Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
3-membered is an adjective meaning "of a chemical compound having a ring with three members". It carries one recorded sense.
of a chemical compound having a ring with three members
Definitions, synonyms and semantic relations for 3-membered come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.