Interconversions of the silylene-to-silene and germylene-to-germene types: direct spectroscopic studies and calculations

Abstract

The recent advances in spectroscopic and quantum-chemical studies of carbene-to-olefin isomerization of carbene analogs of Group 14 elements are discussed. Primary attention is devoted to the use of matrix isolation spectroscopy, whose successful combination with modern calculation techniques has resulted in the first spectroscopic characterization of a number of novel short-lived silylenes and germylenes and their structural isomers with unsaturated Si=C, Ge=C, and Si=O bonds.

An investigation of the prototype germylene addition reaction, GeH2 + C2H4: Time-resolved gas-phase kinetic studies and quantum chemical calculations of the reaction energy surface

“…6 (for convenience the p-complex for GeH 2 + C 2 H 4 is omitted). Recent theoretical explorations (MP2/6-311G**// MP2/6-31G* level) of the SiC 3 H 8 and GeC 3 H 8 surfaces by some of us 50,51 reveal similar findings concerning the relative stabilities of the 3-membered ring heterocycles and their heavy carbene isomers, viz., methylethylgermylene is more stable than 1-methylgermirane, but methylethylsilylene is less stable than 1-methylsilirane. Another point worth noting here is that germiranes which do not contain a 1-H substituent, will no longer have the easy isomerisation pathway, and therefore should be more stable.…”

2 Matrix isolation

“…A recent publication reviews the processes of this type which have been studied and extends the discussion to germylene-germene isomerisations. 34 The compounds triphenylsilyl azide and diphenylsilyl azide have been irradiated using a KrF excimer laser (l = 248 nm) in argon matrices at 15 K. 35 Both molecules show intense blue phosphorescence under such conditions and, moreover, both are photolysed. Triphenylsilyl azide yields 1,1,2-triphenylsilanimine (Ph 2 SiNNPh); the diphenyl compound gives two isomeric diphenylsilanimines (Ph 2 SiNNH).…”

Theoretical studies on the structures and isomerization of methylene lithium‐chlorosilylenoid H2CSiLiCl

“…Undoubtedly, because of the difficulties in experiments, only a few silenes have been obtained so far. However, silene chemistry has been of considerable interest in recent years 6–17. It can be believed that greater progress in the studies of silenes will be made in the near future.…”