heterometamerism

Heterometamerism is a mode of structural organization in metal-containing compounds where the repeating units, or metamers, are not all identical. In such systems, two or more chemically distinct metamers—defined fragments with a fixed metal core, stoichiometry, and connectivity—alternate or are otherwise arranged within the same molecule or extended solid. The presence of different metamers can be along a one-dimensional chain, a two- or three-dimensional network, or in a discrete cluster where metamers occupy distinct positions.

The concept is often used in coordination polymers, metal-organic frameworks, and polyoxometalate chemistry to describe materials that incorporate, for example, two different metal centers in defined proportions. Heterometamerism differs from homometamerism, where the repeating metamer units are identical throughout. The deliberate design of heterometameric sequences allows tuning of properties such as magnetic behavior, catalytic activity, redox potential, and optical features, by exploiting interactions between dissimilar metamers.

Characterization relies on crystallography for structural arrangement; spectroscopic and electrochemical methods assess function. Synthetic strategies include stepwise assembly, selective metal incorporation, and directed self-assembly to place specific metamers in predetermined positions.

Applications are found in catalysis, magnetism, and materials science, where modular assembly of diverse metamers offers a route to customizable multimetal systems.