Theoretical investigation of the conventional CX1X2− (X1, X2 = H, F, Cl, Br, and I) compounds

► Compounds CX1X2− (X1, X2 = H, F, Cl, Br, I) were studied in detail using quantum chemical methods. ► The compound with heavier substituent presents stronger stability. ► The PA and IE of compound all are associated with the size of substituent. ► Compound with less heavier substituent possesses stronger PA but not lower IE.