* Electronegativity: Oxygen (O) is much more electronegative than chlorine (Cl). This means oxygen has a stronger pull on electrons. In a bond between oxygen and chlorine, oxygen would attract the shared electrons more strongly, creating a polar covalent bond.

* Ionic Bond Formation: Ionic bonds occur when there is a significant difference in electronegativity between two atoms, leading to the transfer of electrons and the formation of ions (positively charged cations and negatively charged anions). This large difference in electronegativity is not present between oxygen and chlorine.

Instead, oxygen and chlorine form a covalent bond. Specifically, they form a polar covalent bond because of the electronegativity difference.

Let me know if you'd like more details about covalent bonds!