Cyclic Tribismuthide as a Piano Stool Complex Ligand – Synthesis and Crystal Structure of (η³‐Bi₃)M(CO)₃³– (M = Cr, Mo)

The reactions between K 5 Bi 4 , [(C 6 H 6 )Cr(CO) 3 ] or [(C 7 H 8 )Mo(CO) 3 ], and [2.2.2]crypt in liquid ammonia yielded the compounds [K([2.2.2]crypt)] 3 (η 3 ‐Bi 3 ) M (CO) 3 · 10NH 3 ( M = Cr, Mo), which crystallize isostructurally in P 2 1 / n . Both contain an 18 valence electron piano‐stool complex with a η 3 ‐coordinated Bi 3 ‐ring ligand. The Bi–Bi distances range from 2.9560(5) to 2.9867(3) Å and are slightly shorter than known Bi–Bi single bonds but longer than Bi–Bi double bonds. The newly found compounds complete the family of similar complexes with E 3 ‐ring ligands ( E = P‐Bi).