From Small Metal Clusters to Molecular Nanoarchitectures with a Core–Shell Structure: The Synthesis, Redox Fingerprint, Theoretical Analysis, and Solid-State Structure of [Co(38)As(12)(CO)(50)](4–)

[Image: see text] The cluster [Co(38)As(12)(CO)(50)](4–) was obtained by pyrolysis of [Co(6)As(CO)(16)](−). The metal cage features a closed-packed core inside a Co/As shell that progressively deforms from a cubic face-centered symmetry. The redox and acid–base reactivities were determined by cyclic voltammetry and spectrophotometric titrations. The calculated electron density revealed the shell-constrained distribution of the atomic charges, induced by the presence of arsenic.