The SiF₃²⁺ Dication: Chemistry Counts!

Abstract

Waking the dead: The SiF32+ dication is a superelectrophile capable of activation of molecules as inert as dinitrogen. It is demonstrated that the reactivity of SiF32+ with neutral molecules M (M=N2, H2, CO, CO2, O2) is determined by formation of intermediates SiF3M2+ and the observed electron transfer is due to a large internal energy stored in the intermediate in the gas phase.

Formation of Organoxenon Dications in the Reactions of Xenon with Dications Derived from Toluene

“…The ions C 7 H 7 + , Xe + , and XeH + have the same onset as the parent ion and peak at about E lab = 0 eV, which is behavior characteristic for exothermic or thermoneutral ion/molecule reactions via an intimate collision complex. [17,21] The curve for the dicationic product C 7 H 6 Xe 2 + has a similar shape, but the maximum is shifted by about 1 eV. Whereas the general energy behavior of this channel also implies the involvement of a collision complex, the formation of C 7 H 6 Xe 2 + thus appears to be favored by a small amount of excess energy.…”

Bond-Forming Chemistry in the Gas-Phase Reactions of Atomic and Molecular Dications and Trications

“…SiF 3 2+ also forms dicationic products with a number of other small molecules, with energetic considerations concerning the collision complexes again allowing the rationalization of the competition between SET and product dication formation. 84,102 It is important to note, at this point, the value of modern computational chemistry in allowing the rationalization of the reactivity that is observed in all of the experiments discussed above. For example, computational work proved vital in explaining the reactivity of C 7 H 8 2+ dications, formed from toluene, with Xe to form C 7 H 6 Xe 2+ ; here, the potential energy landscape mapped out by the electronic structure calculations shows that the formation of the product occurs in a single step and is slightly endothermic.…”

“…84,102 At low collision energies, as shown by GIB experiments, SiF 3 2+ reacts with N 2 to form SiF 2 N 2 2+ as the major product, despite SET being exothermic for this collision system. At these low collision energies, it seems that a 'Coulomb barrier' to the formation of the electron transfer products causes the [SiF 3 -N 2 ] 2+ collision complex to favor the formation of the product dication.…”

Silicon Compounds of Neon and Argon

“…[18] Part of the signal assigned to SiF + is overlapped by N 2 SiF 2 2+ (#) formed from SiF 3 2+ and background nitrogen in analogy to reaction (1). [19] Inset in (a) shows a neutral gain spectrum [20,21] of the SiF 3 2+ isotopes with an offset Dm = 10.5 amu of the second quadrupole analyzer to detect the corresponding precursor isotope pattern of the 40 ArSiF 2 2+ product formed at U oct = 2 V. b) The dependence of the most important channels from the voltage applied to the octopole collision cell; note the offset of U oct is such that the zero of the E lab scale is at U oct = ca. 2 V. 2+ dications with neon (p(Ne) = 9 10 À4 mbar, black trace) and without gas (gray trace; shifted vertically by 0.001) at a collision energy circa 0 eV (that is, octopole voltage U oct adjusted to 2 V).…”