Solvate‐Induced Semiconductor to Metal Transition: Flat [Formula: see text] [Bi(1−)] Zigzag Chains in Metallic KBi⋅NH(3) versus [Formula: see text] [Bi(1−)] Helices in Semiconducting KBi

Polymeric [Formula: see text] [Bi](−) in KBi⋅NH(3) has planar zigzag chains with two‐connected Bi atoms and metallic properties, whereas KBi, which has helical chains of Bi atoms, is semiconducting. The isomerization of the Bi chain is induced by solvate molecules. In the novel layered solvate structure uncharged [Formula: see text] [KBi] layers are separated by intercalated NH(3) molecules. These layers are a structural excerpt of the iso(valence)electronic CaSi, whose metallic properties arise from the planarity of the zigzag chain of Si atoms. Computational studies support this view, they show an anisotropic metallic behavior along the Bi chain. Electron delocalization is also found in the new cyclic anion [Bi(6)](4−) isolated in K(2)[K(18‐crown‐6)](2)[Bi(6)]⋅9 NH(3). Although [Bi(6)](4−) should exhibit one localized double bond, electron delocalization is observed in analogy to the lighter homologues [P(6)](4−) and [As(6)](4−). Both compounds were characterized by single‐crystal X‐ray structure determination.