Über die Umsetzung von Tris(dimethylamino)phosphin,Triisopropylphosphin und tButyldifluorphosphin mit tertiären Alkylaziden: Phosphazidbildung versus Phosphinimidbildung. Röntgenstrukturen von Triphenylmethylazid und Tris(dimethylamino)-N-triphenylmethylphosphazid

Reaction of Tris(dimethylamino)phosphine, Triisopropylphosphine and ^tButyldifluorophosphine with Tertiary Alkyl Azides: Phosphazide Formation versus Phosphinimide Formation. X-Ray Crystal Structures of triphenylmethylazide and Tris(dimethylamino)-N-triphenylmethyl Phosphazide Tris(dimethylamino)-phosphine and triisopropylphosphine react with tertiary alkyl azides RN₃ (R = ^tBu, 1-Ad, Trt) to give the corresponding phosphazides 1a–1c and 2a–2c , which involve a linear PN₃R-unit. The coordination geometries of the N₃ chains in triphenylmethylazide and 1c are completely different, associated with a change of hybridisation. Hence, the N₃-group of the triphenylmethylazide is nearly linear, whereas that of 1c shows approximately tetrahedral angles. The coordination geometry at the central nitrogen atom also depends on the substituents, possibly because of their varying ability to delocalize the π-electron system. In contrast, the reaction of ^tbutyldifluorophosphine with the same azides RN₃ led to the ^tbutyldifluorophosphinimides 3a–3c of the type ^tBuP(:NR)F₂. The hydrolysis of these compounds afforded the ^tbutylphosphonamidic fluorides ^tBuP(:O)(NHR)F (R = 1-Ad: 4b , Trt: 4c ), instead of the expected substitution products ^tBuP(:NR)(OH)F.