ISOMERISM AND CONFORMATION OF (N-SILYL)BIS(DIPHENYLPHOSPHINO)AMINES AND BIS(N-SILYL)DIPHENYLPHOSPHINOAMINES

Article abstract of DOI:10.1016/0022-328X(84)85173-6

Lithium bis(diphenylphosphino)amide (2) reacts with chlorotriorgano- and dichlorodiorganosilanes to form either N-silylbis(diphenylphosphino)amides (3) or the isomeric P-diphenylphosphinodiphenylphosphine(silylimides) (4), or an equilibrium mixture of both.The nature of the product depends strongly on the nature of the substituents attached to silicon. 29Si and 31P NMR spectroscopy were used to differentiate between the two structures.In N,N-bis(trimethylsilyl)aminodiphenylphosphine the two silyl groups were found by NMR spectroscopy to be non-equivalent at low temperature in solution, and this is attributed to hindered rotation about the P-N bond, with an in-plane (Si2NP) orientation of the lone pair of electrons at phosphorous as the ground state.The reaction of 2 with (CH3)2PCl does not yield triphosphinoamine species; instead, a P-phosphinophosphinimine (5) is obtained, which is closely related to the silyl analogues of formula 4.