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Ab initio equation-of-motion coupled-cluster singles and doubles method (EOM-CCSD) calculations are carried out on molecules [H.sub.m]X-Y[H.sub.n] for X, Y = [super 15]N, [super 17]O, [super 31]P and [sup.33.S] in order to investigate the variation of one-bond X-Y spin-spin coupling constants [super 1]J(X-Y) and components of J with rotation about the X-Y single bond. It is found that the reduced Fermi-contact terms for all the molecules are negative and decrease in absolute value as the rotational angle [theta] changes from zero degree. more...

A kinetic and thermodynamic investigation of phenols para-substituted with thiyl (SR), sulfinyl (SOR) and sulfonyl (S[O.sub.2]R) groups and ortho-substituted with thiyl groups is presented. The ESI-MS analysis of the products that are formed by reacting the sulfides with peroxyl radicals from the azoinitiator AIBM has revealed the formation of a complex mixture of products that might play a vital role in determining the overall antioxidant activity of the parent compounds. more...

The migration of H atoms over S and Fe atoms in the reaction domain of FeMo-co, the active site of nitrogenase is described and used to explain mechanistic data on the catalyzed reductions of [N.sub.2] and [C.sub.2][H.sub.2]. The positions of H atoms influence the binding of substrates [N.sub.2] and [C.sub.2][H.sub.2] and the bound substrate blocks further migration of H atoms past the binding site. more...

The mechanism of the .OH-induced oxidation of S-ethylthioacetate (SETAc) and S-ethylthioacetone (SETA) was investigated in aqueous solution using pulse radiolysis and steady-state y radiolysis combined with chromatographic and ESR techniques are discussed. The results show that alpha-positioned acetyl group in SETAc destabilizes hydroxysulfuranyl radicals within the five-membered structure that leads to the formation of alkyl-substituted radicals. more...

The molecular structure of small Cu (sub x) S (sub y)(super -) anionic clusters was studied by the combination of ab initio and atom-in-molecules (AIM) calculations. The results stated that covalent Cu-Cu bonding was weak, unstable and not realized even when the intratomic distances were found to be within normal Cu-Cu bond range. more...

Asterisks that comprise of six semigrid arms projecting from a benzene nucleus are synthesized with one, two, or three aromatic rings (connected by sulfur atoms) in each of the six arms. A phosphomonoester at the termini of each arm solubilized the asterisks in water. more...

The binding energies of the ground state, S(sub 0), the first excited state, S(sub 1), and the ion ground state, I(sub 0), of the p-methoxyphenethylamine(H2O)(sub(1-4) complexes were analyzed by threshold ion fragmentation. The knowledge of these energies and the set of the origin brand transitions of the bare molecule yielded the determination of the ground state, the first electronic excited state, and the ion state, binding energies, the most relevant features of the weakly bound complexes. more...

The study stated that dispersed fluorescence (DF) spectroscopy was used to record a 22500 cm(super -1) spectrum of the vibrational energy levels of formyl fluoride (HFCO) which determined harmonic frequencies and anharmonic constants of the S(sub 0) potential energy surface. The analysis of the spectrum resulted in 240 assignments, which include 196 new assignments, and 56 assignments above the approximate 17000 cm(super -1) dissociation barrier. more...

X-ray absorption spectroscopy was used to demonstrate the coordination of As(III) with three sulfur atoms which is consistent with the three cysteine residues forming the As(III) binding site. The transfer of As(III) from ArsD to ArsA which occurred in the presence of MgATP suggested that transfer occurs with a conformation of ArsA transiently formed during the catalytic cycle. more...

Mossbauer investigation is used for studying the whole cells overexpressing pyruvate formate-lyase activating enzyme (PFL-AE) following incubation under aerobic and/or anaerobic conditions and have shown that PFL-AE undergoes cluster interconversions in vivo. The studies have shown that the [[4Fe-4S].sup.2+] cluster of PFL-AE in whole cells contains a valence-localized [Fe.sup.III][Fe.sup.II] pair and the addition of adenosyl moieties to purified PFL-AE has reproduced the valence-localized state of the [[4Fe-4S].sup.2+] cluster. more...

First-principles calculations are employed to study the stable configuration, electronic structures, and magnetic behaviors for S adsorption on graphene. The results provide insight into the coverage dependent absorption site of S on graphene and the surface potential energy curve which confirmed graphene as suitable candidate for the S storage. more...

The growth of persistent edge-on hexa-peri-hexabenzocoronene (HBC) nanocolumns chemically grafted on gold via terminal anchoring groups containing sulfur atoms is described. The degree of ordering and length and their transport properties are directly related to the length and flexibility of the spacer bearing the grafting chemical function. more...

A simple synthesis and unique structural characteristics and reactivity of the first supersulfidonickel complex with the 'side-on' [S.sub.2.sup.-] ligand is reported. The dimerization of complex via [pi]*(SOMO)-[pi]*(SOMO) interaction revealed a four-sulfur two-electron bond in the dimer. more...

The flash vacuum pyrolysis of benzannulated thiopyrans which cause the extrusion of the sulfur atom and aryl-aryl bond formation to yield the ring contracted hydrocarbon product is demonstrated. The thermal extrusion of sulfur from benzannulated thiopyrans is observed to be less demanding energetically than thermal decarbonylation of aromatic ketones. more...

The density functional theory method was used to study the mechanism and diastereoselectivity of synthetically useful sulfur ylide promoted cyclopropanation reactions. The high trans selectivity predicted for stabilized ylides was found to originate from the difference in degree of steric encumbrance associated with the diastereomeric torsional TSs. more...

Adsorption of atomic sulfur at different coverages on the Fe(110) surface is examined using density functional theory (DFT) in order to investigate the effect that adsorbate-adsorbate interactions may have on the surface properties. The bonding of S to the surface is found to change from being S-Fe dominated at the lower coverages to being S-S dominated at the higher coverages where the adjacent S atoms are closer together and interact strongly with each other. more...

New Arrhenius rate expressions are determined for the abstraction of bromine atom from 2-phenethyl bromide and sulfur atom from propylene sulfide by tributylstannyl radical. The results revealed that increase in rate of bromine atom abstraction by tin radical from the thiiranylmethyl bromide provides evidence for synchronous thiirane ring opening providing an enthalpic enhancement of the bromine atom abstraction rate. more...

The triatomic system, Silicon-Oxygen-Sulphur Oligomers (SiOS)(sub n) is the most simple molecule combining the reactivity of sulfur and fractionality of Si-O bonds. The oligomers are found to be stable with respect to dissociation and disproportion processes. more...

A temperature-dependent effective potential energy function for internal motion of protein backbone amide bond vectors is developed and validated using computational simulations. The parameters W(sub 0) and alpha that define the potential can be obtained from the experimental temperature dependence of the generalized order parameter S. more...