posted on 2021-08-25, 16:03authored byZhenghai Yang, Chao He, Shane Goettl, Ralf I. Kaiser, Valeriy N. Azyazov, Alexander M. Mebel
The aminosilylene molecule (HSiNH2, X1A′)the
simplest representative of an unsaturated nitrogen-silylenehas
been formed under single collision conditions via the gas phase elementary
reaction involving the silylidyne radical (SiH) and ammonia (NH3). The reaction is initiated by the barrierless addition of
the silylidyne radical to the nonbonding electron pair of nitrogen
forming an HSiNH3 collision complex, which then undergoes
unimolecular decomposition to aminosilylene (HSiNH2) via
atomic hydrogen loss from the nitrogen atom. Compared to the isovalent
aminomethylene carbene (HCNH2, X1A′),
by replacing a single carbon atom with silicon, a profound effect
on the stability and chemical bonding of the isovalent methanimine
(H2CNH)–aminomethylene (HNCH2) and aminosilylene
(HSiNH2)–silanimine (H2SiNH) isomer pairs
is shown; i.e., thermodynamical stabilities of the carbene versus
silylene are reversed by 220 kJ mol–1. Hence, the
isovalency of the main group XIV element silicon was found to exhibit
little similarities with the atomic carbon revealing a remarkable
effect not only on the reactivity but also on the thermochemistry
and chemical bonding.