Photoelectron Spectroscopy and Theoretical Studies of PCSe−, AsCS−, AsCSe−, and NCSe−: Insights into the Electronic Structures of the Whole Family of ECX− Anions (E=N,P, As; X=O,S, Se)

The newly synthesized phosphorus‐ and arsenic‐containing analogues of the thio‐ and seleno‐cyanate anions, PCSe^?, AsCS^?, and AsCSe^?, as well as the known ion NCSe^? were investigated in the gas phase by negative‐ion photoelectron spectroscopy (NIPES), velocity‐map imaging (VMI) spectroscopy, and quantum‐chemical computations. The electron affinities (EA), spin–orbit (SO) splittings, and “symmetric”/“asymmetric” stretching frequencies of the neutral radicals ECX^. (E=N, P, As; X=S, Se), generated by electron detachment from the corresponding anions, were obtained from the spectra. The calculated EAs, SO splittings, and vibrational frequencies are in excellent agreement with the experimental measurements. These newly obtained values, when combined with those previously determined for the lighter analogues, show interesting trends on descending the pnictogen and chalcogen series. These trends are rationalized based on electronegativity arguments, the electron distributions in the HOMOs, and NBO/NRT analyses.     

Spectroscopic constants and molecular properties of CN−, SiH−, PO−, SO−, SF−, and SiS−: Density functional study

Spectroscopic constants and molecular properties of selected diatomic anions namely CN^?, SiH^?, PO^?, SO^?, SF^?, and SiS^? in their ground states have been studied in detail using the hybrid HF/DF B3LYP method. The consistency of the calculated values has been verified with four different basis sets, with improved quality. The spectroscopic constants and molecular properties calculated with the aug‐cc‐pVTZ basis set agree very well with the experimental and theoretical values wherever available. Most of the spectroscopic constants and molecular properties of the selected diatomic anions, particularly the spectroscopic constants and molecular properties of SO^? and SiS^? are reported for the first time. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

A General Synthesis of Phosphorus‐ and Arsenic‐Containing Analogues of the Thio‐ and Seleno‐cyanate Anions

A general synthetic protocol for the synthesis of phosphorus‐ and arsenic‐containing analogues of the thio‐ and seleno‐cyanate anions is reported. This procedure allows for the isolation of three unprecedented species: the phosphaethynselenolate, PCSe^? ( 1 ), the arsaethynthiolate, AsCS^? ( 2 ), and the arsaethynselenolate, AsCSe^? ( 3 ), anions. The structures, electronic properties, and spectroscopic signatures of these species are reported.     

Density functional theory study of the free and tetraprotonated spheroidal macrotricyclic ligands and the complexes with halide anions: F−, Cl−, Br−

Theoretical studies of the macrotricyclic tetramine hexaether (SC), its tetraprotonated form SC‐4H⁺, and the corresponding complexes X^??SC‐4H⁺ (This expression represents the structural properties of the halide inclusion complex formed though the free ligand SC‐4H⁺ and the halide anion X^?: the spherical halide anion X^? is held by a tetrahedral array of ⁺N? H ··· X^? hydrogen bonds inside the intramolecular cavity of the tetraprotonated form SC‐4H⁺) of SC‐4H⁺ with the halide anions: F^?, Cl^?, and Br^? have been performed using density functional theory (DFT) with B3LYP/6‐31G method implemented in the Gaussian 03 program package. The optimized geometric structures obtained from DFT calculations are used to perform Natural Bond Orbital (NBO) analysis. The three main types of hydrogen bonds ⁺N? H ··· F^?, ⁺N? H ··· Cl^?, and ⁺N? H ··· Br^? are investigated. The results indicate that hydrogen bonding interactions are dominant and the halide anions: F^?, Cl^?, and Br^? offer lone pair electrons to the contacting σ* (N? H) antibond orbital of SC‐4H⁺. For all the structures, the most pronounced changes in geometric parameters upon interaction are observed in the proton‐donor molecule. The intermolecular interaction energies are predicted by using B3LYP/6‐31G methods with basis set superposition error (BSSE) and zero‐point energy (ZPE) correction. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Structural parameters of the ground states of the quasi‐stable diatomic anions CO−, BF−, and BCl− as obtained by conventional Ab Initio methods

The experimental electron affinity (EA) of CO(X¹Σ⁺) is ?1.5 eV, signifying the metastability of the CO^?(X²Π) anion. The electronic structure and bonding of CO^?, BF^?, and BCl^? vis‐à‐vis their neutral counterparts have been studied by conventional coupled‐cluster (CCSD(T)) and multireference (MRCI) methods. Our results are in agreement with experiment for the CO/CO^? system, indicating as well the metastable nature of the BF^?(X²Π) and BCl^?(X²Π) anions, their MRCI EAs being ?0.8 ± 0.1 and ?0.3 ± 0.1 eV, respectively. Our work clearly shows the usefulness of stationary state ab initio methods to the elucidation of metastable species. © 2015 Wiley Periodicals, Inc.     

Exploring Sustainable Rocket Fuels: [Imidazolyl−Amine−BH2]+‐Cation‐Based Ionic Liquids as Replacements for Toxic Hydrazine Derivatives

The application of hypergolic ionic liquids as propellant fuels is a newly emerging area in the fields of chemistry and propulsion science. Herein, a new class of [imidazolyl?amine?BH₂]⁺‐cation‐based ionic liquids, which included fuel‐rich anions, such as dicyanamide (N(CN)₂^?) and cyanoborohydride (BH₃CN^?) anions, were synthesized and characterized. As expected, all of the ionic liquids exhibited spontaneous combustion upon contact with the oxidizer 100 % HNO₃. The densities of these ionic liquids varied from 0.99–1.12 g cm^?3, and the heats of formation, predicted based on Gaussian 09 calculations, were between ?707.7 and 241.8 kJ mol^?1. Among them, the salt of compound 5 , that is, (1‐allyl‐1H‐imidazole‐3‐yl)?(trimethylamine)?dihydroboronium dicyanamide, exhibited the lowest viscosity (168 MPa s), good thermal properties (T_gT_d>130 °C), and the shortest ignition‐delay time (18 ms) with 100 % HNO₃. These ionic fuels, as “green” replacements for toxic hydrazine‐derivatives, may have potential applications as bipropellant formulations.     

SIMS using O−, F−, Cl−, Br− and I− primary ion bombardment

The success of secondary ion mass spectrometry (SIMS) analyses depends largely on the ionization probability of the analyzed elements. The chemical state of the surface changes with the chemical nature and the concentration of implanted ions. The positive ionization probability can be enhanced by bombarding the surface with electronegative elements. In view of such an enhancement of the positive secondary ion yield, we present SIMS analyses carried out with O^?, F^?, Cl^?, Br^? and I^? primary ion beams. Useful yields were experimentally determined for metal (Al, Ni, Cu, Ag and Ta) and semiconductor samples (Si, Ge, InP and GaAs). For metal samples, an enhancement of the useful yield under halogen bombardment, compared with O^? bombardment, was observed for Ni, Cu and Ag under F^? bombardment (enhancement of up to two orders of magnitude). For semiconductors, lower useful yields are obtained under halogen bombardment as compared with O^? bombardment. The observed results are discussed in terms of the surface concentration of the implanted primary ion species and their electronegativity. Copyright © 2012 John Wiley & Sons, Ltd.     

Investigation of Large Polychloride Anions: [Cl11]−, [Cl12]2−, and [Cl13]−

For decades the chemistry of polyhalides was dominated by polyiodides and more recently also by an increasing number of polybromides. However, apart from a few structures containing trichloride anions and a single report on an octachloride dianion, [Cl₈]^2?, polychlorine compounds such as polychloride anions are unknown. Herein, we report on the synthesis and investigation of large polychloride monoanions such as [Cl₁₁]^? found in [AsPh₄][Cl₁₁], [PPh₄][Cl₁₁], and [PNP][Cl₁₁]?Cl₂, and [Cl₁₃]^? obtained in [PNP][Cl₁₃]. The polychloride dianion [Cl₁₂]^2? has been obtained in [NMe₃Ph]₂[Cl₁₂]. The novel compounds have been thoroughly characterized by NMR spectroscopy, single‐crystal Raman spectroscopy, and single‐crystal X‐ray diffraction. The assignment of their spectra is supported by molecular and periodic solid‐state quantum‐chemical calculations.     

Theoretical study of XCN− (XF,Cl) anions

Geometrical parameters, vibrational frequencies, zero‐point energy, dipole moment, NBO atomic charges of FCN^?, ClCN^? and their isomers, and the isomerization energy of FCN^? and ClCN^? are studied in detail using the ab initio MP2, CCSD, CCSD(T), and density functional B3LYP methods. The results are compared with the existing data reported using various theoretical methods in conjunction with different basis sets. The effect of electron correlation on the structural properties of these molecular anions is discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Polymer‐based fluoride‐selective chemosensor: Synthesis,sensing property,and its use for the design of molecular‐scale logic devices

A new styryl‐type monomer, 2‐(4‐vinylbenzyloxy)‐1 ‐naphthaldehyde thiosemicarbazone (VNT), was synthesized and then copolymerized with methyl methacrylate (MMA) by reversible addition fragmentation chain transfer polymerization affording a series of poly(MMA‐co‐VNT)s with different functional unit content, predetermined molecular weight, and narrow molecular‐weight distribution. The desired copolymers were structurally confirmed by various spectroscopic characterizations. Colorimetric and fluorescent titration spectra revealed that the copolymers are highly selective toward fluoride anions over other competitive species including Cl^?, Br^?, I^?, H₂PO₄^?, AcO^?, and HSO₄^?. On addition of F^?, a remarkable colorless‐to‐yellow color change is easily observed by naked eyes. The influence of the copolymer composition and molecular weight on its sensing capacity was then carefully investigated. The results showed that higher VNT‐incorporation amount within the copolymer chains leads to higher sensitivity toward F^? ions. Interestingly, the chromogenic process of the polymeric sensor can be switched back and forth by successively adding F^? and HSO₄^? anions into the dimethyl sulfoxide solution of the polymer, which may be represented by a complementary “IMPLICATION/INHIBIT” logic gate at molecular level using both the ions as the chemical inputs. Based on such a reversible and reproducible sensing system, we designed a molecular‐scale sequential information processing circuit displaying “writing–reading–erasing–reading” behavior and “multiwrite” function in the form of binary logic. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

ESI activity of Br−, BF4−, ClO4− and BPh4− anions in the presence of Li+ and NBu4+ counter‐ions

To improve our understanding of the electrospray ionization (ESI) process, we have subjected equimolar mixtures of salts A⁺X⁻ (A⁺ = Li⁺, NBu₄⁺; X⁻ = Br⁻, ClO₄⁻, BF₄⁻, BPh₄⁻) in different solvents (CH₃CN, tetrahydrofuran, CH₃OH, H₂O) to negative‐ion mode ESI and analyzed the relative ESI activity of the different anionic model analytes. The ESI activity of the large and hydrophobic BPh₄⁻ ion greatly exceeds that of the smaller and more hydrophilic anions Br⁻, ClO₄⁻ and BF₄⁻, which we ascribe to its higher surface activity. Moreover, the ESI activity of the anions is modulated by the action of the counter‐ions and their different tendency toward ion pairing. The tendency toward ion pairing can be reduced by the addition of the chelating ligands 12‐crown‐4 and 2.2.1 cryptand and is, although to a smaller degree, further influenced by the variation of the solvent. Complementary electrical conductivity measurements afford additional information on the interactions of the ionic constituents of the sample solutions. Copyright © 2017 John Wiley & Sons, Ltd.     

Comparison of Hydrogen and Gold Bonding in [XHX]−, [XAuX]−, and Isoelectronic [NgHNg]+, [NgAuNg]+ (X=Halogen,Ng=Noble Gas)

Quantum chemical calculations at the MP2/aug‐cc‐pVTZ and CCSD(T)/aug‐cc‐pVTZ levels have been carried out for the title compounds. The electronic structures were analyzed with a variety of charge and energy partitioning methods. All molecules possess linear equilibrium structures with D_∞h symmetry. The total bond dissociation energies (BDEs) of the strongly bonded halogen anions [XHX]^? and [XAuX]^? decrease from [FHF]^? to [IHI]^? and from [FAuF]^? to [IAuI]^?. The BDEs of the noble gas compounds [NgHNg]⁺ and [NgAuNg]⁺ become larger for the heavier atoms. The central hydrogen and gold atoms carry partial positive charges in the cations and even in the anions, except for [IAuI]^?, in which case the gold atom has a small negative charge of ?0.03 e. The molecular electrostatic potentials reveal that the regions of the most positive or negative charges may not agree with the partial charges of the atoms, because the spatial distribution of the electronic charge needs to be considered. The bonding analysis with the QTAIM method suggests a significant covalent character for the hydrogen bonds to the noble gas atoms in [NgHNg]⁺ and to the halogen atoms in [XHX]^?. The covalent character of the bonding in the gold systems [NgAuNg]⁺ and [XAuX]^? is smaller than in the hydrogen compound. The energy decomposition analysis suggests that the lighter hydrogen systems possess dative bonds X^?→H⁺←X^? or Ng→H⁺←Ng while the heavier homologues exhibit electron sharing through two‐electron, three‐center bonds. Dative bonds X^?→Au⁺←X^? and Ng→Au⁺←Ng are also diagnosed for the lighter gold systems, but the heavier compounds possess electron‐shared bonds.     

Sensitivity and Selectivity of Polypyrrole Based AC‐Amperometric Sensors for Electroinactive Ions – Frequency and Applied Potential Influence

Oxidation/reduction of polypyrrole films coupled with ion exchange on the polymer/solution interface can be utilized for amperometric sensing of electroinactive ions. Anion or cation exchanging films (polypyrrole doped by chloride or poly(4‐styrenesulfonate) ions, respectively) can be used to determine common anions (as Cl^?, NO , SO etc) or cations (K⁺, Na⁺, Li⁺, Ca²⁺, Mg²⁺) under conditions of alternating current (AC) amperometry in the range 10^?4–1 M. A sensitivity can be tuned by choosing appropriate electrode potential, corresponding to polypyrrole oxidation (anion‐exchanging films) or reduction (cation‐exchangers). Electrochemical impedance spectroscopy and AC‐voltammetry studies have shown that applied frequency and potential could also affect the observed dependence of the signal (admittance or AC‐current) on ion concentration. For high frequency the sensitivity is higher but selectivity lower, due to influence of solution conductivity on the response. For low frequencies the sensitivity is lower; however, a selectivity increase was observed due to diverse mobility of ions in the polymer film. Selectivity of AC‐amperometric responses was studied both in separate and mixed solutions.     

Die kubischen Phasen Na16(ARb6)Sb7, Verbindungen mit den Anionen A = Rb−, Na−, Au−, I−

The Cubic Phases Na₁₆(ARb₆)Sb₇, Compounds with the Anions A = Rb^?, Na^?, Au^?, I^? The novel compounds Na₁₆(ARb₆)Sb₇ have been synthesized from the elements in sealed Nb ampoules at 873 K (A = Rb) and 823 K (A = I, Na, Au). They form brittle cuboctahedra (silver metallic; A = Rb) and irregular polyhedra (silver metallic lustre; A = Na, I; golden metallic lustre; A = Au). They rapidly decompose in moist air to gray products. Their crystal structures have been determined by single crystal X-ray crystallography (A = Rb: a = 1565.8(2) pm; A = I: a = 1563.3(2) pm; A = Na: a = 1562.6(2) pm; A = Au: a = 1560.7(2) pm). They crystallize cubically in the space group Fm3 m (no. 225) with Z = 4 formula units and are isotypic with Sc₁₁Ir₄. The compounds are ZINTL phases and their structures can be described as an eightfold defect variant of the Li₃Bi type of structure (cF128-8; a = 2a′(Li₃Bi)). The Sb atoms form a network of cuboctahedra, centered alternatingly by a SbNa₈ cube or a ARb₆ octahedron. Main structural features are the anions A^? within the Rb₆ octahedron. Supporting the existence of A^? are the isotypical compounds with the more common anion forming elements (A = Au, I), as well as electrostatic potential considerations together with calculations of the volume increments. The semiconducting properties (E_g = 0.33 eV) of Na₁₆(RbRb₆)Sb₇, as well as the diamagnetism χ_mol = ?508 × 10^?6 cm³ mol^?1, are in accordance with those to be expected from the Zintl concept.     

Aroyleneimidazophenazine: A Sensitive Probe for Detecting CN− Anion and its Solvatochromism Effect

A novel electron‐deficient heteroacene 15H‐pyrazino[2″,3″:3′,4′]pyrrolo[1′,2′:1,2]imidazo[4,5‐b]phenazin‐15‐one ( 1 ) has been successfully synthesized and characterized. Compound 1 can selectively recognize CN^? and F^? over other 10 anions including BF₄^?, PF₆^?, Cl^?, SO₄^2?, NO₃^?, I^?, H₂PO₄^?, ClO₄^?, Ac^?, and Br^? in CHCl₃/DMF mixed solvents with dual responses, including absorption signals and fluorescent “turn‐off” effects. CN^? and F^? can be distinguished by the completely quenched fluorescence (for CN^?) and partially reduced fluorescence (for F^?). Especially, compound 1 exhibits higher sensitivity to CN^? than F^? with the response concentration as low as 5.0 × 10^?6 mol/L. Moreover, compound 1 shows very interesting solvatochromism effect, and the CHCl₃ solution of compound 1 is sensitive to triethylamine, and its emission could change from green to red upon the addition of triethylamine, which is attributed to the n–π intermolecular charge‐transfer interaction.     

Rapid Preparation of Silsesquioxane‐Based Ionic Liquids

Three new hybrid ionic liquids (ILs) based on cage silsesquioxane (SQ) were rapidly prepared in high yields from octa(mercaptopropyl)silsesquioxane and 1‐allyl‐3‐methylimidazolium salts (Br^?, BF₄^?, PF₆^?) through the photochemical thiol–ene reaction. These SQ‐based ILs exhibited low glass transition temperatures and good thermal stability. The unique amphiphilic nature of these hybrid ILs cause them to self‐assemble into perfect vesicles with “yolk–shell” structures, in which cages formed the “yolk” due to their aggregation and outer anions formed the “shell”.     

新型三脚架苯甲醛苯腙醋酸根选择性比色化学传感器

本文合成了一个新的基于三脚架苯甲醛苯腙的能够选择地检测醋酸根离子的比色化学传感器1。用紫外可见吸收光谱证实了受体1在二甲基亚砜溶液中对醋酸根离子高选择的键合能力超越了其它阴离子。和其他所研究的阴离子相比,其在二甲基亚砜中紫外可见吸收光谱对具有高选择性醋酸根离子的存在显示了应答,当存在（2´10^-5mol·dm^-3）醋酸根离子时其溶液的颜色也由黄色变化到蓝色。当用其他不同的客体阴离子（F^-, Cl^-, Br^-, I^-, H₂PO₄ ^–和 OH^-）处理受体1时,仅出现了很小的紫外可见吸收光谱变化。受体1对醋酸根的结合常数 K_ass为1.69´ 10⁴。     

Syntheses and Characterization of Mixed‐Anions Lead(II) Complexes, [Pb(phen)2(CH3COO)]X (X=NCS—, NO3— and ClO4—), Crystal Structure of [Pb(phen)2(CH3COO)](ClO4)

The 1:2 adduct lead(II) complexes with 1, 10‐phenanthroline (phen) containing three different anions, [Pb(phen)₂(CH₃COO)X] (X=NCS^—, NO₃^— and ClO₄^—), have been synthesized and characterized by CHN elemental analysis, IR‐, ¹H‐ and ¹³C NMR spectroscopy. The structure of [Pb(phen)₂(CH₃COO)(ClO₄)] was determined by single crystal X‐ray analysis. The Pb atom of the monomeric complex is coordinated by four nitrogen atoms of two 1, 10‐phenanthroline ligands and two oxygen atoms of the acetate ligand to form an irregular octahedron. The arrangement of the 1, 10‐phenanthroline and acetate ligands, exhibits a coordination gap around the Pb^II ion, possibly occupied by a stereochemical electron active lone pair on lead(II), which results in a hemidirected lead compound. The π‐π stacking interaction between the parallel aromatic rings may help to increase the coordination ‘gap’ around the Pb^II ion.     

Spectroelectrochemical Investigation of TPPMn(III/II)‐Driven Liquid | Liquid | Electrode Triple Phase Boundary Anion Transfer into 4‐(3‐Phenylpropyl)‐Pyridine: ClO4−, CO3H−, Cl−, and F−

The triple phase boundary transfer of anions from the aqueous into an organic phase can be driven electrochemically here with the tetraphenylporphyrinato‐Mn(III/II) (or TPPMn) redox system in 4‐(3‐phenylpropyl)‐pyridine) (or PPP). Anions investigated are perchlorate, chloride, fluoride, and bicarbonate. The bicarbonate and fluoride transfer processes are shown to be chemically more complex compared to the perchlorate and chloride cases with UV‐vis‐spectroelectrochemical measurements indicating a combination of HCO₃^?/CO₃^2? transfer processes and association of fluoride with TPPMn(III)⁺, respectively. In situ spectroelectrochemistry is developed for ion‐transfer voltammetry into sub‐microliter organic phase regions on mesoporous ITO conducting film electrodes.