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Research has been conducted on 2-pyridinethiol and 2-pyridinethione. The solvent dependent preference and gas phase of the tautomerization between these compounds have been investigated via the use of variable temperature Fourier transform infrared experiments and density functional theory computations and the results are reported.

The relative energies obtained when density functional theory (DFT) was applied to cumulene and poly-yne isomers. It was clear from the results that as the carbon-chain length of cumulenes and poly-ynes increases the probability that bending modes are energetically accessible increases.

The organized geometries, adiabatic electron affinities, vertical electron affinities, vertical electron detachment energies (for the anions) and IR-active vibrational frequencies have been predicted for the long linear carbon chains HC(sub 2n+1)H(n=4-11). The predicted structures display an intermediate cumulene-polyacetylene type of bonding, with the inner carbons appearing cumulenic and the outer carbons polyacetylenic.

Research has been conducted on the neutral in-plane tris-homoaromaticity. The study of this homoaromaticity in tris(bismethano)benzene has been carried out and the hypothesis that the pi-orbitals might interact in the plane via the unsaturated carbon atoms has been tested and discussed.

A complete range of density functional methods is used to study the adiabatic electron affinity (AEA) for the Watson-Crick guanine-cytosine (GC) DNA base. It was found that the bracketing procedure with DFT functional and analogy to microsalvation, gives good evidence that AEA of GC is positive, and since this is positive the observation of isolated GC should be possible.

A study of the equilibrium geometries and frequencies of endohedral complexes between H, He, Ne, AR, Li, LI(sub +), BE, BE(sub +), Be(sub 2+). NA, NA(sub +) Mg, Mg(sub+) and Mg(sub 2+) and dodecahedrane ( X@C(sub 20)H(sub 20)) is presented. The results show that the changes in the dodecahedrane geometry were due to donation of electron density from the encapsulated metal atom into the C-C bonding and C-H antibonding endohedral complex HOMO, which has a structure closely resembling the LUMO of dodecahedrane.

Illustrative quantum - chemical calculations for selected atomic and molecular chemisorbates on Pt(111) (modeled as a finite cluster) are undertaken as a function of external field, F, by using Density Functional Theory (DFT) in order to ascertain the sensitivity of the field-dependent metal-absorbate binding energetics and vibrational frequencies to the natures of the surface coordination in electrochemical systems.

The electron affinity of 3-tert-butyl-1-bicyclo [1.1.1] pentyl radical (14.8 plusminus 3.2 Kcal/mol) is measured by bracketing as well as the acidity of 1-tert-butylbicyclo [1.1.1] pentane (408.5 plusmns 0.9) is determined by the DePuy kinetic method. The bridgehead C-H bond dissociation energy (109.7 plusmns 3.3 Kcal/mol) is much greater than a typical tertiary C-H bond (~ 96 Kcal /mol) and more typical of an aromatic or alkene C-H bond.

The potential energy surface (PES) for the phenyl + propyne reaction, which might contribute to the growth of polycyclic aromatic hydrocarbons (PAHs) under a wide variety of reaction conditions, is described. The addition of aromatic radical units to unsaturated, nonacetylene hydrocarbons has the potential to be an important channel for PAH growth; supplementing the rate of PAH growth through the traditional, acetylene based reaction mechanisms.

Research has been conducted on the amido- and imidochlorogallanes. The structural characteristics of different compounds and the thermodynamic analyses of the processes taking place in the gas phase are presented.

The authors review publications on the electron affinity, the energy difference between the uncharged species and its negative ion. The topics of interest include experimental and theoretical determination of the atomic and molecular electron affinities, the experimental methods exploiting the photoeffect and examination of the experimental photoelectron affinities.

Research has been conducted on the binuclear homoleptic carbonyls. The use of different density functional methods in studying the structure, vibrational frequencies and energetics of these carbonyl compounds is described.

Studies were conducted to examine the potential energy surfaces for SiH4-nHaln + 2NH3(I) and SiH (sub n)Hal (sub 4-n)+2H2O (II) systems (n=2,4; Hal = F, Cl). Studies did not find any minimum with energy below those of the reactants for the SiCl4 +2H2O system.

The three lowest-lying electronic states of PH2, X~B1(super 2), A~ A1(super 2) and B~B2(super 2) are studied by means of ab initio electronic structure theory. The total energies, equilibrium structures and physical properties are investigated using ab initio self-consistent field (SCF), configuration interaction (CISD), complete active space and coupled cluster wave functions with a wide variety of basis sets.

Research is presented concerning the use of density functional theory and ab initio methods to investigate the stability of the singlet and triplet states of 2,6-dibromo-4-tert-butyl-2',6'-bis(trifluoromethyl)-4'-isopropyldiphenylcarb ene.

Research describing the DNA and RNA bases' electron affinities is presented. The paper predicts adiabatic electron affinities and shows that those for guanine and cytosine fluctuate between small negative and positive values.

The thermodynamics of association reactions of organogallium precursors for GaN chemical vapor deposition is reported. The results suggest that under the experimental conditions of the GaN deposition process small clusters of Ga-N compounds may play a key role as intermediate.

The triplet electronic states of isocynaic acid are systematically investigated with the help of the electronic structure methods, including various correlation techniques. Vertical excitation energies were determined for the lowest 13 triplet states and potential energy curves for bending to and from linearity were generated, which revealed intricate state interactions and numerous avoided crossings.

The cobalt carbonyl Co(sub)2(CO)(sub)5 exhibits a monobridged closed-shell singlet with a 2.17 angstrom cobalt-cobalt bond of the order of four. The Co(sub)2(CO)(sub)8 form possesses a crystal structure of C(sub)2 symmetry. The latter compound shows three energetically low-lying equilibrium structures and the Co-Co stretches exhibit identical vibration patterns.