Novel cyclopentadienyl silanes and disilanes: synthesis, structure and gas-phase pyrolysis

1.2-Bis(pentamethylcyclopentadienyl)tetrachlorodisilane and its reduction to decamethylsilicocene

“…The Cp * groups are σ -bound to the silicon atoms via the allylic carbon atoms and exhibit typical diene-type structures. The Si C(Cp * ) bond lengths as well as the Si Si bond length are in the expected range [9]. The steric requirements of the Cp * groups lead to a widening of the C(Cp * ) Si Si angles and correspondingly to a shrinking of the Cl Si Cl angles.…”

“…Compound 2 has been characterized by NMR, MS and analytical data. 1 H and 13 C NMR spectra indicate that the Cp * substituent is σ -bound to the silicon exhibiting fluxional behaviour at temperatures above −70 • C [9].…”

“…Reaction of hexachlorodisilane in hexane as solvent with a suspension of potassium pentamethylcyclopentadienide in hexane leads to the metathesis product pentamethylcyclopentadienyl(pentachloro)disilane (2) in good yields ( Figure 1) [9]. A reaction temperature of −90 • C is necessary to avoid Si Si bond splitting.…”

“…A solution of 15.0 g (40.7 mmol) Cp * Si 2 Cl 5 [9] in 100 ml THF is added at −20 • C to a suspension of 10.0 g Cp * K (57.4 mmol) in 130 ml THF. After warming to room temperature and refluxing for 12 h all volatiles are removed in vacuo.…”

“…For example, the steric effect of the σ -bonded Cp * substituent causes the stability of the chlorosilane Cp * 2 SiCl 2 against hydrolysis [6], whereas kinetic and thermodynamic effects allow the isolation of the π-complex decamethylsilicocene (1) [7]. On the other hand, the comparatively rather weak silicon-carbon bond in Cp * silicon compounds enables Cp * group migration [8] and easy homolytic bond fission [9].…”