Crystallographic report: Bis(isonicotinonitrile)cadmium diselencyanate, [Cd(SeCN)2(pyCN)2] (pyCN = isonicotinonitrile)

The title compound, [Cd(SeCN)₂(pyCN)₂]_∞, adopts an extended one‐dimensional chain structure in which the neighboring cadmium atoms are bridged by two selenocyanate ions. The central cadmium atom has a distorted octahedral geometry defined by two isonicotinonitrile and four selenocyanate ions in a 4N2Se fashion. Copyright © 2003 John Wiley & Sons, Ltd.     

Investigation on crosslinking behaviors of NBR/PVC filled with anhydrous copper sulfate particles by dynamic mechanical analysis

Crosslinking behaviors of acrylonitrile butadiene rubber (NBR)/poly (vinyl chloride) (PVC) alloy, filled with anhydrous copper sulfate (CuSO₄) particles, were investigated for the first time by dynamic mechanical analysis (DMA) under hetero and isothermal modes, respectively. In the heterothermal testing, (NBR/PVC)/CuSO₄ compound showed two marked increases in the storage modulus (E′), corresponding to coordination crosslinking of NBR-CuSO₄ and self-crosslinking of NBR and PVC respectively. During the isothermal testing, a dramatic increase in E′ was found at the initial stage while that of original NBR/PVC alloy was not detected. The marked increase in E′ of (NBR/PVC)/CuSO₄ compound was mainly due to the crosslinking induced by coordination between  CN and Cu²⁺. The increasing extent of E′ increased with the rise of CuSO₄ content, suggesting the formation of a greater number of crosslinks. Moreover, the activation energy (E_a) of crosslinking process was about 139 kJ/mol. In this work, fourier transform infrared spectrum (FT-IR) and equilibrium swelling method were also performed for the characterization of the compound. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 41–51, 2007     

Crystallographic report: Crystal structure of a one‐dimensional zinc(II) coordination polymer containing 4,4′‐biphenyldicarboxylate hemihydrate

A one‐dimensional zinc(II) coordination polymer has been constructed from zinc(II), 4,4′‐biphenyldicarboxylate and pyridine in which each zinc(II) atom is coordinated by two pyridine ligands and two monodentate 4,4′‐biphenyldicarboxylate ligands that define a distorted tetrahedral geometry. Copyright © 2003 John Wiley & Sons, Ltd.     

Weak Attractive Ligand–Polymer and Related Interactions in Catalysis and Reactivity: Impact,Applications, and Modeling

The notion of weak attractive ligand–polymer interactions is introduced, and its potential application, importance, and conceptual links with “cooperative” ligand–substrate interactions are discussed. Synthetic models of weak attractive ligand–polymer interactions are described, in which intramolecular weak C? H???F? C interactions (the existence of which remains contentious) have been detected by NMR spectroscopy and neutron and X‐ray diffraction experiments. These C? H???F? C interactions carry important implications for the design of catalysts for olefin polymerization, because they provide support for the practical feasibility of ortho‐F???H_β ligand–polymer contacts proposed for living Group 4 fluorinated phenoxyimine catalysts. The notion of weak attractive noncovalent interactions between an “active” ligand and the growing polymer chain is a novel concept in polyolefin catalysis.     

Protonation constant of salicylidene (N-benzoyl)glycyl hydrazone and its coordination behaviour towards some bivalent metal ions

Protonation constant of an unsymmetrical Schiff base, salicylidene(N-benzoyl)glycyl hydrazone (SalBzGH), and formation constants of its complexes have been determined potentiometrically at different temperatures in aqueous dioxane medium. Complexes of SalBzGH with VO(IV), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) have been prepared. Elemental analyses, pH-metric, molar conductance, magnetic susceptibility, electronic, IR, ESR, XRD (powder) and NMR studies have been carried out to study the coordination behaviour of SalBzGH toward these metal ions. pH-metric and 1H NMR studies show the presence of two dissociable protons in the ligand. IR and NMR spectra suggest the tridentate nature of the ligand, coordinating as a uninegative species in the Mn(II) complex and as a dinegative species in all the other complexes. Presence of two different conformers of the ligand at room temperature and stabilization of a single conformer upon complex formation have been established from¹H NMR spectra of the metal-free ligand, Zn(II) and Hg(II) complexes recorded at 296 K. Electronic and ESR spectra indicate highly distorted tetragonal geometry for VO(IV) and Cu(II) complexes. XRD powder patterns of the Zn(II) complexes are indexed for an orthorhombic crystal system.     

Coordination Sorption of Urea by Novel Urea Sorbent——Polymer-bound Metal Complexes

Urea can be sorbed by coordination (or complexation)with transitional metalpolyacrylic acid complex and transitional metal-polyacrylamide containing polyethylenepolyamine ligand complexes. The experimental results indicate that the sorbents can sorb about 60mg urea per gram of sorbent at 37℃ and the concentration of urea was 1300.0rag/1 in NaH_2PO_4 and Na_2HPO_4 buffer solution (pH=7.0) and the urea sorption capacity was affected by many factors such as other competive ligands, sorption time, pH and the concentration of urea.     

Oligonucleotide Analogues with Integrated Bases and Backbone. Part 14

The self‐complementary tetrameric propargyl triols 8, 14, 18 , and 21 were synthesized to investigate the duplex formation of self‐complementary, ethynylene‐linked UUAA, AAUU, UAUA, and AUAU analogues with integrated bases and backbone (ONIBs). The linear synthesis is based on repetitive Sonogashira couplings and C‐desilylations (34–72% yield), starting from the monomeric propargyl alcohols 9 and 15 and the iodinated nucleosides 3, 7, 11 , and 13 . Strongly persistent intramolecular H‐bonds from the propargylic OH groups to N(3) of the adenosine units prevent the gg‐type orientation of the ethynyl groups at C(5′). As such, an orientation is required for the formation of cyclic duplexes, this H‐bond prevents the formation of duplexes connected by all four base pairs. However, the central units of the UAUA and AAUU analogues 18 and 14 associate in CDCl₃/(D₆)DMSO 10 : 1 to form a cyclic duplex characterized by reverse Hoogsteen base pairing. The UUAA tetramer 8 forms a cyclic UU homoduplex, while the AUAU tetramer 21 forms only linear associates. Duplex formation of the O‐silylated UUAA and AAUU tetramers is no longer prevented. The self‐complementary UUAA tetramer 22 forms Watson–Crick‐ and Hoogsteen‐type base‐paired cyclic duplexes more readily than the sequence‐isomeric AAUU tetramer 23 , further illustrating the sequence selectivity of duplex formation.     

配位聚合物{[MnL][FeⅡFeⅢ(ox)3·1.5H2O]}∞的合成及其磁学性质

合成和表征了一种新的Schiff碱配合物MnL(ClO4)*3H2O(1)(其中L为n(水杨醛)∶n(二乙撑三胺)=1∶1缩合而成的Schiff碱).1与FeSO4*7H2O和K3[Fe(ox)3]*3H2O(ox=oxalate)进一步反应,生成了双金属层状配位聚合物{[MnL][FeⅡFeⅢ(ox)3]*1.5H2O}∞(2).IR和Mssbauer谱测定结果表明,2具有二维层状结构,其阴离子层由[FeⅡFeⅢ(ox)3]-单元构成.变温磁化率(5K～100K)测试结果表明,2中的自旋载体之间存在反铁磁交换作用.5K时的磁滞现象表明2在低温时可能存在铁磁有序,这可能是亚铁磁或自旋倾斜造成的.     

氮杂冠醚研究Ⅶ、双仲胺型氮杂冠醚对过渡金属离子的选择性萃取作用

合成了五种新型双仲胺型氦杂冠醚，研究了它们对过渡金属离子进行液—液萃取，并用原子吸收法测定其浓度。实验结果表明：这类冠醚对Ａｇ￣＋、Ｐｄ￣（２＋）、和Ｐｔ￣（４＋）等贵金属离子有较强的选择配位性能，对选择性分离这些金属离子有重要的意义。     

The influence of the mercury and thallium atoms in organomercury and organothallium nitroxyl radicals on their reactivity

An increase is found in the reactivity of organomercury and organothallium nitroxyl mono- and biradicals of the imidazoline type in comparison with the analogous compounds without organometallic fragments. This is explained by the formation of coordination bonds NHg, NTl, and NOHg.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 224–226, January, 1993.