Bismuth as a Z‐Type Ligand: an Unsupported Pt−Bi Donor‐Acceptor Interaction and its Umpolung by Reaction with H2.

Establishing unprecedented types of bonding interactions is one of the fundamental challenges in synthetic chemistry, paving the way to new (electronic) structures, physicochemical properties, and reactivity. In this context, unsupported element‐element interactions are particularly noteworthy since they offer pristine scientific information about the newly identified structural motif. Here we report the synthesis, isolation, and full characterization of the heterobimetallic Bi/Pt compound [Pt(PCy3)2(BiMe2)(SbF6)] (1), bearing the first unsupported transition metal→bismuth donor/acceptor interaction as its key structural motif. 1 is surprisingly robust, its electronic spectra are interpreted in a fully relativistic approach, and it reveals an unprecedented reactivity towards H2. [ABSTRACT FROM AUTHOR]