Cp^PEt₂ As₄ -An Organic-Substituted As₄ Butterfly Compound

Cp^PEt₂ As₄ (Cp^PEt =C₅ (4-EtC₆ H₄ )₅ ) (1) is synthesized by the reaction of Cp^PEt. radicals with yellow arsenic (As₄ ). In solution an equilibrium of the starting materials and the product is found. However, 1 can be isolated and stored in the solid state without decomposition. As₄ can be easily released from 1 under thermal or photochemical conditions. From powder samples of Cp^PEt₂ As₄ , yellow arsenic can be sublimed under rather mild conditions (T=125 °C). A similar behavior for the P₄ -releasing agent was determined for the related phosphorus compound Cp^BIG₂ P₄ (2; Cp^BIG =C₅ (4-nBuC₆ H₄ )₅ ). DFT calculations show the importance of dispersion forces for the stability of the products.