Synthesis of 1,3-Dichloro-cyclo-1,3-diphosphadiazanes from Silylated Amino(dichloro)phosphanes

The synthesis of 1,3-dichloro-cyclo-1,3-diphosphadiazanes [ClP­(μ-NR)]₂ via elimination of Me₃SiCl from silylated amino­(dichloro)­phosphanes, R–N­(SiMe₃)­PCl₂, was studied by different synthetic protocols starting from R–N­(H)­SiMe₃ (R = Si­(SiMe₃)₃ = Hyp, N­(SiMe₃)₂, Mes* = 2,4,6-tri-tert-butylphenyl, Ter = 2,4-bis­(2,4,6-trimethylphenyl)­phenyl, Dipp = 2,6-diisopropylphenyl, Dmp =2,6-dimethylphenyl, Ad = Adamantyl, Trityl = Ph₃C, Tos = tosyl = CH₃C₆H₄SO₂, n-Oct = n-octyl, and Me₃Si). A new synthetic route using trimethylsilyl-substituted amino­(dichloro)­phosphanes, R–N­(SiMe₃)­PCl₂, was developed to form cyclo-diphosph­(III)-azanes simply by adding a mixture of R_fOH/base (R_fOH = hexafluoroisopropanole). By this method electron-rich/-poor aryl-, silyl-, and bissilylamino-substituted cyclo-diphosph­(III)-azanes are accessible such as the unprecedented (Me₃Si)₂N-substituted species [ClP­(μ-NN­(SiMe₃)₂)]₂ starting from tris­(trimethylsilyl)­hydrazine and PCl₃. Additionally, the difficulties with the preparation of cyclo-diphosphadiazanes depending on the starting materials, solvents, and bases due to the competition of different reaction channels are studied.