82881-47-8Relevant academic research and scientific papers
Element-Organic Amine/Imine Compounds, XXIII. Rotamers of Aminophosphanes and Aminophosphoranes
Scherer, Otto J.,Puettmann, Michael,Krueger, Carl,Wolmershaeuser, Gotthelf
, p. 2076 - 2124 (2007/10/02)
The diazaphosphasiletidines 3a - h can be synthesized from R2Si(NCR3Li)2 and Cl2PNR1R2 (1) as well as from (2) and MNR1R2 (R = CH3).At ambient temperature they show hindered rotation about the P - NR1R2 bond. 3g is separated as a pair of E/Z-rotamers, whose structure has been elucidated by NMR and X-ray analyses.The kinetically measured P - N rotation barriers (ΔG* ca. 30 kcal/mol) are until now the highest that have been measured.The isomerization of 3g (E) -> 3g(Z) (P - N rotation, P inversion, or both) is a P - N rotation which has been established by the synthesis and the NMR spectroscopically measured rearra ngement of (3i) (R = CH3, four isomers).The interaction of 3a - h with sulfur, selenium, and methyl iodide gives 4 - 6a - h.Below 0 deg C they all show hindered rotation about the P - NR1R2 bond. 4 and 5 are suitable for the study of the structure dependence of 1H NMR ASIS effects.The oxidation of 3g(E/Z) to the isomers 4g - 6g(E/Z) occurs with retention of configuration.These compounds show significant differences with respect to their thermal stability and their reaction with methanol.The comparison of the ΔG* values of the P - N rotation barriers of 3 - 6 shows that the steric influence of the exo-amino substituents R1 and R2 is most important.The E/Z equilibrium of the unsymmetrically substituted compounds gives evidence that the two ground states of P - N rotation are mostly sterically, possibly also electronically.
