The New Complexes of Tris(2-Methoxy-5-Bromophenyl)Stibine with Silver Nitrate

By mixing solutions of tris(2-methoxy-5-bromophenyl)antimony and silver nitrate in a methanol : acetonitrile mixture (1:1 vol.), nitrato-O,O'-(acetonitrile)[tris(2-methoxy-5-bromophenyl)antimony]silver complex with the general formula [(C6H3ОMe-2-Br-5)3SbAg(μ2-NO3)(Ме3CN)]2•2[(C6H3ОMe-2-Br-5)3SbAgNO3(Ме3CN)] (1) has been obtained. An addition of silver nitrate solution in the methanol : acetonitrile mixture to the tris(2-methoxy-5-bromophenyl)antimony dioxane solution has led to the formation of a small amount of dark crystals of the ionic complex [(2-MeО-5-Br-C6H3)3SbAg(H2O)Sb(C6H3Br-5-OMe-2)3]+[(2-MeО-5-Br-C6H3)3SbAg(m-NO3)3 AgSb(C6H3Br-5-OMe-2)3]-×3C4H8O2 (2). Complexes 1 and 2 have been characterized by IR spectroscopy, and their structures have been determined by X-ray diffraction analysis. The IR spectra of complexes 1 and 2 contain the bands characterizing the Sb-O, Sb-C, С≡N-, and NO3-group band vibrations. X-ray diffraction analysis of the complexes has been carried out on an automatic four-circle D8 Quest Bruker diffractometer (МоКα radiation, λ = 0.71073 Å, graphite monochromator) at 293 K. Crystallographic characteristics of 1: triclinic, P-1 space group, a = 9.32(3), b = 17.50(7), c = 17.97(5) Å, a = 97.56(14), β = 92.90(19), g = 99.45(19) grad., V = 2859(16) Å3, Z = 2, rcalc = 2.069 g/cm3, 2: monoclinic, С2/с space group, a = 17.417(14), b = 21.041(15), c = 32.01(2) Å, a = 90, β = 97.79(3), g = 90 grad., V = 11624(15) Å3, Z = 4, rcalc = 2.006 g/cm3. In the monomeric and dimeric molecules of crystal 1, nitrate ligands are chelating and bridging, respectively. In the cation of complex 2, the silver atom is bonded to two antimony ligands, the third coordination site is occupied by a water molecule. In the dimeric anion there are one antimony ligand and three bridging nitrate groups surrounding each silver atom.

The spatial organization of trace silver atoms on a DNA template

This review summarized the direct link between the silver atom organization on the DNA secondary structure and the performance of AgNCs, providing an all-round support for understanding the origin of DNA/AgNCs.

Modification of Pyrolyzed Polyacrylonitrile with Silver Atoms

Recently, the search for new materials for nanoelectronics has attracted the interest of scientists. New materials, which are metal-polymer nanocomposites, can be used in modern electronics. The paper presents the possibility and mechanisms for the formation of a metal composite based on single-layer and two-layer pyrolyzed polyacrylonitrile when interacting with silver atoms. The results of the silver atom adsorption on the polymer surface are described, the possibility of filling the interlayer space with metal atoms is shown, and geometric and electron-energy characteristics are established. Theoretical calculations were performed using a molecular cluster model using a non-empirical method in the STO basis. The structure and electron-energy state of a metal-carbon nanocomposite based on pyrolyzed polyacrylonitrile with silver atoms are studied. It was found that the silver atom is adsorbed on the surface of PPAN, and the adsorption process is almost independent of the selected adsorption center. The introduction of metal atoms into the interplanar space of PPAN causes the initially planar monolayers of PPAN to bend, while the structure retains its stability. It was found that the presence of metal atoms in the PPAN structure causes a change in the band gap, which leads to a change in the conductive properties of the resulting nanocomposite.

Silver(I) nitrate two-dimensional coordination polymers of two new pyrazinethiophane ligands: 5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine and 3,4,8,10,11,13-hexahydro-1H,6H-bis([1,4]dithiocino)[6,7-b:6′,7′-e]pyrazine

The two new pyrazineophanes, 5,7-dihydro-1H,3H-dithieno[3,4-b:3′,4′-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexahydro-1H,6H-bis([1,4]dithiocino)[6,7-b:6′,7′-e]pyrazine, C12H16N2S4, L2, both crystallize with half a molecule in the asymmetric unit; the whole molecules are generated by inversion symmetry. The molecule of L1, which is planar (r.m.s. deviation = 0.008 Å), consists of two sulfur atoms linked by a rigid tetra-2,3,5,6-methylenepyrazine unit, forming planar five-membered rings. The molecule of L2 is step-shaped and consists of two S–CH2–CH2–S chains linked by the central rigid tetra-2,3,5,6-methylenepyrazine unit, forming eight-membered rings that have twist-boat-chair configurations. In the crystals of both compounds, there are no significant intermolecular interactions present. The reaction of L1 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[(μ-5,7-dihydro-1H,3H-dithieno[3,4-b;3′,4′-e]pyrazine-κ2 S:S′)(μ-nitrato-κ2 O:O′)silver(I)], [Ag(NO3)(C8H8N2S2)] n , (I), with the nitrato anion bridging two equivalent silver atoms. The central pyrazine ring is situated about an inversion center and the silver atom lies on a twofold rotation axis that bisects the nitrato anion. The silver atom has a fourfold AgO2S2 coordination sphere with a distorted shape. The reaction of L2 with silver nitrate also leads to the formation of a two-dimensional coordination polymer, poly[[μ33,4,8,10,11,13-hexahydro-1H,6H-bis([1,4]dithiocino)[6,7-b;6′,7′-e]pyrazine-κ3 S:S′:S′′](nitrato-κO)silver(I)], [Ag(NO3)(C12H16N2S4)] n , (II), with the nitrate anion coordinating in a monodentate manner to the silver atom. The silver atom has a fourfold AgOS3 coordination sphere with a distorted shape. In the crystals of both complexes, the networks are linked by C—H...O hydrogen bonds, forming supramolecular frameworks. There are additional C—H...S contacts present in the supramolecular framework of II.

Multicenter electron-sharing σ-bonding in the AgFe(CO)4− complex

For the AgFe(CO)4− anion, the silver atom is covalently bonded to the anionic tetracarbonyl-iron, an isolobal analogue of the methyl radical, via a peculiar decentralized electron-sharing σ bond.