Weak Intermolecular Hydrogen Bonds Research Articles

Supramolecular Entanglement in a Hydrogen‐Bonded Organic Framework Enables Flexible‐Robust Porosity for Highly Efficient Purification of Natural Gas

AbstractThe development of porous materials with flexible‐robust characteristics shows some unique advantages to target high performance for gas separation, but remains a daunting challenge to achieve so far. Herein, we report a carboxyl‐based hydrogen‐bonded organic framework (ZJU‐HOF‐8a) with flexible‐robust porosity for efficient purification of natural gas. ZJU‐HOF‐8a features a four‐fold interpenetrated structure with dia topology, wherein abundant supramolecular entanglements are formed between the adjacent subnetworks through weak intermolecular hydrogen bonds. This structural configuration could not only stabilize the whole framework to establish the permanent porosity, but also enable the framework to show some flexibility due to its weak intermolecular interactions (so‐called flexible‐robust framework). The flexible‐robust porosity of ZJU‐HOF‐8a was exclusively confirmed by gas sorption isotherms and single‐crystal X‐ray diffraction studies, showing that the flexible pore pockets can be opened by C3H8 and n‐C4H10 molecules rather by C2H6 and CH4. This leads to notably higher C3H8 and n‐C4H10 uptakes with enhanced selectivities than C2H6 over CH4 under ambient conditions, affording one of the highest n‐C4H10/CH4 selectivities. The gas‐loaded single‐crystal structures coupled with theoretical simulations reveal that the loading of n‐C4H10 can induce an obvious framework expansion along with pore pocket opening to improve n‐C4H10 uptake and selectivity, while not for C2H6 adsorption. This work suggests an effective strategy of designing flexible‐robust HOFs for improving gas separation properties.

Supramolecular Entanglement in a Hydrogen-Bonded Organic Framework Enables Flexible-Robust Porosity for Highly Efficient Purification of Natural Gas.

The development of porous materials with flexible-robust characteristics shows some unique advantages to target high performance for gas separation, but remains a daunting challenge to achieve so far. Herein, we report a carboxyl-based hydrogen-bonded organic framework (ZJU-HOF-8a) with flexible-robust porosity for efficient purification of natural gas. ZJU-HOF-8a features a four-fold interpenetrated structure withdiatopology, wherein abundant supramolecular entanglements are formed between the adjacent subnetworks through weak intermolecular hydrogen bonds. This structural configuration could stabilize the whole framework to establish the permanent porosity, but also enable the framework to show some flexibility(so-called flexible-robust framework). The flexible-robust porosity of ZJU-HOF-8a was confirmed by gas sorption isotherms and SCXRDstudies, showing that the flexible pore pockets can be opened by C3H8and n-C4H10rather by C2H6and CH4. This leads to notably higher C3H8and n-C4H10uptakes with enhanced selectivities than C2H6over CH4, affording one of the highest n-C4H10/CH4selectivities. The gas-loaded single-crystal structures coupled with theoretical simulations reveal that the loading of n-C4H10can induce an obvious framework expansion along with pore-pocket opening to improve n-C4H10uptake and selectivity, while not for C2H6adsorption. This work suggests an effective strategy of designing flexible-robust HOFs for improving gas separation properties.

The dawn of hydrogen and halogen bonds and their crucial role in collisional processes probing long-range intermolecular interactions.

This perspective review focuses on the results of an internally consistent study developed in the Perugia laboratory, centered on the fundamental interaction components that, at large intermolecular distances, determine the formation of weak intermolecular hydrogen (HB) and halogen (XB) bonds. This investigation exploits old and novel molecular beam scattering experiments involving several gaseous prototypical systems. In particular, we focus on the kinetic energy dependence of the total (elastic + inelastic) integral cross-sections. Of particular interest is the measure of quantum interference patterns in the energy dependence of cross-sections of targeted systems and their shift compared to that of known reference systems. We interpreted these findings as interaction energy stabilization components, such as charge transfer, σ-hole, and polar flattening, that emerge at intermediate separation distance ranges and selectively manifest for specific geometries of collision complexes. Another significant observable we discuss is the absolute value of the cross-section and its dependence on permanent multipole moments of the collisional partners. Specifically, we show how the spontaneous orientation of rotationally cold and polar molecules, due to the electric field gradient associated with the interaction between permanent multipole moments, can significantly modify the magnitude of the total cross-section, even at high values of the impact parameter. We are confident that the present results can help extend the force field formulation to various interacting systems and carry out molecular dynamics simulations under conditions of application interest.

Triphenylamine-based 1,3,4-thiadiazole derivative: Solvatochromism, aggregation-induced emission and reversible turn-on mechanofluorochromism

In this work, a new versatile AIE-active triphenylamine-based donor-acceptor fluorophore DPTA (N,N-diphenyl-4-(5-phenyl-1,3,4-thiadiazol-2-yl)aniline) has been synthesized, whose photophysical properties in different solvents, aggregates emission behaviors and solid states were investigated systematically. It was found that DPTA exhibited well-defined ICT (intramolecular charge transfer) characteristics with remarkable positive solvatochromism. More importantly, DPTA exhibited reversible high-contrast turn-on mechanofluorochromism response to mechanical force with obviously increase of QY (the solid fluorescence quantum yield) from 6.4 % (pristine) to 31.8 % (being grinded), and the emitting wavelengths of DPTA were red-shifted from 469 nm to 496 nm upon grinding. The interesting mechanofluorochromic behaviors were rationalized to be caused by the reversible phase transition between ordered crystalline and amorphous states, which was proved by the measurement results of PXRD, DSC and FESEM. Single crystal X-ray diffraction analysis indicated the presence of twisted conformations and weak intermolecular hydrogen bonds, which are also responsible for the mechanofluorochromic behavior.

Super-enrichment of ultra-low concentration rhenium via synergistic co-flocculation precipitation using CTAB and ferric salt hydrolysis micelles

Super-enrichment and recovery of associated Rhenium (Re) in sandstone-type uranium deposits is challenging due to its sparse distribution and ultra-low contents in raw ores. Conventional industrial processes are extremely difficult to achieve economic recovery of Re with a concentration below 0.1 mg/L from in-situ leaching solutions of sandstone-type uranium deposits. This study proposes a novel approach for achieving super-enrichment ultra-low concentration of Re using a synergistic co-flocculation precipitation system composed of cetyltrimethylammonium-bromide (CTAB) and ferric salt (FeCl3) hydrolysis micelles. Experimental results reveal that the enriched content of Re in the co-flocculation precipitates is as high as 503 g/t, nearly 3353 times higher than that in the in-situ leaching solutions. The synergistic precipitation percentage of Re can reach more than 60%, which is larger than the sum of using CTAB micellar flocculation (30.16%) and FeCl3 hydrolysis micellar flocculation (5.43%) separately. Furthermore, the synergistic co-flocculation and precipitation mechanism of Re is examined by SEM, turbidity, Fourier transform infrared spectroscopy, Zeta potential analysis, and DTF calculations. Results demonstrate that the ReO4- anions first form ion associations with CTA+ cations through electrostatic force, which are subsequently captured to forms insoluble co-flocculating precipitate via weak intermolecular hydrogen bond force between Fe(OH)3 and ReO4-, which promotes the super-enrichment of the ultra-low concentration Re. In summary, this process presents great potential for the efficient recovery Re from a large amounts of sandstone-type uranium deposits leaching solution, and provides new insights into the enhancement mechanism of synergistic co-flocculation precipitation.

Crystal structures of di-μ-chlorido-bis-({(E)-5-(ethyl-amino)-4-methyl-2-[(pyridin-2-yl)diazen-yl]phen-o-lato}copper(II)) and chlorido-bis-(1,10-phen-anthroline)copper(II) chloride tetra-hydrate.

The dark-red title complex crystallized from an equimolar methanol solution of (E)-5-(ethyl-amino)-4-methyl-2-[(pyridin-2-yl)diazen-yl]phenol and CuCl2(phen) (phen = 1,10-phenanthroline) as a centrosymmetric dimer, [CuCl(C14H15N4O)]2. The Cu atoms are bridged by two Cl ligands and have a slightly distorted square-pyramidal coordination, where two N atoms from the azo and the pyridine moieties, a phenolic O and a Cl atom comprise the base and the other Cl occupies the apex position. The apical Cu-Cl bond, 2.6192 (4) Å, is longer than the basal one, 2.2985 (3) Å, due to Jahn-Teller distortion. The dimers are associated via weak inter-molecular hydrogen bonds and π-π stacking inter-actions between phenyl and pyridine rings. A monomeric by-product of the same reaction, [CuCl(phen)2]Cl·4H2O, has a trigonal-bipyramidal coordination of Cu with equatorial Cl ligand, and extensive outer-sphere disorder. In the structure of 4, the packing of cations leaves continuous channels containing disordered Cl- anions and solvent mol-ecules. The identity of the solvent (water or a water/methanol mixture) was not certain. The disordered anion/solvent regions comprise 28% of the unit-cell volume. The disorder was approximated by five partly occupied positions of the Cl- anion and ten positions of O atoms with a total occupancy of 3, giving a total of 48 electrons per asymmetric unit, in agreement with the integral electron density of 47.8 electrons in the disordered region, as was estimated using the BYPASS-type solvent-masking program [van der Sluis & Spek (1990). Acta Cryst. A46, 194-201].

Synthesis, spectra, crystal, DFT, molecular docking and in vitro cholinesterase inhibition evaluation on two novel symmetrical Azine Schiff bases

The two new azine Schiff bases AZ1 and AZ2 called (1E,2E)-1,2-bis(2,4-dimethylbenzylidene) hydrazine and (1E,2E)-1,2-bis(3-methoxylbenzylidene)hydrazine, respectively were prepared through a condensation of the appropriate substituted aldehyde and the hydrazine hydrate. The two azine structures were investigated by FT-IR, NMR techniques and determined by single crystal X-ray diffraction (XRD). AZ1 and AZ2 structures crystallize in Monoclinic and Orthorhombic systems with space groups P21/c and P212121, respectively. AZ1 molecules are interconnected with hydrogen bonds CH…π and the crystal structure of AZ2 is stabilized by weak intermolecular hydrogen bonds CH…O. Theoretical calculations have been carried out at DFT/B3LYP level for the optimized geometries and TD-DFT methods. The results show an excellent agreement with the experimental data (Spectroscopic and XRD). Docking studies were performed to examine potential inhibitions of the designed azines against cholinesterases. The activities effect considering the enzymes: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are evaluated in vitro and the results show that both Azines AZ1 and AZ2 are moderate AChE inhibitors (IC50 = 23.60±0.63 µg/mL; IC50 = 28.59±0.07 µg/mL, respectively). The BChE measurements indicated an important inhibition activity of AZ1 (IC50 = 57.88±0.045 µg/mL) and no activity of AZ2.The results of these tests were in sync with the docking.

Synthesis, structure and Hirshfeld surface analysis of diaquadinitratobis(4-nitroaniline)copper(II)

A new metal complex, [Cu(NO3)2(C6H6N2O2)2(H2O)2], was synthesized from water–ethanol solutions of Cu(NO3)2 and 4-nitroaniline (PNA). The complex molecules are located on inversion centers in monoclinic crystals with space group P21/c. The copper(II) ions are monodentately coordinated by two neutral PNA molecules through the nitrogen atom of the amino group, two NO3 − anions and two water molecules. The coordination polyhedron of the central ion is a distorted octahedron as a result of the Jahn–Teller effect. There is a weak intramolecular hydrogen bond between the N—H group and the oxygen atom of one nitrate anion. Six relatively weak intermolecular hydrogen bonds associate the complex molecules into a three-dimensional network. The Hirshfeld surface analysis indicates that 55.8% of the intermolecular interactions are from O...H/H...O contacts, 13.3% are from H...H contacts while other contributions are from C...O/O...C, C...H/H...C, O...O and other contacts.

The microwave spectra and molecular structures of the chiral and achiral rotamers of 2,3,3-trifluoropropene and their gas-phase heterodimers with the argon atom

The microwave spectra of two rotamers, connected by rotation of the –CHF2 group, of 2,3,3-trifluoropropene and all three of the singly substituted 13C isotopologues of each are obtained in the 5.6 – 18.1 GHz region using broadband chirped pulse Fourier transform microwave spectroscopy. The lower energy rotamer, stabilized by a weak intermolecular hydrogen bond, is chiral, existing as a pair of enantiomers, while the higher energy isomer, lacking this interaction but having a plane of symmetry, is achiral. Heterodimers of both rotamers with the argon carrier gas are also observed in the broadband spectrum and further analyzed using spectra obtained from 5.0 to 20.6 GHz with a Balle-Flygare cavity Fourier transform microwave spectrometer. Although all singly substituted 13C isotopologues are observed, in addition to the normal species, for the argon complex with the lower energy rotamer, only a single isotopologue of the argon complex, the parent, is observed with the higher energy rotamer. Despite differing slightly in detail, the argon atom occupies a similar position in the heterodimer with each rotamer, one that is also similar to the location of the argon atom in argon-2,3,3,3-tetrafluoropropene.

Self-Assembly of a Pyridine-Based Amphiphile Complexed with Regioisomeric Dihydroxy Naphthalenes into Supramolecular Nanotubes with Different Inner Diameters.

A pyridine-based amphiphile complexed with 1,5-, 1,6-, 2,6-, or 2,7-dihydroxy naphthalene self-assembled in water to form nanotubes with inner diameters of 46, 38, 24, 18, and 11 nm in which the naphthalene molecules formed J-type aggregates. In contrast, the amphiphile complexed with 1,2-, 1,3-, 1,4-, 1,7-, 1,8-, or 2,3-dihydroxy naphthalene formed nanofibers in which the naphthalene molecules formed H-type aggregates. The inner diameter of the nanotubes strongly depended on the regioisomeric dihydroxy naphthalene. UV-vis, fluorescence, infrared spectroscopy, X-ray diffraction analysis, and differential scanning calorimetry showed that nanotubes with smaller inner diameters had weaker intermolecular hydrogen bonds between the tilted amphiphiles complexed with the naphthalene molecules within the membrane walls and showed larger Stokes shifts in the excimer fluorescence of the naphthalene moiety. These findings should be useful not only for fine-tuning the inner diameters of supramolecular nanotubes but also for controlling the aggregation states of functional aromatic molecules to generate nanostructures with useful optical and electronic properties in water.

Synthesis, structural elucidation, and antioxidant activity of new phenolic derivatives containing piperidine moiety: Experimental and theoretical investigations

The incorporation of the piperidine ring into drugs may play an interesting role to fulfill significant tasks and act as an active ingredient in various treatments. Herein, three novel derivatives of 3‐acetyl‐2‐hydroxybenzoic acid (3‐5) containing a piperidine ring were synthesized through the rearrangement of triacetic acid lactone in the presence of piperidine. Their molecular structures were characterized by 1H and 13C NMR and single crystal X‐ray diffraction techniques. The experimental data were compared with the predicted ones obtained in the polarizable continuum model at the B3LYP/6‐311++G(d,p) level of theory. Relatively good correlations were obtained between the experimental data (spectral and Z‐matrix coordinates) and the predicted ones, with correlation coefficients higher than 97%. The intercontacts between the closest units of 3‐5 were identified through the analysis of the Hirshfeld surface and electrostatic potentials (ESP) maps. Hirshfeld surface and ESPs analyses reveal that the closest interactions between the units of the compounds are between hydrogen atoms (59%‐67%). The antioxidant activity of 3‐5 was evaluated using DPPH free radical scavenging and ABTS assays. They exhibit moderate antioxidant activity, which probably is attributable to the presence of a phenolic moiety in their basic skeleton. Molecular docking calculations suggest that 3‐5 may mainly bind to the active binding site of peroxiredoxin 5 through strong and weak intermolecular hydrogen bonds.

Effect of Glycine Position on the Inner Diameter of Supramolecular Nanotubes Consisting of Glycolipid Monolayer Membranes

Abstract Three novel glycolipids were synthesized by amide bond formation among a d-gluconolactone, 12-aminododecanoic acids, and a glycine. Self-assembly of the glycolipids in water produced nanotubes, in which the glycolipids were tilted, packed in parallel, and formed monolayer membranes. The inner diameters of the nanotubes were smaller in glycolipids with a shorter distance between the glycine unit and the glucose headgroup. X-ray diffraction, infrared, and circular-dichroism spectroscopy revealed that the nanotubes with smaller inner diameter had weaker intermolecular hydrogen bonds between glycolipids and larger supramolecular chirality amplified by twist packing of the tilted glycolipids within the monolayer membranes. J-type aggregates of achiral dye molecules encapsulated into nanotubes with smaller inner diameter exhibited induced circular dichroism. These findings should be useful for the fine tuning of the inner diameter of supramolecular nanotubes.

Nature and role of the weak intermolecular bond in enantiomeric conformations of H2O2–noble gas adducts: a chiral prototypical model

The role and nature of the weak intermolecular bond in the H2O2–noble gas enantiomeric conformations are presented. Charge transfer associated with the formation of a weak intermolecular hydrogen bond tends to stabilize the cis-barrier conformation.

Determination of Phonon Density of States from Constant-Pressure Heat Capacity Data of Soft Organic Materials in the Glassy and Crystalline States by Using the Real-Coded Genetic Algorithm.

A method was proposed to derive the phonon density [g(ω)] of states of materials from their heat capacity data by using Real-Coded Genetic Algorithm (RCGA) with Just Generation Gap + Real-Coded Ensemble Crossover. The performance of the method was confirmed by testing whether or not the RCGA reproduces a reasonable g(ω) by analyzing the set of heat capacity data evaluated from an initially assumed model g0(ω) composed of Debye and optical modes. As an example, constant-pressure heat capacities (CPs) were measured for soft molecular materials, diphenyl phosphate (DPP) and diphenylphosphinic acid, in the condensed state, and their g(ω)s were determined from the CP data by applying the RCGA. The unusual behavior that the CP value of glass was smaller than the one of the crystal in the temperature range from 10 to 70 K was observed in DPP; the behavior is contrary to that expected ordinarily for the glass as compared with the crystal. The g(ω)s determined by the RCGA demonstrated that the unusual behavior was attributed to the blue shift in g(ω) of ω = 30-240 K in the glass compared with the crystal. The blue shift and other effects were discussed reasonably as originating from the competitive concurrence of strong and weak intermolecular hydrogen bonds in DPP, with the help of determination of their intramolecular vibrations for the isolated molecule by the density functional theory calculation. It was concluded that the method using the RCGA is of value for obtaining the microscopic information of g(ω) from the precise heat capacity data and for investigating any difference between the details of g(ω)s in different phases of materials.

Investigating differences and similarities between two new abiraterone polymorphs and its hydrochloride salt monohydrate

Crystal and molecular structures of two polymorphs (forms II and III) of abiraterone are presented. Both crystal modifications crystallize in the monoclinic crystal system P21 with one molecule in the asymmetric unit. Molecules are involved in strong and weak intermolecular hydrogen bonds of O-H⋅⋅⋅N and C-H⋅⋅⋅O types. Differences in crystals packing and intermolecular interactions were demonstrated by the Hirshfeld surface analysis.The spectroscopic studies showed the correlation of O⋅⋅⋅N distances with wavenumbers of OH groups for abiraterone polymorphs. The IR results agree with a density rule for form III suggesting that this form has a lower thermodynamic stability at 0 K.Abiraterone hydrochloride monohydrate is a direct product of abiraterone acetate hydrolysis under acidic conditions. The salt is unstable during crystallization and transforms into abiraterone base. The detailed description of hydrogen bonds and the analysis of main intermolecular contacts to the Hirshfeld surface of the salt measured at 100 K are presented.

Deciphering the hydrogen-bonding scheme in the crystal structure of triphenylmethanol: a tribute to George Ferguson and co-workers.

The crystal structure of triphenylmethanol, C19H16O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson et al. over 25 years ago [Ferguson et al. (1992). Acta Cryst. C48, 1272-1275] and that published by Serrano-González et al., using neutron and X-ray diffraction data [Serrano-González et al. (1999). J. Phys. Chem. B, 103, 6215-6223]. As predicted by these authors, the hydroxy groups are involved in weak intermolecular hydrogen bonds in the crystal, forming tetrahedral tetramers based on the two independent molecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the R-3 space group. However, the reliable determination of the hydroxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of ca 0.74 and 0.26. Secondly, all hydroxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The prochiral character of the hydrogen-bonded tetrameric supramolecular clusters leads to enantiomorphic three-dimensional graphs in each tetramer. The crystal is thus a racemic mixture of supS and supR motifs, consistent with the centrosymmetric nature of the R-3 space group.

Cadmium(II) and Nickel(II) 1-Oxypyridyl-2-Selenolates: Synthesis and Molecular and Crystal Structures

Cadmium (C20H16Cd2N4O4Se4) (I) and nickel (C10H8N2NiO2Se2) (II) selenolates are synthesized by the exchange reactions of sodium 1-oxypyridyl-2-selenolate and cadmium(II) and nickel(II) chlorides. The molecular and crystal structures of the complexes are determined by X-ray structure analysis (CIF files CCDC nos. 1585246 (I) and 1585251 (II)). Complex I forms a centrosymmetric dimer in which the coordination polyhedron of the cadmium atom is a distorted trigonal bipyramid and the selenium atoms take the trans configuration. Complex II containing the solvate C2H5OH molecule has a square structure and is a monomer. Unlike complex I, in complex II the selenium atoms of the ligands take the cis configuration. The crystal packings in complexes I and II are formed by weak intermolecular hydrogen bonds C–H···O and C–H···Se.

Nanosecond X-ray diffraction of shock-compressed superionic water ice.

Since Bridgman's discovery of five solid water (H2O) ice phases1 in 1912, studies on the extraordinary polymorphism of H2O have documented more than seventeen crystalline and several amorphous ice structures2,3, as well as rich metastability and kinetic effects4,5. This unique behaviour is due in part to the geometrical frustration of the weak intermolecular hydrogen bonds and the sizeable quantum motion of the light hydrogen ions (protons). Particularly intriguing is the prediction that H2O becomes superionic6-12-with liquid-like protons diffusing through the solid lattice of oxygen-when subjected to extreme pressures exceeding 100gigapascals and high temperatures above 2,000kelvin. Numerical simulations suggest that the characteristic diffusion of the protons through the empty sites of the oxygen solid lattice (1) gives rise to a surprisingly high ionic conductivity above 100 Siemens per centimetre, that is, almost as high as typical metallic (electronic) conductivity, (2) greatly increases the ice melting temperature7-13 to several thousand kelvin, and (3) favours new ice structures with a close-packed oxygen lattice13-15. Because confining such hot and dense H2O in the laboratory is extremely challenging, experimental data are scarce. Recent optical measurements along the Hugoniot curve (locus of shock states) of water ice VII showed evidence of superionic conduction and thermodynamic signatures for melting16, but did not confirm the microscopic structure of superionic ice. Here we use laser-driven shockwaves to simultaneously compress and heat liquid water samples to 100-400 gigapascals and 2,000-3,000kelvin. In situ X-ray diffraction measurements show that under these conditions, water solidifies within a few nanoseconds into nanometre-sized ice grains that exhibit unambiguous evidence for the crystalline oxygen lattice of superionic water ice. The X-ray diffraction data also allow us to document the compressibility of ice at these extreme conditions and a temperature- and pressure-induced phase transformation from a body-centred-cubic ice phase (probably ice X) to a novel face-centred-cubic, superionic ice phase, which we name ice XVIII2,17.

Triarylbismuth Dicarboxylates Ar3Bi[OC(O)R]2, Ar = p-Tol, R = CH2Cl; Ar = Ph, R = C6H4OMe-2, CH=CHPh

Triarylbismuth dicarboxylates Ar3Bi[OC(O)R]2, Ar = p-Tol, R = CH2Cl (I); Ar = Ph, R = C6H4OMe-2 (II), CH=CHPh (III) have been synthesized by the reactions of tri(para-tolyl)bismuth with monochloroacetic acid and triphenylbismuth with 2-methoxybenzoic and cinnamic acids in methyl-tert-butyl ether in the presence of tert-butyl hydroperoxide with a high yield. The Bi atoms in complexes I–III have a distorted trigonal bipyramidal coordination with carboxylate ligands in axial positions (OBiO angles, 171.06(6)° (I), 170.46(12)° (II), 175.39(8)° (III)). The Sb-O and Sb-C bond lengths are 2.283(2), 2.288(2) A and 2.185(2)–2.199(2) A (I), 2.265(7), 2.268(7) A and 2.194(7)–2.218(8) A (II), and 2.310(2), 2.310(2) A and 2.200(2)–2.210(3) A (III). Molecules of complexes I–III have intramolecular contacts between the Bi atom and the O atoms of carbonyl groups: the Bi⋯O(=C) distances are 2.990(2), 2.985(3) A (I), 2.753(8), 2.739(8) A (II), and 2.688(2) A (III). The structural organization in crystals of complexes I–III is caused by weak inter-molecular hydrogen bonds H⋯O of 2.61–2.65 A (I), 2.47–2.50 A (II), and 2.56 A (III).

1-(2-Methoxyphenyl)-1,4-Dihydro-5H-Tetrazole-5-Thione and Its Complex with Cd(II): Molecular and Crystal Structures

The molecular and crystal structures of 1-(2-methoxyphenyl)-1,4-dihydro-5H-tetrazole-5-thione (L) and its complex with cadmium(II) (II) are studied by X-ray diffraction analysis (CIF files CCDC nos. 1567109 (L) and 1547252 (II)). Free ligand L is nonplanar thione. The dihedral angle between the tetrazole and benzene cycles is 85.21(7)°. These cycles form centrosymmetric dimers in the crystal by two hydrogen bonds N–H···S. The dimers contain the central planar eight-membered ring {S=C–N–H···S=C–N–H···}. Complex II has a chain structure of the composition [(C8H7N4OS)2Cd]n. The coordination mode of the Сd(II) atom is a distorted tetrahedron consisting of two nitrogen atoms and two sulfur atoms of four ligands L. The 1D chains contain the eight-membered rings {←S=C–N–Cd ← S=C–N–Cd} in the boat conformation. Weak intermolecular hydrogen bonds C–H···N are observed between the adjacent 1D chains along the c axis in the crystal.