cluster

https://doi.org/10.1351/goldbook.CT06769
A number of metal centres grouped close together which can have direct metal bonding interactions or interactions through a @B00741@, but are not necessarily held together by these interactions.
Source:
PAC, 1997, 69, 1251. (Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997)) on page 1265 [Terms] [Paper]