic form of the title indole alkaloid was extracted from Aristotelia chilensis. Its crystal structure is described and compared with a previously reported polymorph.

4,4′-{Diazenediylbis[(1,4-phenyl­ene)bis­(carbon­yloxy)]}bis­(2,2,6,6-tetra­methyl­piperidinyloxidan­yl): the first crystal structure determination from powder data of a nitroxide radical

The structure of a nitroxide radical determined from laboratory X-ray powder diffraction data is reported for the first time. The attractive forces between the mol­ecules in the crystal structure are mainly of dispersive nature.

Tosyl­ate salts of the anti­cancer drug lapatinib

Two tosyl­ate salts of lapatinib, an anti­cancer drug, crystallize in centrosymmetric and noncentrosymmetric space groups. The crystal packing in both structures is influenced by a combination of N—H⋯O hydrogen bonds and C—H⋯O inter­actions

(9E)-9-Benzyl­idene-2-methyl­sulfanyl-5-phenyl-6,7,8,9-tetra­hydro­pyrim­ido[4,5-b]quinolin-4(3H)-one: a hydrogen-bonded R₂²(8) dimer

A tetra­hydro­pyrimidin-4(3H)-one, prepared by mild oxidation of the corresponding hexa­hydro analogue, forms hydrogen-bonded (8) dimers.

4-Oxo-N-phenyl-4H-chromene-2-carboxamide and of a new polymorph of 7-meth­oxy-4-oxo-N-p-tolyl-4H-chromene-2-carboxamide and its hemihydrate

The structures of 4-oxo-N-phenyl-4H-chromene-2-carboxamide and of a new polymorph of 7-meth­oxy-4-oxo-N-p-tolyl-4H-chromene-2-carboxamide and its hemihydrate. The structures have an anti-rotamer conformation about the C—N bond; however, the amide O atom can be either trans- or cis-related to the O atom of the pyran ring.

Imidazolidin-2-one: pseudosymmetry and twinning

The imidazolidin-2-one ring displays a half-chair conformation. N—H⋯O hydrogen bonds connect the mol­ecules to form (8) rings and thence ribbons parallel to the a and b axes. The crystal was merohedrally twinned.

Two-dimensional hydrogen-bonded supra­molecular networks in the compounds of benzene-1,2,4,5-tetra­carb­oxy­lic acid (pyromellitic acid) with 2,2′-bi­imidazole and 4,4′-di­methyl-2,2′-bi­pyridine

Two salts obtained from the proton-transfer reactions of benzene-1,2,4,5-tetra­carb­oxy­lic acid (pyromellitic acid, PMA) with 2,2′-bi­imidazole and 4,4′-dimethyl-2,2′-bipyridine form one-dimensional O—H⋯O hydrogen-bonded chain structures extended into two-dimensional supra­molecular layers and sheets via O—H⋯O and N—H⋯O hydrogen bonding.

Head-to-tail square-shaped cyclic hydrogen bonds leading to dimeric aggregates: 1,8-di­benzoyl-2,7-di­hydroxy­naphthalene and a comparison with its analogous benzoyl­naphthalene

In 1,8-dibenzoyl-2,7-di­hydroxy­naphthalene, centrosymmetric dimeric aggregates arise from two intra- and inter­molecular O—H⋯O=C hydrogen bonds, forming head-to-tail square-shaped cyclic ⋯O⋯H⋯O⋯H⋯ hydrogen bonds. These dimeric aggregates are connected into layers in the bc plane by inter­molecular (naphthalene)C—H⋯O=C inter­actions.

Three-dimensional hydrogen-bonded assembly in 2,2′-disulfanyl­idene-5,5′-biimidazolidinyl­idene-4,4′-dione–di­methyl­formamide–water (3/2/4)

2,2′-Disulfanyl­idene-5,5′-biimidazolidinyl­idene mol­ecules aggregate through N—H⋯S hydrogen-bonding inter­actions with cyclic motifs [graph set (8)], giving two-dimensional ribbon structures which are close to being parallel. Two independent water mol­ecules associate to form centrosymmetric cyclic hydrogen-bonded (H₂O)₄ tetra­mer units [graph set (8)].

Two polymorphs of 2-ethyl-3-hy­droxy-6-methyl­pyridinium hydrogen N-acetyl-L-glutamate from powder diffraction data

The crystal packing motifs in two polymorphic modifications (monoclinic and ortho­rhom­bic) of the title salt are different, but the conformations of the anions are generally similar.

Transannular S⋯N inter­actions in 10-ethynyl-10H-pheno­thia­zine 5-oxide and 5,5-dioxide

The title compounds are oxidation products of the parent compound 10-ethynyl-10H-pheno­thia­zine and differ with respect to transannular S⋯N inter­actions, the intra­molecular S⋯N contact being shorter in the dioxide.

Isolation, pharmacological activity and structure determination of physalin B and 5β,6β-ep­oxy­physalin B isolated from Congolese Physalis angulata L.

Two physalin compounds have been isolated from Congolese Physalis angulata L. plants and their structure and pharmacological activity has been determined. In both structures, physalin dimers are formed by inter­molecular hydrogen bonding.

Inter­molecular C—H⋯O, Cl⋯Cl and π–π inter­actions in the 2-di­chloro­methyl derivative of vitamin K₃

The title 1,4-naphtho­quinone is a chlorinated derivative of vitamin K₃, which is a synthetic compound also known as menadione. Mol­ecules are planar, lie on a crystallographic mirror plane (Z′ = 0.5) and are connected to each other by C—H⋯O hydrogen bonds, forming two-dimensional layers parallel to the ac plane.