[Bi12Ni7(CO)4](4-): Aggregation of Intermetalloid Clusters by Their Thermal Deligation and Oxidation

Reported are the synthesis and structure of the anionic intermetalloid cluster [Bi12Ni7(CO)4](4-). It was synthesized from the known smaller clusters Bi3Ni4(CO)6(3-), Bi3Ni6(CO)9(3-), and Ni@Bi6Ni6(CO)8(4-) by their aggregation as a result of thermal deligation and oxidation. The new cluster is structurally characterized by single-crystal X-ray diffraction in the compound (K[crypt])4[Bi12Ni7(CO)4] (1), and its presence in solution is confirmed by electrospray mass spectrometry. It can be viewed as composed of a Ni-centered icosahedral core of Bi6Ni6(CO)4 where two diametrically opposed Ni atoms are capped by Bi3 triangles. However, its electron count is rationalized based on a structure made of fused tetrahedra.