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 RfOH/base (RfOH = 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.