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The data on the kinetics of the reaction between hexachlorocyclotriphosphazatriene (the phosphazene) with pyridine N-oxide in mixed organic solvents in the presence of water are presented. The reaction of the phosphazene with pyridine N-oxide leads to the formation of the onium salt. It has been found that water catalyzes this reaction, the catalytic action resulting from the solvation of the polar transition state due to the formation of the phosphazene complex with hydrogen bonding, thus facilitating the rupture of the phosphorus bond with the leaving anion. [ABSTRACT FROM AUTHOR]

The title compound 2,2'-bipyridin-10-ium 1-oxide bromide crystallizes as a monohydrate, C10H9N2+·Br-·H2O. Structural disorder is observed due to the fact that protonation, as well as oxidation, of the N atoms of 2,2'-bipyridine occurs at either of the N atoms. The disorder extends to the remainder of the cation, with a refined occupancy rate of 0.717 (4) for the major moiety. An intramolecular N--H...O hydrogen bond forces the bipyridine unit into an s-cis conformation. Each pair of neighbouring 2,2'-bipyridin-1'-ium ions forms a dimeric aggregate by hydrogen bonds between their respective N--O and the N--H functions. These dimers and hydrogen-bonding interactions with bromide ions and the water molecule give rise to a complex supramolecular arrangement. [ABSTRACT FROM AUTHOR]

A chiral mononuclear Dy III complex, formulated [Dy(PNO) 6 (H 2 O) 2 ]Cl 3 ( 1 ) (PNO = pyridine- N -oxide), has been prepared by using an achiral ligand through spontaneous resolution. Structure analyses show that complex 1 consists of a Dy III mononuclear unit and such units interact with each other by hydrogen bonds to form helical chains along a axis. The crystals of 1 are optically active and opposite Cotton effects can be observed in the circular dichroism (CD) spectra. Magnetic studies reveal that complex 1 exhibits field-induced single molecule magnet behavior with an energy barrier of 49 K. [ABSTRACT FROM AUTHOR]

Three manganese(II) N-oxide complexes have been synthesized from the reaction of manganese(II) chloride with either pyridine N-oxide (PNO), 2-methylpyridine N-oxide (2MePNO) or 3-methylpyridine N-oxide (3MePNO). The compounds were synthesized from methanolic solutions of MnCl2⋅4H2O and the respective N-oxide, and subsequently characterized structurally by single-crystal X-ray diffraction. The compounds are catena-poly[[aquachlorido-manganese(II)]-di-μ-chlorido-[aquachloridomanganese(II)]-bis(μ-pyridine N-oxide)], [MnCl2(C5H5NO)(H2O)]n or [MnCl2(PNO)(H2O)]n (I), catena-poly[[aquachloridomanganese(II)]-di-μ-chlorido-[aquachloridomanganese(II)]-bis(μ-2-methylpyridine N-oxide)], [MnCl2(C6H7NO)(H2O)]n or [MnCl2(2MePNO)(H2O)]n (II), and bis(μ-3-methylpyridine N-oxide)bis[diaquadichloridomanganese(II)], [Mn2Cl4(C6H7NO)2(H2O)4] or [MnCl2(3MePNO)(H2O)2]2 (III). The MnII atoms are found in pseudo-octahedral environments for each of the three complexes. Compound I forms a coordination polymer with alternating pairs of bridging N-oxide and chloride ligands. The coordination environment is defined by two PNO bridging O atoms, two chloride bridging atoms, a terminal chloride, and a terminal water. Compound II also forms a coordination polymer with a similar metal cation; however, the coordination polymer is bridged between MnII atoms by both a single chloride and 2MePNO. The distorted octahedrally coordinated metal cation is defined by two bridging 2MePNO trans to each other, two chlorides, also trans to one another in the equatorial (polymeric) plane, and a terminal chloride and terminal water. Finally, complex III forms a dimer with two bridging 3MePNOs, two terminal chlorides and two terminal waters forming the six-coordinate metal environment. All three compounds exhibit hydrogen bonding between the coordinating water(s) and terminal chlorides. [ABSTRACT FROM AUTHOR]

A strategy for threading an axle having a hydrogen bond acceptor unit in the cavity of a C3v symmetric amido-amine macrobicycle is investigated. The macrobicycle acts as a wheel in its neutral as well as triprotonated states to form threaded architectures with a pyridine N-oxide derivative. The negative oxygen dipole of the axle is capable of [2]pseudorotaxane formation in two different orientations with the wheel in its neutral and triprotonated states. [ABSTRACT FROM AUTHOR]

The H-bonded complexes of pyridine N-oxide (PyO) with H2O, acetic, cyanoacetic, propiolic,tribromoacetic, trichloroacetic, trifluoroacetic, hydrochloric, andmethanesulfonic acids have been studied by FTIR and NMR spectroscopy,X-ray diffraction, and quantum chemical DFT calculations. Correlationsbetween vibrational frequencies of the NO stretching and PyO ringmodes and geometric parameters of the H-bond have been established.FTIR experiments show and DFT calculations confirm that definite discontinuityis present in the vicinity of the midpoint in the proton transferpathway. The established correlations significantly aid in the understandingof fine effects such as the isotope (deuteration) effect, crystal-to-solutiontransition, or criticality of aqueous solutions induced by ionic pairs.Geometric isotope effect in the ionic H-bond aggregate of PyO·H(D)Clwas found to be extraordinary large. Measured FTIR, CP/MAS, and high-resolution 13C NMR spectra indicate that H-bond in the PyO·HCl complexin polar solvent can potentially be more ionic than in the crystal.Vibrational modes of ionic pairs originating via proton transfer inH-bond complexes can provide new information concerning the interionicinteraction and its role in the phase separation and mezo-structuringprocesses. The results are compared to the relevant data for PyO·HClcomplex in argon matrix. [ABSTRACT FROM AUTHOR]

X-ray crystal structures of two isomers C8H11N3O3, i.e. 2-N-ethylamino-5-methyl-4-nitropyridine N-oxide (EN5MPO) and 2-N-ethylamino-3-methyl-4-nitropyridine N-oxide (EN3MPO) have been determined. The different substitutions of the - CH3 groups lead to change of the unit-cell structure, molecular and intermolecular arrangement. Both structures are monoclinic, space group P21/c and P21/n with a parallel and antiparallel orientation along the a-axis, respectively. In each of the two subunits, the methyl carbons and N-atoms of the nitro group are almost coplanar with the pyridine ring, but the N-oxide bonds are inclined from this plane. The crystal structures are stabilized by a set of the weak inter- and intramolecular hydrogen bonds of the N-H⋯O type. The structures of both isomers have been confirmed by the results of IR and Raman spectra measurements, quantum chemical calculations and potential energy distribution (PED). The role of methyl group introduced in 3 or 5 position of 2-N-ethylamino-4-nitropyridine N-oxide has been analysed. [ABSTRACT FROM AUTHOR]

A well-resolved discrete water dodecameric cluster containing core cyclic chair-conformational hexamer has been observed within a metal-organic network built from the combination of 4,4'-bipyridine and 4,4'-dipyridine-N,N'-dioxide linkers. [ABSTRACT FROM AUTHOR]