Yurii A. Borisov

Gas-phase formation of mono- and dications from iron-subgroup decamethylmetallocenes and their calculation by the density functional method

Abstract The possibility of forming mono- [C 5 Me 5 MC 5 Me 4 CH 2 ] + ( 1 ) and dications [1,2(CH 2 ) 2 C 5 Me 3 MC 5 Me 5 ] 2+ ( 2 ) and 1,1′-[M(C 5 Me 4 CH 2 ) 2 ] 2+ ( 3 ) starting from iron subgroup decamethylmetallocenes (Fe ( a ), Ru ( b ), Os ( c )) was studied using electron-impact mass-spectrometry. The peaks of both single ( M + ) and doubly charged ( M 2+ ) molecular ions are present in the mass-spectra of all compounds studied. The basic fragmentation patterns are the elimination of one ( M + ) and two atoms of hydrogen ( M 2+ ) to give the corresponding mono- ( 1 ) and dications ( 2 and/or 3 ). The density-functional method was used for ab initio calculations of the geometry and total energies of cations 1 and 2 and the anti , syn , and gauche conformers of 3 for comparison with the dication [1,3-(CH 2 ) 2 C 5 Me 3 MC 5 Me 5 ] 2+ ( 2b ′). The calculation data for monocations 1a – c are in a good agreement with the results of X-ray analysis of these cations except for the MCH 2 interatomic distances and angles α , which are presumed to be most sensitive to phase changes. The relative order of stabilities of the mono- and dications was as follows: F

Generation of [1,2-(CH2)2C5Me3MC5Me4CH2-1′]3+ (M=Ru, Os) trications and determination of their structures by comparing NMR-spectra with density-functional method calculations

Abstract A general method for generating [1,2-(CH 2 ) 2 C 5 Me 3 MC 5 Me 4 CH 2 ] 3+ trications, where M=Ru ( 4a ) and Os ( 4b ) , from the salts of monocations [C 5 Me 5 MC 5 Me 4 CH 2 ] + An − ( 1a , b , An − =BF 4 ) by the action of dioxygen in a solution CF 3 SO 3 H superacid is presented. The energy characteristics of 4a and 4b have been calculated. NMR-spectra have been registered and analyzed. Conclusions received from NMR data for solutions of trications were compared with DFT calculation results of them in the gaseous phase.

Ab initio study of the Wolff rearrangement of C6H4O intermediate in the gas phase

Ab initio calculations of the geometry and reactivity of 1,2-ketocarbene C6H4O as an intermediate in organic reactions were performed using the second-order Møller-Plesset (MP2) perturbation theory in the 6-311G* basis set. Only the singlet state of the intermediate was considered. An oxirene-like structure (6) with a six-membered ring and a ketene-like structure (5) with a five-membered ring were localized on the potential energy surface. Attempts to locate a quinone type structure characteristic of aliphatic ketocarbenes failed. The energy of structure5 is −70 kcal mol−1 lower than that of structure6. Harmonic frequencies and intensities of normal vibrations in the IR spectra of6 and5 were calculated. The activation energy of the Wolff rearrangement6→5 was estimated at 12.5 kcal mol−1. The geometry of the transition state of this reaction resembles the quinone-like structure.

Chemical Fate of Contaminants in the Environment: Chlorinated Hydrocarbons in the Groundwater

Chlorinated hydrocarbons (CHCs) are the most common contaminant found at hazardous waste sites and are the most prevalent contaminants on (Department of Energy) DOE weapons production sites. Many of the chlorinated hydrocarbons are either known or suspected carcinogens and thus pose health risks to the public and/or site workers. Chlorinated hydrocarbons, unlike simple hydrocarbons, are resistant to biodegradation, but can degrade by abiotic processes such as hydrolysis, nucleophilic substitution, and dehydrochlorination. Unfortunately, few studies of the reactions of chlorinated hydrocarbons have been reported in the literature, and disagreement still exist about the mechanisms and rates of many of the key reactions.