Atomic Cations Research Articles

Tetra-methyl-ammonium hydrogen terephthalate.

The asymmetric unit of the title salt, C4H12N+·C8H5O4 −, contains one half of a tetra­methyl­ammonium cation and one half of a hydrogen terephthalate monoanion. The N atom of the ammonium cation lies on a twofold rotation axis and the centre of mass of the terephthalate anion is on a centre of inversion. In the crystal, the centrosymmetric terephthalate ions are linked by a very short symmetric O—H⋯O hydrogen bond [O⋯O = 2.4610 (19) Å] into a one-dimensional polymeric chain along [1-12]. The tetra­methyl­ammonium cations and terephthalate anions are then connected through a pair of bifurcated acceptor C—H⋯O hydrogen bonds, generating a three-dimensional supra­molecular network. The carboxyl­ate groups at both ends of the terephthalate anion are charge-shared with an equal probability of 0.5.

3-(diallylamino)propanenitrile ((C3H5)2NC2H4CN, L) π-complexes with copper(I) ionic salts. Syntheses and crystal structures of compounds [Cu(H+L)ClO4]ClO4 · H2O, [Cu(H+L)BF4]BF4 · H2O, and [Cu(H+L)(H2O)]SiF6 · H2O

Qualitative single crystals of π-complexes Cu(H+L)(ClO4)]ClO4 · H2O (I), Cu(H+L)(BF4)]BF4 · H2O (II), and [Cu(H+L)(H2O)]SiF6 · H2O (III) are synthesized from solutions of 3-(diallylamino)propanenitrile (L) in propanol, ethanol, and methanol-water acidified with the corresponding acid to pH 3.5–5 and from the copper(II) salts (Cu(ClO4)2 · 6H2O, Cu(BF4)2 · 6H2O, and CuSiF6 · 4H2O) using the alternating-current electrochemical method on copper wire electrodes. The crystal structures of the complexes are determined. All compounds crystallize in the monoclinic crystal system: complexes I and II are isostructural, space group P21/n, Z = 4. For compound III, space group P21/c, Z = 8. Unit cell parameters: for Ia =7.8153(3), b = 16.7824(7), c = 12.4426(5) A, β = 93.410(2)°, V = 1629.1(1) A3; for II, a = 7.6755(4), b = 16.7119(7), c = 12.3784(6) A, β = 94.354(2)°, V = 1583.2(1); and for IIIa = 9.826(2), b = 24.009(3), c = 12.061(2) A, β = 91.820(6)°, V = 2843.9(7) A3. The trigonal pyramidal coordination of the copper atom in complexes I-III is formed by two C=C bonds of the allyl groups of H+L, the nitrile N atom of the adjacent cation of the ligand, and the O or F atom of the ClO4− or BF4− anions. In structure III, the apical position of the pyramid is occupied by the O atom of the water molecule, since the SiF62− anion is considerably remote from the copper(I) atom. However, this anion is bound to the organic cation by hydrogen bonds F…H (2.05–2.51 A).

Tris(2,2′-bipyridine-κ2N,N′)cobalt(III) bis[bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6)cobaltate(III)] perchlorate dimethylformamide hemisolvate 1.3-hydrate

In the title compound, [Co(C10H8N2)3][Co(C7H3NO4)2]2(ClO4)·0.5C3H7NO·1.3H2O, the CoIII atom in the complex cation is pseudoocta­hedrally coordinated by six N atoms of three chelating bipyridine ligands. The CoIII atom in the complex anion is coordinated by two pyridine N atoms and four carboxyl­ate O atoms of two doubly deprotonated pyridine-2,6-dicarboxyl­ate ligands in a distorted octa­hedral geometry. One dimethyl­formamide solvent mol­ecule and two water mol­ecules are half-occupied and one water mol­ecule is 0.3-occupied. O—H⋯O hydrogen bonds link the water mol­ecules, the perchlorate anions and the complex anions. π–π inter­actions between the pyridine rings of the complex anions are also observed [centroid–centroid distance = 3.804 (3) Å].

Nitrogen Dioxide Reactions with 46 Atomic Main-Group and Transition Metal Cations in the Gas phase: Room Temperature Kinetics and Periodicities in Reactivity

Experimental results are reported for the gas-phase room-temperature kinetics of chemical reactions between nitrogen dioxide (NO(2)) and 46 atomic main-group and transition metal cations (M(+)). Measurements were taken with an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer in helium buffer gas at a pressure of 0.35 ± 0.01 Torr and at 295 ± 2 K. The atomic cations were produced at ca. 5500 K in an ICP source and allowed to decay radiatively and to thermalize to room temperature by collisions with Ar and He atoms prior to reaction with NO(2). Measured apparent bimolecular rate coefficients and primary reaction product distributions are reported for all 46 atomic metal cations and these provide an overview of trends across and down the periodic table. Three main types of reactions were observed: O-atom transfer to form either MO(+) or NO(+), electron transfer to form NO(2)(+), and addition to form MNO(2)(+). Bimolecular O-atom transfer was observed to predominate. Correlations are presented between reaction efficiency and the O-atom affinity of the metal cation and between the prevalence of NO(+) product formation and the electron recombination energy of the product metal oxide cation. Some second-order reactions are evident with metal cations that react inefficiently. Most interesting of these is the formation of the MNO(+) cation with Rh(+) and Pd(+). The higher-order chemistry with NO(2) is very diverse and includes the formation of numerous NO(2) ion clusters and a number of tri- and tetraoxide metal cations. Group 2 metal dioxide cations (CaO(2)(+), SrO(2)(+), BaO(2)(+)) exhibit a unique reaction with NO(2) to form MO(NO)(+) ions perhaps by NO transfer from NO(2) concurrent with O(2) formation by recombination of a NO(2) and an oxide oxygen.

Synthesis of ZrO<sub>2</sub>: ƞ wt% Re<sub>2</sub>O<sub>3</sub> Powders by the Heterogeneous Coprecipitation Technique

The zirconia in its cubic phase (C-ZrO2) has gained scientific and technological interest because it has high ionic conductivity and is useful in applications where the transport of oxygen ions prevails, for example, in the oxygen sensors and solid oxide fuel cells [1,. In the pure zirconia, the Zr4+ ion is too small to sustain the fluorite structure at low temperatures, so it has to be partially replaced by a higher atomic radius cation and lower valence number, for example, the Y3 +, Mg2 +, Ca2 + and the rare earth cations TR3 +, [. Currently there are several synthesis methods used to obtain cubic zirconia, the most popular being the mixture of oxides and coprecipitation used industrially in the research labs, but these methods provide powders with different characteristics which will be decisive for a specific application. In this context, the objective of this study was the preparation of homogeneous mixtures of zirconia-rare earth in different concentrations in order to stabilize the C-ZrO2, using the technique of heterogeneous coprecipitation for potential applications in oxygen sensors.

Stepwise Association of Hydrogen Cyanide and Acetonitrile with the Benzene Radical Cation: Structures and Binding Energies of (C6H6•+)(HCN)n, n = 1–6, and (C6H6•+)(CH3CN)n, n = 1–4, Clusters

Equilibrium thermochemical measurements using the ion mobility drift cell technique have been utilized to investigate the binding energies and entropy changes associated with the stepwise association of HCN and CH(3)CN molecules with the benzene radical cation in the C(6)H(6)(•+)(HCN)(n) and C(6)H(6)(•+)(CH(3)CN)(n) clusters with n = 1-6 and 1-4, respectively. The binding energy of CH(3)CN to the benzene cation (14 kcal/mol) is stronger than that of HCN (9 kcal/mol) mostly due to a stronger ion-dipole interaction because of the large dipole moment of acetonitrile (3.9 D). However, HCN can form hydrogen bonds with the hydrogen atoms of the benzene cation (CH(δ+)···NCH) and linear hydrogen bonding chains involving HCN···HCN interaction. HCN molecules tend to form externally solvated structures with the benzene cation where the ion is hydrogen bonded to the exterior of HCN chains. For the C(6)H(6)(•+)(CH(3)CN)(n) clusters, internally solvated structures are formed where the acetonitrile molecules are directly interacting with the benzene cation through ion-dipole and hydrogen bonding interactions. The lack of formation of higher clusters with n > 4, in contrast to HCN, suggests the formation of a solvent shell at n = 4, which is attributed to steric interactions among the acetonitrile molecules attached to the benzene cation and to the presence of the blocking CH(3) groups, both effects make the addition of more than four acetonitrile molecules less favorable.

Redetermination of (acetonitrile-κN)dicarbonyl(η5-cyclopentadienyl)iron(II) tetrafluoridoborate

The crystal structure of the title compound, [Fe(C5H5)(CH3CN)(CO)2]BF4, of which only the coordinates of the non-H atoms of the cation have previously been reported [Fadel et al. (1979 ▶). Z. Anorg. Allg. Chem. 453, 98–106] has been redetermined. The FeII atom in the complex cation is coordinated by a cyclo­penta­dienyl ring, two carbonyl ligands and an acetonitrile mol­ecule displaying a three-legged piano stool structure. Three of the four F atoms of the BF4 − anion are disordered over two sets of sites, with a site-occupancy factor of 0.709 (10) for the major occupied site.

Ionic Liquids for Electrolyte-Gating of ZnO Field-Effect Transistors

We investigate the influence of the chemical structure of a range of imidazolium-based ionic liquids (IL) on their properties as electrolytes and the device characteristics of electrolyte-gated field-effects transistors (FETs) based on spray-deposited polycrystalline zinc oxide (ZnO). We find a decrease of electron field-effect mobility that correlates with the capacitance of the ionic liquids and not only with the size of the IL-cation. The device stability depends significantly on testing conditions. While they are reasonably stable in nitrogen, ZnO-FETs degrade rapidly in ambient air due to absorption of water by the IL and the resulting ZnO surface reactions. Replacement of the most acidic hydrogen atom of the imidazolium cation and surface passivation of ZnO with hexamethyldisilazane improve environmental stability.

Bis[1,3-bis(diphenylphosphanyl)propane]copper(I) tetrachloridogallate(III)

In the title compound, [Cu(C27H26P2)2][GaCl4], the CuI atom in the complex cation is P,P′-chelated by two 1,3-bis­(diphenyl­phosphan­yl)propane ligands in a distorted tetra­hedral geometry, while the GaIII cation is coordinated by four chloride anions in a distorted tetra­hedral geometry. In the crystal, weak C—H⋯π inter­actions occur between adjacent complex cations.

Bis(2,S-dimethyldithiocarbazate-κ2 N 3,S)(nitrato-κO)copper(II) nitrate

The title complex, [Cu(NO3)(C3H8N2S2)2]NO3, represents a low-symmetry polymorph (P-1, Z = 4) of a previously reported form [P-1, Z = 2; Ali et al. (2011 ▶). Polyhedron, 30, 542–548]. The CuII atom in each independent cation is found within a distorted square-pyramidal N2S2O coordination geometry defined by two N,S-bidentate ligands and an O atom derived from a monodentate nitrate. The primary difference between the cations is found in the relative orientations of the coordinated nitrate groups, which are directed to opposite sides of the mol­ecule. Supra­molecular layers along [110] and sustained by N—H⋯O inter­actions feature in the crystal packing. These are connected along the c axis by C—H⋯O inter­actions.

Aurophilicity in gold(i) thiosemicarbazone clusters

The reaction of the phosphine thiosemicarbazone ligands HLPH and HLPMe with Au(I) ions yields the gold complexes [Au(3)(HLPH)(2)Cl(2)]Cl·2MeOH (1·2MeOH) and [Au(2)(HLPMe)Cl(2)] (2). The structures determined by X Ray diffraction, [Au(3)(HLPH)(2)Cl(2)]Cl·4MeOH (1·4MeOH) and [Au(2)(HLPMe)Cl(2)](2) (2), are the first examples of gold(I) thiosemicarbazone clusters showing aurophilicity. The structure of the trinuclear cation 1 contains the Au(1) atom located in an inversion centre, being connected to another gold(I) atom, Au(2), through a phosphino thiosemicarbazone molecule which acts as a S,P-bridging ligand. Additionally, every gold(I) atom in the trinuclear cation 1 assembles into trinuclear linear cluster units by means of close gold-gold interactions, being connected through the crystal cell in a 2D zigzag mode. The crystal structure of [Au(2)(HLPMe)Cl(2)](2) (2) contains one discrete molecule [(AuCl)(2)(HLPMe)] in the asymmetric unit, which is further assembled into tetranuclear [(AuCl)(2)(HLPMe)](2) units by means of close gold-gold interactions. Both clusters are highly luminescent in solution.

Hexakis(dimethyl sulfoxide-κO)nickel(II) bis(2,2-dicyanoethene-1,1-dithiolato-κ2S,S′)nickelate(II)

The reaction of NiCl2·6H2O with sodium 2,2-dicyano­ethene-1,1-dithiol­ate [Na2(i-mnt)] in dimethyl sulfoxide produces the title complex, [Ni(C2H6OS)6][Ni(C4N2S2)2]. There is half each of an [Ni(C2H6OS)6]2− complex anion and an [Ni{(CH3)2SO}6]2+ complex cation in the asymmetric unit. The i-mnt ligand coordinates in a bidentate manner to the Ni atom in the anion through the two chelating S atoms in an approximate square-planar geometry. The Ni atom in the complex cation has an octahedral coordination environment with six dimethyl sulfoxide mol­ecules as ligands.

2-Bromo-1,3-diisopropyl-4,5-dimethyl-1H-imidazol-3-ium dicyanidoargentate

The title structure, (C11H20BrN2)[Ag(CN)2)], is built up from an approximately C 2v-symmetric imidazolium cation and a nearly linear dicyanidoargentate anion [N—Ag—N = 176.6 (9)° and Ag—C—N = 178.8 (9) and 177.2 (11)°]. These two constituents are linked by a remarkably short inter­action between the Br atom of the imidazolium cation [C—Br = 1.85 (3) Å] and one N atom of the cyanidoargentate anion [Br⋯N = 2.96 (2) Å], which is much less than the sum of the van der Waals radii (3.40 Å). The crystal studied was twinned by merohedry.

Effect of ionizing irradiation on the mechanism of current passage in TlInSe2 single crystals

The temperature dependence of the electrical conductivity and current-voltage characteristics of γ-irradiated TlInSe2 single crystals with an electrical resistivity of ∼108 Ω cm have been investigated. It has been established that the anomalies of the conductivity observed in weak electric fields and at low dozes of irradiation are related to the decomposition of neutral complexes containing an interstitial cation atom. In strong electric fields, a thermal-field ionization of traps occurs. The main mechanism of radiation defect formation is the formation of complexes [VIn−Ini+], [VSe−Sei−], and others with the structural defects characteristic of unirradiated crystals. The activation energy, trap concentrations, and the potential well shape near the traps have been determined.

Hydroxylammonium fluorometalate: synthesis and characterisation of a new fluorozincate

A new coordination compound of zinc fluoride and hydroxylammonium, (NH3OH)2ZnF4, was obtained after dissolving zinc powder in hydrofluoric acid (40%) and adding solid hydroxylammonium fluoride. The colourless crystals were characterised chemically, magnetically, structurally by single-crystal X-ray diffraction analysis, and thermogravimetrically by TGA and DSC analysis. The structure consists of NH3OH+ cations and ZnF6 octahedra in which the metal ion lies on the inversion centre. Each of the ZnF6 octahedra shares four of its vertices in a way that each vertex is shared between two octahedra. Oxygen and nitrogen atoms of hydroxylammonium cations are donors of hydrogen bonds. Hydroxylamonium fluorozincate crystallizes monoclinic, P21/c, with cell parameters a = 8.1604(4) A, b = 5.8406(3) A, c = 5.6586(2) A and β = 94.745(3)°. The compound decomposes above 373 K in four steps, obtaining ZnO as the final residue. Magnetic properties of the compound were studied between 2 and 300 K, giving the prevailing diamagnetic behaviour with room temperature susceptibility of −9 × 10−5 emu mol−1.

Optimization of the temple lower bound

The Temple formula is perhaps the most common method used in the uncommon endeavor of calculating a lower bound to the ground-state energy of an atomic or molecular system. We generalize the Temple formula by introducing a parameter that can be varied to optimize the lower bound. This generalization does not require any information that is not already used for the traditional Temple lower bound. Examples with the helium cation and neutral atom show that improvement is greatest when the approximate wave function poorly approximates the true ground-state wave function. The examples also show that in some cases the traditional Temple lower bound may already be optimal so that our generalization gives no improvement.

Crystallographic, vibrational and theoretical studies of 2,3-diaminopyridinium selenate

The new organic–inorganic salt, 2,3-diaminopyridinium selenate, has been synthesized and characterized by means of single-crystal X-ray crystallography, FT-IR and FT-Raman spectroscopy. A diprotonated organic ligand, H 2 1,3L 2+, existing in the crystal structure was theoretically shown to be the most stable cationic species of 2,3-diaminopyridine. The weak non-covalent forces of N–H⋯O type between the hydrogen atoms of the amino and ammonio groups of 2,3-diaminopyridinium cation and oxygen atoms of tetrahedral selenate anions determine three-dimensional arrangement with complex network of intermolecular interactions of hydrogen bond type (donor–acceptor distances from 2.697(3) Å to 3.088(3) Å). Vibrational spectra have been discussed in comparison with X-ray results. Juxtaposition of spectra of the complex with the pure organic ligand and deuterated analogue of the title compound allowed to give reliable assignments of most observed vibrational bands. Presented data can be useful in elucidation of molecular mechanism of uptake of tetrahedral SeO 4 2− anion by the living organisms.

Bis{N-methyl-N′-[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine}zinc bis(perchlorate)

The title mononuclear zinc(II) complex, [Zn(C10H15N3)2](ClO4)2, was obtained by the reaction of 2-acetyl­pyridine, N-methyl­ethane-1,2-diamine and zinc perchlorate in methanol. The asymmetric unit of the complex contains two independent [Zn(C10H15N3)2]2+ cations and four perchlorate anions. The ZnII atom in each complex cation is six-coordinated by two pyridine N, two imine N and two amine N atoms from two N-methyl-N′-[1-(pyridin-2-yl)ethyl­idene]ethane-1,2-diamine Schiff base ligands in a distorted octa­hedral geometry. The pyridine rings in each of the complex cations are approximately perpendicular to each other, making dihedral angles of 88.4 (3) and 87.9 (3)°. The perchlorate anions are linked to the complex cations through N—H⋯O hydrogen bonds

Theoretical study of crown ethers with incorporated azobenzene moiety

A series of crown ethers containing the azobenzene moiety incorporated into crowns of various sizes [Cr(O(6))(,) Cr(O(7)) and Cr(O(8))] and their corresponding alkali metal cation (Li(+), Na(+), K(+), Rb(+)) complexes have been studied theoretically. The density functional theory (DFT) method was employed to elucidate the stereochemical structural natures and thermodynamic properties of all of the target molecules at the B3LYP/6-31 G(d) and LANL2DZ level for the cation Rb(+). The fully optimized geometries had real frequencies, thus indicating their minimum-energy status. In addition, the bond lengths between the metal cation and oxygen atoms, atomic torsion angles and thermodynamic energies for complexes were studied. Natural bond orbital (NBO) analysis was used to explore the origin of the internal forces and the intermolecular interactions for the metal complexes. The calculated results show that the most significant interaction is that between the lone pair electrons of electron-donating oxygens in the cis-forms of azobenzene crown ethers (cis-ACEs) and the LP (1-center valence antibond lone pair) orbitals of the alkali-metal cations (Li(+), Na(+), K(+) and Rb(+)). The electronic spectra for the cis-ACEs [cis-Cr(O(6)), cis-Cr(O(7)) and cis-Cr(O(8))] are obtained by the time-dependent density functional theory (TDDFT) at the B3LYP/6-31 G(d) level. The spectra of the cis-isomers show broad π → π (S(0) → S(2)) absorption bands at 310-340 nm but weaker n → π (S(0) → S(1)) bands at 480-490 nm. The calculated results are in good agreement with the experimental results.

A neutralization-reionization and reactivity mass spectrometry study of the generation of neutral hydroxymethylene

Neutral hydroxymethylene HCOH is an important intermediate in several chemical reactions; however, it is difficult to observe due to its high reactivity. In this work, neutral hydroxymethylene and formaldehyde were generated by charge exchange neutralization of their respective ionic counterparts and then were reionized and detected as positive-ion recovery signals in neutralization-reionization mass spectrometry in a magnetic sector instrument of BEE geometry. The reionized species were characterized by their subsequent collision-induced dissociation mass spectra. The transient hydroxymethylene neutral was observed to isomerize to formaldehyde with an experimental time span exceeding 13.9 µs. The vertical neutralization energy of the HCOH(+•) ion has also been assayed using charge transfer reactions between the fast ions and stationary target gases of differing ionization energy. The measured values match the result of ab initio calculations at the QCISD/6-311 + G(d,p) and CCSD(T)/6-311 + + G(3df,2p) levels of theory. Neutral hydroxymethylene was also produced by proton transfer from CH(2) OH(+) to a strong base such as pyridine, confirmed by appropriate isotopic labeling. There is a kinetic isotope effect (KIE) for H(+) versus D(+) transfer from the C atom of the hydroxymethyl cation of ∼3, consistent with a primary KIE of a nearly thermoneutral reaction.