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Five potential charge transfer complexes of trimeric perfluoro-o-phenylene mercury (I) with tetrathiafulvalene (TTF) and tetramethyltetraselenefulvalene (TMTSF) were grown from different solvent mixtures. The adducts (I)2·TTF (1) and I·TTF (2) were grown by slow evaporation from the 1:1 mixture of dichloromethane (CH2Cl2, DCM) and carbon disulfide (CS2). Use of the different 1:1 solvent mixtures of dichloromethane (CH2Cl2, DCM) and dichloroethane (C2H4Cl2, DCE) has led to the crystalline adducts I·TTF (3) and I·TTF·DCE (4). Adduct I.TMTSF (5) was grown by the interface crystallization on the border of two immiscible layers, ethyl acetate, and carbon disulfide. The cocrystals differ by the donor–acceptor ratio, molecular packing, and the solvent inclusion. The components in 1–5 form mixed donor–acceptor stacks. The stacks are stabilized by Hg···S and Hg···C short contacts, while the lateral interactions between stacks include F···F, CH···F, and S/Se···F short contacts.

The molecular and crystal structures of two energetic fused furazans, 4H,8H-bis-furazano[3,4-b:3′,4′-e]pyrazine (1) and 4H,9H-bisfurazano[3,4-b:3′,4-g]-pyrazino[2,3-e]pyrazine (2), have been studied by single crystal X-ray diffraction analysis. These materials were found to have rather high crystal densities for organic compounds (2.032 and 1.882 g·cm–3). Very short interplanar distances between overlapping molecules in crystals (less than 3.15 A) suggest the presence of stacking interaction between planar rings. High-resolution low-temperature X-ray diffraction data for both compounds were used to analyze the electron density distribution in the area of stacking interaction and hydrogen bonds, as interpreted through the framework of Bader’s AIM theory. A weak accumulation of the electron density, and (3, −1) bond critical points were found in the area of this interaction between overlapping molecules in the crystal. It was established that the energy of the stacking interactions in 1 and 2 are 3.9 and 3....

Here, we report the synthesis, characterization, and properties of novel nanohybrids formed by self-assembly of negatively charged MoS2 nanoplates and positively charged iron oxide nanoparticles (NPs) of two different sizes, 5.1 and 11.6 nm. Iron oxide NPs were functionalized with an amphiphilic random copolymer, quaternized poly(2-(dimethylamino)ethyl metacrylate-co-stearyl metacrylate), synthesized for the first time using atom transfer radical polymerization. The influence of the MoS2 fraction and the iron oxide NP size on the structure of the nanohybrids has been studied. Surprisingly, larger NPs retained a larger fraction of the copolymer, thus requiring more MoS2 nanoplates for charge compensation. The nanohybrid based on 11.6 nm NPs was studied in oxidation of sulfide ions. This reaction could be used for removing the dangerous pollutant from wastewater and in the production of hydrogen from water using solar energy. We demonstrated a higher catalytic activity of the NP/MoS2 nanohybrid than that of...

The product of exfoliation and restacking of MoS2 in acidic conditions is studied in detail using X-ray powder diffraction, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The temperature dependence of powder patterns reveals that the heating of exfoliated-restacked MoS2 is a way to a new nanostructured MoS2-based layered material that remains nanosized even upon heating to 850 °C. Previously this material has been described as 2H-MoS2, but according to the X-ray diffraction (XRD) data, its structure cannot be correctly described by any of the “usual” MoS2 polytypes. A model of the structure of the material describing its XRD patterns and thermal behavior is discussed in detail.

A new restraint scheme for Rietveld refinement based on Morse bond energy potential is introduced, in which the asymmetry of the Morse potential allows the refinement to `break' the incorrectly placed bonds. The analysis of bond-length distributions at different values of restraint strength reveals a visible difference in behavior of wrong and correct structures, which can be detected using robust statistical methods. This fact is employed as a basis for a novel structure verification criterion. The approach is demonstrated on known difficult cases of acetolone and γ-quinacridone and used for the Rietveld refinement ofN-(6-phenylhexanoyl)glycyl-L-tryptophanamide, an organic molecule of a potential anxiolytic containing 32 non-H atoms and 14 single bonds. The results are verified using density functional theory calculations with periodic boundary conditions.

Three thermochromic phases (α, green; β, red; γ, yellow) and six polymorphic modifications (α(1), monoclinic, P2(1)/n, Z = 2; β(1), monoclinic, P2(1)/c, Z = 4; β(2), triclinic, P1[overline], Z = 4; β(3), monoclinic, P2(1)/n, Z = 4; γ(1) and γ(2), tetragonal, P4(2)/n, Z = 4) have been found and structurally characterized for copper(II) diiminate Cu[CF(3)-C(NH)-CF═C(NH)-CF(3)](2) (1). The α phase is stable under normal conditions, whereas the high-temperature β and γ phases are metastable at room temperature and transform slowly into the more stable α phase over several days or even weeks. X-ray diffraction study revealed that the title molecules adopt different conformations in the α, β, and γ phases, namely, staircase-like, twisted, and planar, respectively. The investigation of the α, β, and γ phases by differential scanning calorimetry showed that the three endothermic peaks in the range 283, 360, and 438 K are present on their thermograms upon heating/cooling. The two peaks at 283 and 360 K correspond to the solid-solid phase transitions, and the high-temperature peak at 438 K belongs to the melting process of 1. The temperature and thermal effect of all the observed transitions depend on the prehistory of the crystalline sample obtained. A reversible thermochromic single-crystal-to-single-crystal α(1)--β(1) phase transition occurring within a temperature interval of 353-358 K can be directly observed using a CCD video camera of the X-ray diffractometer. A series of other solid-solid α(1)→γ(1), β(2)→γ(1), β(3)→γ(1), and γ(1)--γ(2) phase transitions can be triggered in 1 by temperature. It has been suggested that, under equilibrium conditions, the α(1)→γ(1) and β(2)→γ(1) phase transitions should proceed stepwise through the α(1)→β(1)→β(2)→β(3)→γ(1) and β(2)→β(3)→γ(1) stages, respectively. The mechanism of the phase transitions is discussed on the basis of experimental and theoretical data.

The dimeric triple-decker type halides [CpCo(μ-1,3-C3B2Me5)MX2]2 (M = Rh, X = Cl, 1; M = Ir, X = Cl, 2; M = Rh, X = Br, 3; M = Ir, X = Br, 4) react with Me2SO and PPh3 giving adducts CpCo(μ-1,3-C3B2Me5)M(L)X2 (5–12). The Me2SO ligand is S-bonded to the metal atom in the solid state, while in acetone it is O-bonded. Structures of 5–12 were confirmed by X-ray diffraction.

The reaction of CpCo(1,3-C3B2Me5H) (1) with CpTl affords the thallium derivative CpCo(1,3-C3B2Me5)Tl (2). The structures of 1 and 2 were determined by X-ray diffraction at 100 K. An “extra” hydrogen atom in 1 occupies a C–H···B bridging position. According to DFT calculations, 1 exists as a mixture of two enantiomers with an enantiomerization barrier of only 0.5 kcal mol–1. The transition state has Cs symmetry with an endo-CH hydrogen atom. The isomeric iso-1with the Co–H···B bridge is less stable than 1 by 10 kcal mol–1.The formation of 1 and iso-1 from C3B2Me5H and CpCo(C2H4)2 have almost equal activation energies. The isomerization of iso-1 to 1 was shown to proceed as a two-step hydrogen transfer. The bonding of the “extra” hydrogen atom in the related CHB-bridged carborane nido-2,3,5-C3B3R5H2 and metallacarboranes M(C5R5)(C3B2R′5H) (R, R′ = H, Me; M = Co, Rh, Ir) as well as their hydridic isomers MH(C5R5)(C3B2R′5) was compared. According to energy decomposition analysis, the bonding of the parent anion [CpCo(1,3-C3B2H5)]– with metal cations becomes stronger in the following order: K+ < Na+ < Tl+ < Li+ < [RuCp]+. The attractive interactions between the [CpCo(1,3-C3B2H5)]– and Tl+ fragments are 68 % electrostatic and 32 % covalent.

The results of the single crystal X-ray diffraction analysis of 2,5-diphenylphosphacymantrene (η5-C4H2Ph2P)Mn(CO)3 (1) and experimental charge density distribution study of [(η4-C4H2Ph2P(O)H)Mn(СO)3]−[NH2Et2]+ (2) are discussed. The resultant density was analyzed using the quantum theory of atoms in molecules (QTAIM). Here, we focused on the analysis of the interaction between the metal atom and the π-ligand depending on the mutual orientation of the Mn(CO)3 moiety and the heterocyclic fragment (cis and trans conformers). The electronic structures of cis and trans conformers of both the complexes 1 and 2 have also been studied by ab initio density functional theory calculations, showing rather a good agreement with the experiment. Redistribution of the electron density in the vicinity of the metal atom upon the reorientation of the carbonyl groups causes the changes in the geometric and electronic characteristics of the heterocycle. The most significant changes occur in the molecular topology, in particular, in the connectivity of the metal atom with the π-ligand.

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C6H5O)(CO)3], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C6H5O)(CO)3], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in atransposition relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographiccaxis for (I) and along the [201] direction for (II). Symmetry-related stacks are bound to each other by weak intermolecular C—H...O hydrogen bonds, leading to the formation of the three-dimensional network.

Access to unsymmetrical secondary dihetarylamines through the Cu(OAc)2/2-acetylcyclohexanone catalyzed cross-coupling of s-tetrazinylamines with iodofurazans has been developed. The reaction displays good functional group tolerance, involving nitro, azido, and azo groups, which are critical for the construction of energetic materials. Both 3,6-disubstituted and annelated s-tetrazines react readily with iodofurazans to furnish the desired products.

Six new derivatives of the previously reported chromophore 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (OH1) with potential application in electrooptics were synthesized and their crystal structures characterized using a single crystal X-ray technique. The presented chromophores have a D–π–A structure with a phenol donor, ring locked polyene conjugated bridge and dicyanomethylydene acceptor. In order to potentially alleviate problems with the quality of melt grown films of OH1, the melting point was tuned through the introduction of alkoxy groups of various lengths and onto various positions on the chromophore core as well as through the modification of the bridge structure. We show that the melting point of these materials can be significantly decreased with the increased number of carbon atoms in alkoxy group. However, the molecular arrangement was found to be highly sensitive to the addition of substituents, and regardless of the size and position of the alkoxy groups, all presented chromophores formed centrosymmetric structures. The distinctions in crystal packing are explained by the mutual arrangement of donor (OH) and H-acceptor (OAlk, C(CN) 2 ) groups in the molecules. Static first order hyperpolarizabilities along with molecular geometry in isolated state were calculated using DFT.

Novel radial tetra(ferrocenyl)- and tetra(cymantrenyl)cyclobutadienecobalt complexes were prepared by metal carbonyls free protocol of [2 + 2] cycloaddition reaction of 1,2-diferrocenyl- or 1,2-dicymantrenylethynes with chlorotris(triphenylphospine)cobalt(I) and carboethoxycyclopentadienide sodium with good yields. The molecular structure of these products was confirmed with X-ray analysis, and their electrochemical behavior was studied.

( 3E , 5E )-3,5-Bis(benzylidene)-4-oxopiperidinium tetrafluoroborate [C 19 H 18 NO][BF 4 ] ( 1 ), ( 3E , 5E )-3,5-bis[4-(dimethylammonio)benzylidene]-4-oxopiperidinium bearing mixed tetrafluoroborate and bis(hexafluoro(μ-hydroxo)diborate) anions [C 23 H 30 N 3 O][B 2 F 6 OH] n [BF 4 ] m · x H 2 O ( 2 ), and ( 3E , 5E )-3,5-bis[4-(diethylammonio)benzylidene]-4-oxopiperidinium tris(tetrafluoroborate) monohydrate [C 27 H 38 N 3 O][BF 4 ] 3 ·H 2 O ( 3 ) were obtained via mediated by the boron trifluoride etherate aldol-crotonic condensation of the corresponding aldehyde and piperidin-4-one hydrochloride monohydrate. Their structures were studied by IR and multinuclear NMR spectroscopy, and single crystal X-ray diffraction. The X-ray analysis revealed the presence of monoprotonated piperidinium cation in 1 and triprotonated cations in 2 and 3 . The hexafluoro(μ-hydroxo)diborate anion was found in the mixed-anionic salts 2A and 2B which differ by the ratio of the anions. The extended hydrogen-bonded system is registered in all compounds. Static first order hyperpolarizabilities for the neutral ( 3E , 5E )-3,5-bis[4-(dimethylamino)benzylidene]-piperidin-4-one and its positively charged derivatives along with their molecular geometries and binding energy of 1 were calculated using DFT approach.

Low melting organic esters, ethyl acetate (1), diethyl carbonate (2), methyl benzoate (3) and phenyl acetate (4), have been grown using the miniature zone melting in situ crystallization technique and their molecular and crystal structures have been determined. Co-crystallization of the esters 1–4 with Lewis acid 1,2-bis(chloromercurio)tetrafluorobenzene (II) resulted in three adducts with a ratio of organic to organometallic components of 1:1 (II·1, II·3, and II·4), and one complex with a corresponding ratio of 1:2 (2(II)·2). X-ray analysis revealed presence of supramolecular 1D chain associates in crystals of II·1 and II·3, which are similar to those found before in the crystal of individual II. The crystal structures of complexes 2(II)·2 and II·4 have demonstrated the presence of 2D layer supramolecular associates. Both 1D and 2D associates are stabilized mostly by strong Hg···Cl interactions between molecules of II, which in some cases are additionally strengthen via Hg···O, Hg···π, and π–π interactio...

A series of pseudo-octahedral metal (M = Mn, Fe, Co, Ni, Cu, Zn) complexes 4 of a new redox-active ligand, 2,4,6,8-tetra(tert-butyl)-9-hydroxyphenoxazin-1-one 3, have been synthesized, and their molecular structures determined with help of X-ray crystallography. The effective magnetic moments of complexes 4 (M = Mn, Fe, Co, and Ni) measured in the solid state and toluene solution point to the stabilization of their high-spin electronic ground states. Detailed information on the electronic structure of the complexes and their redox-isomeric forms has been obtained using density functional theory (DFT) B3LYP*/6-311++G(d,p) calculations. The energy disfavored low-spin structures of manganese, iron, and cobalt complexes have been located, and based on the computed geometries and distribution of spin densities identified as Mn(IV)[(Cat-N-SQ)](2), Fe(II)[Cat-N-BQ)](2), and Co(II)[Cat-N-BQ)](2) compounds, respectively. It has been shown that stabilization of the high-spin structures of complexes 4 (M = Mn, Fe, Co) is caused by the rigidity of the molecular framework of ligands 3 that sterically inhibits interconversions between the redox-isomeric forms of the complexes. The calculations performed on complex 4 (M = Co) predict that a suitable structural modification that might provide for stabilization of the low-spin electromeric forms and create conditions for the valence tautomeric rearrangement via stabilization of the low-spin electromer and narrowing energy gap between the low-spin ground state tautomer and the minimal energy crossing point on the intersection of the potential energy surfaces of the interconverting structures consists in the replacement of an oxygen in the oxazine ring by a bulkier sulfur atom.

Phenanthro[4,5-abc]phenazine-18-crown-6 chromophore (1) was synthesized, and its two polymorphic modifications were obtained by recrystallization from dichloromethane/methanol and dichloromethane/hexane solvent mixtures. Both polymorphs 1a and 1b crystallize in the same monoclinic P21/c space group, and represent conformational polymorphs, which differ by the conformation of the macrocyclic cavity. The crystal structures obtained have been compared with molecular structures computed by density functional theory (DFT). As revealed by quantum chemical calculations, both polymorphs reach different minima on potential energy surface that supports our results that different solvents template distinctive conformational isomers found in crystals.

Interaction of copper(II) acetate with benzoic acid (benzene-1,3,5-tricarboxylic acid = H3-btc and 3,5-dinitro-benzoic acid = H-dnb) and pyridine (Py) resulted in two mononuclear square-planar complexes with the compositions [Cu(H2-btc)2(Py)2] (1) and [Cu(dnb)2(Py)2] (2). The recrystallization of 2 from dimethylsulfoxide (DMSO) yielded the square-bipyramidal complex [Cu(dnb)2(DMSO)2(H2O)2] (3). Crystal structures of 1–3 were determined by single crystal X-ray diffraction at 100 K. The square-planar Cu(II) geometry with the Cu–O and Cu–N distances of 1.924(2), 1.925(2) and 2.024(3) and 2.025(3) A in 1, and 1.930(4) and 2.033(5) A in 2 was found. The extended H-bonding system in 1 built on the robust carboxylic synthons is giving rise to the high-ordered porous layered structure. Insight into metal center environment and stabilizing intramolecular short interactions is obtained through quantum theory of atoms in molecules (QTAIM). As revealed by QTAIM, in octahedral complex 3 Cu-dnb and Cu-DMSO bonds are stronger than Cu–N bonds in 1 and 2.

Nitration of 3,4-diaminofurazan with HNO3, followed by condensation of the di(nitramine) intermediate with N , N -bis(hydroxymethyl)- N -nitroamine or N , N -bis(acetoxymethyl)- N -nitroamine in ionic liquids affords the title compound in good yield.

Interaction of mefenamic acid [2-(2,3-dimethylphenyl)aminobenzoic acid, maH] with piperazine (ppz), 1,4,7,10-tetraazacyclododecane (cyclen), meso-5,7,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (teta), and tris(hydroxymethyl)aminomethane (tris) resulted in crystalline proton-transfer complexes of the compositions (ppzH2)(ma)2·4H2O 1, (cyclenH2)(ma)2·2H2O 2, (tetaH2)(ma)2·2H2O 3, and (trisH)(ma)·H2O 4. Immediate cation−anion hydrogen bonds and those mediated by water molecules are the prime driving forces for the maH and amine assembly. Persistent CH···π interactions involving the aromatic rings were found to play an important role in the formation of final structures. All complexes reveal the pronounced segregation of hydrophilic and hydrophobic regions.

Theoretical and experimental data array confirming the possibility of occurrence of bonding interactions in a crystal between like-charged species, namely anions, that contribute significantly to the crystal packing formation is analyzed. The main types of anion–anion interactions, their strength and contribution to the stabilization of ionic crystals are systematically analyzed for a wide range of organic and inorganic salts. The potential of various theoretical and experimental methods of investigations aimed at detection of anion–anion interactions and estimation of their energy is discussed.

The present study reports the evidence for the multiple carbon― carbon bond insertion into the metal― heteroatom bond via a five-coordinate metal complex. Detailed analysis of the model catalytic reaction of the carbon― sulfur (C―S) bond formation unveiled the mechanism of metal-mediated alkyne insertion: a new pathway of C― S bond formation without preliminary ligand dissociation was revealed based on experimental and theoretical investigations. According to this pathway alkyne insertion into the metal―sulfur bond led to the formation of intermediate metal complex capable of direct C— S reductive elimination. In contrast, an intermediate metal complex formed through alkyne insertion through the traditional pathway involving preliminary ligand dissociation suffered from "improper" geometry configuration, which may block the whole catalytic cycle. A new catalytic system was developed to solve the problem of stereoselective S—S bond addition to internal alkynes and a cost-efficient Ni-catalyzed synthetic procedure is reported to furnish formation of target vinyl sulfides with high yields (up to 99%) and excellent Z/E selectivity (> 99:1).

Thermal reaction of Ru3(CO)12 with 1-(4-tolyl)-3-phenylaminoprop-2-en-1-one (1) proceeds in heptane with the formation of a number of new chelate mononuclear complexes, cis-Ru(CO)2[O═C(Tol)CH═CHNPh...

Peculiarities of chemical bonding in crystalline 3-isopropyl-4-thiomethyl-N6-benzoylsidnone imine with four independent molecules were investigated by means of R. Bader's “Atoms in Molecule” theory. For the fist time the pseudosymmetry phenomenon was explored at both the molecular (charge density within the molecular species) and supramolecular (network of intermolecular interactions) level.

The structures of the three title monosubstituted ferrocenes, namely 1-chloro­ferrocene, [Fe(C5H5)(C5H4Cl)], (I), 1-bromo­ferrocene, [Fe(C5H5)(C5H4Br)], (II), and 1-iodo­ferrocene, [Fe(C5H5)(C5H4I)], (III), were determined at 100 K. The chloro- and bromo­ferrocenes are isomorphous crystals. The new triclinic polymorph [space group P , Z = 4, T = 100 K, V = 943.8 (4) Å3] of iodo­ferrocene, (III), and the previously reported monoclinic polymorph of (III) [Laus, Wurst & Schottenberger (2005 ▶). Z. Kristallogr. New Cryst. Struct. 220, 229–230; space group Pc, Z = 4, T = 100 K, V = 924.9 Å3] were obtained by crystallization from ethanolic solutions at 253 and 303 K, respectively. All four phases contain two independent mol­ecules in the unit cell. The relative orientations of the cyclo­penta­dienyl (Cp) rings are eclipsed and staggered in the independent mol­ecules of (I) and (II), while (III) demonstrates only an eclipsed conformation. The triclinic and monoclinic polymorphs of (III) contain nonbonded inter­molecular I⋯I contacts, causing different packing modes. In the triclinic form of (III), the mol­ecules are arranged in zigzag tetra­mers, while in the monoclinic form the mol­ecules are arranged in zigzag chains along the a axis. Crystallographic data for (III), along with the computed lattice energies of the two polymorphs, suggest that the monoclinic form is more stable.

8-Trifluoromethyl-6,7-dihydro-5H-1,4,8a-triaza-s-indacene and 9-trifluoromethyl-5,6,7,8-tetrahydropyrazolo[5,1-b]quinazolines were efficiently generated by condensation of 5(3)-aminopyrazoles with (2-ethoxycycloalkenyl)-2,2,2-trifluoroethanones and isolated in excellent yields. The regiochemistry of the prepared compounds was established by 1H, 13C and 19F NMR spectroscopy and X-ray diffraction analysis.

Pancratistatin is a phenanthridone-type natural product isolated from several plants of the Amaryllidaceae family. Its potent antiproliferative, antivascular, antiviral, and antiparasitic properties have attracted the attention of synthetic, biological, and medicinal chemists. Pancratistatin's low natural availability and complex structure have steered many of these research projects toward the preparation of its simplified synthetic analogues with useful levels of activity. In this work we have developed synthetic chemistry aimed at the preparation of pancratistatin analogues with a truncated cyclitol portion of the molecule. The described synthetic pathways are based on a highly anti-diastereoselective arylcuprate conjugate addition to gamma-alkoxy-alpha,beta-enoates and syn-selective azidation at the alpha-position of ester enolates. Analogues with the formally cleaved C3-C4 bond, and thus containing an open ring C, as well as a compound containing a truncated lactol moiety in lieu of the cyclitol, were prepared. Several of the analogues exhibited weak antiproliferative activity, with the highest potency observed in the case of the lactol analogue. From these results implications for the design of future pancratistatin analogues are discussed. Furthermore, the synthetic pathways can be used to construct pancratistatin-mimetic libraries, in which the cyclitol moiety is replaced by other cyclic motifs.

Molecular structures of hexakis(amino)cyclotriphosphazene, N3P3(NH2)6, neutral and cationic forms of hexakis(ethylamino)cyclotriphosphazene, N3P3(NHC2H5)6, and dicationic form of octakis(ethylamino)cyclotetraphosphazene, N4P4(NHC2H5)8, were established through the X-ray diffraction experiments at 120(2), 165(2) and 110(2) K, respectively. Geometry of the six- and eight-membered cyclophosphazene rings of the molecules are discussed with the help of B3LYP/6-311G∗∗ method/basis DFT calculations of their methylamino analogs and topological analysis of the electron density distribution. In all cases P–N bonds show high polar nature with considerable P → N charge transfer. Change of the P–N bond lengths upon the cycle protonation well correlated with the net charge redistribution at the P and N centers but separately for the endocyclic and exocyclic bonds. Presence of the additional π-bonding covalent contribution, as it is evidenced from the analysis of the bonds ellipticity, has to be suggested to explain these separate correlations. In the cyclotriphosphazene cation the finer details of the endocyclic P–N bond lengths changes can be attributed to the interplay of the variable π-bonding contribution with the change in the bond ionicity. In the crystal all compounds demonstrate large variety of bridged hydrogen bond patterns though the N–H…N and N–H…Cl interactions.

The theoretical and practical aspects of the use of atomic energy in R Bader's theory 'Atoms in Molecules' for solving problems of physical and structural chemistry are considered

Triple-decker complexes with a bridging diborolyl ligand CpCo(μ-1,3-C3B2Me5)M(ring) (M(ring) = RuCp, 4; RuCp*, 5; Co(C4Me4), 6) were synthesized by electrophilic stacking of the sandwich anion [CpCo(1,3-C3B2Me5)]− with the [(ring)M(MeCN)3]+ cations. Structures of 4−6 were confirmed by X-ray diffraction. The electrochemical and spectroelectrochemical behavior of the complexes prepared was studied. DFT calculations of the redox potentials were also performed. Similar bonding properties of anions [CpCo(1,3-C3B2R5)]− and [C5R5]− (R = H, Me) toward [M(ring)]+ cations were established both experimentally (synthesis, electrochemistry, and X-ray diffraction) and theoretically (energy decomposition and Mulliken population analysis).

Catalyst leaching from Pd and Ni particles stabilized by organic sulfur and selenium ligands occurs in solution in the presence of phosphanes. This process has been monitored in real time by 1D and 2D NMR spectroscopy and the nature of the metal species established. This catalyst leaching is shown to be a powerful tool for generating new catalytic activity from species formed in situ where the parent bulk particles are inactive. The catalytic system developed has been successfully implemented in a novel synthetic procedure that provides new types of cyclic sulfur and selenium compounds in high yields through the reaction between alkynes and dichalcogenides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The reaction of fluorosilanes XYSiF2 (X = Y = F; X = F, Y = Ph; X = Ph, Y = Me) with diethanolamines and their O-trimethylsilyl derivatives affords novel Si-fluoro substituted quasisilatranes 3, 5 and 9. These compounds were characterized by the multinuclear NMR spectroscopy and X-ray diffraction analysis. Experimental and theoretically calculated electron density distribution functions in crystal structure of 9 have shown that the N ? Si coordination bond corresponds to polar bond with pronounced ionic contribution. Calculated N ? Si bond order in the compound 9 does not exceed 1/3 of the normal Si–N bond. A strong N ? Si coordination bond exists in compounds 3, 5 and 9 the length of which varies in the range 1.98–2.175 A. 2008 Published by Elsevier B.V.

Reaction between the coordinated propanenitriles in trans-[PtCl4(EtCN)2] and the cyclic nitronate (1) gives the N-acylated iminocomplex (2) which is unstable in wet solvents and undergoes hydrolysis to furnish (3). The formulation of 2 and 3 was supported by satisfactory C, H, and N elemental analyses, agreeable HRESI+-MS, IR, 1H NMR spectroscopies, and single-crystal X-ray diffraction (for trans-3).

Compounds (299) containing 494 symmetrically independent pyridine-2,6-dicarboxylate moieties have been investigated. Among them the structures of Na3[Nd(Pydc)3]·14H2O and Na3[Er(Pydc)3]·11.5H2O, where H2Pydc is pyridine-2,6-dicarboxylic acid, were determined by single-crystal X-ray diffraction, while the others were taken from the Cambridge Structural Database. The characteristics of any complex by means of the `method of crystallochemical analysis' are described, and the coordination types of all the Pydc ions and crystallochemical formulae of all the compounds were determined. Although the ion can act as a mono-, bi-, tri-, tetra- and pentadentate ligand, 96% of Pydc ions are coordinated to the central A atom in the tridentate-chelating mode. The dependence of the denticity and geometry of pyridine-2,6-dicarboxylate, as well as of the composition of Pydc-containing complexes, was studied as a function of the nature of the A atom, the molar ratio Pydc:A and the presence of neutral or acidic ligands in the reaction mixture.

Co-crystallization of 1,2-bis(chloromercurio)tetrafluorobenzene (II) with nitrobenzene (1) and three nitrotoluene isomers (2−4) results in four complexes with a ratio of organometallic to organic components of 1:1 and one complex with a corresponding ratio of 2:1. All crystals of complexes with a 1:1 ratio have a platelike shape, while crystals of the complex with a 2:1 ratio are needlelike. X-ray studies reveal supramolecular organization in the 1:1 “plate” complexes, showing that they are built of molecular layers where the central section of layers is stabilized with nonbonded interactions of Hg atoms, while the layer surface is formed with phenyl rings of both co-crystal components. Two types of layer superposition in these complexes were found: parallel, producing an acentric structure, and antiparallel, that leads to a centrosymmetric space group. This indicates that supramolecular organization involving Hg nonbonded interactions in some cases will be helpful to produce acentric structures of polar ...

The molecular and crystal structures of low melting isomers of nitrotoluene (orto- and meta- derivatives) have been determined. The single crystals of o- and m-isomers have been grown using the miniature zone melting in situ crystallization technique. It is found that m-nitrotoluene undergoes on cooling an order−disorder phase transition from monoclinic to triclinic phase at about 200 K. X-ray diffraction analysis and quantum calculations on the MP2/6-31G** level show that all nitrotoluenes have similar structural parameters close to those found in toluene and nitrobenzene. In crystals of the isomers studied, molecules are linked in sheets by short N−O···H interactions.

Sublimation of sulflower, octathio[8]circulene C 16S 8 ( 1), on heating under high vacuum ( approximately 10 (-5) Torr) leads to successive formation of two modifications: a white film ( 1W) and a red polycrystalline solid ( 1R). When kept at room temperature for several weeks, 1W spontaneously turns pink, reflecting the monotropic phase transition 1W --1R. The accurate molecular and crystal structure of 1R has been studied using low-temperature (100 K) high-resolution single crystal X-ray analysis. The C 16S 8 molecule in crystal is strictly planar with nearly equalized bonds of each type (C-C, C-S, and CC). The point symmetry group of the free molecule is D 8 h , and the crystal space group is P2 1/ n. These data allowed group-theoretical analysis of vibrational normal modes to be accomplished. Investigation of the charge density distribution of 1R including Bader's AIM approach has revealed rather strong intermolecular S...S, S...C, and C...C interactions of charge transfer and pi-stacking types with overall lattice energy of 28.5 kcal/mol. The charge transfer due to the S...S interactions is the reason for the red coloration of 1R. The latter is reflected by its UV-vis spectrum exhibiting absorption bands in the visible region which are absent from that of 1W. Both modifications were studied comparatively by vibrational (Raman, IR) and electronic spectroscopies as well as XRD powder diffraction. All the results obtained are fully consistent and show that 1W is much less ordered than 1R with significantly weakened intermolecular interactions. Rationalizing of these results has led to an idea that 1W could be soluble, in contrast to 1R. Indeed, 1W appeared soluble in common solvents; this finding opens the way to the study of the chemistry of 1 and investigation of its electrooptical properties.

Bischelate complexes of germanium with different chelate rings were prepared by double transmetallation. The earlier reported (O,O)-chelate [from the reaction of trichloro(chloromethyl)germane and N,N-dimethyl-2-(trimethylsilyloxy)-2-phenylacetamide (1)], 2-[dichloro(chloromethyl)germyloxy]-N,N-dimethyl-2-phenylacetamide (2) was reacted with trimethylsilylamides, 2,2-dimethyl-3-trimethylsilylbenzo[2H]-1,3-oxazin-4-one (5, B–SiMe3) and 4-methyl-1-trimethylsilylquinolin-2-one (6, Q–SiMe3) resulting in mixed (O,O),(C,O)bischelate complexes, 2-[dichloro[(2,2-dimethyl-4-oxo-2H-benzo[e][1,3]oxazin-3(4H)yl)methyl]germyloxy]-N,N-dimethyl-2-phenylacetamide (7) and 2-[dichloro[(4-methyl-2oxoquinolin-1(2H)-yl)methyl]germyloxy]-N,N-dimethyl-2-phenylacetamide (8). Crystallographic analyses established pentacoordination of germanium in 2 and hexacoordination in 7 and 8; the latter two compounds are the first reported mixed (O,O), (C,O)-bischelate complexes with two O→Ge coordinate bonds.

An investigation of the crystal structures of 3346 silicon- and 718 germanium-containing compounds was carried out with a geometrical–topological analysis. The descriptors of inter- and intramolecular contactsA...Dare given. Information on the descriptors ofT—A...D(whereT= leaving group) interactions in terms of a stereoatomic model of crystal structures was described as being helpful in modelling SN2 reactions. It was established that the formation of multiple intermolecular contacts in crystal structures is unfavorable. The dependence of the descriptors of intermolecular contactsT—A...D was studied as a function of the nature ofT(leaving group in substitution reactions) andD(nucleophile atom or group of atoms) groups, and the coordination number of anAatom. The constancy of theT—AandA...Dbond-order sum in crystal structures was demonstrated.

In a search for cytotoxic fluorescent materials a series of N-alkylated and N,N-dialkylated 3,5-bis(arylidene)piperidones was synthesized. Alkylation of 3,5-bis(arylidene)-4-piperidone afforded quaternary salts only while condensation of N-alkyl-4-piperidones with substituted benzaldehydes was a convenient route to the corresponding N-alkylated compounds. Compounds and their pharmaceutically acceptable salts demonstrated high activity against resistant human lung carcinoma cell line A549 with IC50 values in the range of 0.3-6.5 μM.

Lewis base free hydrido complexes of yttrium and lutetium supported by bulky cyclohexyl- substituted guanidinato ligands, [Ln(mu-H){(Me3Si)(2)NC(NCy)(2)}(2)](2) (Ln = Y, Lu), were synthesized and characterized. Single-crystal X-ray diffraction studies revealed dimeric structures. H-1 NMR spectroscopy shows that complex [Y(mu-H){(Me3Si)(2)NC(NCy)(2)}(2)](2) retains its dimeric structure in C6D6 solution. Scrambling of the hydrido complexes [Ln(mu-H){(Me3Si)(2)NC(NCy)(2)}(2)](2) (Ln = Y, Lu) in C6D6 resulted in an equilibrium mixture containing the heterodimetallic species [{(Me3Si)(2)NC(NCy)(2)}(2)Y(mu-H)(2)-Lu{(Me3Si)(2)NC(NCy)(2)}(2)], indicating the dissociation of dimers and the presence of monomeric species in solution. Both compounds initiate the polymerization of ethylene: the activity of the cyclohexyl- substituted yttrium complex, [Y(mu-H){(Me3Si)(2)NC(NCy)(2)}(2)](2), is much lower than that of the isopropyl-substituted analogue, [Y(mu-H){(Me3Si)(2)NC(NiPr)(2)}(2))(2), while in the case of lutetium the activities of [Ln(mu-H){(Me3Si)(2)NC(NR)(2)}(2)](2) (R = iPr, Cy) are similar. Complexes [Ln(mu-H){(Me3Si)(2)NC(NR)(2)}(2)](2) (Ln = Y, Lu; R = iPr, Cy) were shown to catalyze efficiently the hydrosilylation of 1-nonene with PhSiH3 (at a 1:1 substrates mol ratio) to give the terminal silane PhSiH2(n-C9H19) exclusively. If the hydrosilylation reaction is carried out in the presence of a twofold molar excess of 1-nonene, double addition takes place and leads to the formation of tertiary silane PhSiH(n-C9H19)2, which was obtained in 96% yield. The hydrido complexes [Ln(mu-H){(Me3Si)(2)NC(NiPr)(2)}(2)](2) (Ln = Y, Lu) efficiently initiate the ring-opening polymerization of epsilon-caprolactone to give polymers with molar mass up to 80000. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).

We have developed two new catalytic systems based on Ni and Pd complexes to solve the challenging problem of dialkyldichalcogenide (Alk2E2; E=S, Se) addition to alkynes. A comparative study of two catalytic systems—Ni/PMe2Ph and Pd/PCy2Ph—has revealed that the Ni catalyst is superior with respect to high catalytic activity and more general scope relative to the Pd system. A novel synthetic methodology was developed for the preparation of (Z)-bis(alkylthio)alkenes and (Z)-bis(alkylseleno)alkenes from terminal alkynes with excellent stereoselectivity and high yields.

The molecular and crystal structure of three organogermanes Cl 3 GeCH 2 OC(O)R (where R = –NHC 6 H 11 , –C 10 H 15 , and –NH 2 ) has been determined by X-ray diffraction method in order to investigate geometrical regularities of these molecules. The nature of Ge–O bonding in these molecules was investigated by quantum chemistry method. It was shown that the influence of the nature of ligand, attached to carbon atom of the carbonyl group, on Ge⋯O interatomic distance is incidentally small in isolated molecule while in the crystal it is much more pronounced due to the crystal packing effect. The nature of Ge⋯O bonding corresponds to intermediate type of interatomic interaction in terms of “Atoms in molecules” theory.

A detailed analysis of monodentate and bidentate complexation of tris(pentafluorophenyl)silyl (TPFS) derivatives with neutral Lewis bases was performed. The NMR spectroscopy and X-ray diffraction analysis (11 structures) were the key methods to characterize tetra- or pentacoordinate silicon compounds, whereas the peculiarities of crystal packing were analyzed by means of DFT calculations. The interaction of TPFS-X (X = F, Cl, OTf) with strong Lewis bases (HMPA, N -methylpyrrolidinone) may afford three different species: neutral pentacoordinate TPFS(X)-L, cationic tetracoordinate TPFS-L + X − , and cationic pentacoordinate TPFS-(L) + 2 X − , representatives of each type were characterized by X-ray diffraction. A variety of complexes with bidentate complexation, featuring the trigonal bipyramidal geometry with apical C 6 F 5 -group was prepared and structurally characterized. The extent of Si–C apical bond elongation depends on the donating ability of the coordinating ligand, with the longest Si–C bond of 1.981(1) A observed for six-membered complex of TPFS-ether of N -(2-hydroxybenzoyl)pyrrolidine.

A tetranuclear KZn3 complex consisting of three tridentate dibasic N2O donor ligands (derived from mono-N-phenyl-substituted 5-nitro-o-phenylenediamine) and one methylato group has been synthesized. Single-crystal multi-temperature (100–350K) X-ray diffraction studies of the complex reveal that {[ZnL]3OMe}− units are assembled by K…ON2 contacts into layers. Mutual position of the KO6 and {[ZnL]3OMe}− fragments of neighboring layers is temperature dependent.

Cyclocondensation of aliphatic diamines with CH2O and H2S (1:3:2 ratio, 0 °C) was carried out to give thiadiazabicyclanes and dithiadiazabicyclanes (1:6:4 ratio), which were previously difficult to synthesize. Symmetric α,ω-bis-1,3,5-dithiazinanes were synthesized at 80 °C by this reaction. The stereochemistry of thiadiazabicyclanes was assigned by 1H and 13C NMR spectroscopy and by theoretical DFT calculations, and of bis-dithiazinanes by X-ray diffraction study in the solid state.