Direct detection of chlorosilylene and time resolved study of some of its reactions in the gas-phase using a new photochemical precursor

Gas‐Phase Kinetics of Chlorosilylene Reactions II. ClSiH + C2H4: Absolute Rate Measurements and Quantum Chemical and RRKM Calculations for the Prototype π Addition Reaction

“…To our knowledge, there have been no previous studies of reaction (1), either experimental or theoretical, apart from our own measurement of k 1 at room temperature and 1.3 kPa total pressure. [9] Experimental…”

“…At pressures of 1.3 kPa (in SF 6 ) and at room temperature SiH 2 reacts 3.2 times faster than ClSiH with C 2 H 4 . [9] Of interest will be to see how rate constants compare at infinite pressure, the true bimolecular limit. To assist with the interpretation of mechanism the experimental work of this paper has been augmented by quantum chemical calculations of the structures and energies of the intermediates and transition states involved in the addition and related processes.…”

“…1.5 m. A portion of the monitoring beam was split off before entering the vessel for reference purposes. The monitoring laser was tuned to the 457.9 nm line, fortunately co-incident [9] with the known transition,Ã 1 A"(0,2,0) ! ~X 1 A' (0,0,0), in the ClSiH vibronic band.…”

“…Comparison of an earlier study of ClSiH + SiH 4 [10] with that for SiH 2 + SiH 4 [11] shows an astonishing rate constant reduction of 75 500. [9] In part I of this series of papers [12] we extended our ClSiH studies to the investigation of the temperature dependence of its reaction with Me 3 SiH, a typical SiÀH insertion process. By combining rate measurements with quantum chemical calculations of the potential energy surface, we were able to show that the rate constant reductions for ClSiH (for all SiÀH insertions), compared with SiH 2 , could be accounted for by high secondary energy barriers for rearrangement of the initially formed complexes.…”

“…Relatively little attention has been paid to the monosubstituted silylenes, XSiH, although we have carried out studies of SiÀH insertion reactions for both MeSiH [7] and PhSiH [8] which showed only small rate reductions for Me and Ph substitution in the silylene. More recently, [9] using a new photochemical precursor, we studied the kinetics of ClSiH with thirteen different substrate molecules at room temperature at 1.3 kPa total pressure (in SF 6 ). Comparisons with reactions of SiH 2 with eight of the same substrates showed a wide variation in relative rate constants, with Cl-for-H substitution producing rate reduction factors of between 2 and 1300.…”