chemical entity dioxygen(2+) 2 31.98873 31.998 dioxygen(2+) NIWXMCONPJOXBL-UHFFFAOYSA-N gmelin:48980 dioxidanebis(ylium) [O+]#[O+] [O2](2+) InChI=1S/O2/c1-2/q+2 O2(2+) O2 CHEBI:29371 chebi_ontology dioxygen(2+)