Jerry A. Boatz

General atomic and molecular electronic structure system

A description of the ab initio quantum chemistry package GAMESS is presented. Chemical systems containing atoms through radon can be treated with wave functions ranging from the simplest closed‐shell case up to a general MCSCF case, permitting calculations at the necessary level of sophistication. Emphasis is given to novel features of the program. The parallelization strategy used in the RHF, ROHF, UHF, and GVB sections of the program is described, and detailed speecup results are given. Parallel calculations can be run on ordinary workstations as well as dedicated parallel machines.

Accurate methods for large molecular systems.

Three exciting new methods that address the accurate prediction of processes and properties of large molecular systems are discussed. The systematic fragmentation method (SFM) and the fragment molecular orbital (FMO) method both decompose a large molecular system (e.g., protein, liquid, zeolite) into small subunits (fragments) in very different ways that are designed to both retain the high accuracy of the chosen quantum mechanical level of theory while greatly reducing the demands on computational time and resources. Each of these methods is inherently scalable and is therefore eminently capable of taking advantage of massively parallel computer hardware while retaining the accuracy of the corresponding electronic structure method from which it is derived. The effective fragment potential (EFP) method is a sophisticated approach for the prediction of nonbonded and intermolecular interactions. Therefore, the EFP method provides a way to further reduce the computational effort while retaining accuracy by treating the far-field interactions in place of the full electronic structure method. The performance of the methods is demonstrated using applications to several systems, including benzene dimer, small organic species, pieces of the alpha helix, water, and ionic liquids.

N5+ : A NOVEL HOMOLEPTIC POLYNITROGEN ION AS A HIGH ENERGY DENSITY MATERIAL

No Abstract

N5+: ein neuartiges homoleptisches Polystickstoff-Ion als Substanz mit hoher Energiedichte

Das dritte Beispiel erst fur eine homoleptische Polystickstoff-Verbindung ist nach N2 und N3− das N5+-Ion; es ist erstaunlich stabil und kann in makroskopischem Masstab als AsF6−-Salz isoliert werden. Das Vorliegen der hier gezeigten, berechneten C2v-symmetrischen Struktur wurde durch IR- und Raman- sowie 14N- und 15N-NMR-spektroskopische Untersuchungen am isotopenmarkierten Produkt bestatigt.

Energetic Ionic Liquids based on Lanthanide Nitrate Complex Anions

Energetic ionic liquids based on anionic lanthanide nitrate complexes Cat(+) (3)[Ln(NO(3))(6)](3-), where Cat(+) is guanidinium, 4-aminotriazolium, 4-amino-1-methyltriazolium, 4-amino-1-ethyltriazolium, 4-amino-1-butyltriazolium, 1,5-diaminotetrazolium, and 1,5-diamino-4-methyltetrazolium, were prepared. The hexanitratolanthanate (-cerate) salts with the last two cations, which are the first CO-balanced energetic ionic liquids that are stable to hydrolysis and air, have impact sensitivities of about 27 J. These ionic liquids were obtained by an environmentally friendly, simple method using nitrate-containing precursors. All salts were fully characterized by IR and NMR spectroscopy, elemental analysis, and determination of thermal stability, phase behavior, density, and water content. According to theoretical calculations, these new compounds have potential as propellants.

Hypergolic Ionic Liquids to Mill, Suspend and Ignite Boron Nanoparticles

Boron nanoparticles prepared by milling in the presence of a hypergolic energetic ionic liquid (EIL) are suspendable in the EIL and the EIL retains hypergolicity leading to the ignition of the boron. This approach allows for incorporation of a variety of nanoscale additives to improve EIL properties, such as energetic density and heat of combustion, while providing stability and safe handling of the nanomaterials.

Cation−Cation π−π Stacking in Small Ionic Clusters of 1,2,4-Triazolium

The existence of cation−cation π−π stacking in the 1,2,4-triazolium−dinitramide tetramer and 1,2,4-triazolium−chloride tetramer (two cations and two anions) is predicted based on the structures optimized using second-order perturbation theory (MP2). In the most stable tetramer structure of 1,2,4-triazolium−dinitramide, π−π stacking is formed with an interplane distance of ∼3.2 A and a parallel displacement of ∼1.4 A. In the most stable tetramer structure of 1,2,4-triazolium−chloride, π−π stacking is formed with an interplane distance of ∼2.9 A and a parallel displacement of ∼1.0 A.

The syntheses and structure of the vanadium(IV) and vanadium(V) binary azides V(N3)4, [V(N3)6]2-, and [V(N3)6]-.

During the last decade, there has been much interest in inorganic polyazide chemistry. Because of the energetic nature of the azido group, polyazides are highly endothermic compounds, the energy content of which increases with an increasing number of azido ligands. It is, therefore, not surprising that the synthesis of molecules with a high number of azido groups is very challenging owing to their explosive nature and shock sensitivity. A significant number of pentavalent binary azido compounds of the heavier Group 5 elements have been prepared and characterized, namely Nb(N3)5, Ta(N3)5, Nb(N3)5·CH3CN, Ta(N3)5·CH3CN, [Nb(N3)6] , [Ta(N3)6] , [Nb(N3)7] 2 and [Ta(N3)7] 2 . 15] However, the situation is different for vanadium for which only trivalent binary azides were known. Thus, the UV/Vis spectra of solutions containing the ions [V(N3)] , [V(N3)4] , and [V(N3)6] 3 , and also the vibrational and electronic spectra of the [V(N3)6] 3 ion have been reported. For the higher oxidation states of vanadium, only ternary or quatenary azides, such as VOCl2N3, [19]

On the XeF+/H2O System: Synthesis and Characterization of the Xenon(II) Oxide Fluoride Cation, FXeOXeFXeF+

The reported synthesis of the H(2)OF(+) cation as a product of the oxidative fluorination of H(2)O by [XeF][PnF(6)] (Pn = As, Sb) in HF solution has been reinvestigated. The system exhibits complex equilibria, producing two new Xe(II) compounds, [Xe(3)OF(3)][PnF(6)] and [H(3)O][PnF(6)] x 2 XeF(2), refuting the original claim for the synthesis of the H(2)OF(+) cation. Both compounds have been isolated and characterized by vibrational spectroscopy and single-crystal X-ray diffraction. The X-ray crystal structures of the [Xe(3)OF(3)][PnF(6)] salts contain the Z-shaped FXeOXeFXeF(+) cation, which represents the first example of an isolated Xe(II) oxide fluoride. The crystal structure of the [H(3)O][AsF(6)] x 2 XeF(2) adduct contains XeF(2) molecules that interact with the H(3)O(+) cations. The vibrational assignments for the Xe(3)OF(3)(+) cation have been made with the aid of quantum-chemical calculations and were confirmed by (18)O-enrichment, and the assignments for [H(3)O][AsF(6)] x 2 XeF(2) were confirmed by (2)D- and (18)O-enrichment. Quantum-chemical calculations have also been carried out for H(3)O(+) x nXeF(2) (n = 1-4) and have been used to interpret the X-ray crystal structure and vibrational spectra of [H(3)O][AsF(6)] x 2 XeF(2). The energy-minimized geometries and vibrational frequencies for HOF and H(2)OF(+) have been calculated, further disproving the original report of the H(2)OF(+) cation. Both FXeOH and FXeOH(2)(+) have also been computed and are viable intermediates in the proposed equilibria between XeF(+) and H(2)O that lead to the Xe(3)OF(3)(+) cation.

Pairing Heterocyclic Cations with closo-Icosahedral Borane and Carborane Anions. I. Benchtop Aqueous Synthesis of Binary Triazolium and Imidazolium Salts with Limited Water Solubility

Ten new salts that pair triazolium and imidazolium cations with closo-icosahedral anions [B(12)H(12)](2-) and [CB(11)H(12)](-) were synthesized in water solvent using an open-air, benchtop method. These unreported [Heterocyclium](2)[B(12)H(12)] and [Heterocyclium][CB(11)H(12)] salts extend reports of [Imidazolium][CB(11)H(12)] and [Pyridinium][CB(11)H(12)] salts that were synthesized in anhydrous organic solvents under an inert atmosphere with glovebox or Schlenk techniques. Spectroscopic data, melting points, and densities are reported for each salt. Single-crystal X-ray structures are provided for the five new [B(12)H(12)](2-) salts.