Precisely designing metal nanoparticles (NPs) is the
cornerstone
for maximizing their efficiency in applications like catalysis or
sensor technology. Metal–organic frameworks (MOFs) with their
defined and tunable pore systems provide a confined space to host
and stabilize small metal NPs. In this work, the MOF encapsulation
of various atom-precise clusters following the bottle-around-ship
approach is investigated, providing general insights into the scaffolding
mechanism. Eleven carbonyl-stabilized Pt(M) (M = Co, Ni, Fe, and Sn)
clusters are employed for the encapsulation in the zeolitic imidazolate
framework (ZIF)-8. Infrared and UV/Vis spectroscopy, density functional
theory, and ab initio molecular dynamics revealed
structure–encapsulation relationship guidelines. Thereby,
cluster polarization, size, and composition were found to condition
the scaffolding behavior. Encaging of [NBnMe3]2[Co8Pt4C2(CO)24] (Co8Pt4
) is thus achieved as the first
MOF-encapsulated bimetallic carbonyl cluster, Co8Pt4
@ZIF-8, and is fully characterized including
X-ray absorption near edge and extended X-ray absorption spectroscopy.
ZIF-8 confinement not only promotes property changes, like the T-dependent magnetism, but it also further allows heat-induced
ligand-stripping without altering the cluster size, enabling the synthesis
of naked, heterometallic, close to atom-precise clusters.