A bridging bis-phosphanido-phosphinidene complex of lanthanum supported by a sterically encumbering PN ligand.

Synthesis of a bulky anilidophosphine ligand (short PNTerph) and its lanthanum complexes 1 and 3 is reported. When exposed to KPHMes, both complexes form the first example of a bis-phosphanido-phosphinidene complex 2. This complex undergoes Phospha-Wittig type reactions and its reactivity towards strong bases is further investigated.

A novel rapid additive manufacturing concept for architectural composite shell construction inspired by the shell formation in land snails.

State-of-the-art rapid additive manufacturing (RAM)-specifically fused filament fabrication (FFF)-has gained popularity among architects, engineers and designers for the quick prototyping of technical devices, the rapid production of small series and even the construction scale fabrication of architectural elements. The spectrum of producible shapes and the resolution of detail, however, are determined and constrained by the layer-based nature of the fabrication process. These aspects significantly limit FFF-based approaches for the prefabrication and in situ fabrication of free-form shells at the architectural scale. Snails exhibit a shell building process that suggests ways to overcome these limits. They produce a soft, pliable proteinaceous film-the periostracum-which later hardens and serves, among other functions, as a form-giving surface for an inner calcium carbonate layer. Snail shell formation behavior is interpreted from a technical point of view to extract potentially useful aspects for a biomimetic transfer. A RAM concept for the continuous extrusion of thin free-form composite shells inspired by the snail shell formation is presented.

Cobaltoceniumethynyl gold(I) as an unusual heterodinuclear bioorganometallic fragment to study the biological properties of alkynyl gold complexes.

A cobaltoceniumethynyl gold(i) complex with a triphenylphosphane ligand triggered efficient cytotoxic effects in cancer cells in contrast to a derivative with two cobaltocenium moieties. The complex effectively inhibited the enzyme thioredoxin reductase (TrxR) suggesting this enzyme as a possible biological target. The cellular uptake of both metal fragments of the active complex was studied by atomic absorption spectroscopy and indicated a high biological stability of the complex.

Factors relevant for the regioselective cyclopolymerization of 1,6-heptadiynes, N,N-dipropargylamines, N,N-dipropargylammonium salts, and dipropargyl ethers by Ru(IV)-alkylidene-based metathesis initiators.

The factors relevant for the regioselectivity of insertion of various 1,6-heptadiynes, N,N-dipropargylamines, N,N-dipropargylammonium salts and dipropargyl ethers into different Ru(IV)-alkylidenes, i.e., [Ru(CF(3)COO)(2)(IMesH(2))(CHR), (R = 2,4,5-(MeO)(3)-C(6)H(2) (I1), 2-(2-PrO)-5-NO(2)-C(6)H(3) (I3), 2-(2-PrO)-C(6)H(4) (I4)), [Ru(CF(3)COO)(2)(1,3-dimesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene)(CH-2-(2-PrO)-5-NO(2)-C(6)H(3))] (I2), [Ru(CF(3)COO)(2)(3-mesityl-1-((1'R)-1'-phenylethyl)-imidazolin-2-ylidene)(CH-2-(2-PrO)C(6)H(4))] (I5) and [Ru(C(6)F(5)COO)(2)(IMesH(2))(CH-2-(2-PrO)-C(6)H(4))] (I6), (IMesH(2) = 1,3-dimesitylimidazolin-2-ylidene), is described. (13)C NMR experiments revealed that all polymers synthesized by the action of I1-I6 consisted virtually solely (>95%) of five-membered repeat units, i.e., (cyclopent-1-enylene)-1,2-vinylenes, 3,4-(1H-2,5-dihydropyrrylenium)-3,4-vinylenes, and (2-pentyl-2,5-dihydrofurylene)-3,4-vinylenes, respectively. The (13)C NMR-based assignments were supported by the synthesis of model compounds, i.e., (cyclopent-3-ene-1,1-diyldimethylbis(tris(3,5-dimethoxyphenyl)carboxylate) (MC1) and N-propyl-N-ethyl-2,5-dihydropyrrolium tetrafluoroborate (MC2), as well as by ene-yne cross metathesis reactions of 3-(propargyloxy)-1-octyne (M6) with trimethylallylsilane. In the polymerization of N-ethyl-N,N-dipropargylamine (M9), an intermediate was isolated that sheds light onto the role of heteroatoms in the 4-position of 1,6-heptadiynes in cyclopolymerization. In addition, in the cyclopolymerization of M9 by I4 the product resulting from back-biting has been isolated and explains for the low polymerization propensity of Ru-alkylidenes for N-alkyl-N,N-dipropargylamines.

The utility of the general practice research database to examine selected congenital heart defects: a validation study.

OBJECTIVE: The purpose of this research was (1) to validate that ventricular septal defect (VSD), tetralogy of Fallot (TOF), and coarctation of the aorta (COA) can be studied in the UK General practice research database (GPRD) and (2) to understand which of the available GPRD components (computerized medical records, questionnaires, and maternal/infant free text) provide maximal information about these heart defects. METHODS: Using a practitioner questionnaire, the positive predictive value (PPV) of the computerized medical record for VSD, TOF, and COA were determined. Both infant and maternal free text was examined. Concordance between the infant free text information and questionnaires was calculated. The proportion of infant information captured in the maternal free text was determined. RESULTS: A 93% response rate was achieved. Based on questionnaire responses, an overall PPV of 93.5% was achieved (VSD = 95%, TOF = 90%, COA = 100%). Approximately half of the records contained infant free text information including information on the type and size of VSD, echocardiogram findings, and surgery. Concordance between the infant's free text and questionnaire information occurred in most of the cases (92-100%). The proportion of infant information in the maternal free text was low (4-19%). CONCLUSION: The GPRD computerized medical records are sufficient to assess VSD, TOF, and COA. This study confirms that maternal free text provides a low yield of limited information pertaining to the infants' defect, while the infant free text may provide an additional information usually obtainable from practitioner questionnaires. The information provided by an infant free text may limit the need for practitioner questionnaire validation.

Ionic liquids as advantageous solvents for headspace gas chromatography of compounds with low vapor pressure.

The potential of ionic liquids as solvents for headspace gas chromatography was investigated. Three compounds with boiling points above 200 degrees C were selected to demonstrate the feasibility of the concept described. 2-Ethylhexanoic acid, formamide, and tri-n-butylamine as examples of acidic, neutral, and basic analytes were dissolved in acidic 1-n-butyl-3-methylimidazolium hydrogen sulfate (1), neutral 1-n-butyl-2,3-dimethylimidazolium dicyanamide (2), and 2 containing 1,8-diazabicyclo[5.4.0]undec-7-ene to adjust basic conditions. All analytes could be determined with limits of detection and limits of quantification in the low-ppm concentration range.

Synthesis, structural and magnetic properties of a series of copper(II) complexes containing a monocarboxylated perchlorotriphenylmethyl radical as a coordinating open-shell ligand.

A series of complexes of copper(II)-containing a perchlorotriphenylmethyl radical functionalized with a carboxylic group as a new ligand is reported. The compounds [Cu(PTMMC)(2)(L)(3)](PTMMC = (tetradecachloro-4-carboxytriphenyl)methyl radical; L =(1) H(2)O, (2) pyrimidine and ethanol or (3) pyridine), [Cu(2)(PTMMC)(2)(MeCOO)(2)(H(2)O)(2)](4) and [Cu(HPTMMC)(2)(L)(3)](HPTMMC =alpha-H-(tetradecachlorotriphenyl)methane-4-carboxylic acid; L = pyridine)(5) were structurally characterized. In complexes 1, 2, 3, and 5, the copper(II) ion is coordinated to two PTMMC (or HPTMMC) units in a slightly distorted square planar surrounding, while 4 shows a paddle-wheel copper(II) dimer structure, where each Cu metal ion has four O atoms of different carboxylate groups, two of them belonging to two PTMMC radicals. The copper(II)-radical exchange couplings are antiferromagnetic for complexes 1, 2 and 3. A linear three-spin model was applied to complexes 1, 2 and 3 to give J/k(B)=-24.9, -15.0 and -20.7 K, respectively. Magnetic properties of 4 show that it is one of the scarce examples of a spin-frustrated system composed of organic radicals and metal ions. In this case, experimental data were fitted to a magnetic model based on a symmetrical butterfly arrangement to give a copper(II)-copper(II) exchange coupling of J/k(B)=-350.0 K and a copper(II)-radical exchange coupling of J/k(B)=-21.3 K, similar to that observed for the copper(II)-radical interactions in complexes, and.

A new multifunctional ferrocenyl-substituted ferrocenophane derivative: optical and electronic properties and selective recognition of Mg2+ ions.

The synthesis, characterisation, and X-ray structure of a new strained asymmetric diferrocene derivative (2) is reported. Compound 2 acts as a highly specific electrochemical and optical Mg(2+) ion sensor, as revealed by spectroscopic and electrochemical techniques. Thus, in the presence of Mg(2+), a new redox peak appears in the cyclic voltammogram (CV) that is anodically shifted compared to the E(1/2) of the free receptor (DeltaE(1/2)=340 mV). Diferrocene derivative 2 also gives a highly visual response upon addition of Mg(2+), namely a change of colour from orange to deep purple. In addition, compound 2 does not show any significant sensing activity in the presence of Ca(2+) or alkaline ions. On protonation, it is converted into the stable diferrocenylcarbenium salt 4, in which two different modes of stabilisation of the alpha-carbocationic centre are clearly demonstrated by a combination of (1)H NMR and (57)Fe Mössbauer spectroscopic measurements. Finally, by a partial (chemical or electrochemical) oxidation, compound 2 forms the asymmetric mixed-valence species 2(+), which can be isolated as the solid salt 6 by using CF(3)SO(3) (-) as a counterion. This mixed-valence species shows a fast intramolecular electron-transfer process, as ascertained by several spectroscopic techniques.

Bulk spontaneous magnetization in the new radical cation salt TM-TTF[Cr(NCS)(4)(isoquinoline)(2)] (TM-TTF = tetramethyltetrathiafulvalene).

A new organic-inorganic hybrid salt [TM-TTF][Cr(NCS)(4)(isoquinoline)(2)] (1) (TM-TTF = Tetramethyltetrathiafulvalene) has been synthesized. Compound 1 crystallizes in the triclinic P space group with a = 8.269(1), b = 10.211(2), and c = 11.176(2) A, alpha = 89.244(9), beta = 88.114(6), and gamma = 74.277(7) degrees, V = 907.6(3) A(3), and Z = 1. The crystal structure was resolved in the temperature range between 223 and 123 K, showing that changes in the crystal structure at low temperature result in stronger interactions between anions and cations. The packing of 1 consists of mixed anion-cation layers in the bc plane containing S.S and pi-pi anion-cation interactions, the layers being connected by very short S.S contacts between anions and cations. Magnetic measurements in a small external field show bulk spontaneous magnetization with a T(c) of 6.6 K consistent with the presence of weakly coupled ferrimagnetic order in compound 1. The EPR measurements also demonstrate the interaction between the d and pi electrons and the presence of an internal magnetic field brought about by the magnetic ordering.

Observation of a P/M interconversion of a gold-phosphine helicate via 31P NMR.

Ligands containing P-CH2-CH2-P elements have been shown to form double-stranded helicates whose axis consists of gold atoms with Au...Au contacts; the interconversion of the P and M forms of the helicate [Au3(mu-pp2)2](OTf)3 (pp2 = PhP(CH2CH2PPh2)2) is monitored via 31P NMR.

Stereochemistry of phenyl alpha-nitronyl nitroxide radicals

An extensive investigation of the conformations adopted by the family of phenyl alpha-nitronyl nitroxides has been carried out. A database containing 110 crystal structures was used in a statistical study of the solid-state geometries and conformations of these radicals. This study revealed that the favoured conformations involve a twisted distortion in the imidazolyl rings and a twist between the aromatic and heterocyclic rings in the molecules. As a consequence, these radicals show two types of preferred conformations in the solid state: the pseudo-anti enantiomeric pair and the pseudo-eclipsed pair, the latter type being the most statistically probable. A new chiral member of this group of radicals that bears a lactate moiety, (R)-1, and its corresponding racemic compound, (R,S)-1, have been prepared in order to study the influence of chiral induction from the stereogenic centre on the torsion angle between the aromatic and heterocyclic rings of the alpha-nitronyl nitroxides. The X-ray crystal structures of the enantiopure and racemic compounds, which both reveal chains of molecules sustained by strong O-H...O hydrogen bonds between the carboxylic acid group and the ON group of the radical in the solid, as well as their magnetic properties have been determined. Remarkably, the molecules with a given stereogenic centre have a single helical sense between their component rings, even in the racemic crystal. Chiral induction from the stereogenic centre to the radical unit has also been proved by CD spectroscopy in the solid state. The results of these experiments have been rationalised by ab initio calculations of the spectra.

A highly enantiopure biconcave porphyrin with effective D4-structure

A first representative of an effectively D4-symmetric biconcave porphyrin (1) was prepared from a tetramerizing condensation of a C2-symmetric pyrrole (2). The chiral pyrrole 2 was synthesized in a six-step reaction sequence starting from the C2h-symmetric 2,6-di-tert-butylanthracene. The relevant stereochemistry was introduced in a highly diastereo-discriminating Diels-Alder reaction with fumaric acid di(-)menthyl ester, catalyzed by aluminum chloride. X-ray analyses of two of the dimenthyl esters prepared unambiguously secured their tentatively assigned absolute configuration and that of the pyrrole 2 (as the S,S isomer). The enantiomeric purity of the pyrrole 2 was determined as 99% ee, using the Co11 complex of the porphyrin 1 as a chiral shift reagent. The pyrrole 2 lent itself to a stereochemically nearly uniform preparation of the chiral, biconcave porphyrin 1. Applying Horeau's principle, 1 was calculated to be present in an enantiomeric excess of about 10(9):1. The validity of the statistical considerations relevant for this estimate were verified by examination of the results from preparative tetramerization experiments in which the enantiomeric purity of the pyrrole 2 was deliberately lowered.

Transmission of Magnetic Interactions through an Organometallic Coupler: A Novel Family of Metallocene-Substituted alpha-Nitronyl Aminoxyl Radicals.

The capability of metallocene bridges as new organometallic magnetic couplers is evaluated by studying the family of diradicals 2 (M = Fe, Ru) consisting of two purely organic alpha-nitronyl aminoxyl radicals connected by a 1,1'-metallocenylene bridge. Preliminary studies performed with 2-metallocenyl-alpha-nitronyl aminoxyl monoradicals 1 (M = Fe, Ru, Os), as reference compounds, show the presence of a small spin density on the central metal of the metallocenes. This fact makes the metallocene units effective bridges to transmit magnetic interactions by a spin polarization mechanism. The study of the magnetic properties of diradicals 2 in the solid state and in diluted frozen solutions reveals the existence of an intramolecular antiferromagnetic exchange interaction between the radical subunits whose strength is highly dependent on the molecular conformation adopted by the diradical. As shown by crystal data and by ESR measurements, an intramolecular hydrogen bond between the two radical units forces the molecule to adopt a cisoid molecular conformation, which determines that the magnetic interaction occurs by a direct through-space interaction between the two SOMOs of the two radical units along with the classical spin polarization mechanism through the sigma-bonds of the metallocene unit. Lattice constants for both structures are as follows: 1 (M = Fe), C(17)H(21)FeN(2)O(2), a = 7.170(1) Å, b = 10.135(2) Å, c = 10.683(2) Å, alpha = 88.88(3) degrees, beta = 83.42(3) degrees, gamma = 79.75(3) degrees, triclinic, P&onemacr;, Z = 2; 2 (M = Fe), C(24)H(32)FeN(4)O(4), a = 11.848(3) Å, b = 11.785(2) Å, c = 17.728(4) Å, beta = 106.25(2) degrees, monoclinic, P2(1)/n, Z = 4.

Structure of leuconolam sesquihydrate.

8a-Ethyl-7,8,8a,10,11,12a-hexahydro-12a- hydroxyindolizino[8,1-ef][1]benzazonine-6,13-(5H,9H)-dione sesquihydrate, C19H22N2O3.3/2H2O, Mr = 353.42, triclinic, P1, a = 9.250 (2), b = 13.366 (3), c = 9.217 (2) A, alpha = 97.786 (3), beta = 119.590 (3), gamma = 70.726 (3) degrees, V = 934.8 A3, Z = 2, Dx = 1.255 g cm-3, Mo K alpha,lambda = 0.71073 A, mu = 0.839 cm-1, F(000) = 378, T = 293 K. The final R value is 0.061 for 1646 significant [I greater than 3 sigma(I)] reflections. The alkaloid from the leaves of Rhazia stricta is built up by a benzene ring ortho disubstituted with a 4,5-dihydro-5-hydroxy-2-oxo-pyrrol-1,4,5-triyl unit and an N(CO)R- unit forming a twelve-membered ring.