This dissertation describes the theoretical, laboratory, and astronomical spectroscopy of negative molecular ions (anions), starting with the laboratory detection of the large carbon chain anion C₆H⁻ in the radio band and its identification in the molecular envelope of the carbon star IRC+10216 and in the cold dark molecular cloud TMC-1. In IRC+10216 the identification solved the long standing problem of the unidentified series of lines with rotational constant 1377 MHz first observed by K. Kawaguchi et al. Rotational spectra of the structurally similar anions---CCH⁻, C₄H⁻, C₈H⁻, CN⁻, and C₃N⁻---have been detected in the laboratory, and three more anions---C₄H⁻, C₈H⁻, and C₃N⁻---have now been identified in space. Molecular structure calculations using the CCSD(T) method and large basis sets predicted accurately the rotational constants (B₀) and centrifugal distortion constants (D[subscript J]) of all six anions and their isotopomers, guiding laboratory searches for these species. Reported here are the radio spectra of C₄H⁻, C₆H⁻, C₈H⁻, and C₃N⁻, measured to within 0.1 ppm in the centimeter-wave band by Fourier transform microwave spectroscopy of supersonic molecular beams and in the millimeter-wave band by absorption spectroscopy of low-pressure DC discharges. The spectroscopic constants derived from these measurements are so accurate, that the rotational frequencies of the anions can be calculated to within 1 km s⁻¹, adequate for radio searches in essentially all astronomical molecular sources. Radio astronomical observations with the 100 m Green Bank Telescope (GBT) toward TMC-1 yielded detection of C₈H⁻, as well as an improved estimate of the column density of C₆H⁻. The two anions are surprisingly abundant relative to their neutral radicals: a C₆H⁻/C₆H ratio of 1.6% and a C₈H⁻/C₈H ratio of 5% was derived. Upper limits were obtained for C₄H⁻/C₄H (< 0.004%) and C₃N⁻/C₃N (< 0.8%). A survey of C₆H⁻ and the related radicals C₄H and C₆H was done with the GBT toward 24 galactic molecular sources. The C₆H⁻ ion was newly detected in two dark clouds: L1544 and L1521F; C₄H was detected in nearly all dark clouds surveyed (in six for the first time); and C₆H was newly detected in five dark clouds and a translucent cloud. The observed C₆H⁻/C₆H (1%-4%) and C₆H/C₄H (0.2%-1%) ratios suggest that C₆H⁻ may be close to detection in many other dark clouds. / text

One new dianion was prepared and many alkylation and oxidation reactions of this new dianion and several known dianions were carried out. These reactions provide the best synthetic routes to most of the compounds prepared. More specifically, many oxidation products were obtained when 3-methyl-1,4-pentadiene dianion was treated with alkyl bromides. A quantitative yield of substitution product was obtained by reacting this dianion with trimethylsilyl chloride. New compounds obtained by treating this dianion with 1,2-dichloroethane are shown below: The dianion shown below was prepared from 2,5-dimethyl-1,5-hexadiene and Lochmann's base. Many different 2,5-disubstituted 1,5-hexadienes and related compounds were made by treating this dianion with alkyl halides, sulfates and alkyl (alpha),(omega)-dihalides. Attempts to make a cyclic hexapyridyl by treating 2-methyleneallyl dianion with 6,6'-dicyano-2,2'-dipyridyl (see below) apparently failed.

Molecular and cluster anions have been investigated using a newly built tandem time-of-flight mass spectrometer combined with photoelectron imaging system. Solvation particularly hydration is shown not only to stabilize metastable anions such as CO₂⁻ in their ground state and impede autodetachment but also to alter the dynamics in the excited states. For instance, the 355 nm photoelectron image of mass-selected CO₂⁻(H₂O)(m) evolves from anisotropic to isotropic as m increases indicating excited state decay via electron autodetachment. Dissociation channels open at m=2 at 266 nm, resulting in O−(H₂O)m-k and CO₂⁻(H₂O)(m-k) products, the later becoming dominant as m increases. The photoelectron imaging of (CS₂)₂⁻ has revealed the coexistence of four electronic isomers: CS₂⁻•CS₂ [C(s)(₂A′)] and three covalent C₂S₄⁻ [C₂ᵥ(²B₁), D(2h)(²B(3g)), and D(2d)( ²A₁)] structures. Water-mediated intermolecular interactions have been shown to facilitate the formation of the global minimum C₂ᵥ(²B₁) structure rather than the less stable local minima C(s)(₂A′) and D(2d)(²A₁) structures that are favored in the dry source condition. In the (CS2)(n)⁻, n ≥ 3 and (CS₂)₂⁻ (H₂O)(m), m > 0 clusters, the population of the C₂ᵥ(²B₁) structure diminishes drastically due to more favorable solvent interactions with the CS2 − monomercore. Photoexcitation of the (CS₂)₂⁻ also results in the formation of CS₂⁻ and C₂S₂⁻ at 532 nm, and C₂S₂⁻, CS₂⁻, CS₃⁻, S₂⁻, and S⁻ at 355 and 266 nm. The relative yields of C₂S₂⁻ is significantly higher when (CS₂)₂⁻ is formed under wet source condition suggesting C₂ᵥ(²B₁) structure as the origin of C₂S₂⁻. An abrupt decrease in the relative yield of C₂S₂⁻ is observed upon adding CS₂ or H₂O to (CS₂)₂⁻. The CS₂⁻ based clusters are the likely origin of the S− photoproduct, while CS₃⁻ is formed through the secondary S⁻+CS₂ reaction. Novel anions (CS₂O₂⁻ and CS₃O⁻) are observed in the CS₂+O₂+e⁻ reaction. The photoelectron imaging and photodissociation results of these and other anionic products are presented. In addition, CS₂⁻•O₂ ion-neutral complex is formed depending on the conditions in the ion source. Despite the positive electron affinity of O₂, no clear signature of O₂⁻•CS₂ ion-neutral complex is seen in the photoelectron image. CO₃⁻ ion is also formed abundantly as a result of CS₂+CO₂+O₂+e⁻ reaction.

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Investigation on a series of hydrogen-bonded networks constructed with N-heteroaryl acids is described in Section 3.4. In this section, we focused on the connection modes within the heteroaryl dimer. The study of co-crystals and inclusion compounds based on 2-thiobarbituric acid (TBA) or trithiocyanuric acid (TCA) indicated that the dimer of TBA is present in all three crystals in the forms of ribbon, tetramer or separated dimer. In the case of 5-nitrobarbiturate, its dimer occurs in two ammonium salts and in three of its four thiourea complexes, but is absent in all three urea complexes. / Self-assembly of two-dimensional hydrogen-bonded honeycomb grids exhibiting the rosette motif has been conducted with the guanidinium cation and various anions as the building blocks, tetraalkylammonium ions of suitable bulk being employed as interlayer templates. It is noteworthy that the rosette layer constructed from three different trigonal-planar molecular components has been achieved. In addition, deviating from conventional topological design, the generation of new rosette layers, albeit highly distorted, has also been accomplished with 1,2-dithiosquarate and the dianionic form of 1,1'-biphenyl-2,2',6,6'-tetracarboxylate that do not conform to C3-symmetry. Although threefold molecular symmetry is regarded as a sacrosanct requirement for molecular building blocks in the construction of hydrogen-bonded rosette motif, this study shows that rosette motifs can be generated even if one of the building blocks does not have inherent threefold symmetry. / Study of compounds containing the deprotonated forms of Kemp's triacid (H3KTA) has revealed the chair or twist-boat conformation in six crystal structures. X-ray structural analysis showed that [C(NH2) 3+] &middot; [C6H6(CH3) 3(COOH)2(COO-)] (2.2.2) exhibits a corrugated layer structure which mimics the rosette motif constructed from the guanidinium ion and the hydrogen carbonate dimer. The tricarboxylate form of Kemp's triacid KTA3- in 3[C(NH2) 3+] &middot; [C6H6(CH3) 3(COO-)3] (2.2.4) registers a record number of eighteen acceptor hydrogen bonds involving the convergent N--H donor sites from nine guanidinium ions. The crystal structure of 3[(C2H5)4N+] &middot; 20[C(NH 2)3+] &middot; 11[C6H6(CH 3)3(COOH) (COO-)2] &middot; [C6H6(CH3)3(COOH)2(COO -)]&middot;17H2O (2.2.3) features a hydrogen-bonded aggregate with a centrosymmetric pseudo-octahedral arrangement of H2KTA- anions surrounding an inner core composed of eight guanidinium ions. The unusual twist-boat conformation of KTA3- is found in [(CH3)4N +] &middot; 2[C(NH2)3+] &middot; [C6H6(CH3)3(COO- )3] &middot; 2H2O (2.2.6), which is stabilized by the co-existence of guanidinium and tetramethylammonium cations. / Systematic investigation on hydrogen-bonded supramolecular assembly using aromatic carboxylic acids bearing linear or bent skeletons with urea/guanidinium resulted in the formation of mainly R228 and R126 synthon motifs. In addition, isostructures were also constructed by varying the length of the linker between two carboxylate groups, as in naphthalene-2,6-dicarboxylate (2.3.2) and biphenyl dicarboxylate (2.3.3). / This thesis reports a systematic investigation on the generation of new inclusion compounds by the combined use of urea/thiourea, guanidinium ion and various organic anions as building blocks of hydrogen-bonded host lattices and selected quaternary ammonium ion as the enclosed guests. / Various acids bearing specific functional groups have been explored as structure building components, including boric acid, Kemp's triacid, heterocyclic (thio)urea derivatives, aryl and N-heteroaryl carboxylic acids and (dithio)squaric acid. All the co-crystals and inclusion compounds built of molecular components in the afore-mentioned categories have been characterized by single-crystal X-ray analysis. As a result, the complexes exhibit a rich variety of inclusion topologies, such as networks containing isolated cages, open channels, intersecting tunnels, double-layer systems, and sandwich-like as well as wave-like layer structures. / Han, Jie. / Adviser: Thomas C. W. Mak. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0337. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 204-218). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Chi-Keung Lam. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 202-210). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The solid phase of an aquifer has an effect on the aqueous phase; if groundwater quality is degraded by the solid phase of an aquifer this is referred to as geogenic pollution. In this study, the Piney Point aquifer in the Virginia Coastal Plain was assessed for mechanisms that may release anions from the solid to aqueous phases and effect water quality. This was done by conducting leaching experiments modified from Balintova et al. (2013). Piney Point aquifer sediments and groundwaters were also analyzed to give a baseline for these experiments. Sedimentary analysis was found to be consistent with McFarland (2017) and groundwater anion concentrations were found to be less than the U.S. Environmental Protection Agency’s (EPA) established Maximum Contaminant Levels (MCL). Leaching experiments found that low pH environments may lead to the release of fluoride in association with phosphorus in sediments and general release of chloride. Nitrate release mechanisms in confined aquifers require further study, but it appeared as total inorganic carbon was dissolved, sedimentary total nitrogen concentrations increased. Sulfate concentrations in leaching experiments were found to be associated with sulfur concentrations in the solid phases. Furthermore, leaching experiments showed that when sediments are exposed to oxic environments then re-exposed to groundwater, higher concentrations of anions were released to the aqueous phases. This could be a particular issue with sulfate concentrations, which were above the EPA MCL in the majority of sediment samples in all leachate treatments.

Thesis (M.S.)--Washington State University, December 2007. / Includes bibliographical references.

L'objectiu principal del present estudi és aprofundir, des d'un punt de vista teòric i experimental en els aspectes cinètics i mecanístics de les fragmentacions unimoleculars de radicals anions que evolucionen per donar lloc a radicals i anions. Tractarem de veure el comportament que presenten aquests radicals anions en diferents famílies d'espècies i extreuren conclusions que ens permetin veure quin patró segueixen. El treball s'agrupa en diferents capítols (del capítol 4 al capítol 6), segons el tipus d'enllaç estudiat, i el qual és susceptible de ser fragmentat una vegada generat l'anió radical. / The main purpose of this study is to deeply investigate, in a theoretical and experimental point of view, the kinetics and mechanisms of unimolecular radical anion fragmentations to obtain corresponding radical and anions. We will discuss about the behavior of these radical anions in different families of molecules to achieve concrete reasons to explain these fragmentations. The study is presented in different chapters (from 4 to 6), depending on the type of bond studied which is susceptible to be broken.

Th. doct.--Physique théorique--Göteborg (Suède)--Göteborgs université, 2003. / Bibliogr. p. 69-75.