A New Phosphorus Selenide P4Se4

The tetraphosphorus tetraselenide P4Se4 is prepared and described for the first time. It is synthetised easily by heating between 250°C and 300°C a mixture of selenide P4Se3 and selenium. It exists under two allotropie forms, α P4Se4 transforming in β P4Se4 at 300°C. α P4Se4 cristallises in the orthorhombie system (a = 7.199 Å; b = 8.661 Å; c = 12.619 Å) as β P4Se4 (a = 9.3200 Å; b = 16.8601 Å; c = 14.3399 Å). The results of the mass spectrometry and the infra‐red spectrometry suggest that the structure of the new compound derives from the tetrahedral structure of white phosphorus.