https://doi.org/10.1351/goldbook.H02740
A
Lewis acid
with an acceptor centre of low
polarizability
. Other things being approximately equal, complexes of hard acids and
bases
or soft acids and bases have an added stabilization (sometimes called 'HSAB' rule). For example the hard O- (or N-) bases are preferred to their S- (or P-) analogues by hard acids. Conversely a
soft acid
possesses an acceptor centre of high
polarizability
and exhibits the reverse preference for
coordination
of a
soft base
. These preferences are not defined in a quantitative sense.
See also:
class (a) metal ion
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1120 [Terms] [Paper]