Rate constants for the gas-phase reactions of silylene with methanol, deuterated methanol, and water

被引:25
作者
Alexander, UN
King, KD
Lawrance, WD
机构
[1] Flinders Univ S Australia, Sch Chem Phys & Earth Sci, Adelaide, SA 5001, Australia
[2] Univ Adelaide, Dept Chem Engn, Adelaide, SA 5005, Australia
关键词
D O I
10.1021/jp012773v
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Gas-phase reaction rate constants for the reaction of silylene, SiH2, with deuterated methanol, CD3OD, have been determined over the temperature range 294-423 K and at total pressures over the range 100-800 Torr of the inert bath gas, Ar. Rate constants have also been measured for the reaction of SiH2 with CH3OH at 294 K over the range 100-800 Torr, also with Ar. Rate constants for the reaction of SiH2 with H2O over the range 50-200 Torr in Ar have been determined at 294 K. The second-order rate constants are pressure-dependent up to the maximum pressures investigated. For CD3OD, for which temperature-dependent data have been obtained, the rate constants decrease with increasing temperature, indicating that the reaction proceeds via the formation of a complex. At the highest temperature studied (423 K), the experimental decay curves indicate the system approaching equilibrium, providing direct experimental evidence for the formation of the complex. Analysis of the 423 K decay curves provides an experimental determination of the equilibrium constant, K-eq, and a value for the dissociation energy of the complex of 83.0 +/- 1.3 kJ mol(-1). The Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation modeling gives a dissociation energy for the SiH2-CD3OD complex of 83.7 kJ mol(-1). Ab initio calculations, performed at the MP2/6-311+G** level of theory, give a value of 75.4 kJ mol(-1), in reasonable agreement with this value. The RRKM/master equation modeling for SiH2 + CD3OD, when adjusted to account for the changes arising from deuteration, reproduces the behavior observed for SiH2 + CH3OH. The high-pressure limit predictions of the RRKM/master equation modeling are quite unusual and may indicate unusual pressure and temperature behavior in weakly bonded systems.
引用
收藏
页码:973 / 981
页数:9
相关论文
共 37 条
[1]   Phenylgermane as a suitable precursor for laser flash photolysis measurements of germylene kinetics [J].
Alexander, UN ;
Trout, NA ;
King, KD ;
Lawrance, WD .
CHEMICAL PHYSICS LETTERS, 1999, 299 (3-4) :291-295
[2]   Pressure and temperature dependence of the gas-phase reaction of silylene with dimethyl ether [J].
Alexander, UN ;
King, KD ;
Lawrance, WD .
PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 2001, 3 (15) :3085-3094
[3]   Temperature dependence of germylene reactions with acetylene, trimethylsilane, and phenylgermane [J].
Alexander, UN ;
King, KD ;
Lawrance, WD .
CHEMICAL PHYSICS LETTERS, 2000, 319 (5-6) :529-534
[4]   GAS-PHASE KINETIC-STUDY OF THE PROTOTYPE SILYLENE ADDITION-REACTION SIH2+C2H4 OVER THE TEMPERATURE-RANGE 298-595-K - AN EXAMPLE OF A 3RD-BODY MEDIATED ASSOCIATION [J].
ALRUBAIEY, N ;
WALSH, R .
JOURNAL OF PHYSICAL CHEMISTRY, 1994, 98 (20) :5303-5309
[5]  
[Anonymous], 1993, UNIMOL PROGRAM SUITE
[6]   TIME RESOLVED KINETIC-STUDIES OF THE GAS-PHASE REACTIONS OF DIMETHYLSILYLENE WITH SOME O-DONOR MOLECULES .1. ROOM-TEMPERATURE STUDIES [J].
BAGGOTT, JE ;
BLITZ, MA ;
FREY, HM ;
LIGHTFOOT, PD ;
WALSH, R .
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, 1992, 24 (02) :127-143
[7]   TIME-RESOLVED STUDIES OF THE REACTIONS OF GAS-PHASE DIMETHYLSILYLENE [J].
BAGGOTT, JE ;
BLITZ, MA ;
FREY, HM ;
LIGHTFOOT, PD ;
WALSH, R .
CHEMICAL PHYSICS LETTERS, 1987, 135 (1-2) :39-45
[8]   THE REACTION OF GAS-PHASE DIMETHYLSILYLENE WITH DIMETHYL ETHER [J].
BAGGOTT, JE ;
BLITZ, MA ;
LIGHTFOOT, PD .
CHEMICAL PHYSICS LETTERS, 1989, 154 (04) :330-334
[9]   PROTOTYPE SI-H INSERTION REACTION OF SILYLENE WITH SILANE - ABSOLUTE RATE CONSTANTS, TEMPERATURE-DEPENDENCE, RRKM MODELING AND THE POTENTIAL-ENERGY SURFACE [J].
BECERRA, R ;
FREY, HM ;
MASON, BP ;
WALSH, R ;
GORDON, MS .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 1995, 91 (17) :2723-2732
[10]   The gas-phase reaction of SiH2 with dimethylether:: kinetic evidence for direct formation of a donor-acceptor adduct [J].
Becerra, R ;
Carpenter, IW ;
Gutsche, GJ ;
King, KD ;
Lawrance, WD ;
Staker, WS ;
Walsh, R .
CHEMICAL PHYSICS LETTERS, 2001, 333 (1-2) :83-90