Reaction of silicon ion (/sup 2/P) with silane (SiH/sub 4/, SiD/sub 4/). Heats of formation of SiH/sub n/, SiH/sub n//sup +/ (n = 1, 2, 3), and SiH/sub n//sup +/ (n = 0, 1, 2, 3). Remarkable isotope exchange reaction involving four hydrogen shifts

Journal Article · Wed Jun 10 00:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00246a010· OSTI ID:6137603

Boo, B H; Armentrout, P B

The reaction of ground-state silicon ion with silane is investigated by using a guided ion beam tandem mass spectrometer. Reaction cross sections of all possible fragments, Si/sub m/H/sub n//sup +/ (m = 1, 2; n = 0, 1, 2, 3), as a function of relative kinetic energy are determined. All thermal energies, the major product is Si/sub 2/H/sub 2//sup +/. One remarkable reaction, the interchange of the projectile silicon ion with the target silicon atom, is observed at near zero kinetic energy. Labeling experiments employing /sup 30/Si/sup +/ for the beam or SiD/sub 4/ for the reactant indicate the intermediacy of the disilicon hydrides for the formation of the observed products. From the endothermicities of several reactions, the 298 K heats of formation for several ionic and neutral silicon hydrides are derived: ..delta..H/sub f//sup 0/(SiH) = 90.0 +/- 1.7, ..delta..H/sub f//sup 0/(SiH/sub 2/) = 69.0 +/- 2, ..delta..H/sub f//sup 0/(SiH/sub 3/) = 48.5 +/- 1.6, ..delta..H/sub f//sup 0/(SiH/sub 2//sup +/) = 276.1 +/- 1.7, ..delta..H/sub f//sup 0/(SiH/sub 3//sup +/) = 237.1 +/- 2, ..delta..H/sub f//sup 0/(Si/sub 2//sup +/) less than or equal to 328.0 +/- 2, ..delta..H/sub f//sup 0/(Si/sub 2/H/sup +/) less than or equal to 304.4 +/- 1.6, ..delta..H/sub f//sup 0/(Si/sub 2/H/sub 2/) less than or equal to 268.0 +/- 2.6, ..delta..H/sub f//sup 0/(Si/sub 2/H/sub 3//sup +/) = 266 +/- 2, all in kcal/mol. From an evaluation of these and other experiments, values of ..delta..H/sub f//sup 0/(SiH/sub 2//sup +/) and ..delta..H/sub f//sup 0/(SiH/sub 2/) of 278.0 +/- 1.4 and 68.5 +/- 1.5 kcal/mol, respectively, are recommended.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 6137603
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 109:12
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DEUTERIUM
ISOTOPIC EXCHANGE
DEUTERIUM COMPOUNDS
CHEMICAL REACTIONS
SILANES
LABELLING
SILICON
SILICON 30
CATIONS
FORMATION HEAT
ION-MOLECULE COLLISIONS
KINETIC ENERGY
MASS SPECTROSCOPY
CHARGED PARTICLES
COLLISIONS
ELEMENTS
ENERGY
ENTHALPY
EVEN-EVEN NUCLEI
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ION COLLISIONS
IONS
ISOTOPES
LIGHT NUCLEI
MOLECULE COLLISIONS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
SEMIMETALS
SILICON COMPOUNDS
SILICON ISOTOPES
SPECTROSCOPY
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation