Gas-phase reactions of SiH(n)+ (n = 1,2) with NF3: a computational investigation on the detailed mechanistic aspects.
The mechanism of the gas-phase reactions of SiH(n)(+) (n = 1,2) with NF(3) were investigated by ab initio calculations at the MP2 and CAS-MCSCF level of theory. In the reaction of SiH(+), the kinetically relevant intermediates are the two isomeric forms of fluorine-coordinated intermediate HSi-F-NF(2)(+). These species arise from the exoergic attack of SiH(+) to one of the F atoms of NF(3) and undergo two competitive processes, namely an isomerization and subsequent dissociation into SiF(+) + HNF(2) , and a singlet-triplet crossing so to form the spin-forbidden products HSiF(+) + NF(2). The reaction of SiH(2)(+) with NF(3) involves instead the concomitant formation of the nitrogen-coordinated complex H(2)Si-NF(3)(+) and of the fluorine-coordinated complex H(2)Si-F-NF(2)(+). The latter isomer directly dissociates into NF(2)(+) + H(2)SiF, whereas the former species preferably undergoes the passage through a conical intersection point so to form a H(2) SiF-NF(2)(+) isomer, which eventually dissociates into H(2)SiF(+) and NF(2).
Dipartimento di Chimica, Università di Torino, C.so M. D' Azeglio, 48, 10125 Torino, Italy. paola.antoniotti@unito.it
Paola
P
Antoniotti
Elena
E
Bottizzo
Stefano
S
Borocci
Maria
M
Giordani
Felice
F
Grandinetti
D005461:Fluorine / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry*; D011789:Quantum Theory; D017655:Silicon Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D017655:Silicon Compounds; D005461:Fluorine; D006859:Hydrogen; D009584:Nitrogen