Controlled Dimerization and Bonding Scheme of Icosahedral M@Au12 (M=Pd, Pt) Superatoms.

Targeted syntheses of MM'Au36 (PET)24 (M, M'=Pd, Pt; PET=SC2 H4 Ph) were achieved by hydride-mediated fusion reactions between [MAu8 (PPh3 )8 ]2+ and [M'Au24 (PET)18 ]- . Single-crystal X-ray diffraction analysis indicated that the products have bi-icosahedral MM'Au21 cores composed of M@Au12 and M'@Au12 superatoms. Although the MM'Au21 superatomic molecules correspond to O2 in terms of the number of valence electrons (12 e), the distances between the icosahedrons were larger than that in the bi-icosahedral Au23 core of Au38 (PET)24 corresponding to F2 and the spin state was singlet. These counterintuitive results were explained by a "bent bonding model" based on tilted (non-orthogonal) bonding interaction between the 1P superatomic orbitals of M@Au12 and M'@Au12 superatoms.