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After the Hindu-Arabic decimal positional system was introduced in Europe, throughout many centuries textbooks on elementary arithmetic, intended for beginners, had a more or less fixed organization of content, usually starting with chapters on numeration. These chapters, as a rule, contained one or more examples of large integers the purpose of which was simply to be named (read out loud), sometimes also vice versa. This tradition apparently began with the two first texts that significantly contributed to the spread of the decimal system in Europe--the Latin translations of al-Khwarizmi's treatise on decimal arithmetic, and Leonardo's Liber Abaci, containing examples of reading a 16-digit and a 15-digit number respectively. Throughout the centuries, the order of magnitude of these introductory numbers increased, in general up to some 30 digits, but in some cases to over 60 digits. In this paper we examine the development and extent of this characteristic of introductory arithmetic textbooks from the period 13th-19th century, and the conditions which lead to this, now extinct, practice. [ABSTRACT FROM AUTHOR]

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two‐dimensional (2D) hydrogen‐bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2− and [H3Fe(CN)6]− anions. The layers are further connected by hydrogen bonds, as well as through π–π stacking of phenazine moieties. Aside from the identical 2D hydrogen‐bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen‐bonded trimers and hexamers within the hydrogen‐bonded networks, which leads to different packing of the hydrogen‐bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry‐independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge‐assisted hydrogen bonding or π‐stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism. [ABSTRACT FROM AUTHOR]

In order to study halogenide anions simultaneously acting as hydrogen bond and halogen bond acceptors, we have prepared and crystallised halogenide salts (chlorides, bromides and iodides) of the three isomers of iodopyridine, 2-iodopyridine (2-IPy), 3-iodopyridine (3-IPy) and 4-iodopyridine (4-IPy). In all nine structures the pyridinium cations and the halogenide anions are interconnected through C–I⋯X− halogen and N–H⋯X− hydrogen bonds (X = Cl, Br, I). Based on the trend observed in the relative shortening of the two interactions, both halogen and hydrogen bonds seem to be decreasing in strength with the size of the halogenide anion, although the decrease is apparently more pronounced for hydrogen bonds. To study this further, we have performed a CSD study of structures comprising a halogenide and both hydrogen and halogen bond donors, which has indicated a tendency of chloride towards hydrogen and of iodide towards halogen bonds, in accord with our experimental results. Additionally, we have obtained crystals of ((2-IPyH)2 Cl I), the first example of a double salt comprising both hydrogen and halogen bond donors and two different halogenides. In this structure, the halogen bonds were formed exclusively with the iodide anion, while the hydrogen bonds were formed only with the chloride anion. [ABSTRACT FROM AUTHOR]

The effect of the choice of crystallisation solvent on the stoichiometry of salts formed by a spherical base (adamantylamine, pKa = 10.7) and a planar triprotic acid (trinitrophloroglucinol, pKa1 < 0, pKa2 = 2.9, pKa3 = 6.5) was studied by dissolving a 3 : 1 mixture of the base and the acid in a series of 13 solvents. This has resulted in isolation of 10 distinct phases: a solvent free 1 : 1 salt, and nine solvates – two of 2 : 1 salts, one of a 5 : 2 salt and six solvates of 3 : 1 salts. With the exception of one 2 : 1 salt, all structures were layered with a hydrogen bonded network comprising anions, –NH3+ groups of the cations, and oxygen atoms or hydroxyl groups of the solvent molecules (if present) in the middle of the layer, and the hydrophobic adamantyl groups on either side. In solvates of the 3 : 1 salts with alcohols, these adamantyl groups form arrays of pentagons with remaining space filled by solvent molecules. This was observed only with smaller alcohols (MeOH, EtOH, trifluoroethanol and propanol) as well as water molecules, while larger alcohols lead to formation of the solvent free 1 : 1 salt. The structures of the 1 : 1 and 2 : 1 salts were found to be similar to those of equivalent adamantylammonium picrate and styphnate. [ABSTRACT FROM AUTHOR]

We provide a systematic investigation of the structures and composition of halogen-bonded cocrystals involving the bent (meta) halogen bond donor 1,3-diiodotetrafluorobenzene (1,3-tfib), in comparison to analogous systems based on its linear (para) 1,4-isomer. In particular, whereas 1,4-tfib has now been established as an archetypal, ubiquitous example of a halogen bond donor, its meta-isomer has remained almost completely unexplored. This study investigates the structures of 14 new cocrystals of 1,3-tfib and 9 new, analogous cocrystals of 1,4-tfib, with 9 monotopic and 7 ditopic nitrogen-based aliphatic and aromatic halogen bond acceptors. Combined with previously reported structures of cocrystals of 1,4-tfib, the results of our study indicate that whereas halogen bond lengths and the thermal stability of the investigated cocrystals are similar, the change in molecular shape between the two halogen bond donors brings about important consequences in supramolecular architectures and preferred stoichiometric compositions of otherwise analogous cocrystals. These preliminary results suggest that the principal factor responsible for such differences might be the different abilities of the cocrystals based on 1,3-tfib and 1,4-tfib to form close-packed structures. [ABSTRACT FROM AUTHOR]

A systematic study of the possibility of controlling the formation of oxalatomolybdate anions by the choice of a counterion and adjustment of pH was presented. Using four CoIII(ammine) macrocations ([Co(NH3)6]3+, [Co(NO2)(NH3)5]2+, [Co(en)3]3+ and [Co(ox)(en)2]+) in acidic aqueous solutions, ten crystalline solids were obtained. They were found to contain a total of six different oxalatomolybdate species, three of which, a cyclic tetramer, [Mo2O4(μ-O)2(ox)2]28−, a linear tetramer [Mo4O8(μ-O)3(ox)4(H2O)2]6− and a polymer, [Mo4O11(ox)4(H2O)]n6n– have not been reported to date. The oxalatomolybdate species found in solids mostly do correspond with the predominant species in solution at the pH of the solution from which they were obtained. Condensation of those species can be correlated with the hydrogen bonding ability of the used macrocation, a complex cation of Co(iii). [ABSTRACT FROM AUTHOR]

Hexacyanoferrates are well-known to form metal-organic frameworks by coordination to metal atoms or acting as hydrogen bond acceptors. In this paper we report a new type of hexacyanoferrate self-assembly, based on direct hydrogen bonding of partially protonated hexacyanoferrate anions. By preparing a series of 15 hexacyanoferrates with various organic bases, we have found that protonated hexacyanoferrates (present in 10 structures) readily form chains (two structures), two-dimensional (four structures), or three-dimensional networks (four structures), whereby the dimensionality of the network generally increases with the protonation degree of the hexacyanoferrates. The exact mode of the self-assembly, including the network type, depends on fine interplay of the pKa value of the base, its steric properties, and the stoichiometry of the formed solid. [ABSTRACT FROM AUTHOR]

A series of 15 salts and cocrystals of an asymmetric aromatic-aliphatic dicarboxylic diacid, N-(2-carboxyphenyl)glycine, and pyridine derivatives was synthesized in order to study whether there is a preference of pyridine binding to either of the carboxylic groups. In nine structures the pyridine was bonded to the aliphatic group, in three to both carboxylic groups, and in three to the aromatic group alone. The preference of pyridine derivatives to bond to the aliphatic group correlates with the more positive electrostatic potential on the aliphatic carboxyl hydrogen atom. The occurrence of proton transfer within the structures was found to follow the basicity of the pyridine derivative, four of the least basic pyridines forming cocrystals, two intermediate bases solids with proton disorder and the more basic pyridine derivatives salts. Proton transfer had a considerable effect on the crystal packing, cocrystals mostly comprising discrete molecular complexes, and salt chains of monoanions. [ABSTRACT FROM AUTHOR]

The reactions of N -arylalkyl derivatives of iminodiacetamide (Bnimda, Peimda, Ppimda; Bn = benzyl, Pe = 2-phenylethyl; Pp = 3-phenylprop-1-yl) with copper(II) sulfate and sodium perchlorate in aqueous solutions were investigated. Three new copper(II) complexes [Cu(Bnimda) 2 ](ClO 4 ) 2 ( 1 ), [Cu(Peimda) 2 ](ClO 4 ) 2 ( 2 ) and [Cu(Ppimda) 2 ](ClO 4 ) 2 ·2H 2 O ( 3 ) were prepared and characterized by infrared spectroscopy and thermal analysis (TG/DTA). Complex 2 was found to be explosive upon heating. The octahedral coordination environments around the copper(II) ions in complexes 1 and 3 consist of two O , N , O ′-tridentate N -arylalkyliminodiacetamide ligands, with imino N atoms in trans -position. Molecules are interconnected by extensive hydrogen bonding between the amide moieties and perchlorate ions or water molecules, forming 3D networks in both structures. However, the difference in the hydrophobic chain lengths leads to significant differences in the hydrogen bonding motifs in the two structures. The molecular geometry and infrared spectra of these complexes were also studied by DFT calculations using B3LYP/6-311G(d,p) computational model. The calculated spectra and molecular geometry agree very well with the experimental results despite the extensive hydrogen bonding frameworks which are present in the crystal structures of these compounds. [ABSTRACT FROM AUTHOR]

A study of strong halogen bonding within three series of halogen-bonded complexes, derived from seven para-substituted pyridine derivatives and three N-halosuccinimides (iodo, bromo and chloro), has been undertaken with the aid of single-crystal diffraction, solution complexation and computational methods. The halogen bond was compared with the hydrogen bond in an equivalent series based on succinimide. The halogen-bond energies are in the range −60 to −20 kJ mol−1 and change regularly with pyridine basicity and the Lewis acidity of the halogen. The halogen-bond energies correlate linearly with the product of charges on the contact atoms, which indicates a predominantly electrostatic interaction. The binding enthalpies in solution are around 19 kJ mol−1 less negative due to solvation effects. The optimised geometries of the complexes in the gas phase are comparable to those of the solid-state structures, and the effects of the supramolecular surroundings in the latter are discussed. The bond energies for the hydrogen-bonded series are intermediate between the halogen-bond energies of iodine and bromine, although there are specific differences in the geometries of the halogen- and hydrogen-bonded complexes. [ABSTRACT FROM AUTHOR]

Two salts of tetrachloro- (chloranil, Cl4Q) and tetrabromosemiquinone (bromanil, Br4Q) radical anions with an organic cation N-methylpyridinium (N-MePy), displaying a variety of tunable electrical and magnetic properties, are characterized. These systems comprise π-stacks of equidistant semiquinone radical anions, without Peierls deformation and diamagnetic spin coupling. Both are stable up to 150 and 120 °C in air, respectively, and are semiconductors with conductivities of 10-6-10-7 (Ω cm)−1 in the single crystals. The room-temperature concomitant crystallization of two polymorphs with different magnetic properties (antiferromagnetic and Peierls-distorted diamagnetic) has been observed for Cl4Q·N-MePy. The semiquinone radical organic salts represent a novel class of potential (multi)functional materials with tunable properties. [ABSTRACT FROM AUTHOR]

The reactions of substituted N-benzyliminodiacetamides (o-CH3Bnimda, m-CH3Bnimda, p-CH3Bnimda, o-ClBnimda, m-ClBnimda, p-ClBnimda, p-FBnimda, and p-BrBnimda; o-CH3Bn = ortho-methylbenzyl, m-CH3Bn = meta-methylbenzyl, p-CH3Bn = para-methylbenzyl, o-ClBn = ortho-chlorobenzyl, m-ClBn = meta-chlorobenzyl, p-ClBn = para-chlorobenzyl, p-FBn = para-fluorobenzyl, and p-BrBn = para-bromobenzyl) with copper(ii) and nickel(ii) nitrate in aqueous solutions were investigated. Sixteen new complexes [Cu(o-CH3Bnimda)2](NO3)20.5H2O (1), [Cu(m-CH3Bnimda)2](NO3)2 (2), [Cu(p-CH3Bnimda)2](NO3)2•2H2O (3), [Cu(o-ClBnimda)2](NO3)2H2O (4), [Cu(m-ClBnimda)2](NO3)2 (5), [Cu(p-ClBnimda)2](NO3)2•2H2O (6), [Cu(p-FBnimda)2](NO3)2•2H2O (7), [Cu(p-BrBnimda)2](NO3)2•2H2O (8), [Ni(o-CH3Bnimda)2](NO3)2H2O (9), [Ni(m-CH3Bnimda)2](NO3)2•2H2O (10), [Ni(p-CH3Bnimda)2](NO3)2H2O (11), [Ni(o-ClBnimda)2](NO3)2 (12), [Ni(m-ClBnimda)2](NO3)22DMF (13) (DMF = N,N-dimethylformamide), [Ni(p-ClBnimda)2](NO3)2•2H2O (14), [Ni(p-FBnimda)2](NO3)2H2O (15), and [Ni(p-BrBnimda)2](NO3)2•2H2O (16) were prepared and characterized by infrared spectroscopy and thermal analysis (thermogravimetric and differential thermal analyses). The molecular and crystal structures of three complexes (2, 5, and 13) were determined by X-ray crystal structure analysis. The octahedral coordination environments around the copper(ii) and nickel(ii) ions in complexes 2, 5, and 13 consist of two O,N,O'-tridentate iminodiacetamide ligands. The complexes are trans-isomers with fac-configuration of the chelators. [ABSTRACT FROM AUTHOR]

Three solid materials, [Pb( HL)(SCN)2] ⋅CH3OH ( 1), [Pb( HL)(SCN)2] ( 2), and [Pb( L)(SCN)] n ( 3), were obtained from Pb(SCN)2 and an unsymmetrical bis-pyridyl hydrazone ligand that can act both as a bridging and as a chelating ligand. In all three the lead center is hemidirectionally coordinated and is thus sterically optimal for participation in tetrel bonding. In the crystal structures of all three compounds, the lead atoms participate in short contacts with thiocyanate sulfur or nitrogen atoms. These contacts are shorter than the sums of the van der Waals radii (3.04-3.47 Å for Pb ⋅⋅⋅S and 3.54 Å for Pb ⋅⋅⋅N) and interconnect the covalently bonded units (monomers, dimers, and 2D polymers) into supramolecular assemblies (chains and 3D structures). DFT calculations showed these contacts to be tetrel bonds of considerable energy (6.5-10.5 kcal mol−1 for Pb ⋅⋅⋅S and 16.5 kcal mol−1 for Pb ⋅⋅⋅N). A survey of structures in the CSD showed that similar contacts often appear in crystals of PbII complexes with regular geometries, which leads to the conclusion that tetrel bonding plays a significant role in the supramolecular chemistry of PbII. [ABSTRACT FROM AUTHOR]

In this study, neutral mercury(ii) complexes of the composition [Hg(L1)(μ-Cl)2Hg3Cl6]n (1), [Hg(L1)(μ-Br)2HgBr2] (2), [Hg(L3)Br2] (2a), [Hg(L1)I2] (3), [Hg(L2)Cl2]·CH3OH (4) and [Hg(L2)(μ-Br)HgBr3]2 (5) (L1 = benzilbis((pyridin-2-yl)methylidenehydrazone); L2 = benzilbis((acetylpyridin-2-yl)methylidenehydrazone)) are described. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending upon the anion coordinated to the metal centre. Iodide gives discrete monomeric complexes, bromide generates a 1D coordination polymer formed through Hg–Br–Hg bridges and chloride gives rise to an inorganic–organic hybrid material. The significant differences in the reaction conditions indicate that the anions exert a substantial influence on the formation of the compounds – smaller anions show a larger potential for bridging metal ions and forming coordination polymers. A minute increase in the bulkiness of the ligand (two extra methyl substituents in L2) dramatically changes the coordination architectures, and leads to the formation of monomeric (chloride and iodide) and oligomeric (bromide) structures, rather than polymeric structures. The noncovalent C–H/π and π-hole interactions observed in the solid state architecture of some complexes have been rationalized by means of theoretical DFT calculations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Five 1,3,3′-triketones derived from dipivaloylmethane have been prepared. [•] Both in the solid and in solution no enol tautomers were detected for any of the compounds. [•] Slow isotopic exchange in CD3OD solution indicates presence of a minute amount of the enol. [•] The predominance of the triketo tautomer is attributed to steric hindrance in enol molecules. [ABSTRACT FROM AUTHOR]

2012/2013 mark the 100th anniversary of von Laue's diffraction of X‐rays from single crystals of copper sulfate, the postulation of Bragg's law, and the solution of the first X‐ray structure. However, even before 1912, the study of crystals was an integral part of chemistry and it played a major role in development of modern chemical science, including key concepts such as atoms, molecules, isomerism, and chirality. [ABSTRACT FROM AUTHOR]

In die Jahre 2012 und 2013 fallen die 100. Jahrestage der Röntgenbeugung an Kupfersulfat ‐ Einkristallen durch Laue, der Postulierung des Braggschen Gesetzes sowie der ersten Strukturbestimmung mit Röntgenmethoden. Die Beschäftigung mit Kristallen war jedoch schon vor 1912 ein integraler Bestandteil der Chemie und trug wesentlich zu ihrer Entwicklung als moderne Wissenschaft, zu Konzepten wie Atom, Molekül, Isomerie und Chiralität bei. [ABSTRACT FROM AUTHOR]

In order to study the effects of intramolecular hydrogen bonding on coordination geometry of a relatively rigid octahedral system, eight coordination compounds derived from bis(benzoylacetonato)manganese(ii) and seven pyridine derivatives (three of them o-aminopyridines) were prepared. Four compounds in which intramolecular hydrogen bonds could not be formed are centrosymmetric with similar lengths of equivalent Mn–L bonds. When o-aminopyridines were employed, an intramolecular hydrogen bond was always formed. In the case of two compounds this led only to minor changes of molecular geometry, while in the other two the coordination complex was changed from a centrosymmetric all-trans configuration to a molecule with cis-configuration of pyridine ligands and of pseudo C2 symmetry. This change was found to affect not only the bond lengths of the coordination molecule, but also to allow for a much better crystal packing as it enabled a closer hydrogen bonding contact between adjacent molecules. [ABSTRACT FROM AUTHOR]

Abstract: The paper describes F. Steindlʼs textbook Institutiones Arithmeticae [1778], the first official mathematics textbook of the Hungarian part of the Habsburg Empire after the reforms of the education system in the 1770s. The textbook includes a detailed description of reckoning methods and their practical applications, illustrated exclusively by “problems in context”. It also includes many instructions for the teacher, making it an early example of a mathematics textbook paying attention to pedagogy. [Copyright &y& Elsevier]

A studyof a solid state phase transition in dipivaloyl(3-cyclopentylpropanoyl)methanewas undertaken by a combination of crystallographic and calorimetricmethods. The high temperature polymorph with two molecules in theasymmetric unit and a disordered cyclopentyl group undergoes a reversiblephase transition into an ordered structure with a single moleculein the asymmetric unit. The transition temperature is −20.80°C with a minimal hysteresis of 1 °C. The nucleation ofthe new phase was followed by differential scanning calorimetry andoccurs in a wide temperature range starting from ca. 0.5 °C aboveand below the transition temperature, and the crystallographic orientationof the crystals of the nascent phase is to a high degree in agreementwith that of the parent crystal. [ABSTRACT FROM AUTHOR]

A survey of the Cambridge Structural Database (CSD) revealed the existence of a new supramolecular homosynthon in oxovanadium coordination compounds (OCCs) that is based on non-covalent V=O…C interactions. V=O…C close contacts were found in 38.7% of structures containing vanadyl or pervanadyl groups. The V=O…C interaction is clearly distinguishable from a putative V=O…H–C hydrogen bond upon analysis of OCC crystal structures deposited in the CSD. In the majority of structures, the OCCs assemble to form dimers or polymers. The V=O…C interactions were also found to lead to self-assembly of two new oxovanadium β-diketonate complexes into dimers in the solid state. [ABSTRACT FROM AUTHOR]

A Schiff base dicarboxylic acid (1) was prepared by condensation of 2-hydroxy-1- naphthaldehyde with 5-aminoisophthalic acid. Its solvates with pyridine (2a and 2b) and dimethylformamide (3) were prepared by liquid-assisted grinding and by conventional solvent-based methods. All products were characterised by FT-IR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The structures of 1, 2b and 3 were determined by single crystal X-ray diffraction. 1 was found to be a pure Schiffbase, 2b a pyridine solvate and 3 a dimethylformamide solvate monohydrate. In all three structures, the Schiff base molecule appears to be present as the ketoamine tautomer. [ABSTRACT FROM AUTHOR]

A series of 22 salts and co-crystals of gentisic acidand pyridinederivatives were synthesized and their crystal structures were studiedby X-ray diffraction. The proton transfer was found to to be absentwhen the difference in pKavalues wasbelow 2, and it always occurred when it was above 2.5. The hydrogenbonds between the carboxylic group and pyridine nitrogen atom werefound in all structures but one. These hydrogen bonds are shorterand apparently stronger in co-crystals than in salts. In the structuresof salts the most significant intermolecular interaction is hydrogenbonding between anions, usually leading to chains or dimers, whereasin co-crystals the direct bonding between neutral gentisic acid moleculesis mostly absent. Using 4,4′-bipyridine, two desmotropes wereobtained in which the difference in hydrogen bonding of gentisic acidmolecules leads to different protonation in two structures. [ABSTRACT FROM AUTHOR]

The calix[4]arene secondary-amide derivative L was synthesized, and its complexation with alkali-metal cations in acetonitrile (MeCN) was studied by means of spectrophotometric, NMR, conductometric, and microcalorimetric titrations at 25 °C. The stability constants of the 1:1 (metal/ligand) complexes determined by different methods were in excellent agreement. For the complexation of M+ (M = Li, Na, K.) with L, both enthalpic and entropie contributions were favorable, with their values and mutual relations being quite strongly dependent on the cation. The enthalpic and overall stability was the largest in the case of die sodium complex. Molecular and crystal structures of free L, its methanol and MeCN solvates, the sodium complex, and its MeCN solvate were determined by single-crystal X-ray dim-action. The inclusion of a MeCN molecule in the calixarene hydrophobic cavity was observed both in solution and in the solid state. This specific interaction was found to be stronger in the case of metal complexes compared to the free ligand because of the better preorganization of the hydrophobic cone to accept the solvent molecule. Density functional theory calculations showed that the flattened cone conformation (C2 point group) of L was generally more favorable than the square cone conformation (C4 point group). In the complex with Na+, L was in square cone conformation, whereas in its adduct with MeCN, the conformation was slightly distorted from the full symmetry. These confonnations were in agreement with those observed in the solid state. The classical molecular dynamics simulations indicated that the MeCN molecule enters the L hydrophobic cavity of both the free ligand and its alkali-metal complexes. The inclusion of MeCN in the cone of free L was accompanied by the conformational change from C2 to C4 symmetry. As in solution studies, in the case of ML+ complexes, an allosteric effect was observed: the ligand was already in the appropriate square cone conformation to bind the solvent molecule, allowing it to more easily and faster enter the calixarene cavity [ABSTRACT FROM AUTHOR]

Morpholine adducts of nickel(II), cobalt(II), and manganese(II) benzoylacetonates, as well as a morpholine solvate of manganese(II) benzoylacetonate, were prepared and characterized by X-ray diffraction and thermal analysis. All four compounds crystallize in the P2/ c space group with two complex molecules per unit cell. The morpholine solvate, along with the two adduct molecules, also contains four solvent morpholine molecules in the unit cell. The non-solvate compounds are isostructural, with crystal structures comprising 2D networks formed by C-H···O hydrogen bonding between phenyl rings and morpholine oxygen atoms. The topology of these networks can be described as intersecting C(24) chains forming R(48) rings. Networks with the same topology are also present in the solvate, but they are heavily distorted due to the presence of solvent morpholine molecules. Thermogravimetric analysis shows similar behavior of the non-solvate compounds upon thermal decomposition, with three degradation steps which can be related to gradual loss of morpholine molecules and subsequent overall decomposition. Decomposition of the solvate also proceeds in several steps, the first of which can be related to loss of solvent morpholine molecules and the further steps are analogous to those in the non-solvate compounds. [ABSTRACT FROM AUTHOR]

Abstract: Novel derivatives of isoindoline, N-phenyl-1-iminophenylisoindoline 6, N-(4-methylphenyl)-1-imino-(4-methylphenyl)-isoindoline 7, N-(pyridin-2-yl)-1-imino-(pyridin-2-yl)-isoindoline 8 and N-(5-methylpyridin-2-yl)-1-imino(5-methylpyridin-2-yl)-isoindoline 9 were prepared by the reaction of condensation of phthalaldehyde and corresponding amines. Structures of all compounds have been studied using one- and two-dimensional 1H and 13C NMR, IR, MS and UV/Vis spectroscopy. The crystal and molecular structures of 7, 8 and 9 were determined by X-ray diffraction on single crystals. In all three molecules the isoindoline system and its N-substituent are approximately coplanar. The crystal structures comprise of discrete molecules linked only by weak C–H⋯N interactions in the case of 8 and 9. NMR analysis showed that conformations of compounds 6 and 7 differ from those of 8 and 9 in solution. Differences between solution and solid state structures were also noticed. All prepared compounds were tested on their antiproliferative activity in vitro. Compound 7 exerted the strongest non-specific antiproliferative effect on all cell lines and compounds 8 and 9 showed selective antiproliferative effect on HepG2 cell line. [Copyright &y& Elsevier]

Tetrakis(benzoylacetonato)cerium(IV), [Ce(bzac)4] and triethylammonium tetrakis(benzoylacetonato)lanthanate(III) tetrahydrate, [Et3NH][La(bzac)4] · 4H2O were prepared and characterized by TG and DCS measurements, IR spectroscopy, and X-ray structure analysis. The coordination polyhedron of cerium is a trigonal dodecahedron, while that of lanthanum is a distorted square antiprism. Thermal and spectroscopic measurements indicate that bonding of the ligand to metal is stronger in [Ce(bzac)4] than in [La(bzac)4]-. [ABSTRACT FROM AUTHOR]

Two novel potential bridging ligands derived from terephtaldialdehyde, namely 1,4-bis((pyridine-3-ylimino) methyl)benzene (1) and 1,4-bis-((1-benzylpiperidin-4-ylimino)methyl)benzene (2), were prepared by the Schiff base condensation. They were characterised by means of IR spectroscopy, thermal analysis and also by powder and singlecrystal X-ray diffraction. The molecules of 1 form 1D chains by intermolecular C-H⋯N interactions. The molecular conformation of 2, governed by intramolecular C-H⋯N interactions, does not permit formation of intermolecular interactions analogous to those in 1. As a consequence, 2 has a markedly lower melting point and fusion enthalpy than 1, although its molecular weight is almost double that of 1. [ABSTRACT FROM AUTHOR]

The first three morpholine- N -carboxylate complexes, with copper(II) and zinc(II) have been prepared and studied by single crystal X-ray diffraction. All three compounds comprise of discrete mono- or dinuclear heteroleptic complex molecules. Three different ways of bonding of morph COO– anions have been observed – as a monodentate, chelating, and as a bridging ligand. In all cases only the carboxyl group of the morpholinecarboxylate anion was found to bind to the metal cation, while the oxygen atom of the morpholine ring participates only in weak C–H‧‧‧O hydrogen bonds. Changes in the geometry of the coordinated morph COO– anion relative to the free ligand (in its morpholinium salt) were observed in all three modes of binding to the metal center. Image 1 • Morpholinecartboxylate has been successfully employed as a ligand. • Its complexes with Cu(II) and Zn(II) have been synthesized and studied. • It always coordinates metal atoms solely with the carboxylate oxygen atoms. • It can coordinate as a monodentate, chelating or a bridging ligand. [ABSTRACT FROM AUTHOR]

Seven tetraammineoxalatocobalt(III) salts with oxomolybdate anions of different nuclearities, such as [Co(C2O4)(NH3)4]2[MoO4]·H2O (1), [Co(C2O4)(NH3)4]2[Mo2O4(μ-O)(C2O4)2(H2O)2]·4H2O (3), Na2[Co(C2O4)(NH3)4]2[Mo2O4(μ-O)2(C2O4)2]·4H2O (4), [Co(C2O4)(NH3)4]4[Mo3O6(μ-O)2(C2O4)3(H2O)2]·5H2O (5), [Co(C2O4)(NH3)4]4[Mo8O26]·12H2O (8), [Co(C2O4)(NH3)4]4[SiMo12O40]·6H2O (9) and [Co(C2O4)(NH3)4]4[Mo8O26]·10H2O (10), along with [Mo5Co2O17(HCO3)(H2C3O4H)(NH3)7]·5H2O (6) and [Mo5Co2O18(NH3)7]·5H2O (7), were isolated using a one-pot reaction of sodium molybdate with [Co(C2O4)(NH3)4]NO3·H2O or [Co(CO3)(NH3)4]NO3· H2O and mono- or dicarboxylic acids in an aqueous medium. Polyoxomolybdate anions are built up from {MoO4}, {Mo2O4(μ-O)}, {Mo2O4(μ-O)2}, {Mo3O6(μ-O)2}, {Mo5O17}, {Mo5O18}, {Mo8O26} and {SiMo12O40} units, respectively, depending on the nature of the carboxylic acid additive used in the synthesis. The isolation of these salts confirmed that the carboxylic acids act not only as ligands, primarly, but also as structure-directing agents in the polyoxoanion self-assembly processes. All products were characterized in the solid state via single-crystal and powder X-ray diffraction, infrared spectroscopy as well as thermogravimetric and elemental analyses. [ABSTRACT FROM AUTHOR]

In order to examine the possibility of controlling formation of hydrogen bonded hexacyanoferrous networks through combination of hydrogen and halogen bonding, seven new crystalline compounds were obtained by reacting hexacyanoferrous acid (H4[Fe(CN)6]) with seven halogenopyridines. The (protonated) halogenopyridines were present in all seven obtained solids, and the extent in which they participate in halogen bonding varied with the halogen atom (Cl, Br and I) and the geometry of the halogenopyridines (o-, m- or p-). Iodopyridines have been found to always form halogen bonds with the cyano groups of the anions, while neither chloropyridine used in this study was found to act as a halogen bond donor. Of the prepared solids, four comprise hydrogen bonded hexacyanoferrate networks achieved by direct binding of H2[Fe(CN)6]2− and H3[Fe(CN)6]− anions through [Fe–CN⋯H⋯NC–Fe] hydrogen bonds into 2D and 3D networks respectively, two are formed from H2[Fe(CN)6]2− anions bridged by water molecules, and one from [Fe(CN)6]4− anions bridged by H3O+ cations. This variability in hydrogen bonding patterns can be brought into connection with different halogen bonding proclivities of the halopyridinium cations. [ABSTRACT FROM AUTHOR]

Halogen and hydrogen bonding were compared in the solid state, solution, and gas phase in three series of halogen ‐ bonded complexes derived from p ‐ substituted pyridine derivatives and 3 N ‐ halosuccinimides (iodo ‐ , bromo ‐ , and chloro ‐ ; NIS, NBS, and NCS) and an equivalent series of hydrogen ‐ bonded complexes of succinimide. The bond energies for the halogen bonds increase with the basicity of the base and Lewis acidity of the halogen, while the hydrogen bond energies are intermediate between those in complexes of NIS and NBS. More information can be found in the Full Paper by V. Stilinović, et al. on page 5244 ff. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue are Vladimir Stilinović and co-workers from the University of Zagreb. The image depicts the winners of the race for the strongest supramolecular interaction. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

In this work, we describe novel halogen bonded o-vanillin imine cocrystals. As cocrystal coformers, we selected perfluorinated diiodobenzenes, 1,2-, 1,3- and 1,4-diiodotetrafluorobenzene, as halogen bond donors. To explore the halogen bonding proclivity of the o-vanillin ortho-methoxy–hydroxy group, two imines were produced by condensation of o-vanillin with amines containing hydrophobic residues that have no additional potential halogen bond acceptor sites other than the o-vanillin oxygen atoms. We have prepared four cocrystals by both one-pot three-component solvent-free synthesis and the conventional solution-based method. The results of our work show that the ortho-methoxy–hydroxy group of the o-vanillin moiety is a good halogen bond acceptor and is capable of forming predictable halogen-bonded synthons. In the studied cocrystal structures, a wide range of varieties of this synthon were observed, including bonds with a single acceptor (either the methoxy O atom – in two structures, or the hydroxy O atom – in one), ‘slightly bifurcated’ bonds with a dominant (hydroxy) and ancillary (methoxy) acceptor, and a geometrically unusual asymmetrical bifurcated bond. [ABSTRACT FROM AUTHOR]

We present a Cambridge Structural Database and experimental study of multicomponent molecular crystals containing bromine. The CSD study covers supramolecular behaviour of bromide and tribromide anions as well as halogen bonded dibromine molecules in crystal structures of organic salts and cocrystals, and a study of the geometries and complexities in polybromide anion systems. In addition, we present four case studies of organic structures with bromide, tribromide and polybromide anions as well as the neutral dibromine molecule. These include the first observed crystal with diprotonated phenazine, a double salt of phenazinium bromide and tribromide, a cocrystal of 4-methoxypyridine with the neutral dibromine molecule as a halogen bond donor, as well as bis(4-methoxypyridine)bromonium polybromide. Structural features of the four case studies are in the most part consistent with the statistically prevalent behaviour indicated by the CSD study for given bromine species, although they do exhibit some unorthodox structural features and in that indicate possible supramolecular causes for aberrations from the statistically most abundant (and presumably most favourable) geometries. [ABSTRACT FROM AUTHOR]

The reactions of N -benzyliminodiacetic acid (BnidaH 2 ) and N -( para -nitrobenzyl)iminodiacetic acid ( p -NO 2 BnidaH 2 ) with cobalt(II) and nickel(II) acetate in aqueous solutions were performed. Three new complexes [Co(Bnida)(H 2 O) 3 ]·H 2 O ( 1a ·H 2 O), [Co( p -NO 2 Bnida)(H 2 O) 3 ]·½H 2 O ( 2a ·½H 2 O) and [Ni( p -NO 2 Bnida)(H 2 O) 3 ]·½H 2 O ( 2b ·½H 2 O) were prepared and characterized by infrared spectroscopy and thermal analysis (TG/DTA). The molecular and crystal structures of 1a ·H 2 O and 2b ·½H 2 O were determined by X-ray crystallography. The octahedral coordination environments around the Co(II) ion in 1a and Ni(II) ion in 2b consist of an O , N , O ′-tridentate N -arylalkyliminodiacetate ion and three water molecules, resulting in the formation of fac -isomers in both cases. The molecular geometry and infrared spectra of these three complexes, together with previously synthesized and characterized complex [Ni(Bnida)(H 2 O) 3 ]·H 2 O ( 1b ·H 2 O) are studied by DFT calculations using BP86/6-311G(d,p) and mPW1PW91/6-311G(d,p) computational model. [ABSTRACT FROM AUTHOR]

The title compound, C14H18O4, comprises discrete centrosymmetric molecules. The crystal structure is stabilized by intermolecular contacts of the type C—H...O. [ABSTRACT FROM AUTHOR]

This work presents a successful application of a recently reported supramolecular strategy for stabilization of metastable tautomers in cocrystals to monocomponent, non-heterocyclic, tautomeric solids. Quantum-chemical computations and solution studies show that the investigated Schiff base molecule, derived from 3-methoxysalicylaldehyde and 2-amino-3-hydroxypyridine ( ap), is far more stable as the enol tautomer. In the solid state, however, in all three obtained polymorphic forms it exists solely as the keto tautomer, in each case stabilized by an unexpected hydrogen-bonding pattern. Computations have shown that hydrogen bonding of the investigated Schiff base with suitable molecules shifts the tautomeric equilibrium to the less stable keto form. The extremes to which supramolecular stabilization can lead are demonstrated by the two polymorphs of molecular complexes of the Schiff base with ap. The molecules of both constituents of molecular complexes are present as metastable tautomers (keto anion and protonated pyridine, respectively), which stabilize each other through a very strong hydrogen bond. All the obtained solid forms proved stable in various solid-state and solvent-mediated methods used to establish their relative thermodynamic stabilities and possible interconversion conditions. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of dehydroacetic acid and p-phenylenediamine afforded a monosubstituted Schiff base, I, with the other amino group free. In further reactions with various salicylaldehyde derivatives, I served as a precursor for synthesis of asymmetric bis-Schiff bases. The synthesized compounds are thus comprised of two subunits, dehydroacetic (dha) and salicylidene (sal), which are bridged by the phenylene linker. All products were investigated by means of elemental analysis, FT-IR and NMR spectroscopy, thermal methods, powder X-ray diffraction and, when possible, by single crystal X-ray crystallography. Structural and spectroscopic studies revealed that in the bis-products, the dha subunit adopts the keto–amino tautomeric form, while the sal subunit adopts the enol–imino form. Tautomeric forms were not affected if a methoxo group was introduced on the salicylidene ring. Both tautomeric subunits are stabilized by strong resonance-assisted hydrogen bonds, RAHB. The two subunits of the prepared bis-Schiff bases predominantly retain in solution the same tautomeric forms as found in the solid state. [ABSTRACT FROM AUTHOR]

Over the past several decades, halogen bonding has become a standard 'tool' in supramolecular chemistry and particularly in crystal engineering. Traditionally, the study of halogen bonding has primarily been focused on organic materials, but lately there has been a constant increase in interest for halogen-bonded metal–organic materials. Numerous reports and reviews dealing with halogen bonding in single-component metal–organic solids and metallate salts have been published to date. In contrast, the design of multi-component crystals involving neutral metal–organic complexes and/or neutral halogen bond donors as building blocks has been much less explored. The purpose of this paper is to give an overview of the current advances in the preparation of halogen-bonded metal–organic multi-component solids, including salts, cocrystals comprising neutral constituents as well as cocrystals comprising ionic constituents. In doing so, we shall outline the general design strategies which can be employed in the design of such materials, and suggest possible directions for further research in this fascinating field. [ABSTRACT FROM AUTHOR]

A series of seven novel salts of tetrachloro- and tetrabromosemiquinone radical anions with organic cations is prepared and structurally characterised by single-crystal X-ray diffraction. Four types of stacks of radical anions have been identified: i) stacks of pancake-bonded dimers (Peierls-distorted stacks), ii) stacks of pancake-bonded trimers, iii) stacks of equidistant radicals and iv) a novel type of equidistant stacks of partially charged radicals (charge: −1/2, imposed by a stoichiometry of 1 : 2). Cations play an important role in stabilisation of the stacks of radical anions; the structures with stacks of equidistant radicals include columns of cations. However, the structures having pancake-bonded dimers and trimers are accompanied by isolated pairs of cations. [ABSTRACT FROM AUTHOR]

The covalent nature of strong N−Br⋅⋅⋅N halogen bonds in a cocrystal (2) of N‐bromosuccinimide (NBS) with 3,5‐dimethylpyridine (lut) was determined from X‐ray charge density studies and compared to a weak N−Br⋅⋅⋅O halogen bond in pure crystalline NBS (1) and a covalent bond in bis(3‐methylpyridine)bromonium cation (in its perchlorate salt (3). In 2, the donor N−Br bond is elongated by 0.0954 Å, while the Br⋅⋅⋅acceptor distance of 2.3194(4) is 1.08 Å shorter than the sum of the van der Waals radii. A maximum electron density of 0.38 e Å−3 along the Br⋅⋅⋅N halogen bond indicates a considerable covalent contribution to the total interaction. This value is intermediate to 0.067 e Å−3 for the Br⋅⋅⋅O contact in 1, and approximately 0.7 e Å−3 in both N−Br bonds of the bromonium cation in 3. A calculation of the natural bond order charges of the contact atoms, and the σ*(N1−Br) population of NBS as a function of distance between NBS and lut, have shown that charge transfer becomes significant at a Br⋅⋅⋅N distance below about 3 Å. [ABSTRACT FROM AUTHOR]

The covalent nature of strong N−Br⋅⋅⋅N halogen bonds in a cocrystal (2) of N‐bromosuccinimide (NBS) with 3,5‐dimethylpyridine (lut) was determined from X‐ray charge density studies and compared to a weak N−Br⋅⋅⋅O halogen bond in pure crystalline NBS (1) and a covalent bond in bis(3‐methylpyridine)bromonium cation (in its perchlorate salt (3). In 2, the donor N−Br bond is elongated by 0.0954 Å, while the Br⋅⋅⋅acceptor distance of 2.3194(4) is 1.08 Å shorter than the sum of the van der Waals radii. A maximum electron density of 0.38 e Å−3 along the Br⋅⋅⋅N halogen bond indicates a considerable covalent contribution to the total interaction. This value is intermediate to 0.067 e Å−3 for the Br⋅⋅⋅O contact in 1, and approximately 0.7 e Å−3 in both N−Br bonds of the bromonium cation in 3. A calculation of the natural bond order charges of the contact atoms, and the σ*(N1−Br) population of NBS as a function of distance between NBS and lut, have shown that charge transfer becomes significant at a Br⋅⋅⋅N distance below about 3 Å. [ABSTRACT FROM AUTHOR]

Ageing a mixture of sodium molybdate, malonic acid, and tris(ethylenediamine)cobalt(iii) chloride using different synthetic routes, namely, solution-based methods at room temperature or 110 °C, and a mechanochemically accelerated vapour-assisted method, yielded the polyoxomolybdate [Co(en)3]5Na[Mo7O24(μ-Mo8O26)Mo7O24]·nH2O (1). The new polyoxomolybdate anion 1 comprised three fragments, namely, two {Mo7O24} units bridged by a {Mo8O26} unit, which were interconnected by the terminal oxygen atoms of MoO6 octahedra and represent a unique structural motif not yet described in the structurally versatile chemistry of polyoxomolybdates (POMos). The ageing reaction was found to occur via a series of intermediates, two of which were isolated and identified as the heptamolybdate coordination polymer [Co(en)3]2[NaMo7O24]Cl·nH2O (2), comprising {Mo7O24} units bridged by a sodium atom, and the heptamolybdate (H3O)[Co(en)3]2[Mo7O24]Cl·9H2O (3). An identical reaction procedure with [Co(C2O4)(en)2]+ instead of [Co(en)3]3+ yielded the orthomolybdate [Co(C2O4)(en)2]2[MoO4]·9H2O (4) and the hydrogen malonate [Co(C2O4)(en)2]C3O4H3 (5). The new polyoxomolybdate [Co(en)3]5Na[Mo7O24(μ-Mo8O26)Mo7O24]·nH2O was also examined as a catalyst for the epoxidation of cyclooctene, and was superior to both heptamolybdate and octamolybdate catalysts over 24 h. The heptamolybdate [Co(NH3)6]2[Mo7O24]·8H2O (6) was isolated as the only reaction product of sodium molybdate and hexaamminecobalt(iii) nitrate in the presence of malonic acid using solution-based methods. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mechanochemically accelerated vapour–assisted aging in the synthesis of (poly)oxalatomolybdates. • Transformation kinetics of the amorphous intermediates into the crystalline products. • In situ reaction monitoring by PXRD. Abstract Mechanochemically accelerated vapour–assisted aging and transformation from the amorphous precipitate by aging to the crystalline products were demonstrated to be the efficient methods to synthesize crystalline hydrate and non-hydrate (poly)oxalatomolybdates, [Co(NO 2)(NH 3) 5 ][MoO 3 (ox)H 2 O]·H 2 O, [Co(NH 3) 6 ] 2 [Mo 4 O 11 (ox) 4 (H 2 O)]·6H 2 O, [Co(NH 3) 6 ] 4 [Mo 4 O 8 (μ -O) 4 (ox) 4 ][MoO 3 (ox)(H 2 O)] 2 ·10H 2 O, [Co(en) 3 ] 4 [MoO 2 (μ -O)(ox)] 2 [MoO 3 (ox)(H 2 O)] 2 ·7H 2 O and [Co(ox)(en) 2 ] 2 [Mo 2 O 5 (ox) 2 (H 2 O) 2 ]·4H 2 O, respectively. We have also studied the transformation kinetics of the amorphous intermediates into the final crystalline oxalatomolybdates in an aqueous slurry at room temperature by in situ powder X-ray diffraction (PXRD) method coupled with numerical methods. Using the principal component analysis, PXRD data tensors were reduced to only one principal component. Reaction profiles were built and total times for completion were determined. [ABSTRACT FROM AUTHOR]

To explore the halogen bonding proclivity of the o-hydroxyimine hydroxyl group, we have prepared two imines as halogen bond acceptors: salicylideneaniline (I) and a 3-pyridyl analogue (II) derived from the condensation of salicylaldehyde and 3-aminopyridine. These two Schiff bases were selected as the two simplest representatives of o-hydroxyimines, where one (II) possesses a potentially competing halogen bond acceptor (pyridine nitrogen) and the other does not. For cocrystal screening, as halogen bond donors, we used perfluorinated iodobenzenes: 1,2-, 1,3-, 1,4-diiodotetrafluoro-benzene (12tfib, 13tfib, and 14tfib) and 1,3,5-triiodotrifluoro-benzene (135tfib). The hydroxyl group has been found to act as a halogen bond acceptor in three out of five crystal structures determined in this study: (II)(13tfib), (II)(135tfib) and (II)2(135tfib). In all three cases, a pyridine nitrogen is also employed in halogen bonding. Our attempts at preparing cocrystals of I were generally unsuccessful and the only cocrystal of I, which has been obtained, with 14tfib, does not exhibit a halogen bond involving a hydroxyl oxygen. These results suggest that the halogen bond motif with an isolated hydroxyl group as the acceptor seems to be less favourable than the previously studied bifurcated halogen bonding motif with the ortho-methoxy–hydroxyl group as the acceptor. [ABSTRACT FROM AUTHOR]

Five new Pb(ii) complexes of hydrazone-based and Schiff-based ligands and three different anionic co-ligands (azide, thiocyanate and bromide) have been synthesized and characterized by structural, analytical and spectroscopic methods. This variety of ligands can coordinate to the Pb(ii) metal center in a tridentate or tetradentate fashion via a different combination of any of nitrogen, oxygen and sulphur donor atoms. Moreover, the organic ligands can be in mono-deprotonated or neutral forms. By using single-crystal X-ray crystallography, we show that the synthesized complexes aggregate into larger supramolecular entities due to the formation of noncovalent tetrel bonding interactions. The Pb(ii) center is hemidirectionally coordinated even in those complexes where the coordination number is six. Consequently, this is sterically ideal for establishing tetrel bonding interactions with electron-rich nitrogen, bromide or sulphur atoms. These contacts are significantly larger than the sums of the covalent radii. Hence, they can be described as non-covalent tetrel bonding interactions. They interconnect the covalently bonded units into supramolecular assemblies (dimers or tetramers). The contribution of contacts involving the Pb atom has been studied using Hirshfeld surface analysis and fingerprint plots. We have analysed the supramolecular assemblies observed in the solid state by means of DFT calculations and characterized them using Bader's theory of atoms-in-molecules. [ABSTRACT FROM AUTHOR]

The use of a dodecanuclear zirconium acetate cluster as a precursor enables the rapid, clean mechanochemical synthesis of high-microporosity metal–organic frameworks NU-901 and UiO-67, with surface areas up to 2250 m2 g−1. Real-time X-ray diffraction monitoring reveals that mechanochemical reactions involving the conventional hexanuclear zirconium methacrylate precursor are hindered by the formation of an inert intermediate, which does not appear when using the dodecanuclear acetate cluster as a reactant. [ABSTRACT FROM AUTHOR]