Semiconductors play a vital role for the development of modern technology. The most important parameter that decides the area of application of any semiconductor is its band gap (Eg). Interestingly, Eg can be engineered at the microscopic level through the crystal structural parameters. The effects studied as band gap anomalies in some of the ternary pnictides, ABC2 (A=Cd; B=Si,Ge,Sn; C=P,As) using theoretical prescription will be presented. These compounds exhibit transitions in the nature of bonding.