A Multiply Bonded Trigonal‐Planar Bismuth(III) Complex: Prodigious Lewis Acidity, Solvatochromism, Etherification, and Semiconducting Characteristics

<jats:title>Abstract</jats:title><jats:p>The formation of a hitherto unknown 4‐center, 6<jats:italic>π</jats:italic>–conjugated trigonal‐planar complex, [Bi{Cr(CO)<jats:sub>5</jats:sub>}<jats:sub>3</jats:sub>]<jats:sup>−</jats:sup> (<jats:bold>1</jats:bold>), is reported, in which the oxidation state of the Bi atom is +3, as evidenced by XAS, XPS, and DFT calculations. The Bi<jats:sup>III</jats:sup> atom in <jats:bold>1</jats:bold> has dual donor and acceptor properties in its bonding mode. In contrast to the mild Lewis acidity of Bi<jats:sup>III</jats:sup>, the central Bi in <jats:bold>1</jats:bold> functions as a prodigious Lewis acid site to exhibit strong affinity toward F<jats:sup>−</jats:sup> ions, unique solvatochromic properties, intriguing etherification through the C−O bond cleavage of alcohols, and surprising semiconducting characteristics with an ultra‐narrow optical band gap of 1.02 eV, which can be attributed to the intermolecular Bi⋅⋅⋅O and O⋅⋅⋅O interactions in the solid state. The tetrahedral Fe(CO)<jats:sub>4</jats:sub>‐adduct [{Fe(CO)<jats:sub>4</jats:sub>}Bi{Cr(CO)<jats:sub>5</jats:sub>}<jats:sub>3</jats:sub>]<jats:sup>3−</jats:sup> (<jats:bold>1‐Fe</jats:bold>) allowed the selective demetallation to afford the isoelectronic multiply bonded BiCr<jats:sub>3</jats:sub>‐complex <jats:bold>1</jats:bold> and the BiCr<jats:sub>2</jats:sub>Fe‐complex, [Bi{Cr(CO)<jats:sub>5</jats:sub>}<jats:sub>2</jats:sub>{Fe(CO)<jats:sub>4</jats:sub>}]<jats:sup>−</jats:sup> (<jats:bold>2</jats:bold>), which may open a novel pathway for the design of the heterometal‐incorporated trigonal‐planar Bi‐Cr complexes.</jats:p>