Solvate‐Induced Metallization: Flat 1∞[Bi1‐] Zigzag Chains in Metallic KBi · NH3 versus 1∞[Bi1‐] Helices in Semiconducting KBi

: Polymeric 1 ∞ [Bi 1- ] in KBi · NH 3 (1) displays planar zigzag chains with two-connected Bi atoms and metallic property, whereas known KBi that contains helical chains of Bi atoms is semiconducting. The isomerization of the Bi atom chain is induced by additional solvate molecules. In the novel layered solvate structure uncharged 2 ∞ [KBi] layers are separated by intercalated NH 3 molecules. We interpret these layers as a structural excerpt of the isoelectronic CaSi, whose metallic properties arise from the planarity of the zigzag chain of Si atoms. Computational studies on a PBE0/TZVP and PBE/TZVP level of theory support this view, as they unfold an anisotropic metallic behavior along the Bi chain. Electron delocalizaion is also observerd in the new cyclic anion [Bi 6 ] 4- isolated in K 2 [K(18-crown-6)] 2 [Bi 6 ] · 9 NH 3 (2). Two-connected Bi atoms form a six-membered ring with a chair conformation and although [Bi 6 ] 4- should exhibit one localized double bond, electron delocalization is observed in anaolgy to the known lighter homologues [P 6 ] 4- and [As 6 ] 4- . Both compounds were characterized by single crystal structure determination.