Home  About us  Contact
 

Benzene Complex (benzene + complex)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

High-Electron-Density C6H6 Units: Stable Ten-,-Electron Benzene Complexes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2005
Martin Diefenbach Dr.
Abstract The first stable benzene molecule with ten , electrons is predicted. Stability is achieved through barium atoms acting as an electron-donating "matrix" to C6H6 in the inverted sandwich complex [Ba2(C6H6)]. The bis(barium)benzene complex has been computed at the density functional level of theory by using the hybrid functional mPW1PW91. Ab initio calculations were performed by using the coupled-cluster expansion, CCSD(T). Nucleus independent chemical shift (NICS) indices imply distinct aromatic character in the benzene ring of bis(barium)benzene. The D6h -symmetric structure with a 1A1g electronic ground state represents a thermochemically stable, aromatic benzene molecule with four excess , electrons, stabilised by two barium ions. A possible molecular wire, built up from Ba end-capped thorium,benzene "sandwiches", is discussed. [source]

Models of S/, interactions in protein structures: Comparison of the H2S,benzene complex with PDB data

PROTEIN SCIENCE, Issue 10 2007
Ashley L. Ringer
Abstract S/, interactions are prevalent in biochemistry and play an important role in protein folding and stabilization. Geometries of cysteine/aromatic interactions found in crystal structures from the Brookhaven Protein Data Bank (PDB) are analyzed and compared with the equilibrium configurations predicted by high-level quantum mechanical results for the H2S,benzene complex. A correlation is observed between the energetically favorable configurations on the quantum mechanical potential energy surface of the H2S,benzene model and the cysteine/aromatic configurations most frequently found in crystal structures of the PDB. In contrast to some previous PDB analyses, configurations with the sulfur over the aromatic ring are found to be the most important. Our results suggest that accurate quantum computations on models of noncovalent interactions may be helpful in understanding the structures of proteins and other complex systems. [source]

High-Electron-Density C6H6 Units: Stable Ten-,-Electron Benzene Complexes

CHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2005
Martin Diefenbach Dr.
Abstract The first stable benzene molecule with ten , electrons is predicted. Stability is achieved through barium atoms acting as an electron-donating "matrix" to C6H6 in the inverted sandwich complex [Ba2(C6H6)]. The bis(barium)benzene complex has been computed at the density functional level of theory by using the hybrid functional mPW1PW91. Ab initio calculations were performed by using the coupled-cluster expansion, CCSD(T). Nucleus independent chemical shift (NICS) indices imply distinct aromatic character in the benzene ring of bis(barium)benzene. The D6h -symmetric structure with a 1A1g electronic ground state represents a thermochemically stable, aromatic benzene molecule with four excess , electrons, stabilised by two barium ions. A possible molecular wire, built up from Ba end-capped thorium,benzene "sandwiches", is discussed. [source]

Formation and photodissociation of M+,C6H6 (M+ = V+ and Ta+) and Ta+,C6H4 complexes in a time-of-flight mass spectrometer

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2001
Hsiu-Fang Lee
Abstract A series of cyclic hydrocarbons were introduced to react with V+ and Ta+ using a pulsed beam expansion source in a time-of-flight mass spectrometer. The third-row metal Ta+ displayed high reactivity in dehydrogenation to form benzyne complexes, whereas benzene complexes were the terminal products for V+. M+,C6H6 (M+ = V+ and Ta+) and Ta+,C6H4 were selected to perform the photodissociation experiments. In contrast to the V+ fragment formation via simple cleavage of the V+,C6H6 bond, a photoinduced loss of C2H2 occurred in both the Ta+,C6H6 and Ta+,C6H4 complexes. Plausible explanations involved in the formation of Ta+,C6H6 and Ta+,C6H4 complexes are given for observing such photo-induced dissociation. The observed photodissociation in Ta+,C6H6 is analogous to the dissociative process previously investigated in metal ion,molecule reactions. The photodissociation spectrum of Ta+,C6H4 was obtained by recording the appearance of Ta+,C4H2 as a function of wavelength and yielded a dissociation energy of 91 ± 1 kcal mol,1. Copyright © 2001 John Wiley & Sons, Ltd. [source]