title: Exotic SiO(2)H(2) Isomers: Theory and Experiment Working in Harmony.
abstract: Replacing carbon with silicon can result in dramatic and unanticipated changes in isomeric stability, as the well-studied CO2H2 and the essentially unknown SiO2H2 systems illustrate. Guided by coupled-cluster calculations, three SiO2H2 isomers have been detected and spectroscopically characterized in a molecular beam discharge source using rotational spectroscopy. The cis,trans conformer of dihydroxysilylene HOSiOH, the ground-state isomer, and the high-energy, metastable dioxasilirane c-H2SiO2 are abundantly produced in a dilute SiH4/O2 electrical discharge, enabling precise structural determinations of both by a combination of isotopic measurements and calculated vibrational corrections. The isotopic studies also provide insight into their formation route, suggesting that c-H2SiO2 is formed promptly in the expansion but that cis,trans-HOSiOH is likely formed by secondary reactions following formation of the most stable dissociation pair, SiO + H2O. Although less abundant, the rotational spectrum of trans-silanoic acid, the silicon analogue of formic acid, HSi(O)OH, has also been observed.
authors.affiliation: Harvard-Smithsonian Center for Astrophysics , Cambridge, Massachusetts 02138, United States.|School of Engineering & Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Michael C
authors.initials: MC
authors.lastname: McCarthy
authors.affiliation: Institut für Physikalische Chemie, Universität Mainz , Mainz 55128, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gauss