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Several alkali metal hydroxoantimonates, K 2 [Sb(O)(OH) 5 ], Na[Sb(OH) 6 ], Cs[Sb(OH) 6 ] and Cs 2 [Sb 2 (μ-O) 2 (OH) 8 ] were isolated from aqueous solutions and characterized by single crystal and powder X-ray diffraction studies and by FTIR and thermal analysis. Crystal structures involving [Sb(O)(OH) 5 ] 2− were never anticipated before, and this is also the first disclosure of a dinuclear antimonate [Sb 2 (μ-O) 2 (OH) 8 ] 2− . Aqueous antimonate solutions of different pH were studied by high resolution electrospray mass spectrometry showing pH indifferent spectra and predominance of the mono and dinuclear antimonate species at pH 4–10.

iotbx.cif is a comprehensive toolbox for the development of applications that make use of the CIF format., iotbx.cif is a new software module for the development of applications that make use of the CIF format. Comprehensive tools are provided for input, output and validation of CIFs, as well as for interconversion with high-level cctbx [Grosse-Kunstleve, Sauter, Moriarty & Adams (2002). J. Appl. Cryst. 35, 126–136] crystallographic objects. The interface to the library is written in Python, whilst parsing is carried out using a compiled parser, combining the performance of a compiled language (C++) with the benefits of using an interpreted language.

The synthesis, chemical and structural characterization of a series of pentamethylcyclopentadienyl (Cp*) tantalum imido complexes and aryloxide derivatives are presented. Specifically, the imido complexes Cp*Ta(N t Bu)(CH2 R)2, where R = Ph [dibenzyl(tert-butylamido) (η5-pentamethylcyclopentadienyl)tantalum(IV) (1)], Me2Ph [tert-butylamido)bis(2-methyl-2-phenylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (2)], CMe3 [(tert-butylamido)bis(2,2-dimethylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (3)], are reported. The crystal structure of (3) reveals α-agostic interactions with the Ta atom. The resulting increase in the tantalum core coordination improves electronic stability. As such it does not react with pentafluorophenol, in contrast to the other two reported imido complexes [(1) and (2)]. Addition of C6F5OH to (1) yields a dimeric aryl-oxide derivative, [Cp*Ta(CH2Ph)(OC6H5)(μ-O)]2 [di-μ-oxido-bis[benzyl(pentafluorophenolato) (η5-pentamethylcyclopentadienyl)tantalum(V)] (4)]. Its crystal structure reveals long Ta—O(C6H5) bonds but short oxo-bridging Ta—O bonds. This is explained by accounting for the fierce electronic competition for the vacant d π orbitals of the electrophilic TaV centre. Steric congestion around each metal is alleviated by a large twist angle (77.1°) between the benzyl and pentafluorophenyl ligands and the ordering of each of these groups into stacked pairs. The imido complex (2) reacts with C6F5OH to produce a mixture of Cp*Ta(OC6F5)4 [tetrakis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V) (5)] and [Cp*Ta(OC6F5)2(μ-O)]2 [di-μ-oxido-bis[bis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V)] (6)]. Steric congestion is offset in both cases by the twisting of its pentafluorophenyl ligands. Particularly strong electronic competition for the empty d π metal orbitals in (6) is reflected in its bond geometry, and owes itself to the more numerous electron-withdrawing pentafluorophenyl ligands. The balance of steric and electronic factors affecting the reactivity of Cp* tantalum imido based complexes with pentafluorophenol is therefore addressed.

Tetrasodium p-sulfonatocalix[4]arene exists as a hydrate with approximately 14 water molecules and has three polymorphic modifications, all of which contain a water molecule in the molecular cavity that is engaged in OH···π interactions. Single-crystal neutron structures are reported for two of these three forms and reveal a "compressed" water molecule with short OH bonds. Partial atomic charges and hardness analysis (PACHA) calculations based on the neutron coordinates give an OH···π interaction energy of 6.9-7.5 kJ mol(-1). The PACHA analysis also reveals the dominance of the charge-assisted hydrogen bonds from the Na(+)-coordinated water molecules. The instability of the crystal towards dehydration can be traced to an uncoordinated lattice water site. The remarkable calixarene-Na(+)-hydrate motif is conserved almost unchanged across all three polymorphs. A single-crystal neutron structure is also reported for pentasodium p-sulfonatocalix[4]arene·12H(2)O, which exhibits an intracavity water molecule that is engaged in both OH···π and OH···O hydrogen bonding. The shorter covalent bond to the hydrogen atom that forms the interaction with the aromatic ring is again apparent.

4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials.

A small series of half-sandwich bis(phosphine) ruthenium acetylide complexes [Ru(C CC 6 H 4 C CSiMe 3 )(L 2 )Cp′] and [Ru(C CC 6 H 4 C CC 6 H 4 R-4)(L 2 )Cp′] (R = OMe, Me, CO 2 Me, NO 2 ; L 2 = (PPh 3 ) 2 , Cp′ = Cp; L 2 = dppe; Cp′ = Cp ∗ ) have been synthesised. One-electron oxidations of these complexes gave the corresponding radical cations, which were significantly more chemically stable in the case of the Ru(dppe)Cp ∗ derivatives. The representative complex [Ru(C CC 6 H 4 C CC 6 H 4 OMe-4)(dppe)Cp ∗ ] was further examined by spectroelectrochemical (IR and UV–Vis–NIR) methods. The results of the spectroelectrochemical studies, supported by DFT calculations, indicate that the hole is largely supported by the ‘RuC CC 6 H 4 ’ moiety in a manner similar to that described previously for simple aryl ethynyl complexes, rather than being more extensively delocalized along the entire conjugated ligand.

A series of 4-styrylpyridine hydroperchlorates were synthesized, and the [2+2] autophotocycloaddition (PCA) reaction in their polycrystalline films and single crystals resulting in the centrosymmetric rctt isomers of 1,2,3,4-tetrasubstituted cyclobutanes was investigated. Unlike neutral styrylpyridines, their protonated forms are better preorganized for the solid-state PCA reaction. According to the X-ray diffraction data, the cations of these compounds, like related styryl dyes, are mainly stacked in crystals in a head-to-head or head-to-tail fashion with equal probability. Only in the latter type of stacks, the PCA reaction is feasible as a single-crystal-to-single-crystal transformation. The crystal packing is stabilized by hydrogen bonds between organic cations and perchlorate anions, as well as by other weak directional interactions, for example, by S…S interactions, thus preventing the atomic displacements in the course of PCA. The completion of the PCA reaction in single crystals without their degradation was observed only for 15-crown-5-containing 4-styrylpyridine hydroperchlorate. The crystals of the latter compound are stabilized not by hydrogen bonds between the cations and anions but by N+-H…O(macrocycle) hydrogen bonds resulting in the formation of head-to-tail stacked dimers. In the crystals, these dimers are surrounded by a soft shell formed by rotationally and translationally mobile anions and benzene solvent molecules, as well as by conformationally flexible crown-ether moieties of adjacent dimer pairs. This leads to a decrease in the steric strain that occurs in the crystals in the course of PCA and prevents the degradation of single crystals. The PCA reaction is accompanied by the reduction in the crystal symmetry due to the doubling of the unit cell.

4,4'-Bipyridine and 2,7-diazapyrene derivatives (A) having two ammonioalkyl N-substituents were synthesized. The complex formation of these compounds with bis(18-crown-6)stilbene (D) was studied by spectrophotometry, cyclic voltammetry, (1)H NMR spectroscopy, and X-ray diffraction analysis. In MeCN, π-donor D and π-acceptors A form supramolecular 1:1 (D·A) and 2:1 (D·A·D) charge-transfer complexes. The D·A complexes have a pseudocyclic structure as a result of ditopic binding of the ammonium groups to the crown-ether fragments. The better the geometric matching between the components, the higher the stability of the D·A complexes (log K up to 9.39). A key driving force of the D·A·D complex formation is the excessive steric strain in the precursor D·A complexes. The pseudocyclic D·A complexes involving the ammoniopropyl derivative of 4,4'-bipyridine were obtained as single crystals. Crystallization of the related ammonioethyl derivative was accompanied by transition of the D·A complexes to a structure of the (D·A)(m) coordination polymer type.

The idea of this event, in the 350th Anniversary Year of the Royal Society, arose from discussions within the Durham Biophysical Sciences Institute in late 2008. The objective of the meeting as a whole was to consider both the positive and negative aspects of climate change and potential global

New palladium nitrosyl carboxylate complexes Pd8(CO)4−m(NO)m(NO2)4(RCO2)8 (m = 2, 4) were obtained by the treatment of palladium carbonyl carboxylates clusters cyclo-Pdn(μ-CO)n(μ-RCO2)n (n = 6) (1) with gaseous nitrogen monoxide. These complexes are the products of CO substitution in early described Pd8(CO)4(NO2)4(RCO2)8 clusters. By adding an excess of corresponding acid to reaction mixture Pd4(CO)2(NO)(RCO2)5 complexes were obtained, their structures were determined by X-ray diffraction analysis. These clusters are intermediate products of transformation of 6-nuclear initial clusters into various 8-nuclear complexes. This fact demonstrates that carboxylate ligands can be used as stabilizers for intermediate unstable polynuclear palladium compounds.

A combination of IR spectroelectrochemistry and DFT calculations has been used to demonstrate that the vinyl ligands in the complexes [Ru(CH═CHC6H4Me-4)Cl(CO)(PMe3)3] and [{RuCl(CO)(PMe3)3}2(μ-CH═CHC6H4CH═CH)] are redox noninnocent, and one-electron oxidation results in radical cations that are best described in terms of metal-stabilized organic radicals.

Dibetaines of unsaturated viologen analogues that form supramolecular complexes with cucurbit[7]uril were synthesized. The pseudorotaxane structure and stability of the complexes were established by UV/Vis and 1 H NMR spectroscopy and by X-ray diffraction analysis. Complexes of this structure are prototypes of a light-controlled molecular machine.

Syntheses, characterization and crystal structures of heterotetranuclear [2 × 1 + 1 × 2] co-crystals [{CuIILZnII(H2O)2}{CuIIL}2](ClO4)2 (1) and [{CuIILCdII(H2O)2(CH3CN)}{CuIIL}2](ClO4)2 (2), dinuclear compound [CuIILHgII(CH2COCH3)](ClO4) (3) and heterotrinuclear [2 × 1 + 1 × 1] co-crystal [{CuIILAgI(H2O)}{CuIIL}](ClO4) (4) derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) are reported herein. Compounds 3 and 4 crystallize in the orthorhombic Pbca and monoclinic P21/c systems, respectively, while the space group of compounds 1 and 2 is monoclinic C2/c. The structure of 3 consists of a monophenoxo-bridged CuIIHgII dinuclear core in which the mercury(II) centre is dicoordinated by the bridging phenoxo oxygen atom and the CH2 carbon atom of the mono-deprotonated acetone anion. The coordination environment of HgII in this compound is almost linear. In the CuII2AgI compound 4, one diphenoxo-bridged [CuIILAgI(H2O)]+ cation is co-crystallized with one mononuclear [CuIIL] moieties. On the other hand, the structures of the CuII3MII compounds 1 (M = Zn) and 2 (M = Cd) consist of one diphenoxo-bridged dinuclear CuIIMII unit and two mononuclear [CuIIL] moiety; the composition of the dinuclear unit being [CuIILZnII(H2O)2]2+ and [CuIILCdII(H2O)2(CH3CN)]2+ for 1 and 2, respectively. The AgI (in 4), ZnII (in 1) and CdII (in 2) ions in the diphenoxo-bridged dinuclear cores are tri-, tetra- and heptacoordinated, respectively. The metal ions are coordinated to two bridging phenoxo oxygen atoms, with the silver(I) and zinc(II) centres being additionally coordinated to one and two water molecules, respectively. While in the case of cadmium(II), the additional five coordination positions are occupied by two ethoxy oxygen atoms, two water oxygen atoms and one acetonitrile nitrogen atom. The coordination environment of silver(I) in 4 is pyramidal with a scalene O3 triangle as the base, whereas those of zinc(II) and cadmium(II) in 1 and 2 are distorted tetrahedral and distorted pentagonal bipyramidal, respectively. The coordinated water molecule in 4 and each of the two coordinated water molecules in 1 and 2 are encapsulated into the O4 compartment of a [CuIIL] moiety resulting in the [2 × 1 + 1 × 1] (for 4) or [2 × 1 + 1 × 2] (for 1 and 2) cocrystallization and self-assemblies. Clearly, the encapsulation of the coordinated water molecule(s) is the governing force for the formation of dinuclear-mononuclear co-crystals in 1, 2 and 4. In addition all four compounds 1–4 have π–π stacking interactions which form dimers between pairs of adjacent molecules in the structure of 3 consisting of CuIIHgII dimers, while one-dimensional stacks are formed in the CuII3ZnII (1), CuII3CdII (2) and CuII2AgI (4) complexes. The compositions of the title compounds are compared with the related systems derived from the same ligand. The [2 × 1 + 1 × 1] co-crystal, 4, is a new type of system in terms of the number of components. Again, in spite of the tri-, tetra- and hepta-coordinated nature of the second metal ion in the dinuclear cores, co-crystallization in 1, 2 and 4, respectively, are new observations. The accommodation/coordination of varieties of metal ions by the O4 compartment of H2L has also been highlighted in the present investigation.

The spontaneous and photoinduced protonation of 4-(2-naphthyl)pyridine (1) in solutions and in complexes with β-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) were studied by absorption and fluorescence spectroscopy. The structure and stability of the complexes (log K = 1.5–2.3) of 1, its protonated form 2, and quaternized derivative, 1-methyl-4-(2-naphthyl)pyridinium perchlorate (3), with β-CD and HP-β-CD were studied by 1H NMR. It was shown that irrespective of the solution pH, compound 1 resides in the cyclodextrin cavity. HP-β-CD better binds the neutral form of 1 than β-CD, while naphthylpyridinium salts have approximately equal binding affinity to both cyclodextrins. The structures of salt 3 and pseudorotaxane complex 1@β-CD were determined by X-ray diffraction analysis. According to spectral data, pKa of 1 in water is 5.12, which promotes protonation of nitrogen both in the ground state and in the excited state. As a consequence, the fluorescence spectrum exhibits only the protonated form with a lifetime of 15 ns. The addition of HP-β-CD to a solution of 1 results in inclusion complex 1@HP-β-CD; simultaneously pKa of 1 decreases to 4.62 and non-protonated form fluorescence (NFF) of 1 with a lifetime of 1.25 ns appears. Thus, the residence of 1 in the HP-β-CD cavity hampers its protonation in the excited state. From comparison of the initial regions of fluorescence of 1 in solution and in the HP-β-CD complex after pulse excitation, a mechanism for appearance of short-lived NFF of 1 was proposed. Quantum chemical simulation of the protonation and complexation of 1 in the presence of water was performed. On the basis of results, reversible photoinduced mechanical motion of 1 in the HP-β-CD cavity was suggested.

The syntheses, characterization and crystal structures of four copper(II)/nickel(II)⋯uranyl(VI) self-assemblies of composition [{NiIIL1}2·{(UVIO2)(NO3)2(H2O)2}] (1), [{CuIIL2}2·{(UVIO2)(NO3)2(H2O)2}]·0.68H2O (2), [{NiIIL2}2·{(UVIO2)(NO3)2(H2O)2}] (3) and [{CuIIL3}·{(UVIO2)(NO3)2(H2O)2}]n (4) are described in this investigation (H2L1, H2L2 and H2L3 are the Schiff base ligands obtained on condensing 3-ethoxysalicylaldehyde with ethylenediamine, o-phenylenediamine and trans-1,2-diaminocyclohexane, respectively). Compounds 1 and 4 crystallized in the monoclinic P21/n and C2/c space groups, respectively, while compounds 2 and 3 crystallized in the triclinic space group P. Two water molecules of the [(UVIO2)(NO3)2(H2O)2] moiety in 1–4, have a linear H2O–U–OH2 arrangement. Each of these two water molecules in 1–3 interacts with the O(phenoxo)2O(ethoxy)2 compartment of a mononuclear copper(II) or nickel(II) moiety due to the formation of bifurcated hydrogen bonds between each of the two water hydrogen atoms and a pair of one phenoxo and one ethoxy oxygen atoms resulting in the interlinking of the two mononuclear 3d units by the [(UVIO2)(NO3)2(H2O)2] synthon and therefore these three compounds may be considered as supramolecular dimers. Compounds 1–3 are also two component [1 × 2 + 1 × 1] co-crystals consisting of two mononuclear copper(II) or nickel(II) units and one [(UVIO2)(NO3)2(H2O)2] moiety. On the other hand, in 4, two water molecules, from two different [(UVIO2)(NO3)2(H2O)2] moieties, interact with one O(phenoxo)2O(ethoxy)2 compartment resulting in the formation of a self-assembled one-dimensional topology. Again, since one mononuclear copper(II) unit and one [(UVIO2)(NO3)2(H2O)2] moiety exist in a single crystal in 4, this compound is a two component [1 × 1 + 1 × 1] co-crystal. The outcomes of the present study utilize [(UVIO2)(NO3)2(H2O)2] synthon to derive 3d⋯5f co-crystals, provide the first observation of the interaction of two water molecules with one O(phenoxo)2O(ethoxy)2 compartment, demonstrate the formation of supramolecular dimers and show the first example of a one-dimensional self-assembly resulting from water⋯O4 compartment hydrogen bonds, and the first example of [1 × 2 + 1 × 1] co-crystals in 3-ethoxysalicylaldehyde-diamine ligand system.

The design and study of organometallic mixed-valence complexes is complicated by the mixing of metal d and bridging ligand π orbitals, which often makes the assignment of metal oxidation states amb...

The intermediate of the reaction between cyclobutanone and diethylamine has been crystallized in situ in form of co-crystal with diethylamine and its structure has been determined by X-ray crystallography. The study made possible to have an insight in the mechanism of the reaction and reveals the potential of in situ cryo-crystallization technique as an additional tool for studying the mechanisms of chemical reactions. The related structure of co-crystal of diethylamine with adipic acid, which is a product of cyclohexanone oxidative cleavage, is also reported.

The use of perbromofluorobenzene derivatives as starting materials for the synthesis of a variety of model liquid crystal systems by a combination of nucleophilic aromatic substitution, debromolithiation/trapping, dehydration and reduction processes is described.

Reactions of tetrafluoropyridazine with iminopiperidine and 2-aminopiccoline gave novel tetrahydropyrido- and pyrido-[1′,2′:1,2]imidazo[4,5-b]pyrazine heterocyclic frameworks respectively in high yields.

XIPHOS has been developed to expand home laboratory facilities closer to those found at central facilities, offering extremes of sample environment and flux densities far greater than standard laboratory sources. The system has a minimum operating temperature of 1.9 K, and has a direct-drive molybdenum rotating-anode generator coupled with the latest multilayer optics. XIPHOS has been specifically designed to accommodate various sample environments and is now operational. Furthermore, it has been calibrated with structural phase transitions from 14 to 148 K. Results are also presented from a full low-temperature data collection ofm-nitroaniline to demonstrate the quality of results attainable from XIPHOS.

Reactions of 1-(2,4-dinitrophenyl)pyridinium chloride and 2-(2,4-dinitrophenyl)isoquinolinium chloride with 2,3-dimethylbenzothiazolium iodide in hot pyridine allows introduction of an aryl residue into the thiazole ring via intermolecular transformation of the pyridine ring of Zincke’s salts with participation of the methyl group in position 2 of the benzothiazolium salt.

While stable in CH2Cl2, hexane or THF, in the presence of MeOH, self-promoted dimerization of the triarylphosphine-alkene 1, a ligand for Pd-catalyzed reactions, produced an unusual racemic bis(phosphine) 2 in high yield. The reaction of 2 with Pd(dba)2, followed by oxidative addition of p-IC6H4NO2, yielded a trans-chelated Pd(II) aryl iodide complex.

International audience; Reaction of [PdMe2(tmeda)] with pyridyl-N-di(tert-butyl)phosphinoimine spontaneously affords an unusual bimetallic palladium(I) ligand-based biradical complex, which behaves as a "masked" form of Pd0 in its reactions with neutral ligands and chlorobenzene.

Highly fluorinated nitrobenzene derivatives are suitable substrates for palladium-catalyzed C-F bond arylation using readily available palladium catalysts under both conventional heating and microwave conditions. Arylation occurs ortho to the nitro group offering a synthetic route to polyfluorinated 2-arylnitrobenzene systems. The regiochemistry of the arylation reactions suggests that there is a significant directing interaction between the nitro group and the incoming nucleophilic palladium catalyst which is facilitated by the presence of several fluorine atoms attached the ring. Investigations into the regioselectivity and reactivity of several tetrafluoro- and trifluoronitrobenzene derivatives provides further evidence for the highly nucleophilic character of the oxidative addition step in contrast to the concerted mechanism of more conventional Suzuki-Miyaura coupling reactions involving aryl iodides and bromides.

The use of tetrafluoropyrimidine as a scaffold for the synthesis of 2,4,6-trisubstituted pyrimidine derivatives by three sequential nucleophilic aromatic substitution processes is assessed. Reactions of tetrafluoropyrimidine with various amine nucleophiles followed by a series of nitrogen and oxygen centred nucleophilic species gave a range of 4,6-disubstituted-2,5-difluoropyrimidine systems regioselectively and in good yield. Displacement of a further fluorine atom from representative difluoropyrimidine derivatives proceeded to give trisubstituted pyrimidine derivatives although mixtures of products could be obtained depending upon the substrate.

Reaction of N-(2′-hydroxyphenyl)-4-R-benzaldimines (L-R, R = OCH3, CH3, H, Cl and NO2) with [Os(PPh3)3Br2] in refluxing 2-methoxyethanol in the presence of triethylamine affords two families of organoosmium complexes (1-R and 2-R). In both 1-R and 2-R complexes a benzaldimine ligand is coordinated to the metal center as tridentate C,N,O-donor. In the 1-R complexes, a bidentate N,O-donor imionsemiquinonate ligand, derived from the hydrolysis of another benzaldimine, and a PPh3 ligand are also coordinated to osmium. In the 2-R complexes, a carbonyl, derived from decarbonylation of 4-R-benzaldehyde (derived from the same hydrolysis stated above), and two PPh3 ligands take up the remaining coordination sites on osmium. Structures of the 1-Cl and 2-OCH3 complexes have been determined by X-ray crystallography. All the 1-R and 2-R complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on the 1-R complexes shows a reversible Os(III)–Os(IV) oxidation within 0.47–0.67 V (vs SCE), followed by an irreversible oxidation of the imionsemiquinonate ligand within 1.10–1.36 V. An irreversible Os(III)–Os(II) reduction is also displayed by the 1-R complexes within −1.02 to −1.14 V. Cyclic voltammetry on the 2-R complexes shows a reversible Os(II)–Os(III) oxidation within 0.29–0.51 V, followed by a quasi-reversible oxidation within 1.04–1.29 V, and an irreversible reduction of the coordinated benzaldimine ligand within −1.16 to −1.31 V.

A number of N-alkylnitrobenzoaza-15-crown-5 with the macrocycle N atom conjugated with the benzene ring were obtained. The structural and complexing properties of these compounds were compared with those of model nitrobenzo- and N-(4-nitrophenyl)aza-15-crown-5 using X-ray diffraction, 1H NMR spectroscopy, and DFT calculations. The macrocyclic N atom of benzoazacrown ethers are characterized by a considerable contribution of the sp3-hybridized state and a pronounced pyramidal geometry; the crownlike conformation of the macrocycle is preorganized for cation binding, which facilitates complexation. The stability constants of the complexes of crown ethers with the NH4 +, EtNH3 +, Na+, K+, Ca2+, and Ba2+ ions were determined by 1H NMR titration in MeCN-d3. The most stable complexes were obtained with alkaline-earth metal cations, which is due to the higher charge density at these cations. The characteristics of the complexing ability of N-alkylnitrobenzoaza-15-crown-5 toward alkaline earth metal cations are comparable with analogous characteristics of nitrobenzo-15-crown-5 and are much better than those of N-(4-nitrophenyl)aza-15-crown-5.

1,2- and 1,3-dibromotetrafluorobenzene react with sodium phenoxide derivatives at sites para to ring bromine because these positions are activated by fluorine atoms ortho and meta to the site of nucleophilic substitution. Fluorine para to the site of nucleophilic attack is usually deactivating in nucleophilic aromatic substitution processes and this is reflected in the significantly reduced reactivity of 1,4-dibromotetrafluorobenzene which undergoes competing hydrodebromination processes to afford, primarily, 3-bromo-1,2,4,5-tetrafluorobenzene.

Three styryl dyes of the 4-pyridine series that form syn-head-to-tail dimeric pairs in polycrystalline films were synthesised. NMR and UV/Vis spectroscopic studies showed that this promotes stereospecific [2+2]-autophotocycloaddition (PCA) in the dimeric pairs to give rctt-isomers of cyclobutane derivatives. For the dye with an N-ammoniopropyl substituent, this transformation was accomplished according to the single-crystal-to-single-crystal pattern. In aqueous solutions, the dyes and cucurbit[n]urils (CB[n], n = 7, 8) form complexes with a pseudorotaxane structure. CB[7] tends to form 1:1 complexes, and CB[8] forms 1:1 and 2:1 complexes. The structure of the termolecular complex formed by the betaine of the N-sulfonatopropyl styryl dye and CB[8] was determined by X-ray diffraction. The stability of the complexes was measured by 1 H NMR titration in a D 2 O/[D 3 ]MeCN (10:1) mixture (log K 1:1 ≥ 3.2, log K 2:1 ≥ 2.6). Free dyes and their complexes with CB[7] in water undergo only (E)/(Z) photoisomerisation. Termolecular complexes of all dyes with CB[8] were found to undergo effective stereospecific PCA reactions to give rctt isomers of cyclobutane derivatives. The 1:1 complexes of the obtained cyclobutanes with CB[8] (log K cb = 3.2-4.8) are less stable than those of the starting dyes with the same stoichiometry. Thus, CB[8] can play the role of a photocontrolled molecular assembler, i.e., even in the presence of 5 mol-% of CB[8], complete conversion of styryl dyes into the corresponding cyclobutane derivatives takes place upon irradiation in solution.

Novel 15-hydroxybenzomonothia-15-crown-5 containing the sulfur atom linked with the benzene ring and its S-oxide were synthesized. The stability constants for the complexes of the obtained benzocrown ethers and a reference 15-hydroxybenzo-15-crown-5 with Na, Ca, AgI, Cd, HgII, and PbII perchlorates were determined by 1H NMR titration. In MeCN-d3, the benzothiacrown ether demonstrates a high selectivity towards the thio- and oxothiophilic Hg2+ (logK 1 = 7.1) and Pb2+ ions (logK 1 = 7.4). In MeCN-d3-D2O mixtures, the stabilities of the most of complexes decrease sharply due to competitive hydration of the metal cations except for the “soft” Ag+ and Hg2+ ions having low affinity for the “hard” oxygen atoms and, on the contrary, very high affinity for the “soft” SII atoms. This results in the change in selectivity of complexation: at the water content in solution of 20%, the benzothiacrown ether binds preferably the Hg2+ (logK 1 = 5.0) and Ag+ ions (logK 1 = 2.7). In MeCN-d3, the benzothiacrown-derived sulfoxide is a weak and non-selective complexing agent towards all the metal cations under study; the reference 15-hydroxybenzo-15-crown-5 forms more stable complexes with the oxophilic sodium, calcium, and lead(ii) cations. The conformational features of the benzocrown ethers and their metal complexes established by NMR spectroscopy and X-ray diffraction are discussed. The found characteristics of the complexing ability of benzomonothia-15-crown-5 where the sulfur atom is in conjugation with the benzene ring reveal that the macrocyclic ligands with such a structure are promising as high-selective and efficient complexing agents for the “soft” mercury(ii) and silver(i) cations in acetonitrile-water mixtures.

Reactions of various perfluorinated heteroaromatic substrates such as tetrafluoro-4-cyanopyridine, tetrafluoropyrazine and tetrafluoropyridazine with 1,3-dicarbonyl systems gave corresponding [5,6]-ring fused furo derivatives. Subsequent reactions of the [5,6] bicyclic scaffolds with nucleophiles gave some highly functionalised heteroaromatic systems.

A series of molybdenum alkynyl complexes [Mo(C≡CR)(dppe)(η-C7H7)] featuring a range of alkynyl substituents R with varying electron-donating and -withdrawing properties have been prepared. Oxidatio...

Photophysikalische Untersuchungen ergaben fur eine Reihe von Rhodiumkomplexen unerwartet hohe Fluoreszenzquantenausbeuten (Φf bis 69 %, τf≈1–3 ns) und ein unerwartet langsames Intersystem-Crossing. Diese neue Verbindungsklasse hinterfragt das gangige Modell zum Verhalten angeregter elektronischer Zustande und zur Rolle von Schweratomen in Intersystem-Crossing-Prozessen. THF=Tetrahydrofuran, Tol=Toluol.

Annelation reactions between pentafluorobenzonitrile and N,N-dimethylethylene diamine and 3-methyl picoline gave [6,6]-bicyclic and [6,5,6]-tricyclic ring-fused systems, respectively. Reaction of 4-morpholino tetrafluorobenzonitrile with hydrazine and phenyl hydrazine gave [5,6] ring-fused systems arising from a tandem SNAr and cyclisation process involving annelation onto the pendant cyano group providing an indication of the synthetic possibilities for heterocycle formation using the pentafluorobenzonitrile scaffold.

Syntheses, characterization and crystal structures of four designed host-guest compounds of the compositions [{Cu II L 1 } 2 ⊂(H 3 N(ethylene)NH 3 )](NO 3 ) 2 (1), [{Cu II L 1 } 2 ⊂(H 3 N-(propylene)NH 3 )](NO 3 ) 2 (2), [{Cu II L 1 } 2 ⊂(H 3 N(butylene)-NH 3 )](NO 3 ) 2 (3) and [{Cu II L 2 } 2 ⊂(H 3 N(ethylene)NH 3 )](NO 3 ) 2 (4) are described in this investigation [H 2 L 1 = N,N'-ethylenebis(3-methoxysalicylaldimine); H 2 L 2 = N,N'-ethylenebis(3-ethoxysalicylaldimine); ethylene = (CH 2 ) 2 ; propylene = (CH 2 ) 3 ; butylene = (CH 2 ) 4 ]. Compounds 2 and 3 crystallize in the orthorhombic Pcab and monoclinic C2/c systems, respectively, while the space group of compounds 1 and 4 is triclinic Pi. In all of these four compounds 1-4, the two + NH 3 sites of the [H 3 N(CH 2 ) n NH 3 ] 2+ dication (n = 2-4) behave as guests in the 0 4 compartment of two [Cu II L 1 /L 2 ] moieties through bifurcated N-H···O(phenoxo) and NH···O(methoxy/ethoxy) hydrogen-bonding interactions. Evidently, two mononuclear copper(II) moieties are interlinked by bridging supramolecular synthons, resulting in the formation of a supramolecular dimer in the title compounds. From the extent of displacement of the N atoms of [H 3 N(CH 2 ) n- NH 3 ] 2+ from the least-squares O(phenoxo) 2 O(methoxy/ ethoxy) 2 plane, it is clear that [Cu II L 1 ] is a better host than [Cu II L 2 ] for the diprotonated diamine guests. Comparison of the inclusion of water and diprotonated diamines in [Cu II L 1 / L 2 ] is also described in the present investigation. Interestingly, of the two guest species, water and diprotonated diamines, [Cu II L 2 ] prefers the former and [Cu II L 1 ] prefers the latter.

The crystals of five new low-melting co-crystals of chloroform with organic solvents had been grown in situ and their crystal structures were determined by single-crystal X-ray crystallography. Various aspects of the molecular packing and the role of Cl⋯Cl interactions in these compounds are discussed.

Novel tricyclic dipyridoimidazole derivatives can be readily synthesised in one pot processes from various highly fluorinated pyridine systems such as pentafluoropyridine and relatively nucleophilic 2-aminopyridine derivatives. Further nucleophilic aromatic substitution reactions of the novel tricyclic scaffolds allow the regioselective synthesis of various nitrogen, oxygen, carbon and sulfur-functionalised dipyridoimidazole products.

The crystal structures of six new partially fluorinated aryl 1,2,3,5-dithiadiazolyls [ArCNSSN]˙ are reported [Ar = 2,6-F2C6H3 (4); Ar = 3,4-F2C6H3 (5); Ar = 3,5-F2C6H3 (6); Ar = 2,3,6-F3C6H2 (9); Ar = 2,4,6-F3C6H2 (11); and Ar = 3,4,5-F3C6H2 (12)] and compared with three previously reported structures in this series (Ar = 2,3-F2C6H3 (1); Ar = 2,5-F2C6H3 (3); Ar = 2,3,4-F3C6H2 (7)]. Radical 4 is shown to be polymorphic. Molecular electrostatic potential maps have been used to rationalise these structures. These reveal that whilst single F atoms appear to have little structure-directing influence, combinations of an ortho-F on the phenyl ring and a heterocyclic ring N, or several F atoms located in mutually ortho positions with respect to each other, generate significant regions of negative charge which have a substantial structure-directing influence.

Syntheses, characterization and structures of heterodinuclear compound [CuIIL1BiIII(NO3)3] (1), sandwich type heterotrinuclear compound [(CuIIL1)2BaII(NO3)2]·0.2H2O (2), heterotetranuclear compound [{CuIIL1PbII(µ-NO3)(NO3)}2] (3) and heterohexanuclear [2 × 1 + 1 × 4] cocrystal [(UVIO2)2(µ-H2O)2(NO3)4]·4[CuIIL1⊂(H2O)] (4) are described in this investigation (H2L1 = N,N′-ethylenebis(3-ethoxysalicylaldiimine)). Compounds 1 and 4 crystallize in orthorhombic P212121 and triclinic Pī systems, respectively, while the space group of compounds 2 and 3 is monoclinic P21/c. The structure of 1 consists of a diphenoxo-bridged CuIIBiIII dinuclear core containing three chelating nitrates and a 10-coordinate bismuth(III) centre. The dinuclear cores are self-assembled to two dimensions through intermolecular nitrate oxygen⋯copper(II) semicoordination and weak C–H⋯O hydrogen bonds. Compound 2 is a double-decker CuIIBaIICuII system in which a barium(II) ion is sandwiched between two mononuclear [CuIIL1] moieties. The barium(II) centre is 11-coordinate, four phenoxo and four ethoxy oxygen atoms and one chelating and one monodentate nitrate ions. Compound 3 is a tetranuclear system (dimer of two dinuclear moieties) in which one nitrate is chelating, while the second nitrate behaves as both a chelating and bridging ligand. The lead(II) centre is 9-coordinate in this compound. Compound 4 is a [2 × 1 + 1 × 4] cocrystal of one diaqua-bridged diuranyl(VI) moiety, containing two chelating nitrates and 8-coordinated hexagonal bipyramidal uranium(VI) centres and four inclusion species [CuIIL1⊂(H2O)]. The governing factor for the self-assembled cocrystallization in 4 are the C–H⋯·π and C–H⋯O hydrogen bonds. The compounds reported in this investigation and other heteronuclear systems derived from N,N′-ethylenebis(3-ethoxysalicylaldiimine) indicate that this ligand system is an important example which gives rise to structurally diverse heteronuclear compounds. In addition to the structural diversity, the structural resemblance of bismuth(III) with lanthanides(III) and utilization of noncovalent interactions to form self-assembly and cocrystals are the major outcomes of the present investigations.

Reactions of metal acetylide complexes M(C CAr)(PP)Cp′ (M = Fe, Ru; Ar = C6H5, C6H4Me-4; PP = (PPh3)2, dppe; Cp′ = Cp, Cp*; not all combinations), or the analogous vinylidene, with cyanogen bromide yield monobromovinylidene complexes [M{C C(Br)Ar}(PP)Cp′]+, isolated as PF6− salts. The trimethylsilyl-capped acetylides M(C CSiMe3)(PP)Cp′ react with cyanogen bromide to give [M(C CBr2)(PP)Cp′]+, the first examples of metal complexes containing a terminal dihalovinylidene ligand, which can be isolated as the BF4− salts. Molecular structures of representative mono- and di-bromovinylidene complexes are reported, together with those of Ru(C CSiMe3)(PPh3)2Cp and Ru(C CSiMe3)(dppe)Cp*.

A simple N,N′-diaryl urea derivative was found to form four different anhydrous crystal forms (I−IV°), which can be crystallized in pure form by several techniques from solution as well as from the melt. These polymorphs were characterized by thermomicroscopy, differential scanning calorimetry, Fourier-transform infrared spectroscopy and single crystal and powder X-ray diffraction. The polymorphs were found to be purely monotropically related with large differences in their heats of fusion (11.1 kJ mol−1 for the least stable form I, 34.5 kJ mol−1 for the most stable form IV°). The crystal structures of all forms show the same conformer for forms I−III and a second conformer in form IV°. However, the hydrogen bonding motifs in all of the polymorphs are the same and thus the compound can be seen as a model for the importance of the entire crystal packing arrangement to the overall energy and stability of the crystal form, as opposed to just a few dominant interactions.

Refluxing of the red compound [CuIIL1blabla(H2O)] (1) in acetone forms two new species: green [CuIIL1(H2O)] (2) and brown [CuIIL1] (3) [H2L1 = N,N′-ethylenebis(3-ethoxysalicylaldimine)]. Whereas both 1 and 2 are converted into 3 upon heating, 3 is converted back into 1 when exposed to air. The structures of all three compounds were determined crystallographically, from which the interesting hydrate isomerism of 1 and 2 are identified; in 1 a water molecule is encapsulated into the O4 section of the ligand through bifurcated hydrogen bonding, whereas in 2 a water molecule coordinates directly to the metal centre. Despite the metal ion binding to the ligand in the same manner in all three cases, the formation of different mononuclear complexes resulting from the presence or absence of water and its coordination or encapsulation is an interesting observation. Thermogravimetric analyses of compounds 1 and 2 showed that the encapsulated water in the former compound is removed at slightly lower temperature than that of the coordinated water molecule, as expected. Although three crystals 1, 2 and 3 were isolated, the composition of species in solution is probably the same as evidenced by 1H NMR spectroscopy. Therefore, the formation of three crystals and the hydrate isomerism described in this investigation are solid-state phenomena.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The reactions between M[N(SiMe3)2]2 (M = Ge, Sn) and three pyridine-based dialcohols yielded germylenes and stannylenes 1–6. The composition and structures of the novel compounds were established by elemental analyses, 1H and 13C NMR spectroscopy. The structures of insoluble species were confirmed by conversion to the corresponding dibromides 7–9. The single crystal structures of stannylene 4 and germylene 5 were determined by X-ray diffraction analyses. The germanium compound was found to be monomeric whilst the tin compound is a dimer. Both compounds possess strong transannular MN interaction in the solid phase.

DFT calculations for the benzothiazole styryl dyes containing a benzo-18-crown-6-ether fragment and an ammonioalkyl or ammonio- p -xylylenyl substituent at the quaternary nitrogen atom of the benzothiazolium residue were carried out. The effect of the length and rigidity of the N -substituent on the structure and the formation energy of the cation-‘capped’ Z isomers of the dyes arising on exposure to light as a result of intramolecular interaction involving the hydrogen bonds of the N -substituent ammonium group (spacer) with the oxygen atoms of the crown-ether fragment was studied. It was found that the dyes in solution are likely to exist predominantly as ion pairs with one perchlorate anion and the most pronounced stabilization of cation-‘capped’ complexes is attained for dyes having rather long ammoniohexyl or ammonio- p -xylylenyl spacer. The DFT results are in good agreement with X-ray diffraction data for the dimeric complex of the dye with an N -ammoniohexyl substituent.

Pyridazin-3(2H)-one systems have very useful biological properties and have found many applications within the pharmaceutical and agrochemical industries but, in general, synthesis of polysubstituted analogues can be very difficult to achieve. An approach to the syntheses of polyfunctional pyridazinone systems involving sequential nucleophilic substitution reactions of N-aryl and N-THP protected 4,5,6-trifluoropyridazin-3(2H)-ones as the core scaffolds is described.

A quaternary 4-styrylpyridinium salt having the N-ammoniopropyl substituent forms a pseudodimeric head-to-tail complex with neutral 18-crown-6-containing 4-styrylpyridine in MeCN through H-bonding. This complex undergoes stereospecific [2+2] photocycloaddition due to preorganization of the ethylene bonds in the syn-arranged chromophoric fragments of the components. The structure of the rctt-isomer of the cyclobutane derivative obtained was established by NMR spectroscopy and X-ray diffraction analysis.

Reactions of a new imido phosphido complex, Cp2Nb(═NBut)(PPh2) (1), with olefin complexes of rhodium afford two types of compounds. With [(μ-Cl)Rh(C2H4)2]2, an imido/phosphido-bridged complex, Cp(Cl)Nb(μ-NBut)(μ-PPh2)RhCp (2), characterized by NMR and X-ray diffraction, was prepared. Formation of 2 represents a rare example of a Cp/Cl exchange reaction in organometallic chemistry. When 1 reacts with [(μ-Cl)Rh(COD)]2, the target phosphido-bridged bimetallic complex Cp2Nb(═NBut)(μ-PPh2)Rh(Cl)(COD) (4) is formed. The structure of this product was established by NMR and an X-ray diffraction study. Both 2 and 4 are catalyst precursors for hydrosilylation of benzaldehyde and acetophenone. The activity of the neutral complex 4 exceeds that of the cation [Cp2Nb(NBut)(PPh2)Rh(COD)]+ derived from 4 by chloride anion abstraction.

The syntheses and structures of a [2×1+1×2] cocrystal [{CuIIL1NaI(H2O)2}{CuIIL1}2](NO3) (1) and [3×1+5×1] cocrystal [{(CuIIL1)2KI}(NO3)]·[{(CuIIL1)3KI2(μ-NO3)}(NO3)]·0.2H2O (2) derived from the hexadentate Schiff base compartmental ligand N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L1) are described. Compounds 1 and 2 crystallize in triclinic P1 and monoclinic P21/c systems, respectively. The structure of 1 consists of the [CuIIL1ΝaI(H2O)3]+ cation and two mononuclear [CuIIL1] moieties. In the dinuclear [CuIIL1ΝaI(H2O)3]+ cation, the metal centers are doubly bridged by the two phenolate oxygen atoms. Each of the two coordinated water molecules of the dinuclear unit is encapsulated in the O4 cavities of the two mononuclear [CuIIL1] moieties resulting in the formation of a [2×1+1×2] cocrystal. In compound 2, one trinuclear double-decker system [{(CuIIL1)2KI}(NO3)] and one pentanuclear triple-decker system [{(CuIIL1)3KI2(μ-NO3)}(NO3)] are cocrystallized. Evidently, compound 2 is a [3×1+5×1] cocrystal. Stru...