Azidophosphenium Cations: Versatile Reagents in Inorganic Synthesis

This work describes the synthesis and characterization of a series of iminophosphorane-substituted phosphenium cations of the type [R2NPNP-(Cl)(2)NPNR'(2)][GaCl4] [R = iPr; R' = iPr (7[GaCl4]), SiMe3 (8)], which are directly derived from azidophosphenium salt [iPrNPN(3)][GaCl4] (2iPr[GaCl4]) and the corresponding chlorophosphane R2NPCl2. The reactivity of 7[GaCl4] toward 2,3-dimethylbutadiene (dmb) and 2,2'-bipyridine (bipy) was investigated, resulting in the formation of 7-dmb[GaCl4] and 7-Cl. In addition, self-condensation of [(Me3Si)(2)NPN3][GaCl4] (2SiMe(3)[GaCl4]) was studied in detail, and [(Me3Si)(2)NPNP(XY)N(SiMe3)(2)][GaCl4] [X = Cl; Y = Cl (13), N-3 (14)] were determined as products on the basis of P-31 NMR spectroscopy. The reaction of 2SiMe(3)[GaCl4] with [(Me3Si)(2)NPCI][GaCl4] (1SiMe(3)[GaCl4]) yielded an unprecedented bicyclic 1,3,2 lambda(3),4.lambda(5)-diazadiphosphetidine (15), which was formed via a GaCl3-assisted Me3SiCl elimination starting from 13. Furthermore, cations of the type [R2NPNPR'(3)][GaCl4] [R = iPr; R' = cHex (19)] were obtained by the effective combination of 2R[GaCl4] (R = iPr, SiMe3) with PR'(3) (R' = Ph, cHex). Azidochlorophosphanes R2NP(N-3)Cl [R = iPr, SiMe3 (20R)] are shown to be accessible when 2R[GaCl4] was combined with bipy. All new compounds were fully characterized by means of X-ray, vibrational spectroscopy, CHN analysis, and NMR experiments. All compounds were further investigated by means of density functional theory, and the bonding situation was accessed by natural bond orbital analysis.