Search

Studies are conducted using quantum chemical computations, on possible polycyclization pathways of the farnesyl cation leading to the complex sesquiterpene pentalenene. Direct deprotonation of intermediates on these pathways leads to sesquiterpene byproducts, such as humulene, protoludene and asterscadiene, supporting the idea that a key function of pentalenene synthase is to regulate the timing and location of proton removal.

The nature of the bonding in a set of nonclassical carbocations with tetracoordinated protons inserted between two C=C pi bonds is investigated using the new computational methodology of generalized population analysis. The substitution of carbon by boron has reduced the strength of multicenter bonding revealing that the generalized population analysis is a useful tool for characterizing multicenter bonding in nonclassical structures.

The Ag 5s energy localization in energy on some AgBr surface geometries are predicted and analyzed, using simple models and group theory. Ag atoms on (100) and (110) surfaces have their 5s levels dispersed because of interactions with the Br 4p levels and hence will yield poor photoelectron traps for Ag cluster formation.

Gas-phase quantum chemical calculations were used to perform theoretical studies on carbocationic rearrangement pathways leading to the sesquiterpene natural products sativene, cyclosativene, and the [alpha]- and [beta]-ylangenes. The results revealed that formation of these four sesquiterpene from a common bicyclic intermediate required minimal enzymatic intervention with flat energy profiles of the pathways.

A compound, Sn(sub 2)I(sub 3)(NPPh3)(sub 3), with nonequivalent Sn atoms in characteristic 2+ and 4+ Sn geometries, raises the idea of an average Sn(super 3+) structure, which seems to be discovered in the extended structures of Sr(sub 4)Sn(sub 2)Se(sub 9) and Sr(sub 4)Sn(sub 2)Se(sub 10). The geometrical features of two different molecules prompt detective story of geometries and oxidation states in tin chemistry.

The structures of the conformers of isoelectric (C(sub 60))(sub 2)(super 2-) and (C(sub 59)N)(sub 2) are analyzed by semiempirical parameterized method and density functional method. The results indicate that these fullerene and hetero-fullerene dimer molecules exist as equilibrium mixtures of anti and gauche conformers, which are considered while interpreting the experimental measurements.