93 research outputs found

    Preparation and characterization of hexamethylenetetramine N-oxide and some acid adducts

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    A macrocyclic tetradentate ligand containing tertiary amine and pyridine functional groups. Electrochemical and X-ray structural studies on [CoII(CR-Me3)Cl]ClO4 (CR-Me3 = meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17), 13,15-triene)

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    The new ligand CR-Me3, meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17), 13,15-triene, has been prepared by methylation of CR-H (CR-H = meso-2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15- triene) with formic acid and formaldehyde. The reaction of CoCl2 with CR-Me3 in methanol yielded [CoII(CR-Me3)Cl]+, which was isolated as the perchlorate. A solution of this salt in acetonitrile yielded a reversible Co(III)/Co(II) couple at 0.69 V vs. the Cp2Fe+/0 couple. The high-spin (μeff = 4.8 μB) and air-stable [CoII(CR-Me3)Cl]ClO4 complex crystallizes in space group P21/n, with a = 9.392 (2) Å, b = 17.696 (5) Å, c = 14.189 (4) Å, β = 107.36 (2)°, and Z = 4. X-ray structural analysis (RF = 0.048 for 3316 observed Mo Kα data) showed that the macrocyclic cation conforms closely to idealized Cs molecular symmetry. The coordination geometry about the Co(II) atom is distorted tetragonal pyramidal, with one tertiary amino N atom at the apex and the metal center located 0.41 Å above the basal plane comprising the chloro ligand, the pyridyl N, and the remaining two tertiary amino N atoms. © 1986 American Chemical Society.link_to_subscribed_fulltex

    A novel monooxoruthenium(V) complex containing a polydentate pyridyl amine ligand. Syntheses, reactivities, and X-ray crystal structure of [RuIII(N4O)(H2O)](ClO4)2

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    The syntheses and characterization of cis-[RuIII(tepa)Cl2]+, [RuIII(N4O)(H2O)]2+, and [RuV(N4O)O]2+ complexes are described [tepa = tris(2-(2-pyridyl)ethyl)amine, N4OH = bis(2-(2-pyridyl)ethyl)(2-hydroxy-2-(2-pyridyl)ethyl)amine]. The molar magnetic susceptibilities for [RuIII(N4O)(H2O)]2+ and [RuV(N4O)O]2+ complexes are 1.79 and 2.2 μB, respectively. The X-ray structure of [RuIII(N4O)(H2O)](ClO4)2 has been determined: [RuIII(C21H23N4O)(H 2O)](ClO4)2, M = 666.43, monoclinic, space group P2/c (no. 13), a = 11.644 (1) Å, b = 11.937 (3) Å, c = 18.856 (6) Å, β = 105.39 (2)°, V = 2527 (1) Å3, Z = 4, Dx = 1.753, Dc = 1.752 g cm-3, μ(Mo Kα) = 8.82 cm-1. The Ru-O(OH2) and Ru-O(N4O) distances are 2.115 (3) and 1.961 (4) Å, respectively. The [RuV(N4O)O]2+ complex shows an intense Ru=O stretch at 872 cm-1 which is absent in the [RuIII(N4O)(H2O)]2+ complex. The Ru(V) state in [RuV(N4O)O]2+ has also been confirmed by spectrophotometric redox titration in 0.1 M HClO4 by using [RuII(NH3)4(bpy)]2+ (bpy = 2,2′-bipyridine) as the redox titrant. A stoichiometry of 1:3 has been obtained. The cyclic voltammograms of both [RuIIIHN4O)(H2O)]2+ and [RuV(N4O)O]2+ complexs show two couples at 0.35 and 1.02 V vs SCE in aqueous medium at pH = 1, assignable to a Ru(III/II) and a Ru(V/III) couple, respectively. At 5.5 > pH > 3.5, the wave for the Ru(V/III) couple splits into two waves, a pH-independent one-electron wave for the Ru(V/IV) couple and a two-proton-one-electron wave with a slope of -117 mV/pH unit for the Ru(IV/III) couple. The Ru(IV) state is found to be thermodynamically unstable with respect to disproportionation into Ru(III) and Ru(V) at pH < 3.5. The [RuV(N4O)O]2+ complex is found to be an active oxidant, capable of oxidizing both activated C-H bonds and the C-H bond of cyclohexane. Studies on the reactions of [RuV(N4O)O]2+ with organic substrates indicated that the Ru(V)=O has a higher affinity for hydrogen atom/hydride abstraction than oxo-transfer reaction to C=C double bond.link_to_subscribed_fulltex

    Synthesis, reactivities, and electrochemical properties of pyridinecarboxamide complexes of rhodium(III) and iridium(III). Crystal structure of [Rh(bpb)(py)2]ClO4 [H2bpb = 1,2-bis(2-pyridinecarboxamido)benzene, py = pyridine]

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    A series of organo and non-organo rhodium and iridium complexes of bpb and bpc ligands [H2bpb = 1,2-bis(2-pyridinecarboxamido)benzene, H2bpc = 4,5-dichloro-1,2-bis(2-pyridinecarboxamido)benzene] have been synthesized. These complexes display reversible one-electron oxidation couples. Stable one-electron-oxidized species have been generated both chemically and electrochemically. The oxidation potentials are affected dominantly by the charge effect but are relatively independent of the nature of the central metal ions and axial ligands. On the contrary, [Rh(bpe)R]·H2O complexes [R = Me or Et; H2bpe = 1,2-bis(2-pyridinecarboxamido)ethane] can only be oxidized irreversibly at a potential of about 0.3 V more anodic than that of the corresponding bpb complexes. The involvement of the equatorial ligand in the oxidation of the bpb and bpc complexes has been suggested. The complex [Rh(bpb)(py)2]ClO4 has been characterized by X-ray crystallography: space group P1, a = 8.316(1), b = 9.620(2), c = 17.405(6) Å, α = 98.87(2), β = 99.57(2), γ = 90.55(2)°, Z = 2, and R = 0.039 for 4 788 observed reflections.link_to_subscribed_fulltex

    Metal nitrido and imido photo-oxidants. Photophysics and photochemistry of nitrido and imido complexes of osmium(VI) and X-ray crystal structure of [Ph4As]2[OsVI(CN)5N]

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    Nitrido- and imido-osmium(VI) complexes with cyanides as ligands have been synthesised and found to display intense photoluminescence in fluid solutions at room temperature; the X-ray structure of [Ph4As]2[Os VI(CN)5N] has been determined with a measured Os≡N distance of 1.647(7) Å.link_to_subscribed_fulltex

    Synthesis and X-ray crystal structure of a bis(trimethylsiloxy)ruthenium(III) complex

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    Treatment of the cis-dioxoruthenium(VI) complex, cis-[RuVI(L)O2](PF6)2 (L = N,N,N′,N′-3,6-hexamethyl-3,6-diazaoctane-1,8-diamine) with tert-butyl(trimethylsilyl)amine in benzene at room temperature resulted in the formation of cis-[RumIII(L) (OSiMe3)2](PF6) (1). which was characterized by X-ray diffraction crystal analysis.link_to_subscribed_fulltex
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