Wikipedia
Interchalcogen
The chalcogens react with each other to form interchalcogen compounds.
Although no chalcogen is extremely electropositive, nor quite as electronegative as the halogen fluorine (the most electronegative element), there is a large difference in electronegativity between the top ( oxygen = 3.44) and bottom ( polonium = 2.0) of the group. Combined with the fact that there is a significant trend towards increasing metallic behaviour while descending the group (oxygen is a gaseous nonmetal, while polonium is a silvery post-transition metal), this causes the interchalcogens to display many different kinds of bonding: covalent, ionic, metallic, and semimetallic.