Abstract: | The reaction of Ph2PCl and PhPCl2 with bis(trimethylsilyl)sulfur diimide in the presence of GaCl3 and AlCl3 yields diadducts of the corresponding cyclodiphosph(V)azene: [Ph2PN]2·(GaCl3)2 ( 1 ), [Ph2PN]2·(AlCl3)2 ( 2 ), and [Ph(Cl)PN]2·(AlCl3)2 ( 3 ). This reaction is triggered by Lewis acids, which catalyse the (CH3)3Si‐Cl and S8 elimination. The structures of 1· 2 CH2Cl2, 2· 2 CH2Cl2 and 3 were determined by single crystal X‐ray studies ( 1 : triclinic, , a = 9.679(2) Å, b = 9.863(2) Å, c = 11.366(2) Å, α = 113.55(3)°; β = 99.59(3)°; γ = 106.67(3)°; V = 902.8(3) Å3, Z = 1; 2 : triclinic, , a = 9.639(2) Å, b = 9.804(2) Å, c = 11.321(2) Å, α = 113.71(3)°; β = 99.44(3)°; γ = 106.70(3)°; V = 889.3(3) Å3, Z = 1; 3 : orthorhombic, Pbca, a = 14.853(3) Å, b = 9.261(2) Å, c = 16.631(3) Å, V = 2287.7(8) Å3, Z = 4. |