Mechanistic Insights into ZIF-8 Encapsulation of Atom-Precise Pt(M) Carbonyl Clusters

Precisely designing metal nanoparticles (NPs) is thecornerstonefor maximizing their efficiency in applications like catalysis orsensor technology. Metal-organic frameworks (MOFs) with theirdefined and tunable pore systems provide a confined space to hostand stabilize small metal NPs. In this work, the MOF encapsulationof various atom-precise clusters following the bottle-around-shipapproach is investigated, providing general insights into the scaffoldingmechanism. Eleven carbonyl-stabilized Pt(M) (M = Co, Ni, Fe, and Sn)clusters are employed for the encapsulation in the zeolitic imidazolateframework (ZIF)-8. Infrared and UV/Vis spectroscopy, density functionaltheory, and ab initio molecular dynamics revealed structure-encapsulation relationship guidelines. Thereby,cluster polarization, size, and composition were found to conditionthe scaffolding behavior. Encaging of [NBnMe3](2)[Co8Pt4C2(CO)(24)] (Co8Pt4 ) is thus achieved as the firstMOF-encapsulated bimetallic carbonyl cluster, Co8Pt4 @ZIF-8, and is fully characterized includingX-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-inducedligand-stripping without altering the cluster size, enabling the synthesisof naked, heterometallic, close to atom-precise clusters.