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The transition metal dichalcogenide TiSe2 has received significant research attention over the past four decades. Different studies have presented ways to suppress the 200 K charge-density-wave transition, vary lowerature resistivity by several orders of magnitude, and stabilize magnetism or superconductivity. Here we give the results of a synthesis technique whereby samples were grown in a high-pressure environment with up to 180 bar of argon gas. Above 100 K, properties are nearly unchanged from previous reports, but a distinct hysteretic resistance region begins around 80 K, accompanied by insulating lowerature behavior. An accompanying decrease in carrier concentration is seen in Hall effect measurements, and photoemission data show a removal of an electron pocket from the Fermi surface in an insulating sample. We conclude that high inert gas pressure synthesis accesses an underlying nonmetallic ground state in a material long speculated to be an excitonic insulator.

The new chiral and configurationally stable cyclopentadienyl amidinate (CPAM) hafnium complexes, (RC, RHf)-2 and (SC, SHf)-3, have been obtained in enantio- and diastereomerically pure form. Upon activation with the borate co-initiator, [PhNHMe2][B(C6F5)4] (B1), 2 and 3 can serve as pre-initiators for the enantioselective living coordinative polymerization (LCP) and living coordinative chain transfer polymerization (LCCTP) of 1,5-hexadiene to provide optically active poly (methylene-1,3-cyclopentane) (PMCP) and end-group-functionalized PMCP (x-PMCP) in scalable quantities, respectively. 13C NMR stereochemical microstructural analyses reveal the role of ligand directing effects for the two-step propagation mechanism of 1,2-migratory insertion/ring-closing cyclization and structure/property relationships for these new PMCP and x-PMCP materials. [ABSTRACT FROM AUTHOR]

Nuclear energy makes large contributions toward meeting global energy needs, but societal concerns remain high given the impacts of the intended release of radioactive materials including 129I and 131I. In this paper we explore the use of a homologous series of acyclic CB[n] type hosts (H1–H4) as adsorbents of iodine from the vapor phase. We find that H2–H4, but not H1 – perform well in this application with uptake capacities of 2.2 g g−1, 1.5 g g−1, and 1.9 g g−1, respectively. The chemisorptive uptake process involves partial oxidation of catechol walled H2 to quinone walled host and capture of I3− and I5−. Solid H2 can be regenerated by treatment with Na2S2O4 and reused at least five times. The x‐ray crystal structure of H2 is also reported. [ABSTRACT FROM AUTHOR]

Two novel cyclic Al3 clusters, Li2[Al3(PR2)6] ⋅ 2(Et2O) [R=Ph (1), Cy (2)] were synthesized through salt metathesis of metastable AlCl ⋅ (Et2O)n solutions with LiPR2. Both complexes were characterized by single crystal X‐Ray diffraction and their solid state and electronic structures are compared to previously reported cyclic Al3 clusters. Compounds 1 and 2 were further characterized using density functional theory (DFT) methods to understand the nature of the free electron and the three‐center two‐electron Al−Al bonds. Calculations revealed that both clusters are influenced by pseudo Jahn‐Teller distortion and are likely in equilibrium between two low energy bonding states. The solid‐state structures of 1 and 2 are unique among Al3 clusters, while the electronic structure is similar to the previously reported [Sit4Al3]. In aluminum chemistry, 1 and 2 are rare examples of clusters containing isoelectronic cores in different ligand environments. The effects of the phosphide ligand sphere and strongly coordinated lithium atoms are discussed in detail. [ABSTRACT FROM AUTHOR]

High occupancy of cation sites is typical for clathrate-I compositions allowing limited tunability of the electrical properties beyond doping and elemental substitution. Herein, we report on the structure and electrical transport of single-crystal Eu2Ga11Sn35, the sole example of a very low (25%) cation concentration clathrate-I material with atypical transport directly attributable to the structure and stoichiometry. [ABSTRACT FROM AUTHOR]

Oxidation of phenyl [Pt.sup.II] complexes K[(dpms)[Pt.sup.II][Ph.sub.2]], 1, (dpms)[Pt.sup.II]Ph(MeOH), 2, (dpms)[Pt.sup.II]Ph(O[H.sub.2]), 3, and methyl [Pt.sup.II] complex (dpms)[Pt.sup.II]Me(N[H.sub.2]Ph), 6, with [O.sub.2] in aqueous or methanol solutions under ambient conditions leads to corresponding (dpms)[Pt.sup.IV]R(X)OH complexes (R = X = Ph, 7; R = Ph, X = OH, 8; R = Ph, X = OMe, 9; R = Me, X = NHPh; 11; dpms = di(2-pyridyl)methanesulfonate). Complexes 7-9 could be isolated in high yield. Complex 11 as well as its phenyl analogue (dpms)[Pt.sup.IV]Ph(NHPh)OH, 10 can be prepared in high yield by oxidation of corresponding (dpms)[Pt.sup.II]R(N[H.sub.2]Ph) with [H.sub.2][O.sub.2] in methanol. Phenyl [Pt.sup.II] complexes (dpms)[Pt.sup.II]Ph(HX) derived from HX = aniline and DMSO, 4 and 5, respectively, are inert toward [O.sub.2]. The rate of oxidation of 1-5 with [O.sub.2] decreases in the order 1 > 3 ≅ 2 >> 4, and 5 is unreactive. Methyl analogues are significantly more reactive compared with their phenyl counterparts. Proposed mechanism of oxidation with [O.sub.2] includes formation of anionic species (dpms)[Pt.sup.II]R(X)- responsible for reaction with dioxygen. Attempts at C-O and C-N reductive elimination from phenyl PtIV complexes 7-10 do not lead to phenyl derivatives PhX at 80-100 °C, consistent with the results of the DFT estimates of corresponding activation barriers, Δ[G.sup.0] exceeding 28 kcal/mol. Key words: platinum phenyl complexes, oxidation, dioxygen, aqueous solution, mechanism. L'oxydation des complexes phenyles du Pt(II), K[(dpms)[Pt.sup.II]Ph2], 1, (dpms)[Pt.sup.II]Ph(MeOH), 2, (dpms)[Pt.sup.II]Ph(O[H.sub.2]), 3, ainsi que du complexe methyle du Pt(II), (dpms)[Pt.sup.II]Me(N[H.sub.2]Ph), 6, effectuee avec de l'oxygene ([O.sub.2]), en solutions aqueuses ou methanoliques et dans des conditions ambiantes, conduit a la formation des derives (dpms)[Pt.sup.IV]R(X)OH correspondants (R = X = Ph, 7; R = Ph, X = OH, 8; R = Ph, X = OMe, 9; R = Me, X = NPh, 11; dpms = di(2-pyridyl)methanesulfonate). Les complexes 7-9 ont ete isoles avec des rendements eleves. Le complexe 11 ainsi que son analogue phenyle, (dpms)[Pt.sup.IV]Ph (NHPh)OH, 10, peuvent etre prepares avec d'excellents rendements par oxydation du (dpms)[Pt.sup.II]R(N[H.sub.2]Ph) avec du [H.sub.2][O.sub.2] dans le methanol. Les complexes phenyles du Pt(II), (dpms)[Pt.sup.II]Ph(HX), dans lesquels X represente l'aniline (5) et le DMSO (6) sont inertes vis-a-vis de l'oxygene. Les vitesses d'oxydation des produits 1-5 par l'oxygene diminuent dans l'ordre 1 > 3 ≅ 2 > 4,5 (inerte). Les analogues methyles sont sensiblement plus reactifs que leurs analogues phenyles. Le mecanisme d'oxydation propose pour l'action de l'oxygene implique la formation d'especes anioniques (dpms) [Pt.sup.II]R[(X).sup.-] qui seraient responsables de la reaction avec le dioxygene. Les essais realises entre 80 et 100 °C en vue d'effectuer une elimination reductrice C-O et C-N a partir des complexes phenyles 7-10 n'ont pas conduit a la formation de derives phenyles, PhX; ces resultats sont en accord avec les resultats d'evaluations, faites a l'aide de la theorie de la densite fonctionnelle (TDF), des barrieres d'activation correspondantes, Δ[G.sup.0], qui seraient superieures a 28 kcal/mol. Mots-cles : complexes phenyles du platine, oxydation, dioxygene, solution aqueuse, mecanisme. [Traduit par la Redaction] Khusnutdinova et al. 120, Introduction The use of oxygen as the terminal oxidant for selective transition-metal-mediated functionalization of organic substrates is an important practical goal (1). One of the possible approaches to selective aerobic [...]

The preparation of five triazene-arylene oligomers and investigations of their folding properties in aqueous solution are reported. The analysis has shown the folding behavior of five triazene-arylene oligomers whose folding properties can be controlled by the presence of cucurbit[n]uril molecular containers and also responds to the presence of competing chemical stimuli.

The synthesis, structure, photophysical and electrochemical properties of cyclometalated iridium complexes with ancillary cyano and isocyanide ligands are reported. The lack of solvatochromism and highly structured emission has indicated that the lowest energy excited state is triplet ligand centered with some admixture of singlet metal-to-ligand charge-transfer character.

The dynamic behavior of a system comprising CB[6], CB[7] and guests cyclohexanediammonium and adamantanealkylammonium is reported. The results have highlighted the inherent potential of pursing a systems approach toward supramolecular chemistry.

The crystal structure, thermal properties and magnetic properties of a three-dimensional (3D) metal-organic open framework, with infinite one-dimensional (1D) Cu(II) oxide chains embedded in the structure are described. The studies indicate that the framework is a 1D antiferromagnetic system with a Neel temperature of 51 K and a paramagnetic impurity dominates the susceptibility below 14 K, implying the synthesized compound to be highly pure.

Homo-ligated dirhodium(II) carboxamidates provide well-defined structural frameworks with which to investigate catalyst-controlled multiple asymmetric induction ('match/mismatch' effects). The incorporation of additional stereocenters into the dirhodium(II) ligands leads to recognizable levels of double asymmetric induction for C-H insertion, cyclopropanation, and heetro-Diels-Alder cycloaddition applications.

Research has been conducted on the iron(III) phosphates. The synthesis of these compounds has been performed from the dehydration of the hydrothermally prepared monolclinic and orthorhombic hydrated phosphates and the hydrates' structure has been determined from the crystal data.