Source Word
mesoionic compound
Noun
(chemistry)
any
of
a
class
of
compounds
having
five-membered
ring
heterocycles
(or
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,
or
nitrogen).
Japanese Meaning
メソイオン性化合物：五員環のヘテロ環（またはそのベンゾ誘導体）を有し、環全体で6個のπ電子が共役している化合物。 / この化合物は、正負の電荷が環内（または共役性の環外原子、通常は酸素、硫黄、または窒素）に非局在化して存在し、いずれか一つの共価結合または極性構造で完全には表現できない特徴を持つ。
Sense（1）
(chemistry)
any
of
a
class
of
compounds
having
five-membered
ring
heterocycles
(or
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,
or
nitrogen).
（ plural ）
