<Tr> <Td> Si - X bond energy (kJ / mol) </Td> <Td> 582 </Td> <Td> 391 </Td> <Td> 310 </Td> <Td> 234 </Td> </Tr> <P> Covalently saturated silicon complexes like SiBr, along with tetrahalides of germanium (Ge) and tin (Sn), are Lewis acids . Although silicon tetrahalides obey the octet rule, they add Lewis basic ligands to give adducts with the formula SiBr L and SiBr L (where L is a Lewis base). The Lewis acidic properties of the tetrahalides tend to increase as follows: SiI <SiBr <SiCl <SiF . This trend is attributed to the relative electronegativities of the halogens . </P> <P> The strength of the Si - X bonds decrease in the order: Si - F> Si - Cl> Si - Br> Si - I . </P> <P> Silicon tetrabromide is synthesized by the reaction of silicon with hydrogen bromide at 600 ° C . </P>

What is the molecular shape of the silicon tetrabromide (sibr4) molecule