Abstract
The effect of intramolecular fluoro-silicon interaction on the formation of Brook-type silabenzene was studied by the help of DFT. The M06-2X calculations reveal that fluoro-silicon interaction makes the transition state more stable and hence decreases the energy of activation for the formation of silabenzene. The hydrogen bonding decreases the stability of transition state and hence increases the energy of activation for the formation of silabenzene. The fluoro-silicon interaction helps in the stabilization of transition state.
•A series of silabenzenes 4a–g were studied.•M06-2X calculations were performed for calculating thermodymical properties of silabenzenes formation.•Effect of fluoro-silicon interaction on the stability of sila-benzenes were studied.•Hydrogen bonding decreases the stability of silabenzenes.•NMR data were also calculated in order to study the aromatic character of silabenzene.
We have performed a quantum chemical investigation using density functional theory (DFT) method with M06-2X functional to spotlight the effect of fluoro-silicon (FSi) intra-molecular interaction on the formation of Brook-type silabenzenes 4a–g. It was observed that these Brook-type silabenzenes 4a–g were formed through a [1,3]-trimethylsilyl (TMS) shift from a sp3 hybridized silicon atom to its neighboring carbonyl oxygen of cyclic conjugated acylpolysilane. The 2-trialkylsiloxy Brook-type silabenzenes show lower energies as compare with their starting reactant acylpolysilane. The value of ΔG* for the [1,3]-trimethylsilyl (TMS) shift that resulted the most stable Brook-type silabenzene 4a is 25.04kcal/mol, which is about 4.48kcal/mol lower than its correspondence stable [4+2] dimer. The activation energy (29.49kcal/mol) for dimerization of 4a to the most stable [4+2] cyclo-adduct indicates that 4a silabenzene can be exist as a monomer at ambient temperature. The energy of formation for 4f (32.04kcal/mol) is about 7kcal/mol higher than 4a (−27.04kcal/mol), most probably due to the hydrogen bonding activation. Present investigation reveals that the studied compounds are aromatic as indicated by nucleus-independent chemical shifts (NICS) as well as their molecular geometries.