The next three members — C4O4, C5O5, and C6O6 — are theoretically possible, but are expected to be quite unstable, and so far they have been synthesized only in trace amounts.
Sledeća tri člana — C4O4, C5O5, i C6O6 — su teoretski moguća, ali se očekuje da su sasvim nestabilna, i do sada su bili sintetisani samo u tragovima.