class (b) metal ion

https://doi.org/10.1351/goldbook.C01095
A metal ion that combines preferentially with @[email protected] containing ligating atoms other than the lightest of their Periodic Group.
See also:
class (a) metal ion
,
hard acid
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1097 [Terms] [Paper]