Polymorphism of Ph 2 P(CH 2 Py)(NSiMe 3 ) and the Staudinger Reaction of Ph 2 P(CH 2 Py) with Hydrogenazide 1)

A new polymorph of the iminophosphorane Ph 2 P(CH 2 Py)(NSiMe 3 ), ( 1 ), is compared to a just recently published. The reaction of the starting material, the phosphane Ph 2 P(CH 2 Py) with N 3 SiMe 3 in the presence of water gives [Ph 2 P(CH 2 Py)(NH 2 )][N 3 ], ( 2 ). A comparison of the structural and NMR parameters of 2 with previously reported derivatives of 1 , suggests that 2 is best described as a phosphonium salt in which the negatively charged imino nitrogen atom is protonated, according to [Ph 2 (CH 2 Py)P + —NH 2 ][N 3 ] — , rather than as an iminiumphosphane salt [Ph 2 (CH 2 Py)P= + NH 2 ][N 3 ] — .