Isolation of a planar π-aromatic Bi5– ring in a cobalt-based inverse sandwich-type complex
Monocyclic aromatic molecules are well-known in organic chemistry and for coordination chemistry. In contrast, isoelectronic cycles comprising (semi)metal atoms only are much rarer. We present Bi5−, the so far elusive heaviest analogue of (C5H5)− which we trapped in an inverse-sandwich-type complex.