Ion Chemistry Laboratory
Centre for Research in Mass Spectrometry
 York University

 

Si+ Chemistry

EXPLANATION OF TABLE

This is a compilation of rate constants and product distributions for positive ion/molecule reactions involving silicon which have been measured with the selected-ion flow tube (SIFT) technique in the Ion Chemistry Laboratory at York University up to 2005.

The table is ordered according to the molecular weight of the reactant ion in the chemical equation. When reactant ions are the same, the reactions are ordered according to the neutral reactant. This latter procedure is based upon counting the number of carbon and hydrogen atoms in the neutral reactant. First priority is given to the number of carbon atoms. The greater the number of carbon atoms, the further down the table the neutral will appear. Within groups of neutrals containing the same number of carbon atoms, the order is determined by the number of hydrogen atoms. If the molecules contain the same number of hydrogen atoms, then the order is dependent alphabetically on the remaining atoms in the neutral. Neutral reactants that do not contain carbon atoms are ordered alphabetically with the earliest letter taking precedence, and precede carbon-containing molecules. In cases where the early letter is the same, the ordering is done by molecular weight with the lower molecular weight taking precedence.

The collision rate constants included in the tabulation, kc, are derived using the combined variational transition-classical trajectory treatment of T. Su and W.J. Chesnavich, J. Chem. Phys., 76, 5183 (1982). Rate constants are presented in units of 10-9 cm3 molecule-1s-1 and are either bimolecular or pseudo-bimolecular. Reactions leading to association were not investigated as a function of total pressure. The experiments were conducted as 296±2K using the SIFT technique in a Helium buffer gas at ca. 0.35 Torr or 1.15 x 1016 helium atoms cm-3.

REACTANTS PRODUCTS BR kexp kc kexp/kc HIGHER ORDER PRODUCTS References
 
Si+(2P)
 
CH2CCH2 SiC3H3+ + H 0.70 1.2 1.4 0.86 10
SiC2H+ + CH3 0.20 1.2 1.4 0.86 10
SiCH2+ + C2H2 0.10 1.2 1.4 0.86 10
CH3CCH SiC3H3+ + H 0.60 1.2 1.7 0.71 10
SiC2H+ + CH3 0.25 1.2 1.7 0.71 10
SiCH2+ + C2H2 0.15 1.2 1.7 0.71 10
CH3CN CH2Si+ + CHN 0.50 2.4 4.49 0.53 3
C2H3NSi+ 0.50 2.4 4.49 0.53 3
CH3COOH SiOH+ + CH3CO 0.70 3.0 2.3 1.3 1
CH3CO+ + SiOH 0.30 3.0 2.3 1.3 1
CH3OH SiOH+ + CH3 0.75 2.2 2.4 0.92 1
SiOCH3+ + H 0.25 2.2 2.4 0.92 1
CH3NH2 SiNH2+ + CH3 0.55 1.2 2.03 0.59 2
CH2NH2+ + SiH 0.35 1.2 2.03 0.59 2
SiNHCH3+ + H 0.10 1.2 2.03 0.59 2
(CH3)2 CO SiOH+ + C3H5 0.45 0.28 3.4 0.08 6
CH3CO+ + SiCH3 0.30 0.28 3.4 0.08 6
C3H6+ + SiO 0.25 0.28 3.4 0.08 6
(CH3)2NH CH2NHCH3+ + SiH 0.60 1.2 1.82 0.66 2
(SiNH2+ + C2H5) 1.2 1.82 0.66 2
SiNHCH3+ + CH3 0.35 1.2 1.82 0.66 2
SiN(CH3)2+ + H 0.05 1.2 1.82 0.66 2
(CH3)3N CH2N(CH3)2+ + SiH 0.80 0.98 1.64 0.60 2
CH2NHCH3+ + SiCH3 0.09 0.98 1.64 0.60 2
(SiNH2+ + C3H7) 0.98 1.64 0.60 2
SiN(CH3)2+ + CH3 0.07 0.98 1.64 0.60 2
SiCH2+ + (CH3)2NH 0.04 0.98 1.64 0.60 2
(CH3CNH+ + SiCH5) 0.98 1.64 0.60 2
CH4 SiCH4+ 1.00 0.00 10
CH4 Si+.CH4 1.00 0.00 1.17 0.00043 6,10
CO NR <0.00002 1,9
CO2 SiCO2+ 1.00 <0.00017 0.92 5
COS SiS+ + CO 1.00 0.90 1.43 0.63 5
CS2 SiCS2+ 1.00 0.07 1.47 0.045 5
C2H2 SiC2H+ + H 0.70 0.35 1.16 0.30 6,10
SiC2H2+ 0.30 0.35 1.16 0.30 6,10
C2H2 SiC2H+ + H 0.70 0.35 9
SiC2H2+ 0.30 0.35 9
C2H4 SiC2H4+ 0.60 0.56 1.3 0.43 10
SiC2H3+ + H 0.40 0.56 10
C2H5OH SiOH+ + C2H5 1.00 2.50 2.4 1.04 1
C2H6 SiCH3+ + CH3 0.80 0.80 1.3 0.62 10
SiCH2+ + CH4 0.15 0.80 1.3 0.62 10
SiC2H4+ + H2 0.03 0.80 1.3 0.62 10
SiC2H6+ 0.02 0.80 1.3 0.62 10
C2N2 CNSi+ + CN 0.55 0.15 3
C2N2Si+ 0.45 0.15 3
C4H2 C4H+ + SiH 1.00 1.60 1.35 1.2 6,9
C6H6 (SiC6H6)+ 1.00 observed 9
C10H8 (SiC10H8)+ 0.90 observed 8
C10H8+ + Si 0.10 observed 8
D2 NR <0.0001 1.1 1,9
HCN CHNSi+ 0.80 0.007 3.75 0.0019 3
CNSi+ + H 0.20 0.007 3.75 0.0019 3
HCOOH SiOH+ + CHO 1.00 2.3 1.9 1.21 1
HC2CN C2HSi+ + CN 0.70 1.4 4.07 0.34 3
C3HNSi+ 0.30 1.4 4.07 0.34 3
H2 NR <0.0002 1.5 1,9
H2O SiOH+ + H 1.00 0.23 2.1 0.11 1,9
NH3 SiNH2+ + H 1.00 0.64 2.41 0.27 2,9
NO SiNO+ 1.00 <0.01 0.85 5
NO2 SiO+ + N2 0.68 0.86 5
NO+ + SiO 0.30 0.86 5
SiNO2+ 0.02 0.86 5
N2O SiO+ + N2 1.00 0.40 1.07 0.37 5
O2 SiO2+ 1.00 <0.0001 5,9
SO2 SO+ + SiO 1.00 0.81 1.96 0.41 5
Si+(4P)
D2 SiD+ + D 1.00 0.77 1.1 0.7 1
SiCH2+
CH2CCH SiC3H3+ + CH3 0.95 0.61 1.3 0.47 10
SiC4H5+ + H 0.05 0.61 1.3 0.47 10
CH3CCH SiC3H3+ + CH3 0.85 0.91 1.5 0.61 10
SiC4H5+ + H 0.15 0.91 1.5 0.61 10
SiC2H+
CH2CCH2 SiC5H5+ 1.00 0.56 1.2 0.47 10
CH3CCH SiC5H5+ 1.00 0.65 1.4 0.46 10
C2H2 SiC4H3+ 0.90 0.20 1 0.2 6
SiC4H+ + H2 0.10 0.20 1 0.2 6
C2H2 SiC4H4+ 1.00 0.20 10
C2H4 SiC2H3+ + C2H5 0.80 0.40 1.1 0.36 10
SiC4H8+ 0.20 0.40 1.1 0.36 10
SiC2H4+
C2H6 products 1.00 0.08 1.1 0.07 10
SiC3H3+
NH3 SiNH2+ + C3H4 0.72 (0.66) 2.1 10
SiC3H3+.NH3 0.72 (0.66) 2.1 10
SiC6H6+
CO NR <0.00009 0.73 9
C2H2 SiC6H6+.C2H2 0.60 0.06 0.94 0.064 9
SiC8H7+ + H 0.06 0.94 0.064 9
C4H2 SiC4H2+ + C6H6 >0.3 0.70 0.98 0.71 9
SiC6H6+.C4H2 <0.70 0.70 0.98 0.71 14
D2 NR <0.0003 1.1 9
H2O SiC6H6+.H2O 0.40 0.20 2 0.1 9
C6H6+ + (SiOH2) 0.35 0.20 2 0.1 9
C6H7+ + SiOH 0.25 0.20 2 0.1 9
NH3 SiC6H6+.NH3 1.00 0.39 2 0.20 9
N2 NR <0.0002 9
O2 C6H6+ + (SiO2) 0.90 0.003 0.6 0.005 9
C6H6O+ + SiO 0.10 0.003 9
SiC10H8+
D2 NR <0.00035 1.1 9
H2O C10H8+ + (SiOH2) 1.00 0.0055 2.2 0.0025 9
NH3 SiC10H8+.NH3 1.00 0.41 2 0.21 9
N2 NR <0.0004 0.63 8,9
O2 C10H8+ + (SiO2) 1.00 0.0004 0.58 0.00064 8,9
CO NR <0.00031 0.7 9
C2H2 C10H8+ + (SiC2H2) 0.90 0.063 0.91 0.069 8,9
(SiC10H8+.C2H2) 0.10 0.063 0.91 0.069 8,9
C4H2 C10H8+ + (SiC4H2) 1.00 1.0 0.93 1.1 8,9
C6H6 NR <0.0006 1 8
SiF+
CO NR < 0.0001 13
SiF2.+
CO SiF2CO+ 1.00 0.00036 7.6 4.737×10-05 13
SiF2CO.+
CO SiF2(CO)2.+ 1.00 0.0002 7.3 2.740×10-05 13
SiF3+
CO SiF3CO+ 1.00 0.041 7.4 5.541×10-03 11,13
SiF3(CO)+
CO SiF3(CO)2+ 1.00 0.00041 7.1 5.775×10-05 13
SiF+
NH3 NR <0.001 22 14
SiF2+
NH3 NH3+ + SiF2 8.0 21 14
SiF3+
NH3 F2SiNH2+ + HF 4.90 21 14
F2SiNH2+
NH3 FSi(NH2)2++HF 5.3 21 0.25 14
F2Si(NH2)NH3+ 5.3 21 0.25 14
NH4++ F2SiNH 5.3 21 0.25 14
SiH+
O2 HSiO2+ 0.01 0.76 0.0066 12
SiOH+ + O 0.01 0.76 0.0066 12
HSiO+ + O 0.01 0.76 0.0066 12
CO2 SiOH+ + CO 0.19 0.91 0.21 12
HCO+ + SiO 0.19 0.91 0.21 12
N2O SiOH+ + N2 0.56 1 0.56 12
HSiO+ + N2 0.56 1 0.56 12
SO2 SiOH+ + SO 1.00 1.2 1.9 0.63 12
SiNH2+
H2 NR <0.00034 2
NH3 NH4+ + SiNH 1.00 0.58, 0.90 2.24 0.26,0.40 2,7
CO NR <0.0002 2
CH3NH2 CH3NH3+ + SiNH 1.00 1.0 1.83 0.55
(CH3)2S CH2SCH3+ + (SiNH3) 0.70 1.5 2.1 0.71
SiNH2+.(CH3)2S 0.25 1.5 2.1 0.71
CH4NSi+ + CH3SH 0.05 1.5 2.1 0.71
(CH3)2CO CH4NSi+ + (C2H4O) 0.85 2.4 3 0.8
SiNH2+.(CH3)2CO 0.15 2.4 3 0.8
SiO+
N2O SiO2+ + N2 1.00 0.48 0.89 0.54 5
NO2 NO+ + SiO2 0.63 1.5 0.94 1.6 5
NO2+ + SiO 0.35 1.5 0.94 1.6 5
SiO2+ + NO 0.02 1.5 0.94 1.6 5
O2 NR <0.0002 0.69 5
SiOH+
H2 NR <0.0002 1.5 1
H2O SiH3O2+ 1.00 0.01 2.5 0.004 1
H2S SiOH+.H2S 1.00 <0.001 1.5 4
NH3 NH4+ + SiO 1.00 2.5 2.2 1.1 4
CO SiOH+.CO 1.00 <0.0003 0.82 1
HCOOH SiH3O2+ + CO >0.9 1.0 1.7 0.59 1
SiOH+.HCOOH <0.1 <0.01 1.7 1
CH3OH SiOCH3+ + H2O 0.90 1.2 2.1 0.55 1
SiOH+.CH3OH 0.10 1.2 2.1 0.55 1
CH3CN SiOH+.CH3CN 0.55 0.48 4 0.12 4
CH3CNH+ + SiO 0.45 0.48 4 0.12 4
CH3COOH CH3CO+ + (SiH2O2) 0.90 2.3 2 1.15 1
CH3COOH2+ + SiO 0.10 2.3 2 1.15 1
C2H5OH SiH3O2+ + C2H4 0.60 2.4 2.1 1.1 1
SiOC2H5+ + H2O 0.30 2.4 2.1 1.1 1
C2H5OH2 + SiO 0.07 2.4 2.1 1.1 1
SiH3O+ + C2H4O 0.03 2.4 2.1 1.1 1
(CH3)2O SiOH+.(CH3)2O 0.80 1.0 1.8 0.53 4
(CH3)2OH+ + SiO 0.20 1.0 1.8 0.53 4
H2CCCH2 SiOH+.C3H4 0.80 1.2 4
C3H5+ + SiO 0.20 1.2 4
SiNHCH3+
CH3NH2 CH3NH3+ + SiNH 1.00 1.3 1.74 0.75 2
(CH3)2NH (CH3)2NH2+ + SiNCH3 0.95 0.70 1.5 0.47 2
SiNHCH3+(CH3)2NH 0.05 0.70 1.5 0.47 2
SiS+
H2 NR >0.00002 1.52 5
O2 SO+ + SiO 0.70 0.089 0.65 0.14 5
SiO+ + SO 0.30 0.089 0.65 0.14 5
CO NR <0.00004 0.78 5
COS SiS2+ + CO 1.00 1.4 1.14 1.2 5
SiSH+
H2O SiOH+ + H2S 1.00 1.1 2.4 0.46 4
H2S H3S+ + SiS 1.00 0.29 1.4 0.21 4
NH3 NH4+ + SiS 1.00 0.97 2.2 0.44 4
HCN HCNH+ + SiS 1.00 0.61 1.6 0.38 4
C2H4 SiSH+.C2H4 1.00 0.018 1.1 0.016 4
SiN(CH3)2+
(CH3)3N SiN(CH3)2+.(CH3)3N 1.00 0.85 1.26 0.67 2
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References [1] Gas-Phase Reactions of Si+ and SiOH+ with Molecules Containing Hydroxyl Groups: Possible Ion-Molecule Reaction Pathways toward Silicon Monoxide, Silanoic Acid, and Trihydroxy-, Trimethoxy-, and Triethoxysilane.
S. Wlodek, A. Fox and D.K. Bohme, J. Am. Chem. Soc. 109, 6663 (1987).

[2] Gas-Phase Reactions of Si+ with Ammonia and the Amines (CH3)xNH3-x (x = 1-3): Possible Ion-Molecule Reaction Pathways toward SiH, SiCH, SiNH, SiCH3, SiNCH3, and H2SiNH.
S. Wlodek and D.K. Bohme, J. Am. Chem. Soc. 110, 2396 (1988).

[3] Gas-Phase Reactions of Si+(2P) with Hydrogen Cyanide. Acetonitrile, Cyanogen, and Cyanoacetylene: Comparisons with Reactions of C+ (2P).
S. Wlodek and D.K. Bohme, J. Am. Chem. Soc. 111, 61 (1989).

[4] Experimental Proton Affinities for SiO and SiS and their Comparison with the Proton Affinities of CO and CS Using Molecular Orbital Theory.
A. Fox, S. Wlodek, A.C. Hopkinson, M.H. Lien, M. Sylvain, C. Rodriguez and D.K. Bohme, J. Phys. Chem. 93, 1549 (1989).

[5] Gas-phase Oxidation and Sulphidation of Si+(2P), SiO+ and SiS+.
S. Wlodek and D.K. Bohme, J. Chem. Soc., Faraday Trans. 2, 85, 1643 (1989).

[6] Chemical Pathways from Atomic Silicon Ions to Silicon Carbides and Oxides.
D.K. Bohme, S. Wlodek and A. Fox, in "Rate Coefficients in Astrochemistry", T.J. Millar and D.A. Williams (Eds), Kluwer Academic Press, 193 (1988).

[7] The Proton Affinity of SiNH and its Formation from SiNH2+ in the Gas Phase.
S. Wlodek, C.F. Rodriguez, M.H. Lien, A.C. Hopkinson and D.K. Bohme, Chem. Phys. Letters 143, 385 (1988).

[8] Novel Chemical Role for Polycyclic Aromatic Hydrocarbons in the Synthesis of Interstellar Molecules.
D.K. Bohme and S. Wlodek, Astrophys. J. 342, L91 (1989).

[9] Formation of Adduct Ions of Si+(2P) with Benzene and Naphthalene and Their Reactions in the Gas Phase: Graphitic Surface Chemistry in the Gas Phase.
D.K. Bohme, S. Wlodek, and H. Wincel, J. Am. Chem. Soc. 113, 6396 (1991).

[10] Gas-Phase Reactions of Si+(2P) with Small Hydrocarbon Molecules: Formation of Silicon-Carbon Bonds.
S. Wlodek, A. Fox, and D.K. Bohme, J. Am. Chem. Soc. 113, 4461 (1991).

[11] Theoretical and Experimental Studies of F3SiCO+ and F3SiOC+.
A.E. Ketvirtis, V.I. Baranov, D.K. Bohme, and A.C. Hopkinson, Int. J. Mass Spectrom. Ion Processes 153, 161 (1996).

[12] Formation of the high-energy isomer HSiO+ by chemical reaction in the gas phase.
A Fox, and D.K. Bohme, Chem. Phys. Letters 187, 5 (1991).

[13] Experimental and Theoretical Studies of SiFn(CO)2+ Cations with n =2 and 3: A Search for Pentacoordinate Cationic Silicon.
A.E. Ketvirtis, V.I. Baranov, A.C. Hopkinson, and D.K. Bohme, J. Phys. Chem. 101, 7258 (1997).

[14] Experimental and Theoretical Studies of Gas-Phase Reactions of SiFx+ (x = 1-3) with Ammonia: Intramolecular H-atom Transfer Reactions with SiF3+ and F2Si(NH2)+.
A.E. Ketvirtis, V.I. Baranov, Y. Ling, A.C. Hopkinson, and D.K. Bohme, Int. J. Mass Spectrom. Ion Processes 185/186/187, 381 (1999).
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For a copy of this table measured with the selected-ion flow tube technique in the Ion Chemistry Laboratory at York University up to 1999, right click and "save target as" Silicon ion chemistry database (in MS WORD format).
Ion Chemistry Laboratory, York University 4700 Keele Street, Toronto, Ontario M3J 1P3