Synthetic Pathways Towards 1,3,4‐Tri‐ and Tetraphospholide Anions from White Phosphorus and Polyphosphides

Sodium polyphosphides Na x P n (Na[ cyclo ‐P 5 ] and Na 3 P 7 ), generated from white phosphorus and elemental sodium, react with phosphaalkynes R–C≡P (R = SiMe 3 , t Bu, Ad, Mes) to give the respective sodium 2,5‐R‐1,3,4‐triphosphacyclopentadienide Na[1,3,4‐( cyclo ‐(CR) 2 P 3 ] either solely, or as a mixture with the corresponding 1,2,3,4‐tetraphosphacyclopentadienide Na[( cyclo ‐(CR)P 4 ]. The one‐pot reaction between Na, P 4 , and carboxylic acid derivatives (acyl chlorides or esters) leads to a mixture that mainly consists of sodium bis(acyl)phosphides Na[(C(O)R) 2 P] and 1,2,3,4‐tetraphosphacyclopentadienides Na[( cyclo ‐(CR)P 4 ] (R = Ar, Alk, ), which can be separated. [( cyclo ‐(CR)P 4 ] – anions represent a class of scarcely investigated aromatic phosphorus‐heterocycles that are of considerable interest in coordination chemistry. Further studies show the possibilities to generate tetraphosphaferrocenes when treated with Fe II precursors.