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The control of the interpenetration and chirality of a family of metal-organic frameworks is discussed. These systems contain two- (A) and four-fold (B) interpenetration of helical three-connected networks generated by binding the 1,3,5-benzenetricarboxylate (btc) ligand to a metal center. These frameworks have the general formula Ni(3)(btc)(2)X(m)Y(n).solvent (where X = pyridine or 4-picoline, Y = ethylene glycol, 1,2-propanediol, 1,4-butanediol, meso-2,3-butanediol, 1,2,6-hexanetriol, glycerol). The structural and chemical effects of modifying the alcohol and aromatic amine ligands bound to the metal center include controlling the thermal stability and the degree of interpenetration. Covalent linking of the four interpenetrating networks in the A family and the switching of diol binding from mono- to bidentate are demonstrated. Recognition of chiral diols by the hand of the network helices is investigated by binding an alcohol ligand with two chiral centers of opposite sense to the same helix. This reveals the subtle nature of the helix-ligand interaction.

We have studied the compressibility and stability of different β-titanium alloys at high pressure, including binary Ti–Mo, Ti–24Nb–4Zr–8Sn (Ti2448) and Ti–36Nb–2Ta–0.3O (gum metal). We observed stability of the β phase in these alloys to 40 GPa, well into the ω phase region in the P–T diagram of pure titanium. Gum metal was pressurised above 70 GPa and forms a phase with a crystal structure similar to the η phase of pure Ti. The bulk moduli determined for the different alloys range from 97 ± 3 GPa (Ti2448) to 124 ± 6 GPa (Ti–16.8Mo–0.13O).

By varying the reaction conditions, the reaction of [W(eg)3] (eg = 1,2-ethanediolato) with p-tert-butylcalix[n]areneHn (n = 6 or 8) in refluxing toluene affords, following work-up, a number of products which have been fully characterized. From the reaction of p-tert-butylcalix[6]areneH6 with one or two equivalents of [W(eg)3], only the oxo-bridged complex {[W(eg)]2(μ-O)p-tert-butylcalix[6]arene} (1) could be isolated, whereas the use of four equivalents of [W(eg)3], in the presence of molecular sieves, afforded {[W(eg)2]2p-tert-butylcalix[6]areneH2}·2MeCN (2); molecules of 2 pack in bi-layers. Under similar conditions, use of one or two equivalents of [W(eg)3] and p-tert-butylcalix[8]areneH8 afforded {[W(eg)]2p-tert-butylcalix[8]arene}·MeCN (3) in which each tungsten centre was bound by four calixarene oxygens. By contrast, the small orange prisms resulting from the use of four equivalents of [W(eg)3] and p-tert-butylcalix[8]areneH8 were shown by synchrotron radiation to be a mixture of two isomers 4a/4b·3.5MeCN). In the major isomer {1,2-[W(eg)2]2p-tert-butylcalix[8]areneH4} (4a), two tungsten centres bind to neighbouring sets of phenolate oxygens, whereas in the minor isomer {1,3-[W(eg)2]2p-tert-butylcalix[8]areneH4} (4b), there is a protonated phenolic group between the two pairs of phenolate oxygens bound to tungsten; the major : minor ratio is about 83 : 17. Use of p-tert-butyltetrahomodioxacalix[6]areneH6 with two equivalents of [W(eg)3] resulted in the isolation of {[WO(eg)]2p-tert-butyltetrahomodioxacalix[6]areneH2} (5·0.83toluene·MeCN), in which each dimethyleneoxa bridge is bound to an oxotungsten(vi) centre. Complexes 1-5, together with the known complex [W(eg)p-tert-butylcalix[4]arene] (6), have been screened for their ability to ring open polymerize (ROP) ε-caprolactone; for 1, 2 and 5, 6 conversion rates were good (88%) at 110 °C over 12 or 24 h, whereas the calix[8]arene complexes 3 and 4 under the same conditions were inactive.

The mononuclear macrocyclic PdIIcomplexcis-[PdCl2([9]aneS3)] ([9]aneS3= 1,4,7-trithiacyclo-nonane) converts at 44 kbar into an intensely coloured chain polymer exhibiting distorted octahedral coordination at the metal centre and an unprecedented [1233] conformation for the thioether ligand. The evolution of an intramolecular axial sulfur–metal interaction and an intermolecular equatorial sulfur–metal interaction is central to these changes. High-pressure crystallographic experiments have also been undertaken on the related complexes [PtCl2([9]aneS3)], [PdBr2([9]aneS3)], [PtBr2([9]aneS3)], [PdI2([9]aneS3)] and [PtI2([9]aneS3)] in order to establish the effects of changing the halide ligands and the metal centre on the behaviour of these complexes under pressure. While all complexes undergo contraction of the various interaction distances with increasing pressure, only [PdCl2([9]aneS3)] undergoes a phase change. Pressure-induced I...I interactions were observed for [PdI2([9]aneS3)] and [PtI2([9]aneS3)] at 19 kbar, but the corresponding Br...Br interactions in [PdBr2([9]aneS3)] and [PtBr2([9]aneS3)] only become significant at much higher pressure (58 kbar). Accompanying density functional theory (DFT) calculations have yielded interaction energies and bond orders for the sulfur–metal interactions.

(4R,5S)-4,5-Diphenylimidazolidine-2-thione is efficiently desymmetrised by stereorandom deprotonation with NaHMDS, followed by kinetic resolution of the resulting racemic intermediate with an enantiomerically pure pentafluorophenyl active ester. The levels of diastereocontrol were found to be excellent (86-92% de at similar to 30% conversion). This desymmetrisation reaction is an example of a masked resolution. (C) 2010 Elsevier Ltd. All rights reserved.

We report two phases containing the hexagonal (6,3) network of the graphene sheet derived by tridentate coordination of 1,3,5-benzenetricarboxylate to octahedral NiII centers. When the solvent used is 2-methyl-1-butanol, water directs the coordination about NiII and ABCA′B′C′ stacking of layers is obtained. The use of 1-butanol as solvent gives a different hydrogen-bonding arrangement around NiII and produces AAA stacking of the layers. We have previously demonstrated that the use of other alcohols such as methanol, ethanol, 1,2-ethanediol, and 1,2-propanediol leads to the formation of 3-D architectures. Here we show that a change in the hydrogen bonding around the metal center leads to 2-D structures which house substantial solvent-filled microcavities. The comparatively weak interactions between layers, and the relative importance of framework–solvent interactions, facilitates slippage of the hexagonal sheets and interconversion between stacking type with guest exchange.

The title compound, [Cd(C2H8N2)3](NO3)2, crystallizes with distorted Cd(en)32+ octa­hedra. Extensive hydrogen bonding is present between the ethyl­enediamine and nitrate groups.

The title complex, [Co2(C2F3O2)4(C5H5N)4(H2O)], crystallizes as a neutral dinuclear mol­ecule with two crystallographically distinct octa­hedrally coordinated CoII ions in the asymmetric unit. The metal ions are connected by two μ2-bridging trifluoro­acetate ions and a single μ2-bridging water mol­ecule. Each cobalt(II) coordination sphere is completed by a further trifluoroacetate ion, which coordinates in a monodentate manner, and also by two pyridine mol­ecules, resulting in local cis-CoN2O4 coordination. The water mol­ecule H atoms participate in intra­molecular O—H⋯O hydrogen bonds to the pendant O atoms of the monodentate trifluoro­acetate ligands.

The crystal structure of the title compound, [Cu(SO4)(C12H8N2)2]·C2H5OH, arises from the assembly of the neutral complex [Cu(SO4)(C12H8N2)2] and an ethanol solvent mol-ecule. The Cu(II) ion is five-coordinate, surrounded by two pairs of N atoms from two independent N,N'-chelating 1,10-phenanthroline ligands, and one O atom of monodentate sulfate ligand, in a distorted trigonal-bipyramidal fashion. Spatial orientation of the ligands and the assembly in the solid state are stabilized by the C-H⋯O hydrogen-bonding inter-actions, established between the O atoms (from the sulfate ligand and the ethanol mol-ecule) and the neighbouring 1,10-phenanthroline mol-ecules. There is also an offset face-to-face π-π stacking between the 1,10-phenanthroline ligands. The ethanol solvent mol-ecule is disordered over two orientations in the ratio 0.663 (10):0.337 (10). The crystal examined was subject to racemic twinning and the refined twin fraction was 0.346 (19).

The title compound, 2C3H7N6+·C6H7NO62−·3H2O, was obtained by mixing melamine and nitrilotriacetic acid in aqueous solution. There is proton transfer from the nitrilotriacteic acid to melamine to produce two melaminium cations and an internal proton transfer to generate the [HN(CH2COO)]2−zwitterion. The melaminium cations are arranged in hydrogen-bonded tapes formed by N—H...N interactions. These tapes extend parallel to the [010] direction and are stacked parallel to theaaxis at a mean separation of 3.3559 (11) Å. Between these tapes lie the anions and lattice water molecules. Further O—H...O and N—H...O hydrogen bonds exist between the water molecules, the anions, and the melaminium cations, generating a three-dimensional array. The crystal examined was found to be twinned by a twofold rotation about the direct lattice direction [100]. The two twin components were present in the ratio 0.5918:0.4082 (14).

Correction for ‘Supramolecular assemblies constructed from inverted cucurbit[7]uril and lanthanide cations: synthesis, structure and sorption properties’ by Qing Li et al., RSC Adv., 2016, 6, 77805–77810.

Despite the simple chemical formula, [Ni(1,10-phenanthroline)2(H2O)2](NO3)2, crystallizes with a remarkably complicated 3-D hydrogen bonding supramolecular assembly. The title compound crystallizes in the monoclinic space group P21/c, with an unusually long b axis and a large cell volume. A huge asymmetric unit has been identified, containing six discrete [Ni(1,10-phen)2(H2O)2]2+ cations and twelve nitrate anions. Detailed analyses of the crystal structure and O-H×××O and C-H×××O hydrogen bonding interactions are reported and discussed. In this way the anion-directed assembly of the 3-D structure is illustrated. The thermal and spectroscopic properties of the compound are described. Upon heating to 308 K, the crystal undergoes a phase change to a much simpler structure with a single [Ni(1,10-phen)2(H2O)2]2+ cation within the asymmetric unit and unit cell volume one sixth of that at low temperature. Although the crystal decomposed during data collection, it was possible to establish the molecular packing in the high temperature form and relate it to that at low temperature.

This paper reports a number of recent developments in the intercalation chemistry of Al(OH)(3). From Rietveld refinement and solid-state NMR, it has been possible to develop a structural model for the recently reported [M(II)Al(4)(OH)(12)](NO(3))(2)·yH(2)O family of layered double hydroxides (LDHs). The M(2+) cations occupy half of the octahedral holes in the Al(OH)(3) layers, and it is thought that there is complete ordering of the metal ions while the interlayer nitrate anions are highly disordered. Filling the remainder of the octahedral holes in the layers proved impossible. While the intercalation of Li salts into Al(OH)(3) is facile, it was found that the intercalation of M(II) salts is much more capricious. Only with Co, Ni, Cu, and Zn nitrates and Zn sulfate were phase-pure LDHs produced. In other cases, there is either no reaction or a phase believed to be an LDH forms concomitantly with impurity phases. Reacting Al(OH)(3) with mixtures of M(II) salts can lead to the production of three-metal M(II)-M(II)'-Al LDHs, but it is necessary to control precisely the starting ratios of the two M(II) salts in the reaction gel because Al(OH)(3) displays selective intercalation of M nitrate (Li > Ni > Co ≈ Zn). The three-metal M(II)-M(II)'-Al LDHs exhibit facile ion exchange intercalation, which has been investigated in the first energy dispersive X-ray diffraction study of a chemical reaction system performed on Beamline I12 of the Diamond Light Source.

Transition metal antimonides including CoSb3, CoSb2, CoSb, NiSb, NiSb2, Cu2Sb, Mo3Sb7, the new ternary series Co1-xNixSb (0.1 ≤ x ≤ 0.9), and the intermetallic SnSb are prepared by heating stoichiometric amounts of the appropriate metal oxides (Co3O4, NiO, CuO, MoO3, SnO, and Sb2O3) under a flow of 10% hydrogen in argon at moderate temperatures (450 °C, 72—120 h).

The hydrothermal synthesis of the compounds Ln2(OH)5NO3·xH2O (Ln: Y, Er, Yb) from aqueous solutions of Ln(NO3)3, NaOH, and NaNO3 (autoclave, 100—220 °C) is monitored by time-resolved, in situ energy-dispersive XRD.

Compositions in the series Ni2−xCoxGeMo3N (0 ≤ x ≤ 2), Co2Ge1−xGaxMo3N (0 < x ≤ 0.7), Co2−xFexGeMo3N (0 ≤ x ≤ 2), and Co2−xFexGe0.5Ga0.5Mo3N (0 ≤ x ≤ 0.8) have been synthesized by the reductive nitridation of binary oxides and studied by appropriate combinations of magnetometry, transport measurements, neutron diffraction, and Mossbauer spectroscopy. All of these compositions adopt the cubic η-carbide structure (a ∼ 11.11 A) and show a resistivity of ∼10−3 Ω cm. No long-range magnetic order was observed in Ni2−xCoxGeMo3N, although evidence of spin freezing was observed in Co2GeMo3N. The introduction of gallium into this composition leads to the onset of antiferromagnetic ordering at 90 K in Co2Ge0.3Ga0.7Mo3N. The magnetic structure consists of an antiferromagnetic arrangement of ferromagnetic Co4 groups, with an ordered magnetic moment of 0.48(9) μB per cobalt atom. The same magnetic structure is found in Co0.5Fe1.5GeMo3N and Co1.2Fe0.8Ge0.5Ga0.5Mo3N. The former orders above room temperature with an avera...

The first metal phosphate analogue of the zeolite Na-J (framework type JBW) has been synthesized by an ionothermal approach along with zincophosphate thomsonite.

In the title compound, C3H7N6+·C7H5O5−·2H2O, the melaminium and benzoate ions are approximately planar (r.m.s. deviation of the non-hydrogen atoms is 0.093 Å) and there is a strong C22(8) hydrogen-bonding embrace between them. The centre of symmetry generates a second acid–base pair which is bound to the first by a C22(8) (N—H...N) embrace common between melamine molecules in similar compounds. Further extensive hydrogen bonding assembles the components into a three-dimensional hydrogen-bonded network.

In an attempt to synthesize new cobalt(II) sulfate framework structures using 1,4-diaza-bicyclo-[2.2.2]octane as a template, crystals of poly[0.35-[hexa-aqua-cobalt(II)] [tri-μ-hydroxido-μ-sulfato-dicobalt(II)]], {[Co(H(2)O)(6)](0.35)[Co(2)(OH)(3)(SO(4))]}(n), were obtained as a mixture with [Co(H(2)O)(6)]SO(4) crystals. The crystal structure can be described as being constructed from discrete brucite-type [Co(4)(OH)(6)(SO(4))(2)] layers, each of which is built up from edge-shared [Co(OH)(6)] and [Co(OH)(4)(OSO(3))(2)] octa-hedra, with partial inter-calation by [Co(H(2)O)(6)](2+) ions. The absence of ca 30% of the [Co(H(2)O)(6)](2+) cations indicates partial oxidation of cobalt(II) to cobalt(III) within the layer.

An important intermediate phase in the crystallization of aqueous solutions of sodium sulfate is the highly metastable sodium sulfate heptahydrate (Na(2)SO(4).7H(2)O). This has been structurally characterized for the first time by in situ single crystal X-ray diffraction. The crystal structure shows that each sodium cation is octahedrally coordinated to water molecules, with a slight distortion due to one of the water molecules being disordered. The hydrated sodium cations are hydrogen-bonded to form a three-dimensional bonded network, which is markedly different from the architecture of one-dimensional bonded chains observed in sodium sulfate decahydrate (mirabilite). This major structural difference explains the reconstructive nature of the transformation observed between the heptahydrate and mirabilite. High-pressure crystallization of a 3.41 mol/kg water aqueous solution of sodium sulfate at 1.54 GPa in a diamond-anvil cell resulted in the formation of a previously unknown sodium sulfate hydrate, which we have determined by single crystal X-ray diffraction methods to be an octahydrate, Na(2)SO(4).8H(2)O. In this structure the sulfate ions are coordinated directly to sodium ions. This resembles anhydrous sodium sulfate (thenardite) but contrasts with the heptahydrate and decahydrate in which the sodium ions are coordinated exclusively by water molecules. This observation demonstrates how the delicate balance of inter- and intramolecular bonds in the crystal structure can be significantly altered by the application of pressure.

A family of layered lanthanide hydroxyhalide intercalation hosts, Ln2(OH)5X·1.5H2O (X = Cl, Br; Ln = Y, Dy, Er, Yb), has been synthesized under hydrothermal conditions and their crystal structure determined. These are the first structures for the m = 1 members of the Ln2(OH)6−m(A)m·nH2O family of intercalation hosts to be determined. Reaction mixtures with Ln = Yb always yield a biphasic product which adopts an orthorhombic or monoclinic crystal structure. In both cases the layer composition is [Yb2(OH)5(H2O)1.5]+ and the Yb is eight or nine coordinated to bridging hydroxide anions and coordinated water molecules. Charge balancing halide anions are located in the interlayer gallery. The orthorhombic structure is adopted by the other chloride host lattices and the monoclinic one by Y2(OH)5Br·1.5H2O. These materials have been shown to undergo facile room temperature anion exchange reactions with a range of organic dicarboxylates.

The reproducible crystallisation of elusive polymorphs and solvates of molecular compounds at high pressure has been demonstrated through studies on maleic acid, malonamide, and paracetamol. These high-pressure methods can be scaled-up to produce 'bulk' quantities of metastable forms that can be recovered to ambient pressure for subsequent seeding experiments. This has been demonstrated for paracetamol form II and paracetamol monohydrate. The studies also show that the particular solid form can be tuned by both pressure and concentration.

A series of clathrate and metal complexes with cyclotriveratrylene-like molecular host ligands show a similar dimeric homomeric inclusion motif in which a ligand arm of one host is the intra-cavity guest of another and vice versa. This "hand-shake" motif is found in the trinuclear transition metal complex [Cu(3)Cl(6)(1)]CH(3)CN1.5 H(2)O in which 1 is tris(4-[2,2',6',2''-terpyridyl]benzyl)cyclotriguaiacylene; in the self-included M(4)L(4) tetrahedral metallo-supramolecular assembly [Ag(4)(2)(4)] (BF(4))(4) in which 2 is tris-(2-quinolylmethyl)cyclotriguaiacylene; in the 1D coordination chains [Ag(4)]ReO(4) CH(3)CN and [Ag(5)]SbF(6)3 DMFH(2)O in which 4 is tris(1H-imidazol-1-yl)cyclotriguaiacylene and 5 is tris{4-(2-pyridyl)benzyl}cyclotriguaiacylene; and in the acetone clathrate of tris{4-(2-pyridyl)benzyl-amino}cyclotriguaiacylene. Clathrates of ligands 2 and 5 do not show the same dimeric motif, although 2 has an extended homomeric inclusion motif that gives a hexagonal network.

Polycrystalline samples of $\mathrm{Fe}{\mathrm{Mo}}_{4}{\mathrm{Ge}}_{3}$ have been synthesized by the reduction of an oxide mixture at $1248\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and characterized by a combination of diffraction, muon spin relaxation $({\ensuremath{\mu}}^{+}\mathrm{SR})$, M\"ossbauer spectroscopy, magnetometry, transport, and heat-capacity measurements. The compound adopts a tetragonal ${\mathrm{W}}_{5}{\mathrm{Si}}_{3}$ structure (space group $I4∕mcm$); the iron and molybdenum atoms are disordered over two crystallographic sites, $16k$ and either $4a$ or $4b$. The synthesis conditions determine which fourfold site is selected; occupation of either leads to the presence of one-dimensional chains of transition metals in the structure. In both cases, the electrical resistivity below $200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ is $\ensuremath{\sim}175\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\ensuremath{\Omega}\phantom{\rule{0.2em}{0ex}}\mathrm{cm}$. The dc magnetization rapidly rises below $35\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ ($\mathrm{Fe}∕\mathrm{Mo}$ on $16k$ and $4b$ sites) or $16\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ ($16k$ and $4a$ sites), and a magnetization of $1{\ensuremath{\mu}}_{\mathrm{B}}$ or $0.8{\ensuremath{\mu}}_{\mathrm{B}}$ per Fe atom is observed in $4\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ at $2\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The ac susceptibility and the heat capacity both suggest that these are glasslike magnetic transitions, although the transition shows a more complex temperature dependence (with two maxima in ${\ensuremath{\chi}}^{\ensuremath{''}}$) when the $4b$ sites are partially occupied by iron. No long-range magnetic order is thought to be present at $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in either structural form; this has been proven by neutron diffraction and ${\ensuremath{\mu}}^{+}\mathrm{SR}$ for the case when Fe and Mo occupy the $16k$ and $4b$ sites.

We describe the synthesis and structures of the first tantalum-containing nitride–chlorides, Ba3Ta3N6Cl and Ba15Ta15N33Cl4, and the structurally related Ba3Si3N5OCl, and their relationship with a theoretical silaceous framework.

A stereocontrolled synthesis of the core of eunicellin is described featuring a Claisen rearrangement and a diastereoselective organocatalytic Diels-Alder reaction as the key steps.

The regiospecific synthesis of C3 macrocyclic scaffolds possessing multiple different functional groups is described.

Ligand flexibility permits framework rearrangement upon evacuation and gas uptake in a new family of porous MOFs.

The structure of the title compound, di-mu3-acetato-1kappa2O,O':2kappaO';2kappaO:3kappa2O,O'-di-mu2-acetato-1kappaO:2kappaO';2kappaO:3kappaO'-octapyridyl-1kappa3N,2kappa2N,3kappa3N-tricobalt(II) bis(hexafluorophosphate), [Co3(C2H3O2)4(C5H5N)8](PF6)2, consists of divalent multinuclear cations in which three CoII ions are bridged by four mu2-acetate groups. The CoII ions are arranged in an approximately linear manner. The bridging acetates adopt two distinct coordination geometries: one pair bridges via a single O atom and the other pair employs both O atoms. The coordination octahedron around each CoII ion is completed by three pyridine molecules for the two outer CoII ions and by two for the inner ion. Charge is balanced by two PF6- anions. Single-crystal synchrotron X-ray studies indicate the existence of two polymorphs, both triclinic, which are distinguished primarily by differences in the relative orientations of the multinuclear cations, which in form 1 are tilted with respect to each other, but in form 2 are co-parallel as a result of the central Co atom lying on an inversion centre. The results of the structural studies allow an insight into the crystallization mechanism and resultant polymorphism. They suggest that a (bidentate carboxyl)C-O...H-C(pyridine) interaction exists in solution. For form 1, crystallized from pyridine, the interaction is not structure determining, as it is satisfied by interactions between solvent and solute. For form 2, crystallized from CH2Cl2, the interaction is between a bound acetate carboxyl group on one cation and a bound pyridine on another and is thus structure directing.

Scientific and technological interest in porous materials with molecule-sized channels and cavities has led to an intense search for controlled chemical routes to systems with specific properties. This Account details our work on directing the assembly of open-framework structures based on molecules and investigating how the response of nanoporous examples of such materials to guests differs from classical rigid porous systems. The stabilization of chiral nanoporosity by a hierarchy of interactions that both direct and maintain a helical open-framework structure exemplifies the approach.

The introduction of group 10 metals into the hypothetical composition Fe2Mo3N allows the isolation of the solid solutions Fe2-xMxMo3N (M = Ni, Pd, Pt), which crystallize with the filled β-manganese structure (space group P4132, a ≈ 6.7 A). These materials display ferromagnetism with the Curie temperature and saturation magnetization being dependent on the iron content; Fe1.25M0.75Mo3N shows the highest ordering temperature in each series (maximized at Tc = 225 K for M = Pt) and the highest magnetization is always observed for x = 0.5 (maximized at 2.44 μB per formula unit for M = Pd).

A trinuclear nickel complex, [Ni3(C9H10NO3)6(CH3O)]·4CH4O, was synthesized and characterized as a neutral cluster containing the incomplete cubane {Ni3(μ1-O)(μ2-O)2(μ3-O)} core of 2M3-1 topology. The three nickel cations show similar octa-hedral coordination, {Ni(μ1-O)(μ2-O)2(μ3-O)(μ1-N)2}; the positive charge is balanced by six tyrosinate ligands and one methoxide ion. The mean oxidation state of each Ni(II) ion is therefore +2.33. The common coordination modes, chelating (via the amino N and the carboxyl-ate O atoms) and bridging (via the carboxyl-ate O atom), are exhibited by the tyrosinates. Three inter-ligand (intra-cluster) N-H⋯O hydrogen-bonding inter-actions stabilize the incomplete cubane-type moiety. Additional N-H⋯O, O-H⋯O and C-H⋯O inter-actions are formed between clusters, and between the clusters and methanol mol-ecules to regulate the spatial orientation of the tyrosinate and the assembly of the clusters in the crystal. The approximate equilateral triangular arrangement of the three nickel cations in the incomplete cubane-type moiety suggests the possible magnetic frustration, and the proximity of these metal cations indicates weak metallic bonds. The structure contains approximately 39% solvent-accessible volume between the clusters. This is filled with 17 mol-ecules of disordered methanol and was modelled with SQUEEZE [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the reported unit-cell characteristics do not take these mol-ecules into account. The H atoms of the solvent mol-ecules have not been included in the crystal data.

In the title compound, C17H16O7, which was isolated from the leaves of Micromelum integerrimum, the furan ring adopts an envelope conformation with the O atom as the flap. An intramolecular C—H...O hydrogen bond occurs. The carbonyl O atom is disordered in a 0.57 (8):0.43 (8) ratio. In the crystal, molecules are linked by weak C—H...O hydrogen bonds into a C(10) chain along [010].

The title compound, [Co(C(10)H(21)N(2))Cl(3)], was obtained as the by-product of the attempted synthesis of a cobalt sulfate framework using 1,4-diaza-bicyclo-[2.2.2]octane as an organic template. The asymmetric unit comprises two distinct mol-ecules, and in each, the cobalt(II) ions are tetra-hedrally coordinated by three chloride anions and one 1-butyl-diaza-bicyclo-[2.2.2]octan-1-ium cation. The organic ligands are generated in situ, and exhibit two forms differentiated by the eclipsed and staggered conformations of the butyl groups. These mol-ecules inter-act by way of C-H⋯Cl hydrogen bonds, forming a three-dimensional hydrogen-bonding array.

The structure of penta­barium ditantalum dichloride nona­oxide, Ba5Ta2Cl2O9, is isotypic with Ba5Ru1.6W0.4Cl2O9 and with one polymorph of Ba5Ru2Cl2O9. It is related to the perovskite structure and shows a ten-layer stacking of BaO3 and BaCl blocks along the c axis. The Ta cations occupy octa­hedral inter­stices, forming Ta2O9 dimers of distorted face-shared TaO6 octa­hedra. Except for one O atom, all atoms are situated on special positions: Ba1 (Wyckoff position \overline 6m2), Ba2 and Ba3 (3m.), Ta (3m.), Cl (3m.) and O1 (mm2).

Mercury(I) actetate, [Hg(C2H3O2)]n, crystallizes as centrosymmetric dimers, CH3COO–Hg–Hg–OOCCH3, with an Hg—Hg distance of 2.5202 (15) A and an Hg—O distance of 2.152 (12) A. The dimers are assembled into infinite ribbons by long, weaker Hg—O bonds [Hg—O = 2.6802 (12) A]. There are no strong inter­molecular forces between the ribbons.

The crystal structure of the melamine:cyanuric acid (CA.M) adduct has been redetermined and the previously reported cell is shown to be incorrect. The true unit cell has approximately twice the volume of the earlier cell. Crystal data for CA.M: monoclinic, space group I2/m, a = 14.8152(19) A, b = 9.6353(18) A, c = 7.0405(9) A, β = 93.194(11)°, V = 1003.5(3) A3, Z = 2. In contrast to the previous report, this contains an ordered array of cyanuric acid and melamine. Hydrogen bonding between the two components is described in detail and precise information about intermolecular distances reported for the first time. The structure contains hydrogen-bonded sheets stacked perpendicular to the crystallographic (101) plane. The molecular geometry of the cyanuric acid and melamine components is described in detail. Possible explanations for the difference between this structure and the previous report are described in the light of quantum chemical calculations.

A coordination polymer with 74% extra-framework volume is prepared by predictable linking of the honeycomb network to generate a framework-structured solid designed with two distinct connecting ligands.

Linking of ‘all chair’ two-dimensional honeycomb networks, structurally analogous to CFx, with the 4-aminopyridine ligand leads to a three-dimensional molecular framework.

Linking of hydrogen bonded sheets by coordination polymer chains produces a three-dimensional solid derived from two distinct structural components.

We describe the synthesis and structures of the first tantalum-containing nitride-chlorides, Ba(3)Ta(3)N(6)Cl and Ba(15)Ta(15)N(33)Cl(4), and the structurally related Ba(3)Si(3)N(5)OCl, and their relationship with a theoretical silaceous framework.