Goumans, TPM; Ehlers, AW; Vlaar, MJM; Strand, SJ; Lammertsma, K; (2002) Structural properties of azaphosphirane and its W(CO)5 complex. A density functional study. Journal of Organometallic Chemistry , 643-644 369 - 375. 10.1016/S0022-328X(01)01268-2.
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Properties and ring opening reactions are investigated for azaphosphirane and its P-phenyl and W(CO)5 complex using density functional theory (B3LYP). Azaphosphirane has a relatively small N-inversion barrier of 10.8 kcal mol−1 and a high 56.8 kcal mol−1 ‘turnstile’ P-inversion barrier. Its strain energy is 26.5 kcal mol−1at G3(MP2). The P---C bond is the weakest bond. Only 27.4 kcal mol−1 is needed to break it, which is half that needed for both the C---N and P---N bonds. This P---C ring opening to the P,N-ylide is endothermic by 8.5 kcal mol−1. P-phenyl substitution has little effect neither on the geometries nor on the energy of the ring opening. Complexation by W(CO)5 leads to a tighter ring but the energy for breaking the P---C bond still requires 27.8 kcal mol−1. The resulting P,N-ylide is only 3.9 kcal mol−1 less stable than azaphosphirane. Cleaving either the C---N or P---N bond remain much more demanding processes. The calculations suggest that the reactivity of azaphosphirane may well have its origin in the readily accessible P,N-ylide. Its influence on the reaction of phosphinidenes with imines is discussed.
|Title:||Structural properties of azaphosphirane and its W(CO)5 complex. A density functional study|
|Keywords:||phosphinidenes, transition metal complexes, bond breaking, ring structures|
|UCL classification:||UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry|
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