Generation of C6S6 and its radical anion and cation in the gas phase

A Theoretical and Structural Investigation of Thiocarbon Anions

Density functional theory energies, geometries, and population analyses as well as nucleus-independent chemical shifts (NICS) have been used to investigate the structural and magnetic evidence for cyclic CnSn(2-) and CnSn (n = 3-6) electron delocalization. Localized molecular orbital contributions to NICS, computed by the individual gauge for localized orbitals method, dissect pi effects from the sigma single bonds and lone pair influences. CnSn(2-) (n = 3-5) structures in Dnh symmetry are minima. Their aromaticity decreases with increasing ring size. C3S3(2-) is both sigma and pi aromatic, while C4S4(2-) and C5S5(2-) are much less aromatic. NICS(0)pi, the C-C(pi) contribution to NICS(0) (i.e., at the ring center), decreases gradually with ring size. In contrast, cyclic C6S6(2-) prefers D2h symmetry due to the balance between aromaticity, strain energy, and the S-S bond energies and is as aromatic as benzene. The theoretical prediction that C6S6(6-) has D6h minima was confirmed by X-ray structure analysis. Comparisons between thiocarbons and oxocarbons based on dissected NICS analysis show that CnSn(2-) (n = 3-5) and C6S6(6-) are less aromatic in Dnh symmetry than their oxocarbon analogues.

Mass spectrometry and its use in tandem with laser spectroscopy

Mass spectrometry is undergoing rapid development, especially with the extension of its range into the hundreds of kilodaltons, the emergence of the quadrupole ion trap as a high-performance instrument, and the development of techniques for recording three-dimensional spectra. These advances are summarized in this review; in addition, the power of the combination of lasers and mass spectrometers is given particular emphasis. Their combination has contributed recently to chemical dynamics, to the study of cluster structure and reactivity, and to the elucidation of the properties of highly excited molecules and ions.