Triplet excition emissions of octafluoronaphthalene crystalline complexes with naphthalene and durene

The phosphorescence spectra of naphthalene-octafluoronaphthalene and durene-octafluoronaphthalene at 4.2 K reveal a localized exciton emission from octafluoronaphthalene, a weak intercomponent triplet-states quasi-resonance and a weak exciton-phonon coupling.     

Ligand dynamics and reactivity in trimetallic clusters

The general relationships between trinuclear cluster reactivity and the ligand dynamical processes in these systems are explored. Three specific mechanistic studies are presented: (1) the rate and stereochemistry of ligand addition to ₃-imidoyl complexes, (2) the factors influencing the rate of carbon-hydrogen bond activation in ₃-alkyne complexes, and (3) the origin of anomalously large kinetic deuterium isotope effect in metal to ligand and ligand to metal hydrogen transfer in trinuclear and binuclear complexes. In all three cases, the current state of the mechanistic studies are summarized and the possible rate of specific ligand dynamical processes in controlling the mechanism are put forth.     

Quasilocalization of extra electrons in high density methane and ethane gases

The extent of electron quasilocalization in the high density gases is greater in ethane than in methane. However, the density required for quasilocalization in methane is n/n_c > 0.1, while that in ethane is n/n_c > 0.4, where n_c is the critical density. The mobilities in methane and ethane cross at n = 6 × 10²¹ molecules/cm³, in the respective fluids along their vapor/liquid coexistence curves.     

Electrophile-mediated cyclizations in carbohydrate chemistry: synthesis of highly functionalized ribofuranose and ribopyranose compounds

Iodine-mediated cyclization of (Z)- and (E)-{=D}-ribohept-2-enonates $\text{1}$ and $\text{2}$ gave exclusively the β-ribofuranose and α-ribofuranose derivatives $\text{3}$ and $\text{4}$, respectively. Cyclization of the (Z)- and (E)-2-heptene-1-ol derivatives $\text{5}$ and $\text{6}$ gave ribofuranose products ($\text{7}$ and $\text{8}$) and a ribopyranose ($\text{9}$), respectively.     

Chemical ionization and electron impact mass spectra of thiosulfinates,thiosulfonates and sulfinyl sulfones

The chemical ionization and electron impact mass spectra of some thiosulfinates, thiosulfonates and sulfinyl sulfones have been studied. The electron impact mass spectra of four of the six thiosulfonates show molecular ions of less than 1%. Inconclusive evidence was obtained for sulfenyl sulfinate type intermediates in the electron impact spectra of thiosulfonates. The electron impact spectra of thiosulfonates were similar to those of thiosulfonates. The chemical ionization (isobutane) mass spectra of thiosulfinates and thiosulfonates generally show protonated molecular ions [MH]⁺ as base peaks and [MH+1]⁺ and [MH+2]⁺ peaks.     

Structural isomers of C2N+: a selected-ion flow tube study

Reactivities of the structural isomers CCN+ and CNC+ were examined in a selected-ion flow tube at 300 +/- 5 K. The less reactive CNC+ isomer was identified as the product of the reactions of C(+) + HCN and C(+) + C2N2; in these reactions only CNC+ can be produced because of energy constraints. Rate coefficients and branching ratios are reported for the reactions of each isomer with H2, CH4, NH3, H2O, C2H2, HCN, N2, O2, N2O, and CO2. Ab initio calculations are presented for CCN+ and CNC+; a saddle point for the reaction CCN+ --> CNC+ is calculated to be 195 kJ mol-1 above the CNC+. The results provide evidence that the more reactive CCN+ isomer is unlikely to be present in measurable densities in interstellar clouds.     

Synthesis of 2-oxo and 2-thioxo-3(2H)-benzothiazoleethanimic acid anhydride with acetic acid and related products

The reaction of the appropriate 2-benzothiazolinone with 2-chloroacetamide under basic conditions afforded the 2-oxo-3(2H)-benzothiazolineacetamides 6–9. The 2-thioxo-3(2H)-benzothiazolineacetamide ( 10 ) was prepared by the reaction of 3-(carbethoxymethyl)benzothiazoline-2-thione with ammonium hydroxide. The reaction of acetamides 6–10 with the appropriate anhydride containing a catalytic amount of the sodium salt of the acid corresponding to the anhydride afforded the titled compounds 11–18 in excellent yields. The omission of the catalyst in the same reaction furnished a mixture containing 57% of the titled compound, 37% of the nitrile and 6% of an unknown. Possible mechanism and supporting nmr, ir and mass spectral data are discussed.     

Taming the rugged landscape: production, reordering, and stabilization of selected cluster inherent structures in the X13-nYn system

We present studies of the potential energy landscape of selected binary Lennard-Jones 13 atom clusters. The effect of adding selected impurity atoms to a homogeneous cluster is explored. We analyze the energy landscapes of the studied systems using disconnectivity graphs. The required inherent structures and transition states for the construction of disconnectivity graphs are found by combination of conjugate gradient and eigenvector-following methods. We show that it is possible to controllably induce new structures as well as reorder and stabilize existing structures that are characteristic of higher-lying minima. Moreover, it is shown that the selected structures can have experimentally relevant lifetimes.