英和和英

名詞

mesoionic compound (複数形 mesoionic compounds)

1. (chemistry) any of a class of compounds having five-membered ring heterocycles (または their benzo derivatives) which possess a sextet of π-electrons in association with the atoms comprising the ring, but which cannot be represented by any one covalent or polar structure; typically the ring structure contains both positive and negative delocalised charges which cannot be associated with any one ring atom, and the negative charge can also be associated with a conjugated exocyclic atom (typically oxygen, sulfur, または nitrogen).