Question
What are electron deficient compunds? Are BCl3 and SiCl4 electron deficient species? Explain.
Solution
Species in which the central atom either does not have eight electrons in the valence shell or those which have 8 electrons in the valence shell but can expand their covalency beyond 4 due to the presence of d-orbitals are called electron deficient molecules.
BCl3 is an electron deficient compound because the central boron atom has only six electrons. As a result, it accepts a pair of electrons from NH3 to form an adduct.
SiCl4 : The electronic configuration of silicon is ns2 np2. This indicates that it has four valence electrons. after forming four covalent bonds with chlorine atoms, it electron count increases from four to eight. Thus, SiCl4 is not an electron-deficient compound.
