Weak interactions in crystals: an integrated approach

Chiara Massera and Helen Stoeckli-Evans introduce this special issue of Acta Crystallographica Section E on `Weak interactions in crystals: an integrated approach' where the contributions serve as an excellent introduction to the importance and the interest these have been acquiring in the scientific arena over the last two decades or so.

Weak inter­actions in crystals: old concepts, new developments

Andrei Batsanov presents a general review of weak interactions in crystals, which highlights the history, state-of-the art and future developments of this field.

Crystal structure of a supra­molecular lithium complex of p-tert-butyl­calix[4]arene

The crystal structure of a supra­molecular lithium complex of p-tert-butyl­calix[4]arene has been determined and analyzed. Different from the majority of calixarene–alkali metal complexes, which are formed by direct coordination of the metal cation to the calixarene hy­droxy groups, this complex is stabilized by an inter­play of weak inter­actions involving the methanol mol­ecules surrounding the metal, giving rise to a second-sphere coordination supra­molecular assembly.

An investigation to elucidate the factors dictating the crystal structure of seven ammonium carboxyl­ate mol­ecular salts

Hydrogen-bonded ladders typically encountered in ammonium carboxyl­ate salts did not form in the presence of a pyridine acceptor group.

Hydrogen bonds and π–π inter­actions in two new crystalline phases of methyl­ene blue

Two unprecedented solid phases of methyl­ene blue (MB⁺), viz. 3,7-bis­(di­methyl­amino)­pheno­thia­zin-5-ium chloride dihydrate and 3,7-bis­(di­methyl­amino)­pheno­thia­zin-5-ium bis­ulfite, have been obtained and structurally characterized. The effective absence of hydrogen-bond donors in the second compound has important consequences on the stacking geometry and supra­molecular inter­actions of the MB⁺ ions, which are analysed by Hirshfeld fingerprint plots.

An exploration of O—H⋯O and C—H⋯π inter­actions in a long-chain-ester-substituted phenyl­phenol: methyl 10-[4-(4-hydroxyphenyl)phen­oxy]decanoate

The superstructure of 4-(9-methyl­oxycarbonyl­non­yloxy)phenyl­phenol is dominated by O—H⋯O and C—H⋯O hydrogen-bonding and C—H⋯π inter­actions. Hirshfeld surface, fingerprint plot, inter­action energy and energy framework analyses were used to explore the nature and strength of the inter­molecular inter­actions.

Structural characterization and Hirshfeld surface analysis of a Co^II complex with imidazo[1,2-a]pyridine

The complex [CoL₂Cl₂] (L = imidazo[1,2-a]pyridine) exhibits a supra­molecular-layered assembly through π–π stacking inter­actions. The overall inter­molecular inter­actions involved in the structure have been qu­anti­fied and fully described by Hirshfeld surface analysis.

Crystal packing analysis of in situ cryocrystallized 2,2,2-tri­fluoro­aceto­phenone

In this present study, the crystal structure of 2,2,2-tri­fluoro­aceto­phenone (TFAP) is determined using in situ cryocrystallization techniques. The main objective of this work is to study its crystal packing associated with the various inter­molecular inter­actions, along with a detailed comparison with the features of substituted analogs. It is inter­esting to note how the chemical substitution of different functional groups influences the crystal packing, the electronic environment of the mol­ecule and the nature of the various inter­molecular inter­actions.

Studying weak inter­actions in crystals at high pressures: when hardware matters

The quality of structural models for 1,2,4,5-tetra­bromo­benzene (TBB), based on data collected from a single crystal in a diamond anvil cell at 0.4 GPa in situ using two different diffractometers belonging to different generations have been compared, alongside the effects of applying different data-processing strategies.

Crystal structure of an iridium(III) complex of the [C(dppm)₂] PCP pincer ligand system and its conjugate CH acid form

The crystal structures of [Ir^III(CO)(C(dppm)₂-κ³P,C,P′)ClH]Cl and [Ir^III(CO)(CH(dppm)₂-κ³P,C,P′)ClH]Cl₂ have been determined. Both complexes show a slightly distorted octa­hedral coordinated Ir^III centre. The PCP pincer ligand system is arranged in a meridional manner.

Crystal structure of (E)-1,2-diferrocenyl-1,2-bis­(furan-2-yl)ethene

The title compound is the product of a new synthetic route towards tetra­aryl/hetaryl-substituted ethenes that reduces the occurrence of side-products. In the crystal, the mol­ecule is centrosymmetric and the cyclo­penta­dienyl rings are nearly coplanar and aligned slightly closer to a staggered conformation than to an eclipsed one.

Crystal structures and Hirshfeld surface analyses of (N-hexyl-N-methyl­dithio­carbamato-κ²S,S′)triphenyl­tin(IV) and [N-methyl-N-(2-phenyl­ethyl)­dithio­carbamato-κ²S,S′]tri­phenyl­tin(IV)

The metal coordination geometry in each of the title mol­ecules, [Sn(C₆H₅)₃(C₈H₁₆NS₂)] (I) and [Sn(C₆H₅)₃(C₁₀H₁₂NOS₂)] (II), is based on a heavily distorted tetra­hedron owing to the asymmetric mode of coordination of the di­thio­carbamate ligand. The persence of C—H⋯π(phen­yl) inter­actions in the crystals lead to dimeric aggregates in (I) and supra­molecular chains (II).

Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-di­phenyl-2-[4-(pyren-1-yl)phen­yl]acrylo­nitrile

There are alternating relatively strong and weak intermolecular π–π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE) characteristics.

{1-[1-(2-Hy­droxy­phen­yl)ethyl­idene]-2-(pyridin-2-yl-κN)hydrazine-κ²N′,O}{1-[1-(2-oxidophen­yl)ethyl­idene]-2-(pyridin-2-yl-κN)hydrazine-κ²N′,O}nickelate(II) nitrate hemihydrate

The asymmetric unit of the title complex comprises a supramolecular dimer composed of the Δ(−) and Λ(−) optical isomers, which are linked by strong hydrogen-bonds, two nitrate anions and one water mol­ecule. In the crystal, the dimers are joined by numerous hydrogen bonds, forming a three-dimensional framework.

Syntheses, Raman spectroscopy and crystal structures of alkali hexa­fluorido­rhenates(IV) revisited

The A₂[ReF₆] (A = K, Rb, Cs) salts are isotypic and crystallize in the K₂[GeF₆] structure type.

The effect of the fused-ring substituent on anthracene chalcones: crystal structural and DFT studies of 1-(anthracen-9-yl)-3-(naphthalen-2-yl)prop-2-en-1-one and 1-(anthracen-9-yl)-3-(pyren-1-yl)prop-2-en-1-one

Two new anthracene chalcones, namely 1-(anthracen-9-yl)-3-(naphthalen-2-yl)prop-2-en-1-one and 1-(anthracen-9-yl)-3-(pyren-1-yl)prop-2-en-1-one, have been successfully synthesized and the effect of the different fused ring substituent system attached to the anthracene chalcone derivative investigated. These compounds show a very narrow band gap due to the large p-conjugated systems, making them promising candidates as optoelectronic materials. Hirshfeld surface analysis has been carried out to show the contribution of inter­molecular contacts and weak inter­actions to supra­molecular stabilization.

Crystal structure, hydrogen bonding and Hirshfeld surface analysis of 2-amino-4-meth­oxy-6-methyl­pyrimidinium 4-chloro­benzoate

In the crystal structure of the title compound, C₆H₁₀N₃O⁺·C₇H₄Cl_O2⁻, the pyrimidine N atom of the cation is hydrogen-bonded to the 4-chloro­benzoate anion through a pair of N—H⋯O_carbox­yl hydrogen bonds, forming an (8) ring motif which is linked through centrosymmetric (8) ring motifs, forming a pseudo­tetra­meric DDAA array.

Crystal structure and Hirshfeld surface analysis of 4′-(2-chloro­phen­yl)-1′-methyl-3′′-phenyl-7′′,8′′-di­hydro-5′′H-di­spiro­[indoline-3,2′-pyrrolidine-3′,6′′-iso­quinoline]-2,5′′-dione

In the crystal structure of the title compound, a di­spiro­[indoline-3,2′-pyrrolidine-3′,6′′-iso­quinoline]-2,5′′-dione, C—H⋯O hydrogen bonding predominates, linking mol­ecules to form chains propagating along [100].

Syn and anti conformers of di­ammonium aqua­bis­(malonato)oxidovanadate(IV) in an anhydrate crystal

In the anhydrate crystal of di­ammonium aqua­bis­(malonato)oxidovanadate(IV), (NH₄)₂[VO(C₃H₂O₄)₂(H₂O)], two conformers (syn or anti conformation on the equatorial plane) of complex cations are detected. The DFT calculations for the isomers indicate a slight influence of the conformation on their thermodynamic stability. The anionic complexes inter­act with adjacent anions and counter-cations through hydrogen bonds, and the hydrogen bonds lead to a structure with alternate stacking of layers consisting of either anti or syn isomers.

Redetermination of the crystal structure of bis­(tri-2-pyridyl­amine)­iron(II) bis­(perchlorate), and a new refinement of the isotypic nickel(II) analogue: treatment of the perchlorate anion disorder

The crystal structure of bis­(tri-2-pyridyl­amine)­iron(II) bis­(perchlorate) has been redetermined, and that of the isotypic bis­(tri-2-pyridyl­amine)­nickel(II) bis­(perchlorate) complex has been rerefined. In each case, the perchlorate anion is disordered over four sets of atomic sites, and the ions are linked by C—H⋯O hydrogen bonds to form a supra­molecular three-dimensional framework.

Expected and unexpected products of reactions of 2-hydrazinylbenzo­thia­zole with 3-nitro­benzene­sulfonyl chloride in different solvents

Two compounds arose from the same reaction in methanol and the other arose from an unexpected reaction with the acetone solvent.

Lamotrigine ethanol monosolvate

The main motif within the structure is a lamotrigine dimer stabilized by two ethanol mol­ecules. Here the lamotrigine dimer forms using amines in the ortho position of the triazine group.

Crystal structure, Hirshfeld surface analysis and anti­oxidant capacity of 2,2′-{(1E,1′E)-[1,2-phenyl­enebis(aza­nylyl­idene)]bis­(methanylyl­idene)}bis­(5-benz­yloxy)phenol

The title Schiff base compound was synthesized via the condensation reaction of 1,2-di­amine­benzene with 4-benz­yloxy-2-hy­droxy­benzaldehyde. The mol­ecule is V-shaped and possesses mirror symmetry; the mirror bis­ects the central benzene ring. There are two intra­molecular O—H⋯N hydrogen bonds present forming S(6) ring motifs.

6,6′-[(1E,1′E)-Oxybis(4,1-phenyl­ene)bis­(aza­nylyl­idene)bis­(methanylyl­idene)]bis­(2-methyl­phenol): supra­molecular assemblies in two dimensions mediated by weak C—H⋯N, C—H⋯O and C—H⋯π inter­actions

The title compound is a flexible Schiff base, as illustrated by its dihedral angles. The sp²-hybridized character of the aza­nylyl­idene groups is confirmed by their bond lengths and bond angles. In the crystal, mol­ecules of the title compound are assembled into two-dimensional networks connected by weak C—H⋯O, C—H⋯N and C—H⋯π inter­molecular inter­actions.

Crystal structure of tetra­kis­[μ-2-(meth­oxy­carbon­yl)benzoato-κ²O¹:O^1′]bis­[(N,N-di­methyl­formamide-κO)copper(II)](Cu—Cu) di­methyl­formamide disolvate

The binuclear Cu^II complex displays a paddle-wheel structure. In the crystal, adjacent DMF mol­ecules coordinated to copper atoms are arranged in a mutual `head-to-tail' manner by offset face-to-face π–π stacking inter­actions, resulting in chains along the c-axis direction. These are assembled into a three-dimensional structure by further weak C—H⋯O and C—H⋯π inter­actions involving the DMF solvent mol­ecules.

Crystal structure of bis­(aceto­nitrile-κN)(4,4′-di-tert-butyl-2,2′-bi­pyridine-κ²N,N′)platinum(II) bis­(tetra­fluorido­borate) packing as head-to-head dimers

The bulky tert-butyl groups of the dbbpy ligand do not preclude the formation of head-to-head dimers in the crystal structure of bis­(aceto­nitrile)(4,4′-di-tert-butyl-2,2′-bi­pyridine)­platinum(II) tetra­fluorido­borate.

Crystal structure of strontium and barium acesulafame (6-methyl-4-oxo-4H-1,2,3-oxa­thia­zin-3-ide 2,2-dioxide)

Strontium and barium acesulfames crystallize in nearly identical isotypic forms, with barium–oxygen inter­atomic distances being longer due to the larger ionic radius of the barium(II) ion. The conformation of the acesulafame ions is a distorted envelope with an out-of-plane S atom. Metal and acesulfame ions are assembled in infinitive chains along the [100] axis. These chains are connected via hydrogen bonds into a three-dimensional network.

2-[(4-Chloro­phen­yl)sulfan­yl]-2-meth­oxy-1-phenyl­ethan-1-one: crystal structure and Hirshfeld surface analysis

A chiral methine-C atom connects the (4-chloro­phen­yl)sulfanyl, benzaldehyde and meth­oxy residues in the racemic title compound. Supra­molecular helical chains are formed in the crystal, being sustained by methyl- and methine-C—H⋯O(carbon­yl) inter­actions.

Crystal structure of 5-[2-(2,4,6-tri­bromo­phen­yl)diazen­yl]tropolone

The title compound is essentially planar, with an r.m.s. deviation of 0.054 Å. The mol­ecular structure is fixed in the azo tautomer by intra­molecular C—H⋯N inter­actions, with O—H⋯O hydrogen bonds creating linked dimers. Charge-transfer inter­actions are observed, with the segregated stacks linked by Br⋯Br inter­actions.

Crystal structure and Hirshfeld surface analysis of 2-oxo-13-epi-manoyl oxide isolated from Sideritis perfoliata

In the crystal of the title compound, mol­ecules are linked by C—H⋯O hydrogen bonds, forming C(11) helical supra­molecular chains along the 2₁ axis running parallel to [100].

Crystal structures and Hirshfeld surface analyses of 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(pyridin-2-yl)acetamide and 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(pyrazin-2-yl)acetamide

The conformation of the title di­amino­pyrimidine sulfanly acetamides, (I) and (II), have similar conformations, with the pyrimidine ring being inclined to the pyridine ring in (I) by 71.10 (9) °, and by 62.93 (15) ° to the pyrazine ring in (II).

Crystal structure of octane-1,8-diaminium 4,4′-(diazene-1,2-di­yl)dibenzoate monohydrate

The preparation and the crystal structure of octane-1,8-diaminium 4,4′-azinodibenzoate monohydrate are reported.

Crystal structure of (4bS,8aR)-1-iso­propyl-4b,8,8-tri­methyl-7-oxo-4b,7,8,8a,9,10-hexa­hydro­phenanthren-2-yl acetate

The title compound, (4bS,8aR)-1-isopropyl-4 b,8,8-trimethyl-7-oxo-4 b,7,8,8a,9,10-hexa­hydro­phenanthren-2-yl acetate, was prepared by a direct acetyl­ation reaction of naturally occurring totarolenone. In the crystal, mol­ecules are linked to each other by C—H⋯O hydrogen bonds and C—H⋯π inter­actions, forming sheets parallel to the bc plane.

Crystal structures of a manganese(I) and a rhenium(I) complex of a bi­pyridine ligand with a non-coordinating benzoic acid moiety

In the title Mn^I and Re^I complexes of the ligand 2-(2,2′-bipyridin-6-yl)benzoic acid, the o-benzoic acid substituent does not coordinate to the metal. In fac-[2-(2,2′-bipyridin-6-yl)benzoic acid-κ²N,N′]tri­carbonyl­chlorido­rhenium(I) tetra­hydro­furan monosolvate, the benzoic acid fragment is positioned near the axial carbonyl ligand, whereas in fac-[2-(2,2′-bipyridin-6-yl)benzoic acid-κ²N,N′]bromido­tri­carbonyl­manganese(I) tetra­hydro­furan monosolvate, the benzoic acid fragment is disordered, such that in the major component the benzoic fragment is positioned near the bromide ligand and in the minor fragment near the axial carbonyl ligand.

(E)-2-{[(2-Amino­phen­yl)imino]­meth­yl}-5-(benz­yloxy)phenol and (Z)-3-benz­yloxy-6-{[(5-chloro-2-hy­droxy­phen­yl)amino]­methyl­idene}cyclo­hexa-2,4-dien-1-one

The synthesis and structures of (E)-2-{[(2-amino­phen­yl)imino]­meth­yl}-5-(benz­yloxy)phenol (I) and (Z)-3-benz­yloxy-6-{[(5-chloro-2-hy­droxy­phen­yl)amino]­methyl­idene}cyclo­hexa-2,4-dien-1-one (II) are reported. The crystal structures of the mol­ecules are stabilized by N—H⋯O, O—H⋯O and C—H⋯π contacts. DFT calculations on the structure of (II) support the Keto–imine tautomeric form found in the solid state structure. The anti­oxident properties of both mol­ecules are investigated.

Crystal structure of di­fluorido­{2-[(4-hy­droxy­phen­yl)diazen­yl]-3,5-di­methyl­pyrrolido}boron

The asymmetric unit contains two independent mol­ecules, which are linked by an O—H⋯O hydrogen bond. The dimers are further assembled into one-dimensional ladder like structure through O—H⋯F hydrogen bonds and stabilized by π–π inter­actions. The ladders are further linked by C—H⋯π contacts.

Crystal structure and Hirshfeld surface analysis of 1-(2,4-di­chloro­benz­yl)-5-methyl-N-(thio­phene-2-sulfon­yl)-1H-pyrazole-3-carboxamide

In the crystal, pairs of mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds, forming inversion dimers with graph-set notation (8) and (11), which are connected by C—H⋯O hydrogen-bonding inter­actions into ribbons parallel to (100). The ribbons are further connected into a three-dimensional network by C—H⋯π inter­actions and π–π stacking inter­actions between benzene and the thio­phene rings.

Crystal structure and Hirshfeld surface analysis of a pyridiniminium bromide salt: 1-[2-([1,1′-biphen­yl]-4-yl)-2-oxoeth­yl]-3-methyl-1,4-di­hydro­pyridin-4-iminium bromide

The Br⁻ anion is linked to the cation by an N—H⋯Br hydrogen bond. C—H⋯O hydrogen bonds link adjacent pyridiniminium cations into inversion dimers with an (18) graph-set motif. These dimers are stacked in a phen­yl–phenyl T-shaped geometry through C—H⋯π inter­actions.

Crystal structure and theoretical study of N,N-bis­[(5-chloro-2-oxo-2,3-di­hydro­benzo[d]oxazol-3-yl)meth­yl]-2-phenyl­ethanamine

One of the nine-membered 2,3-di­hydro-1,3-benzoxazole rings and the phenyl ring are almost parallel to each other, making a dihedral angle of 5.30 (18)°. These rings are almost normal to the mean plane of the other nine-membered 2,3-di­hydro-1,3-benzoxazole ring. The crystal structure features C—H⋯O hydrogen bonds and π–π stacking inter­actions.

Crystal structure of 2-oxo-2H-chromen-7-yl 4-fluoro­benzoate

The structure of a coumarin ester stabilized by C—H⋯O hydrogen bonds and C=O⋯π and π–π stacking inter­actions has been studied by X-ray diffraction, Hirshfeld surface analysis and quantum chemical calculations.