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A hydrogen sulfate salt, C15H18NSe+·HSO4 −·H2O or [BnSeCH2CH(Ph)NH3 +](HSO4 −), of a chiral selenated amine (R)-2-(benzylselanyl)-1-phenylethanamine (BnSeCH2CH(Ph)NH2) has been synthesized and characterized by elemental analysis,1H and 13C{1H} NMR, FT–IR analysis, and single-crystal X-ray diffraction studies. The title salt crystallizes in the monohydrate form in the non-centrosymmetric monoclinic P21 space group. The cation is somewhat W shaped with the dihedral angle between the two aromatic rings being 60.9 (4)°. The carbon atom attached to the amine nitrogen atom is chiral and in the R configuration, and, the –C—C– bond of the –CH2—CH– fragment has a staggered conformation. In the crystal structure, two HSO4 − anions and two water molecules form an R 4 4(12) tetrameric type of assembly comprised of alternating HSO4 − anions and water molecules via discrete D(2) O—H...O hydrogen bonds. This tetrameric assembly aggregates along the b-axis direction as an infinite one-dimensional tape. Adjacent tapes are interconnected via discrete D(2) N—H...O hydrogen bonds between the three amino hydrogen atoms of the cation sandwiched between the two tapes and the three HSO4 − anions of the nearest asymmetric units, resulting in a complex two-dimensional sheet along the ab plane. The pendant arrangement of the cations is stabilized by C—H...π interactions between adjacent cations running as chains down the [010] axis. Secondary Se...O [3.1474 (4) Å] interactions are also observed in the crystal structure. A Hirshfeld surface analysis, including d norm, shape-index and fingerprint plots of the cation, anion and solvent molecule, was carried out to confirm the presence of various interactions in the crystal structure.

Heteroclusters constructed by tethering dissimilar nanoclusters using organic linkers resemble lipids and self-assemble into cubosomes, namely, microparticles of soft crystals composed of unique nanochannel lattices with a defined symmetry and topology. The internal porous crystal structures can be accurately characterized using transmission electron microscopy. We herein describe twin boundaries and five-fold twin boundaries in cubosomes with a double-diamond Pn3m structure. Our analysis indicates a clear distinction in the conformation of the skeletal unit: a centrosymmetric staggered conformation with point group D3d for the normal skeletal unit and a mirror-symmetric eclipsed one with point group D3h for the skeletal unit on the twin boundary. This symmetry distinction causes the channels to change direction and elongate slightly as they pass through the twin boundary, but the topology is maintained. For cubosomes containing five-fold twin boundaries, one of the channels is in the center of the particles seamlessly connecting the five blocks. Our conclusion is that the two distinct channel systems are still continuous. This fundamental understanding will contribute to the development of soft crystals with defined shapes and special inner nanostructures for advanced applications.

Isothermal compression of nickelocene (NiCp2, where Cp denotes cyclopentadienyl ring C5H5–) to 1.3 GPa leads to the ordered phase I′, highly isostructural with that obtained at 0.1 MPa by isobaric cooling to 170 K and with phase I′ of ferrocene (FeCp2) above 3.24 GPa. However, the gradual ordering of Cp rings in NiCp2 and its anomalous crystal strain considerably differs from that in FeCp2. The disorder in NiCp2 molecules can be represented as various combinations of achiral staggered and eclipsed conformers, as well as R-/S-rotamers, which are differently stabilized by the crystal environment. The anomalous lattice strain has been correlated with the molecular conformation, represented as the convolution of disordered Cp rings. The coincidence of the phase transition at 1.3 GPa/296 K with the monoclinic angle assuming 90° value does not occur on lowering temperature at 170 K/0.1 MPa, which is due to a weaker coupling between the lattice strain and the molecular disorder. Compared to FeCp2, the energetic preference in NiCp2 for the eclipsed conformation is lower and the stronger crystal field, favoring the staggered conformation. Therefore, phase I′ of NiCp2 is stable below 170 K, while at 300 K NiCp2 transforms to phase I′ at much lower pressure than FeCp2.

Interconverting different molecular representations can be problematic for many organic chemistry students. This is certainly the case when converting Fischer projections into bond-line structures. When performing the conversion from a Fischer projection into an all-staggered bond-line structure, students are sometimes taught to draw the fully eclipsed conformer first; for smaller molecules, the conversion to a fully eclipsed bond-line representation is relatively straightforward, while the conversion into the staggered conformation is not always as trivial. A systematic approach using the mnemonic “push–pivot–pull” described herein provides organic chemistry students with another option for producing a staggered bond-line structure from the corresponding Fischer projection while foregoing the fully eclipsed representation altogether.

The first nitridogermanates(III) Ca6 [Ge2 N6 ] and Sr6 [Ge2 N6 ] were synthesized from sodium flux and structurally characterized by powder and single crystal X-ray diffraction, respectively. They crystallize isostructurally to each other and homeotypic to Ca6 [Cr2 N6 ]H in space group R 3‾ . They feature unprecedented, mutually isolated, ethane-like [GeIII2 N6 ]12- anions in a staggered conformation. The compounds are semiconductors according to resistivity measurements and electronic structure calculations, yielding band gaps of 1.1 eV for Ca6 [Ge2 N6 ] and 0.2 eV for Sr6 [Ge2 N6 ].

Halogenated carboxylic acids have been important compounds in chemical synthesis and indispensable research tools in biochemical studies for decades. Nevertheless, the number of structurally characterized simple &alpha, brominated monocarboxylic acids is still limited. We herein report the crystallization and structural elucidation of (R)- and rac-2-bromo-3-methylbutyric acid (2-bromo-3-methylbutanoic acid, 1) to shed light on intermolecular interactions, in particular hydrogen bonding motifs, packing modes and preferred conformations in the solid-state. The crystal structures of (R)- and rac-1 are revealed by X-ray crystallography. Both compounds crystallize in the triclinic crystal system with Z = 2, (R)-1 exhibits two crystallographically distinct molecules. In the crystal, (R)-1 forms homochiral O&ndash, H&middot, &middot, O hydrogen-bonded carboxylic acid dimers with approximate non-crystallographic C2 symmetry. In contrast, rac-1 features centrosymmetric heterochiral dimers with the same carboxy syn&middot, syn homosynthon. The crystal packing of centrosymmetric rac-1 is denser than that of its enantiopure counterpart (R)-1. The molecules in both crystal structures adopt a virtually identical staggered conformation, despite different crystal environments, which indicates a preferred molecular structure of 1. Intermolecular interactions apart from classical O&ndash, O hydrogen bonds do not appear to have a crucial bearing on the solid-state structures of (R)- and rac-1.

The crystal structure of 1,2,4,1′,2′,4′-hexamethylferrocene (Me6Fcsym) was determined by X-ray diffraction. In the Me6Fcsym molecule, the C5 rings occur in the staggered conformation. The Fe–(C5 ring center) bond length tends to increase in the series Me2Fcsym, Me6Fcsym, Me8Fcsym, and Me10Fcsym. The relative conformations of the vicinal Me groups in the Me6Fcsym, Me8Fcsym, and Me10Fcsym molecules and the pattern of variation of the 1H and 13C NMR signals of the Me groups in the series of polymethylferrocenes MenFcsym (n = 2, 4, 6, 8, 10) compared with the methylbenzene analogues indicates that Me groups in symmetric polymethylferrocenes are not coupled, but are relatively free to rotate around the C(C5 ring)–C(Me) bond (CIF file CCDC no. 1436882).

Investigation of the structure and conformational properties of ammonia borane molecule in the cavity of C60, C12B24N24, B36N24, C70, B41N29, C80, C14B33N33, and B47N33 fullerenes using the DFT PBE/3ζ method has shown the predominance of the staggered conformation of the encapsulated molecule. The guest molecule has bared a notable negative charge and, as compared to the free molecule of ammonia borane, has a shortened B←N coordination bond. The internal rotation barrier about this bond has depended on the composition of the fullerene shell so that the decrease in the number of carbon atoms due to the replacement with boron-nitrogen fragments has almost always resulted in a notable decrease in the ΔG≠298 value. In this case, the minimal energy of the activation barrier, 1.3–1.8 times lower than that simulated for the free molecule, has been observed for the clusters with the boron-nitrogen-carbon links in the fullerene shell.

The development of non-covalent synthetic strategy to fabricate efficient photocatalysts is of great importance in theranostic and organic materials. Herein, a fluorochrome N,N'-dimethyl 2,5-bis(4-pyridinium)thiazolo[5,4-d]thiazolediiodide (MPT) was transformed into an efficient photocatalyst through supramolecular dimerization in the cavity of cucurbit[8]uril (CB[8]). The host-enhanced charge transfer interaction within the supramolecular dimer 2MPT-CB[8] dramatically promoted intersystem crossing to produce triplet. In addition, the staggered conformation of 2MPT-CB[8] facilitated the energy transfer and electron transfer of the triplet. As a result, 2MPT-CB[8] could serve as a high-efficiency photocatalyst for the oxidative hydroxylation of arylboronic acids. This supramolecular dimerization strategy enriches the supramolecular engineering of functional π-systems. It is anticipated that this strategy can be extended to fabricate various π-systems with tailor-made functions.

Funding Information: This work was supported by the ERC Grant 692891-DAMOCLES, the Academy of Finland Flagship funding (grant no. 337549), the University of Helsinki, Faculty of Science ATMATH project, and the National Center of Meteorology (NCM), Abu Dhabi, UAE, under the UAE Research Program for Rain Enhancement Science. Supercomputing resources were provided by CSC–IT Center for Science, Ltd., Finland. B.R. is grateful to Dr. Stephen Ingram for his advice on setting up the antifreeze protein simulations. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Center of Meteorology, Abu Dhabi, UAE, funder of the research. Publisher Copyright: © 2021 American Chemical Society. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. We propose a novel method based on template matching for the recognition of liquid water, cubic ice (ice Ic), hexagonal ice (ice Ih), clathrate hydrates, and different interfacial structures in atomistic and coarse-grained simulations of water and ice. The two template matrices represent staggered and eclipsed conformations, which are the building blocks of hexagonal and cubic ice and clathrate crystals. The algorithm is rotationally invariant and highly robust against imperfections in the ice structure, and its sensitivity for recognizing ice-like structures can be tuned for different applications. Unlike most other algorithms, it can discriminate between cubic, hexagonal, clathrate, mixed, and other interfacial ice types and is therefore well suited to study complex systems and heterogeneous ice nucleation.

Dynamic processes have many implications in functional molecules, including catalysts, enzymes, host-guest complexes, and molecular machines. Here, we demonstrate via deuterium NMR relaxation experiments how halogen bonding directly impacts the dynamics in solid 2,3,5,6-tetramethylpyrazine cocrystals, catalyzing the methyl group rotation. On average, we observe a reduction of 56% in the rotational activation energy of the methyl groups in the halogen bonded cocrystals, contrasting the reduction of 36% in the hydrogen bonded cocrystals, with respect to pure 2,3,5,6-tetramethylpyrazine. Density functional theory calculations attribute this superior catalytic ability of the halogen bond to the simultaneous destabilization of the staggered conformation and stabilization of the gauche conformation, overall reducing the rotational energy barrier. Furthermore, the calculations suggest that the catalytic ability of the halogen bond may be tuneable, with stronger halogen bond donors acting as superior dynamics catalysts. Thus, halogen bonding may play a role in both assembly and promoting dynamical processes., The halogen bond is well known for its ability to assemble supramolecules. Here, using NMR experiments, the authors reveal the role of these bonds in dynamic processes, finding that the halogen bond directly catalyzes dynamical rotation in solid cocrystals by reducing the associated energy barrier.

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., The title compound, [Fe2(C5H5)2(C20H14O2)], 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 (Cp) rings are nearly coplanar and aligned slightly closer to a staggered conformation than to an eclipsed one. The ethene plane is tilted by 32.40 (18)° with respect to that of the substituted Cp ring and by 63.19 (19)° with respect to that of the furan ring. C—H⋯π inter­actions link the mol­ecules into a three-dimensional supramolecular framework.

The present study reports structural, spectroscopic signatures, reactivity parameters, and in silico anti-depressant activity of the title compound 3-(dimethylamino)-1-(thiophen-2-yl)propan-1-ol (DMATP). The structure of the DMATP compound has been unambiguously obtained through single crystal X-ray diffraction, vibrational spectroscopy, and thermal (TGA-DTA) analysis. DMATP is a chiral molecule containing a chiral methine carbon with S configuration and because of its chirality the compound crystallizes in the non-centrosymmetric orthorhombic P212121 space group. The thiophene ring and the attached nearly-planar side chain (excluding hydroxyl and one of the methyl group) are oriented to each other making a dihedral angle of 11.2(3)°. The –CH2 CH2 bond at the center of the side chain has a staggered conformation. In the crystal structure, the molecules are linked via O H…N hydrogen bonds forming C(6) chains propagating along a-axis resulting in a one dimensional architecture. The intermolecular interactions were analysed qualitatively as well as quantitatively with the aid of 3D-Hirshfeld surface and 2D-fingerprint plot analysis. The optimization of the geometry of the DMATP molecule was performed at DFT/B3LYP/6–311G(d,p) basis set and showed good agreement with the experimental results. The assignment of each vibrational wavenumber was done according to potential energy distribution (PED) analysis. Furthermore, frontier molecular orbital analysis (FMO's), global reactivity parameters, nonlinear optical (NLO) properties, and nonbonding orbital (NBO) analysis were carried out by the same method. Local reactive properties of the title compound were explained by molecular electrostatic potential (MEP), and Fukui functions. The dissociation energies of hydrogen and other single bonds have been also estimated in order to understand the autoxidation mechanism and degradation properties. An anti-depressant study of the DMATP compound was carried out with human serotonin carriers (PDB ID: 5I73 ) and compiled a binding mechanism with standard anti-depressant drugs such as duloxetine, desvenlafaxine, and atomoxetine.

This article presents the unexpected synthesis of 3-phenylethyl-2,4(1 H ,3 H )-quinazolinediones by means of oxidative expansion of the 3-phenylethylimino-2-indolinone ring promoted by sodium borohydride. The 1 H NMR spectroscopic patterns showed the presence of two conformational isomers in equilibrium, the first was a staggered conformation and the second was a gauche structure. The crystal structure of 3-phenylethyl-2,4(1 H ,3 H )-quinazolinedione revealed a staggered conformation with the quinazoline fragment and the phenyl ring in anti -arrangement. The molecules of quinazolinedione are associated in centrosymmetric dimers through two N H⋯O hydrogen bonds between the NH moieties and the adjacent carbonyl groups.

In the title hydrated salt, (C10H28N4)4+·2[Cr2O7]2−·H2O, the two unique cations lie about an inversion centre. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds connect the anions, cations and water mol­ecule, forming a three-dimensional network, The asymmetric unit of the hydrated title salt, (C10H28N4)[Cr2O7]2·H2O [C10H28N4 = H4(cyclam) = 1,4,8,11-tetra­azonia­cyclo­tetra­deca­ne], contains two half-cations (both completed by crystallographic inversion symmetry), two dichromate anions and one water mol­ecule. The two [CrO7]2− anions exhibit a nearly staggered conformation, with bridging angles of 133.37 (11) and 136.28 (12)°. The distortions of the dichromate anions are due to their participation in hydrogen-bonding inter­actions with the water mol­ecule and the cations. Inter­molecular hydrogen bonds involving the cyclam N—H groups and water O—H groups as donor groups, and the O atoms of the dichromate anions as acceptor groups give rise to a three-dimensional network.

The crystal structures of hydrothermally synthesized silver(I) aluminium bis[hydrogen arsenate(V)], AgAl(HAsO4)2, silver(I) gallium bis[hydrogen arsenate(V)], AgGa(HAsO4)2, silver gallium diarsenate(V), AgGaAs2O7, and sodium gallium diarsenate(V), NaGaAs2O7, were determined from single-crystal X-ray diffraction data collected at room temperature. The first two compounds are representatives of the MCV-3 structure type known for KSc(HAsO4)2, which is characterized by a three-dimensional anionic framework of corner-sharing alternating M 3+O6 octahedra (M = Al, Ga) and singly protonated AsO4 tetrahedra. Intersecting channels parallel to [101] and [110] host the Ag+ cations, which are positionally disordered in the Ga compound, but not in the Al compound. The hydrogen bonds are relatively strong, with O...O donor–acceptor distances of 2.6262 (17) and 2.6240 (19) Å for the Al and Ga compounds, respectively. The two diarsenate compounds are representatives of the NaAlAs2O7 structure type, characterized by an anionic framework topology built of M 3+O6 octahedra (M = Al, Ga) sharing corners with diarsenate groups, and M + cations (M = Ag) hosted in the voids of the framework. Both structures are characterized by a staggered conformation of the As2O7 groups.

Treatment of Si2Cl6 with [Et4N][BCl4] in CH2Cl2 furnished the known products of a chloride-induced disproportionation reaction of the disilane, such as SiCl4, [Si(SiCl3)3]−, and [Si6Cl12·2Cl]2–. No Si–B-bonded products were detectable. In contrast, the addition of Si2Cl6 to [Et4N][BI3Cl] afforded the Si–B adduct [Et4N][I3SiBI3]. Thus, a quantitative Cl/I exchange at the silicon atom accompanies the trihalogenosilanide formation. [Et4N][I3SiBI3] was also accessible from a mixture of Si2I6, [Et4N]I, and BI3. According to X-ray crystallography, the anion [I3SiBI3]− adopts a staggered conformation with an Si–B bond length of 1.977(6) A. Quantum-chemical calculations revealed a polar covalent Si–B bond with significant contributions from intramolecular I···I dispersion interactions.

The asymmetric unit of the title compound comprises of one complex cation, one half of a [Cr2O7]2− anion and four water mol­ecules. The CrIII ion has a distorted octa­hedral coordination by four N atoms of the cyclam ligand and one bidentate oxalate ligand in the cis positions; the conformation of the dichromate anion is staggered., The asymmetric unit of the title compound, [Cr(C2O4)(C10H24N4)]2[Cr2O7]·8H2O (C10H24N4 = 1,4,8,11-tetra­aza­cyclo­tetra­decane, cyclam; C2O4 = oxalate, ox) contains one [Cr(ox)(cyclam)]+ cation, one half of a dichromate anion that lies about an inversion centre so that the bridging O atom is equally disordered over two positions, and four water mol­ecules. The terminal O atoms of the dichromate anion are also disordered over two positions with a refined occupancy ratio 0.586 (6):0.414 (6). The CrIII ion is coordinated by the four N atoms of the cyclam ligand and one bidentate oxalato ligand in a cis arrangement, resulting in a distorted octa­hedral geometry. The Cr—N(cyclam) bond lengths are in the range 2.069 (2)–2.086 (2) Å, while the average Cr—O(ox) bond length is 1.936 Å. The macrocyclic cyclam moiety adopts the cis-V conformation. The dichromate anion has a staggered conformation. The crystal structure is stabilized by inter­molecular hydrogen bonds involving the cyclam N—H groups and water O—H groups as donors, and the O atoms of oxalate ligand, water mol­ecules and the Cr2O7 2− anion as acceptors, giving rise to a three-dimensional network.

The reaction of AuCl(tht) with the diphosphine donors 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) and 2,3-bis(diphenylphosphino)- N -phenylmaleimide (bmi) in a 2:1 stoichiometry affords the diphosphine-bridged digold(I) complexes Au 2 Cl 2 (bpcd) ( 1 ) and Au 2 Cl 2 (bmi) ( 2 ), respectively. 1 and 2 have been isolated and characterized in solution by IR and NMR spectroscopy ( 1 H and 31 P), and the solid-state structures established by X-ray crystallography. The X-Au-Au-X (X = Cl, P) atoms in both Au 2 dimers exhibit a gauche-type (staggered) interaction based on a torsion angle of −54° for 1 (X = Cl) and −70° for 2 (X = Cl, mean angle for the two independent molecules). Each Au 2 product displays a weak aurophilic interaction based on a Au-Au internuclear distance on the order of 2.9 A. The bonding in 1 and 2 has been investigated by electronic structure calculations and the composition of the HOMO and LUMO levels determined in the case of 2 . The potential energy surface for the interconversion of 2 to an alternative staggered conformation has been computed, and this transformation takes place through an eclipsed transition structure. The preference for a structure that contains a staggered orientation of Cl-Au-Au-Cl and P-Au-Au-Cl atoms is discussed.

The structure of the complex salt,cis-[Cr(NCS)2(cyclam)]2[Cr2O7]·H2O (cyclam = 1,4,8,11-tetraazacyclotetradecane, C10H24N4), has been determined from synchrotron data. The asymmetric unit comprises of one [Cr(NCS)2(cyclam)]+cation, one half of a Cr2O72−anion (completed by inversion symmetry) and one half of a water molecule (completed by twofold rotation symmetry). The CrIIIion is coordinated by the four cyclam N atoms and by two N atoms ofcis-arranged thiocyanate anions, displaying a distorted octahedral coordination sphere. The Cr—N(cyclam) bond lengths are in the range 2.080 (2) to 2.097 (2) Å while the average Cr—N(NCS) bond length is 1.985 (4) Å. The macrocyclic cyclam moiety adopts thecis-V conformation. The bridging O atom of the dichromate anion is disordered around an inversion centre, leading to a bending of the Cr—O—Cr bridging angle [157.7 (3)°]; the anion has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the cyclam N—H groups and water O—H groups as donor groups, and the O atoms of the Cr2O72−anion and water molecules as acceptor groups, giving rise to a three-dimensional network.

In the title organic–inorganic salt, [CrCl2(tn)2]2[Cr2O7] (tn is propane-1,3-di­amine), the CrIII ions are coordinated by four N atoms from two tn ligands and two chloride ions in a trans geometry, displaying a distorted octa­hedral arrangement. The crystal packing is stabilized by N—H⋯Cl and N—H⋯O hydrogen bonds., The structure of the title compound, [CrCl2(tn)2]2[Cr2O7] (tn = propane-1,3-di­amine; C3H10N2), has been determined from synchrotron data. The asymmetric unit contains one CrIII complex cation and half a [Cr2O7]2− anion. In the complex cation, the CrIII ion is coordinated by the four N atoms of two propane-1,3-di­amine (tn) ligands in the equatorial plane and by two Cl atoms in a trans configuration, displaying a distorted octa­hedral coordination sphere. The two six-membered rings in the complex cation have an anti chair–chair conformation with respect to each other. The mean Cr—N(tn) and Cr—Cl bond lengths are 2.09 (1) and 2.320 (2) Å, respectively. The slightly bent dichromate anion is disordered over two sets of sites (occupancy ratio = 0.7:0.3) and has a staggered conformation. The crystal structure is stabilized by inter­molecular hydrogen bonds involving the NH2 groups of the tn ligands as donors and the O atoms of the [Cr2O7]2− anion and chlorido ligands as acceptors.

Recent high-accuracy X-ray absorption measurements of the sandwich organometallics ferrocene (Fc) and decamethylferrocene (DmFc) at temperatures close to liquid helium are compared with new full-potential modeling of X-ray absorption fine structure (XAFS) covering the near-edge region (XANES) and above up to k = 7 Å(-1). The implementation of optimized calculations of the oscillatory part of the spectrum from the package FDMX allows detailed study of the spectra in regions of the photoelectron momentum most sensitive to differences in the molecular stereochemistry. For Fc and DmFc, this corresponds to the relative rotation of the cyclopentadienyl rings. When applied to high-accuracy XAFS of Fc and DmFc, the FDMX theory gives clear evidence for the eclipsed conformation for Fc and the staggered conformation for DmFc for frozen solutions at ca. 15 K. This represents the first clear experimental assignment of the solution structures of Fc and DmFc and reveals the potential of high-accuracy XAFS for structural analysis.

A new α-amino-1H Indazolyl-phosphonates derivative 3a–e were synthesized and subjected to solid state characterization by single-crystal X-ray diffraction analysis, and to study their NMR and Hirshfeld surface analysis. The P atom exhibits tetrahedral geometry involving two O-ethyl groups, a C atom and a double-bonded O atom. The P–C bond has an approximately staggered conformation, with the aniline and substituted groups in gauche positions with respect to the P O double bond. The molecules are arranged as centrosymmetric or pseudocentrosymmetric dimers connected by two N–H⋯O P hydrogen bonds and also by C–H … π interaction in the case of structures 3a–e, which are responsible for the formation and stability of the molecular assemblies. Hirshfeld surface analysis (dnorm surface and two-dimensional (2D) fingerprint plots) revealed the nature of intermolecular contacts. The most important contributions for the crystal packing are from H⋯H, H⋯C/C⋯H, O⋯H/H⋯O, and H⋯N/N⋯H interactions. In addition, frontier molecular orbitals and Molecular Electrostatic Potential map of the compounds was produced by using the optimized structures.

Density functional theory (DFT) calculations were performed to rationalize the influence of additive acids on chiral vicinal diamine-catalyzed asymmetric aldol reactions of cyclohexanones with aldehydes. Three TS models are explored. The computations reveal that with TFA as additive, the acid anion-containing nine-membered cyclic TS model is preferred to the other two models. While with succinic acid or HAc, the preferred TS model involves an acid anion-containing ten-membered ring. Acid additive-induced conformational changes are responsible for the pronounced changes in the experimentally observed stereoselectivity. With TFA as addictive, the lowest-energy TS exhibits an almost perfect staggered conformation along the forming C－C bond, which is stabilized by weak non-covalent interactions and less steric repulsion affording (R,S) anti isomer, whereas using HAc as additive, the (S,S) syn-selectivity stems primarily from less steric strain and conformational distortion in the favored transition structures, while in the case of succinic acid, the preferred transition structure has more extended conformation and softer low-frequency vibrational mode than other TSs, which induce more vibrational entropy contributions to Gibbs free energy and more stability of the transition state. The theoretical results reproduce the experimental findings and provide a reasonable explanation for highly varied stereoselectivities by different acid additives.

The first example of a homopalladium-stabilized sandwich of thallium (I), the {[Pd9(CO)9(PMe3)6]Tl[Pd3(CO)3(PMe3)3]}+ monocation (1; [PF6]− counterion), is reported with the Tl(I) encapsulated within a Pd9 cage between two unconnected neutral entities, an octahedral-based [Pd9(CO)9(PMe3)6] and triangular [Pd3(CO)3(PMe3)3]. This sandwich cluster was obtained (yields > 70%) from the reaction of Pd8(CO)8(PMe3)7 with TlPF6, and its solid-state structure was unambiguously determined from a 100 K CCD X-ray diffractometry study. This sandwich cluster may be described as a markedly deformed Pd(A)3Pd(B)3 octahedron connected on its triangular Pd(A)3 face by three edge-bridged wingtip Pd(C) atoms and by a symmetrical capping Tl(I) atom, to which are attached the three triangular Pd(D) atoms of the other [Pd3(CO)3(PMe3)3] entity. In sharp contrast to its observed stability, an initially isolated Pd3Tl(I)Pd3 sandwich monocation, {Tl[Pd3(CO)3(PEt3)3]2}+ (2; [PF6]− counterion), is an intermediate, which in polar solutions spontaneously converts (85% yield) into the stable [Tl2Pd12(CO)9(PEt3)9]2+ dication (3; [PF6]− counterion); this instability was attributed to the destabilizing influence of its 6 s2 Tl(I) electron-pair. For three previously reported stable Pd–Tl(I) clusters containing analogous octahedral-based [Pd9(CO)9L6] entities {namely, [Pd9(CO)9L6][TlCo(CO)3L] (4; L = PEt3), [Pd9(CO)9L6][Tl(acac)] (5; L = PPh3), and [Pd9(CO)9L6][Tl(PF6)] (6; L = PPh3)}, it was then suggested (and still proposed) that the Tl(I) exerts a positive stabilizing influence as a two-electron 6s2 donor. Because each of the three edge-bridged wingtip [Pd(μ2-CO)2PR3] fragments (within a Pd9 entity) in 4, 5, 6, and 1 is now assigned (by us) as a 2e donor (instead of 4e donor), each octahedral-based TlPd9 polyhedron in these four clusters now has 80 total CVEs (instead of 86 CVEs given by the Wade-Mingos electron-count for a normal octahedral-based polyhedron). The different-sized sandwich-forming Pd(A)3 and Pd(D)3 triangles in 1 are oriented in an exact angular-eclipsed conformation (due to crystallographic molecular Cs (m) site symmetry) that differs by 11.7° from being parallel compared to 5.2° in 2 along with a twist-angle deviation of 8.7° in 2 from a regular staggered conformation of the identical-sized Pd3 sandwich triangles; idealized parallel bis-triangular regular geometries would possess trigonal prismatic C3v symmetry in 1 and trigonal antiprismatic D3d (centrosymmetric) symmetry in 2. Gradient-corrected DFT calculations performed on model 1-H and 2-H analogues (with P-attached alkyl substituents replaced by H atoms) suggest from a natural population analysis (NPA) that the observed stability of 1 vs. that of 2 is achieved via a small increased Tl(I) 6s2 electron-pair donation onto the Pd cluster manifolds coupled with significantly larger back-donation from the Pd cluster entities onto the empty Tl(I) 6p valence AOs. This indicated strengthening of the Tl(I)–Pd interactions, which is in accordance with the increase in total Wiberg bond index on thallium from 1.70 in 2-H to 2.77 in 1-H, is likewise manifested geometrically in: (a) the mean distance of 2.81 A in 1 for the six sandwich Tl(I)–Pd distances (to the Pd(A)s and Pd(D)s) being 0.1 A shorter than that of 2.91 A in 2; and (b) the intertriangular distance of 4.50 A between the Pd(A) and Pd(D) centroids in 1 being 0.4 A less than that of 4.90 A in 2 (despite the eclipsed conformation in 1 vs. staggered conformation in 2). Intensity ratios of the three types of PMe3 ligands in the 31P{1H} NMR solution spectrum of 1 are consistent with its solid-state structure being retained in CD2Cl2 solution at room temperature.

Azasulfurylpeptides feature an amino acid residue in which the CαH and the carbonyl are replaced respectively by a nitrogen atom and a sulfonyl group. Insight into the conformational preferences of azasulfurylpeptides containing an azasulfurylglycine (AsG) residue has been pursued using X-ray analysis in the solid state. Crystals of N-(Boc)-Pro-AsG-Val-OMe (10) and N-(Cbz)-Ala-AsG-D-Phe-Ot-Bu (11) showed tetrahedral geometries about the sulfur atom with the ω torsion angle preferring a staggered conformation. Furthermore, the ϕ and ψ torsion angles of the central azasulfuryl residue were respectively within close proximity to those of ideal inverse and classical γ-turns. In the crystal lattice, azasulfurylpeptide 11 engaged in intermolecular hydrogen bonds between the sulfonyl oxygen and hydrazide hydrogen in an antiparallel orientation.

The title compound, dimercury(II) divanadium(V) ditellurium(IV) undecaoxide, Hg2V2Te2O11, is a new representative within the family of divalent oxovanadato(V)tellurates(IV). The anionic framework is made up of disphenoidal [TeO4] polyhedra that are linked by corner-sharing to two neighbouring pyrovanadate units, resulting in chains of six-membered rings propagating parallel to [1\overline{1}0]. The bridging O atom of the pyrovanadate unit is located on an inversion centre, leading to a staggered conformation and a linear V—O—V angle between the two [VO4] tetrahedra. The anionic chains are connected by interjacent six-coordinate Hg2+cations into a three-dimensional framework. The 5s2lone electron pair of the TeIVatom is stereochemically active and protrudes into the free space of the chain links.

The absolute structure of (R,R,S Fc,S Fc)-[Fe2(C5H5)2(C38H36BrNP2)]·Br·CH2Cl2 has been determined by X-ray single-crystal diffraction., During the synthesis of an FeBr2 complex with the PNP ligand (R,R,S Fc,S Fc)-[Fe2(C5H5)2(C38H35NP2)] (1), single crystals of the di­chloro­methane monosolvate of the Br− salt of the protonated ligand 1H+ were obtained serendipitously, i.e. [Fe2(C5H5)2(C38H36NP2)]Br·CH2Cl2. The crystal structure of 1H·Br·CH2Cl2 was determined by single-crystal X-ray diffraction. The mean bond lengths in the ferrocene units are Fe—C = 2.049 (3) Å and C—C = 1.422 (4) Å within the cyclo­penta­dienyl rings. The mean C—N bond length is 1.523 (4) Å. The inter­planar angle between the two connected cyclo­penta­dienyl rings is 49.2 (2)°. One ferrocene moiety adopts a staggered conformation, whereas the other is between staggered and eclipsed. The Br− ions and the CH2Cl2 mol­ecules are located in channels extending along . One ammonium H atom forms a hydrogen bond with the Br− ion [H⋯Br = 2.32 (4) Å and C—H⋯Br = 172 (3)°]. The second ammonium H atom is not involved in hydrogen bonding.

The unsymmetric bis-imidazolium salts ligands 4a and b were prepared by stepwise reactions of 2,6-bis(bromomethylene)-4-( t -butyl)anisole ( 1 ) with two different N-substituted imidazoles. Reaction of the bis-imidazolium ligands with Ag 2 O in acetonitrile gave the dinuclear bis(N-heterocyclic carbene) complexes 5a and b . The molecular structure of complex 5a was determined by single-crystal X-ray diffraction analysis. In complex 5a and b, the two C carbene –Ag–C carbene axes are in a crossed conformation, two O atoms from phenoxyl groups weakly coordinate to different Ag ions and the two p - t -butylphenoxyl groups adopted a staggered conformation. To regulate the molecular shape of the N-heterocyclic carbene Ag(I) macrocyclic complexes, two tetradentate imidazolium ligands ( 9a and b ) were prepared. The bimetallic NHC–Ag(I) complexes 10a and b were obtained by the reaction of 9a and b and Ag 2 O in acetonitrile. Constrained by the chain (the dioxoethylene or dioxomethylenebenzene chain in 10a or 10b , respectively) at the O-position of the phenoxyl group, the two p -methylphenoxyl groups in complexes 10a and b might be predicted to have a cone conformation. The ligands and the corresponding NHC metal complexes have been characterized by elemental analysis, 1 H NMR and 13 C NMR, HRMS spectra, as well as TGA and DTA spectra being determined for complexes 10a and b . The TGA curves show that these NHC–Ag complexes have good thermal stability.

The incorporation of spatially oriented aromatic motifs in rigid molecular platforms is of great interest for the design of organic electronic materials. These structures can create unusual packing patterns and charge transport properties in the solid state which are not possible for simple planar structures. Herein, we showed that the novel dispiro and propellane motifs were successfully used as robust molecular platforms for the construction of host materials (TPA, Cz, SF, and SO). The propellane derivative with three functional groups arranged in the staggered conformation was studied for the first time as the host for organic light-emitting diodes (OLEDs). The green and red phosphorescent OLEDs hosted by these dispiro and propellane derivatives exhibited excellent electroluminescence performance. Particularly, the red OLED hosted by the propellane-type SF achieved maximum efficiencies of 47.3 cd A–1, 40.2 lm W–1, and 26.6% and 97.6 cd A–1, 77.8 lm W–1, and 27.0% for the green OLED without any light ou...

We have performed a multiscale approach to study the influence of peripheral substitution in the semiconducting properties of discotic liquid-crystalline triindoles. Charge carrier mobility as high as 1.4 cm V s was experimentally reported for triindoles substituted with alkynyl chains on the periphery (Gómez-Lor et al. Angew. Chem., Int. Ed., 2011, 50, 7399-7402). In this work, our goal is to get a deeper understanding of both the molecular electronic structure and microscopic factors affecting the charge transport properties in triindoles as a function of the spacer group connecting the central cores with the external alkyl chains (i.e., alkyne or phenyl spacers groups). To this end, we first perform Quantum Mechanical (QM) calculations to assess how the peripheral substitution affects the electronic structure and the internal reorganization energy. Secondly, boxes of stacked molecules were built and relaxed through molecular dynamics to obtain realistic structures. Conformational analysis and calculations of transfer integrals for closed neighbours were performed. Our results show that the insertion of ethynyl spacers between the central aromatic core and the flexible peripheral chains results in lower reorganization energies and enhanced intermolecular order within the stacks with a preferred cofacial 60° staggered conformation, which would result in high charge-carrier mobilities in good agreement with the experimental data. This work allows a deeper understanding of charge carrier mobility in columnar phases, linking the structural order at the molecular level to the property of interest, i.e. the charge carrier mobility. We hope that this understanding will improve the design of systems at the supramolecular level aiming at obtaining a more defined conducting channel, higher mobility and smaller fluctuations within the column., D.A.S.F. gratefully acknowledges the financial support from CNPq, grants 304020/2016-8 and 407682/2013-9, and FAP-DF grants 0193.001.062/2015 and 193.001.284/2016. ML thanks SeRC (Swedish e-Science Research Center) for funding and SNIC (Swedish National Infrastructure for Computing) for providing computer resources (project ID snic2015-1-420). Research at University of Malaga was supported by MINECO (CTQ2015-66897-P) and Junta de Andalucia (P09-4708). BGL acknowledges the financial support from MINECO (CTQ2016-78557-R) and Comunidad de Madrid S2013/MIT.

In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium ferrocene-1-carboxylate], (C14H19N4O3)[Fe(C5H5)(C6H4O2)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N—H...O hydrogen bonds, generating a robust R 2 2(8) ring motif (heterosynthon). However, in the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine–ferrocene-1-carboxylic acid (1/1), [Fe(C5H5)(C6H5O2)]·C6H8ClN3, (II), the carboxyl–aminopyrimidine interaction [R 2 2(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O—H...N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N—H...N hydrogen bonds, generating an R 2 2(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site-occupation ratio of 0.573 (10):0.427 (10). In this study, the two five-membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 36.13–37.53° for (I) and 22.58–23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 79.26–80.94°. Both crystal structures are further stabilized by weak π–π interactions.

The synthesis, characterization and structural analysis of triphenylphosphoniummethylenetrifluoroborate are presented., The title compound, C19H17BF3P {alternative name: triphen­yl[(tri­fluoro­boran­yl)meth­yl]phosphanium}, was formed by the reaction of tri­phenyl­phosphine with potassium iodo­methyl­tri­fluoro­borate. The mol­ecule features a nearly staggered conformation along the P—C bond and a less than staggered conformation along the C—B bond. In the crystal, weak C—H⋯F hydrogen bonds between the meta-phenyl C—H groups and the tri­fluoro­borate B—F groups form chains of R 2 2(16) rings along [100]. These chains are are further stabilized by weak C—H⋯π inter­actions. A weak intra­molecular C—H⋯F hydrogen bond is also observed.

The first dianionic compounds bearing a bond between two pentacoordinated germanium atoms have been synthesized in a stable form as candidates for a core unit to construct unprecedented structures in group 14 element chemistry. X-ray crystallographic analysis and computational study indicated the single-bond character of the Ge–Ge bond. They were reversibly converted to the anionic and neutral Ge–Ge-bonded compounds while maintaining the coordination number of the germanium atoms. The interconversion features changes in structures around the germanium atoms, including changes from a staggered conformation of the Ge–O bonds to a parallel conformation.

Eight new structures of dirhodium complexes, each with four biimidazole (H2bim) ligands, were obtained: [Rh2(H2bim)4(H2O)2](NO3)4·4H2O (I), [Rh2(H2bim)4(H2O)2](ClO4)4·5H2O (II), [Rh2(H2bim)4(MeOH)2](ClO4)4(III), [Rh2(H2bim)4(DMF)2](BF4)4(IV), [Rh2(H2bim)4(Mepy)2](SiF6)2·8H2O (V), [{Rh2(H2bim)4(pz)}2(μ-pz)](SiF6)(ClO4)6·12.7H2O (VI), [{Rh2(H2bim)4(pz)}2(μ-pz)](ClO4)8·11.4H2O (VII) and [Rh2(H2bim)4(μ-pz)](SiF6)2·6H2O (VIII). The unbridged Rh—Rh bond distances range between 2.6313 (8) and 2.7052 (5) Å. The dirhodium units adopt a staggered conformation with torsion angles N—Rh—Rh—N of 37.6 (4)–48.98 (8)°. Various assembled structures were constructed by hydrogen bonding between the complexes and the anions: a discrete structure in (IV), one-dimensional structure in (II), two-dimensional structures in (I), (III), (VI), (VII) and (VIII) and a three-dimensional structure in (V).

The conformation of charged surfactants at the oil-water interface was recently reported. With the aim to assess the role of the head group size on the conformation of the adsorbed layer, we have extended these studies to a series of nonionic dodecanol ethoxylate surfactants (C12En, ethylene oxide units n from 6 to 12). The study was performed using neutron reflectometry to enable maximum sensitivity to buried interfaces. Similarly to charged surfactants, the interface was found to be broader and rougher compared to the air-water interface. Irrespective of the head group size, the tail group region was found to assume a staggered conformation. The conformations of the head group were found to be significantly different from those of the air-water interface, moving from a globular to an almost fully extended conformation at the oil-water interface. The stretching of the head groups is attributed to the presence of some hexadecane oil molecules, which may penetrate all the way to this region. It is proposed here that the presence of the oil, which can efficiently solvate the surfactant tail groups, plays a key role in the conformation of the adsorbed layer and is responsible for the broadening of the interface.

Pd(II) (1) and Ru(II) (2) complexes of 2-(4-methoxyphenyltelluro)ethanol (L), were synthesized using Na2 [PdCl4] and [Ru (η6-p-cymene)Cl2]2 as metal ion sources. The new complexes (1 and 2) were characterized by 1H, 13C{1H} NMR, FT-IR, UV–Visible spectroscopy and elemental analyses. Their structures were also confirmed by single crystal X-Ray diffraction. The characterizationdata revealed that the ligand L coordinated to M(II) ion as a monodentate telluroether ligand in both 1 and 2. The structure of cis-[PdCl2(L)2] (1) was square planar about Pd in which two molecules of L coordinated to palladium (II) in cis-fashion. Interestingly, two molecules of 1 were held by strong Te⋯Cl and aromatic π⋯π secondary interactions and oriented in staggered conformation with short Pd-Pd [3.1712 (5) A] distance forming a dinuclear palladium cluster (cis-[PdCl2(L)2])2 (1)2. The complex [Ru (η6-p-cymene)Cl2(L)] (2) has half-sandwich, pueudo-octahedral structure. There exists several intermolecular hydrogen bonds of type: OH⋯Cl and OH⋯O in 1 and CH⋯Cl, CH⋯O and OH⋯Cl in 2. These interactions results in supramolecular assemblies in the new complexes 1 and 2. In-vitro antioxidant activity of L, 1 and 2 was investigated using DPPH assay. Vitamin-C was used as a standard antioxidant. All three compounds showed to exhibit antioxidant activity. The free radical scavenging activity was quantitatively expressed in terms of their IC50 values which found in the order: Vitamin-C ∼2 > L > 1.

The X-ray crystal structures of two new co-crystals comprised of C60 and C70 fullerenes and a dibenzo[a,g]corannulene bowl, namely, (C28H14)·(C60) and (C28H14)2·(C70), are reported. A clear difference is observed between C60 to C70, with the latter fullerene molecule being fully ordered and lacking the orientational disorder found in many fullerene co-crystallized products. In the solid state structure of (C28H14)2·(C70), two bowl-shaped C28H14 molecules encapsulate the C70-cage and exhibit a preferential spatial alignment parallel to the longer axis of the fullerene. In this case, dibenzo[a,g]corannulene utilizes only its concave surface for binding, showing a staggered conformation of carbon atoms over the convex surface of C70-fullerene. In the solid-state structure of (C28H14)·(C60), both convex–convex and convex–concave π···π interactions are observed between the curved surfaces of C28H14 and C60. The C60-core is disordered showing no preferential orientation. In both cases, the formation of π···π ad...

Two examples of core-modified 36π doubly fused octaphyrins that undergo a conformational change from a twisted figure-eight to an open-extended structure induced by protonation are reported. Syntheses of the two octaphyrins (in which Ar=mesityl or tolyl) were achieved by a simple acid-catalyzed condensation of dipyrrane unit containing an electron-rich, rigid dithienothiophene (DTT) core with pentafluorobenzaldehyde followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The single-crystal X-ray structure of the octaphyrin (in which Ar=mesityl) shows a figure-eight twisted conformation of the expanded porphyrin skeleton with two DTT moieties oriented in a staggered conformation with a π-cloud distance of 3.7 Å. Spectroscopic and quantum mechanical calculations reveal that both octaphyrins conform to a [4n]π nonaromatic electronic structure. Protonation of the pyrrole nitrogen atoms of the octaphyrins results in dramatic structural change, which led to 1) a large redshift and sharpening of absorption bands in electronic absorption spectrum, 2) a large change in chemical shift of pyrrole β-CH and -NH protons in the (1)H NMR spectrum, 3) a small increase in singlet lifetimes, and 4) a moderate increase in two-photon absorption cross-section values. Furthermore, nucleus-independent chemical shift (NICS) values calculated at various geometrical positions show positive values and anisotropy-induced current density (AICD) plots indicate paratropic ring-currents for the diprotonated form of the octaphyrin (in which Ar=tolyl); the single-crystal X-ray structure of the diprotonated form of the octaphyrin shows an extended structure in which one of the pyrrole ring of each dipyrrin subunit undergoes a 180° ring-flip. Four trifluoroacetic acid (TFA) molecules are bound above and below the molecular plane defined by meso-carbon atoms and are held by N-H···O, N-H···F, and C-H···F intermolecular hydrogen-bonding interactions. The extended-open structure upon protonation allows π-delocalization and the electronic structure conforms to a [4n]π Hückel antiaromatic in the diprotonated state.

Bis(triphenylphosphine)gold(I) perrhenate [Ph3PAuPPh3]+ReO4 - has been prepared in high yield from Ph3PAuCl, Ph3P and AgReO4 in a mixed solvent. The compound is stable in air and decomposes at 235 °C. In the crystal structure, the two independent perrhenate anions are not approaching the gold centers of the two independent cations, but weak interionic interactions are entertained via π-π stacking of phenyl groups and C-H···O contacts. As three-blade chiral rotors, the Ph3P ligands of the cations are in a staggered conformation at the gold atoms with only slightly bent P-Au-P axes. IR and NMR data show no anomalies and are close to those of alkali or onium perrhenates.

The new ternary compounds UP2S6, UP2S7, U(P2S6)2, and U3(PS4)4 were prepared from uranium metal, phosphorus pentasulfide, and sulfur at 700 °C. The crystal structures were determined by single-crystal X-ray diffraction methods. UP2S6 (I) crystallizes in the ZrP2S6 structure type [tetragonal, P42/m, a = 6.8058(7) A, c = 9.7597(14) A, Z = 2], which consists of central uranium(IV) atoms coordinated by P2S64– anions (staggered conformation). The anions are two-dimensional connectors for four uranium cations arranged in one plane. The structure of UP2S7 (II) [orthorhombic, Fddd, a = 8.9966(15) A, b = 15.2869(2) A, c = 30.3195(5) A, Z = 16] is closely related to the monoclinic ZrP2S7 structure type. It consists of U4+ cations linked by P2S74– ligands, the resulting 3D network contains large pores (diameter approx. 3.5 × 16.7 A). In the previously reported compound U(P2S6)2 (III) [I41/a, a = 12.8776(9) A, c = 9.8367(10) A, Z = 2], the metal atoms are coordinated by four bidentate P2S62– ligands. This arrangement can be considered as a pseudotetrahedral coordination of the uranium atoms by the linear ligands. Three of the resulting diamondoid frameworks are inseparably interwoven in order to optimize space filling. U3(PS4)4 (IV) [I41/acd, a = 10.7440(9) A, c = 19.0969(2) A, Z = 2] crystallizes in a defect variant of the PrPS4 structure type, with 50 % of the U2 sites statistically occupied with uranium atoms. The resulting stoichiometry is U3(PS4)4 with tetravalent uranium atoms. The structure of U3(PS4)4 consists of uranium atoms connected by PS43– groups, each PS4 group linking four central uranium atoms. Vibrational spectra, which were recorded for I–III, show good agreement between the obtained results and the expected values for the anionic units, while magnetic measurements confirm the presence of tetravalent uranium.

A new dinitrogen adduct of a homoleptic uranium tris(siloxide) complex, [U{OSi(Mes)3}3]2(μ-η2:η2-N2), is reported. Synthesis of the 15N-labeled isotopomer and Raman spectroscopy confirm the reductive activation of N2 to a (N2)2– dianion. The 15N NMR shift of the 15N2-labeled isotopomer is also reported. Crystallographic characterization shows a side-on (N2)2– coordinated in either an eclipsed or staggered conformation in different crystals. The U–N2–U complex is stable to vacuum and shows high thermal stability, retaining the formally reduced dinitrogen at 100 °C. The parent three-coordinate uranium(III) [U{OSi(Mes)3}3] could not be isolated in our hands, with N2-free syntheses affording only uranium(IV) compounds. The rational synthesis and full characterization of two such U(IV) byproducts, [U{OSi(Mes)3}{N(SiMe3)2}3] and [U{OSi(Mes)3}4], is also reported.

Crystal structures of partially oxidized cyanoplatinates were determined by single crystal analysis. Rb1.75[Pt(CN)4]·1.25H2O crystallizes monoclinic in the space group P21/c [a = 1171.4(2) pm, b = 3315.3(6) pm, c = 1054.4(2) pm, β = 114.253(2)°, V = 3733.2(11)·106 pm3, Z = 16, Ntotal = 31567, R(F)N = 0.0858]. The compound was obtained by mixing aqueous solutions of Rb2[Pt(CN)4]·1.5H2O and Rb2[Pt(CN)4]Br2. Cs1.75[Pt(CN)4]·0.5H2O crystallizes in the space group Ibam [a = 1266.1(3) pm, b = 1347.5(3) pm, c = 580.4(1) pm, V = 990.2(3)·106 pm3, Z = 4, Ntotal = 5997, R(F)N = 0.0807]. Crystals of the latter were grown by slow electrochemical oxidation of Cs2[Pt(CN)4]·H2O in aqueous solution using platinum wires as electrodes. In both compounds platinum is partially oxidized to Pt+2.25 and the nearly square-planar tetracyanoplatinate groups are arranged to columns in a staggered conformation. The rubidium compound features a large unit cell with nonlinear chains of platinum atoms and short alternating Pt–Pt distances of 292 and 294 pm, the cesium compound crystallizes more symmetrically with Pt–Pt distances of c/2 = 290 pm. The two compounds were also characterized by differential thermal analysis, thermogravimetry, infrared, and Raman spectroscopy.

The synthesis and crystal structures of a series of six crystalline potassium salts of hypodiphosphoric acid, H4P2O6, are reported, namely potassium hydrogen phosphonophosphonate, K+·H3P2O6−, (I), dipotassium dihydrogen hypodiphosphate monohydrate, 2K+·H2P2O62−·H2O, (II), dipotassium dihydrogen hypodiphosphate dihydrate, 2K+·H2P2O62−·2H2O, (III), pentapotassium hydrogen hypodiphosphate dihydrogen hypodiphosphate dihydrate, 5K+·HP2O63−·H2P2O62−·2H2O, (IV), tripotassium hydrogen hypodiphosphate tetrahydrate, 3K+·HP2O63−·4H2O, (V), and tetrapotassium hypodiphosphate tetrahydrate, 4K+·P2O64−·4H2O, (VI). All the hypodiphosphate anions,viz.H3P2O6−, H2P2O62−, HP2O63−and P2O64−, adopt a staggered conformation. The P—P bond lengths [2.1722 (7)–2.1892 (10) Å] do not depend on the basicity of the anion. The compounds are organized into different types of one-, two- or three-dimensional polymeric hydrogen-bonded networks, or simply exist in the form of isolated or dimeric units. The coordination numbers of the K+cations range from 6 to 9, and the cationic sublattices are polymeric one-, two- or three-dimensional networks, or isolated [KO6] or dimeric [K2O12] polyhedra.

Herein, we report on the reaggregation of hexameric trimethylsilylmethyllithium [LiCH2SiMe3]6 with the donor base DABCO (1,4-diazabicyclo[2.2.2]octane) to give the unprecedented octamer [(DABCO)7·(LiCH2SiMe3)8] (1). The structure consists of four dimers, forming Li2C2 four-membered rings, connected to two [(DABCO)3·{(LiCH2SiMe3)2}2] chain fractions, interconnected by a single DABCO molecule. Interestingly, two different conformers of (LiCH2SiMe3)2 dimers are present, caused by different steric demand. Higher steric strain in the center of the molecule causes an ecliptic arrangement of the Me3Si group along the Si–Cα bond, while at the periphery the more relaxed staggered conformation is enabled. The reactivity of trimethylsilylmethyllithium coordinated by DABCO was tested in the benchmark reaction with toluene. Although the aggregation of 1 is much higher than that of the parent [LiCH2SiMe3]6, the reactivity of the first is higher than that of the starting material, provided the octameric aggregation foun...

Single crystals of the alkali-metal hypodiphosphates K4P2O6·8H2O (1) and Na2K2P2O6·8H2O (2) could be obtained and their crystal structures determined. The compounds 1 and 2 crystallize isotypic in the orthorhombic space group Pbca (no. 61) with four formula units in the unit cell. The crystal structures are built up by discrete [P2O6]4– units in an ethane-like staggered conformation, by the corresponding alkali-metal cations and water molecules. FT-IR/FIR and FT-Raman spectra of the crystalline title compounds were recorded and a complete assignment for the [P2O6]4– modes is proposed. Raman spectra of aqueous hypodiphosphate solutions deliver additional polarization data supporting the band assignment. Compounds 1 and 2 show a complete H2O loss in case of slow heating avoiding the formation of a hydrate melt.

Three tetrairon ethanedithiolate complexes [{(μ-EDT)Fe2(CO)5}2L] (EDT = SCH2CH2S; L = (η5-Ph2PC5H4)2Fe, 1; Ph2PCH2CH2PPh2, 2; trans-Ph2PCH = CHPPh2, 3) containing bridging bidentate phosphine ligands were prepared by carbonyl substitution reactions in the presence of the decarbonylating agent Me3NO·2H2O. The new complexes 1–3 were characterized by elemental analysis, IR and 1H (31P, 13C) NMR spectroscopies. Furthermore, their structures were determined by single crystal X-ray diffraction analysis. The molecular structure of 1 is centrosymmetric and the two cyclopentadienyl (Cp) rings reside in a staggered conformation. The molecular structures of 2 and 3 are composed of a zigzag chain, Fe2P1C20C20AP1AFe2A, with the midpoint of the C20–C20A bond as the center of symmetry.

Five copper(I) complexes having general formula [Cu2(μ-X)2(κ2-P,P-B-dppf)2] (X = Cl(1), Br(2), I(3), CN(4), and SCN(5)) were prepared starting with CuX and B-dppf in 1:1 molar ratio in DCM-MeOH (50:50 V/V) at room temperature. The complexes have been characterized by elemental analyses, IR, 1H NMR, 31P NMR and electronic spectral studies. Molecular structures for 1, 2 and 4 were determined crystallographically. Complexes 1, 2 and 4 exist as centrosymmetric dimers in which the two copper atoms are bonded to two bridging B-dppf ligands and two bridging (pseudo-)halide groups in a μ-η1 bonding mode to generate nearly planar Cu2(μ-η1-X)2 framework. Both bridging B-dppf ligands are arranged in antiperiplanar staggered conformation in 1 and 2 (mean value 56.40–56.76°), and twisted from the eclipsed conformation (mean value 78.19°) in 4. The Φ angle value in 4 is relatively larger as compared to 1 and 2. This seems to indicate that the molecular core [Cu2(μ-η1-X)2] in 4 is a sterically demanding system that forces the B-dppf ligand to adopt a relatively strained conformation in comparison to less strained system in 1 and 2. All the complexes exhibit moderately strong luminescence properties in the solution state at ambient temperature.