Synthesis of a stibindolyl anion from trimesitylantimony and potassium

2-(3,5-Dimethylphenyl)-5,7-dimethylstibindolyl potassium–pmdeta (1) (pmdeta = pentamethyldiethylenetriamine) is obtained from trimesitylantimony, potassium and the amine ligand in tetrahydrofuran; crystals of 1 consist of stacks of (pmdeta)K+ ions and stibindolyl anions with alternating Sb–K and 5-SbC4–K interactions.