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Discrete Molecules (discrete + molecule)
Selected AbstractsThe Variable Binding Modes of Phenylbis(pyrid-2-ylmethyl)phosphane and Bis(pyrid-2-ylmethyl) Phenylphosphonite with AgI and CuIEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2009Fernando Hung-Low Abstract A series of new bridging phosphane and phosphonite structures forming three- and six-membered rings with the metal centers were synthesized and characterized. The resulting compounds of phenylbis(pyrid-2-ylmethyl)phosphane (1) with the silver(I) salts of trifluoroacetate (tfa,), tetrafluoroborate (BF4,), and trifluoromethanesulfonate (OTf,), and copper tetrakis(acetonitrile) hexafluorophosphate (PF6,) shows the flexibility of the ligand by displaying different coordination modes associated with the electronic and structural characteristics of the corresponding anion. Accordingly, ligand 1 in these complexes displays two different binding modes. With Agtfa and AgBF4 compounds 3 and 4 are obtained where the ligand chelates to two silver atoms that exhibit normalAg,Ag contacts in the range of 2.9 Å. When AgOTf or Cu(NCCH3)4PF6 are used, one molecule of 1 bridges the metal centers through a phosphorus atom while another is terminally bound. This induces short M,M distances of 2.6871 and 2.568 Å for 5 and 6, respectively. Similarly, the coordination behavior of the heterofunctional bis(pyrid-2-ylmethyl) phenylphosphonite ligand (2) is reported with Cu(NCCH3)4PF6 (7) and AgBF4 (8) to form two novel discrete molecules. In these complexes 2 coordinates through the P and N atoms, with the difference that in 7 the O atom of one of the carbinol arms is also bound to the Cu. Elemental analysis, variable-temperature multinuclear NMR spectroscopy, single-crystal X-ray diffraction, and low-temperature luminescence studies were carried out to fully characterize the compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Transition Metal-Assisted Hydrolysis of Pyrazole-Appended Organooxotin Carboxylates Accompanied by Ligand TransferEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2007Vadapalli Chandrasekhar Abstract The reaction of the potentially multi-site coordination ligands [{nBu2SnO2CL}2O]2 (1), [{nBu2SnO2CL,}2O]2 (2), [nBuSn(O)O2CL]6 (3), and [nBuSn(O)O2CL,]6 (4), (L = (Pz)2CH-); L, = (3,5-Me2Pz)2CH-; Pz = pyrazolyl) with hydrated metal salts leads to the hydrolysis of the organotin carboxylates accompanied by the formation of insoluble organotinoxide/hydroxides and metal complexes. The in situ generated LCOO and L,COO ligands bind to the metal ions. The complexes [Cu(LCOO)2(NO3)2(nBu2Sn((H2O)2)]n[Cu(LCOO)2] (5), [Mg(L,COO)2] (6), [Cu(LCOO)2] (7), and [{(Cu(L,COO)2(Cu(MeOH))3}{ClO4}2]n (8) were isolated and structurally characterized. The solid-state structure of 5 reveals that two discrete molecules are present in the same asymmetric unit; a heterobimetallic coordination polymer, [Cu(LCOO)2(NO3)2(nBu2Sn((H2O)2)]n and a discrete coordination complex, [Cu(LCOO)2]. The cationic portion of the heterobimetallic compound contains alternate six-coordinate SnIV and CuII centers bridged by the carboxylate oxygen atoms of the LCOO ligand.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Nonclassical forces: Seemingly insignificant but a powerful tool to control macromolecular structuresJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2008Michiya Fujiki Abstract Strong chemical forces such as covalent and ionic bonds are responsible for building discrete molecules, nature dwells on noncovalent forces weaker by three orders in magnitude, like the hydrophobic effect, hydrogen bonding, and van der Waals forces. Despite being weak, they possess the potential to drive spontaneous folding or unfolding of proteins and nucleic acids and the recognition between complimentary molecular surfaces. The power of these forces lies in the cooperativity with which they act, thereby generating a cumulative effect of many bonding interactions occurring together. Many ongoing research aims to translate the potential of these forces to the synthetic world to create desired structures with specific chemical functions. Achieving this offers unlimited opportunities for designing and synthesizing the most complex structures with specific applications. This highlight aims to reflect the critical role these noncovalent forces play in controlling macromolecular structures, which hold immense untapped potential for applications defying conventions, and briefly touches on the concept of homochirality in nature based on chiral and weak noncovalent interactions in synthetic nonpolar Si-catenated polymers. It sheds some light on the discovery and characterization of Si/F-C interactions in fluoroalkylated polysilanes in chemosensing of fluoride ions and nitroaromatics with a great sensitivity and selectivity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4637,4650, 2008 [source] Triptycene-Based Metal Salphens,Exploiting Intrinsic Molecular Porosity for Gas StorageCHEMISTRY - A EUROPEAN JOURNAL, Issue 44 2009Jonathan No supramolecular assembly required: Accessible porous materials were formed solely on the basis of inefficient packing of discrete molecules resulting from their specific structure, which hinders close packing. These highly porous materials demonstrate the potential for adsorption and storage of N2 and H2 gases from molecular solids (see figure). [source] | ||||||||||