Synthesis of 3-hydroxy-1-alkenylboronates via phosphine stabilized borylzirconacyclopropenes

Zirconacyclopropenylboronates can be stabilized to dimerization by complexation with tributylphosphine; the phosphine stabilized zirconacycle boronates react with aliphatic and aromatic ketones and aldehydes at C2 of the triple bond to give the previously unknown 3-hydroxyvinylboronates in 61-80% isolated yields.     

Synthesis,structure, and antiviral properties of novel 2-adamantyl-5-aryl-2H-tetrazoles

Chemistry of Heterocyclic Compounds - The reaction of 5-aryl-NH-tetrazoles with adamantan-1-ol in concentrated sulfuric acid proceeds regioselectively with the formation of the corresponding...     

Investigation of the CuBr–LiBr phase diagram

Phase diagram for the system CuBr–LiBr was determined by differential scanning calorimetry and X-ray powder diffraction. The system exhibits a significant solid solubility of the components, especially LiBr in the respective polymorphic modifications of CuBr. Another feature of the system CuBr–LiBr is the occurrence of five invariant three-phase equilibria, which have been assigned to one eutectic (684 K), one peritectoid (668 K), and three eutectoids (679, 645, and 521 K). From the experimental results, formation of a compound LiCuBr₂, at 521 K is discerned.     

Embedding of two-colored right-angled Coxeter groups into products of two binary trees

We prove that every finitely generated 2-colored right-angled Coxeter group Γ can be quasi-isometrically embedded into the product of two binary trees. Moreover we show that the natural extension of this embedding to n-colored groups is not for every group quasi-isometric. Partially supported by Swiss National Science Foundation.     

New higher-order equiaffine invariants

We introduce new affine invariants for smooth convex bodies. Some sharp affine isoperimetric inequalities are established for the new invariants. Partially supported by an NSERC grant and an FRDP grant. Partially supported by an NSF grant, an FRG-NSF grant and a BSF grant.     

Sheaves on abelian surfaces and strange duality

We formulate three versions of a strange duality conjecture for sections of the Theta bundles on the moduli spaces of sheaves on abelian surfaces. As supporting evidence, we check the equality of dimensions on dual moduli spaces, answering a question raised by Göttsche et al. (K-theoretic Donaldson invariants via instanton counting. arXiv:math/0611945).     

Organoselenium(II) complexes containing organophosphorus ligands. Crystal and molecular structure of PhSeSP(S)Ph2, [2-{MeN(CH2CH2)2NCH2}C6H4]SeSP(S)R′2 (R′ = Ph,OPri) and [2-{O(CH2CH2)2NCH2}C6H4]SeSP(S)(OPri)2

Arylselenium(II) derivatives of dithiophosphorus ligands of type ArSeSP(S)R₂ [Ar = Ph, R = Ph (1), OPrⁱ (2); 2-[MeN(CH₂CH₂)₂NCH₂]C₆H₄, R = Ph (3), OPrⁱ (4); 2-[O(CH₂CH₂)₂NCH₂]C₆H₄, R = OPrⁱ (6)] were prepared by redistribution reactions between Ar₂Se₂ and [R₂P(S)S]₂. The derivative [2-{O(CH₂CH₂)₂NCH₂}C₆H₄]SeSP(S)Ph₂ (5) was obtained by the salt metathesis reaction between [2-{O(CH₂CH₂)₂NCH₂}C₆H₄]SeCl and NH₄S₂PPh₂. The compounds were investigated by multinuclear (¹H, ¹³C, ³¹P, ⁷⁷Se) NMR and infrared spectroscopy. The crystal and molecular structures of 1, 3, 4 and 6 were determined by single-crystal X-ray diffraction. In compounds 3, 4 and 6 the N(1) atom is intramolecularly coordinated to the selenium center, resulting in a T-shaped geometry (hypervalent 10-Se-3 species). The dithiophosphorus ligands act as anisobidentate in 1 and monodentate in 3, 4 and 6. Supramolecular architectures based on intermolecular S?H and N?H contacts between molecular units are formed in the hypervalent derivatives 3 and 4, while in the compounds 1 and 6 the molecules are associated into polymeric chains through either Se?S or O?H contacts, with no further inter-chain interactions.     

Polymeric Zn(II) and Cu(II) complexes with exobidentate bridging l-tyrosine: Synthesis,structural and spectroscopic properties

A novel zinc(II) polymeric complex of the formula {[Zn(tyr)₂(H₂O)]H₂O}_n (1) containing l-tyrosine (tyr) was prepared in the crystalline form and characterized by X-ray diffraction, NIR–Vis–UV electronic and IR–FIR vibrational spectroscopy methods. Additionally, for the [Cu(tyr)₂]_n (2) polymer, the vibrational, electronic, EPR spectroscopic and magnetic properties were studied. l-tyrosine in coordination polymers acts as a N,O-bidendate ligand and presents exobidentate bridging with a μ-carboxyl group. The μ-carboxyl exobidentate bridging coordination mode leads to a one-dimensional chain structure. The ZnN₂O₃O′ chromophore has an elongated pseudo-octahedral geometry (1), whereas the CuN₂O₂O′ (2) chromophore presents a distorted square-pyramidal environment with τ = 0.19 around the Cu²⁺ ion.     

Chemical bonding and aromaticity in trinuclear transition-metal halide clusters

Trinuclear transition-metal complexes such as Re(3)X(9) (X = Cl, Br, I), with their uniquely featured structure among metal halides, have posed intriguing questions related to multicenter electron delocalization for several decades. Here we report a comprehensive study of the technetium halide clusters [Tc(3)(μ-X)(3)X(6)](0/1-/2-) (X = F, Cl, Br, I), isomorphous with their rhenium congeners, predicted from density functional theory calculations. The chemical bonding and aromaticity in these clusters are analyzed using the recently developed adaptive natural density partitioning method, which indicates that only [Tc(3)X(9)](2-) clusters exhibit aromatic character, stemming from a d-orbital-based π bond delocalized over the three metal centers. We also show that standard methods founded on the nucleus-independent chemical shift concept incorrectly predict the neutral Tc(3)X(9) clusters to be aromatic.     

ChemInform Abstract: B+13: A Photodriven Molecular Wankel Engine.

Based on DFT and Born—Oppenheimer molecular dynamics calculations a model molecular Wankel motor, the dual‐ring structure B₁₃⁺, driven by circularly polarized IR radiation near 3 THz is proposed as a potential building block for nanomachines.