What is the "Suboxide" explain with examples and structures?

The compounds of oxygen contain more number of central atoms than oxygen atoms. According to valency requirements of all central atoms number of oxygen atoms are not sufficient.

For examples;

N20 (Dinitrogen oxide)

Pb3O (Tripumbulic oxide)

C3O2 (carbon suboxide)

C12O9 (Maletic anhydride or oxide) etc.