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==Energy barrier==
[[File:NvPinvn.png|thumb|244px|Qualitative reaction coordinate for inversion of an amine and a phosphine. The y-axis is energy.]]
The identity of the inverting atom has a dominating influence on the barrier. [[Nitrogen inversion|Inversion of ammonia]] is rapid at room [[temperature]]. In contrast, [[phosphine]] (PH<sub>3</sub>) inverts very slowly at room temperature (energy barrier: 132 kJ/mol).<ref>{{cite journal | last1 = Kölmel | first1 = C. | last2 = Ochsenfeld | first2 = C. | last3 = Ahlrichs | first3 = R. | year = 1991 | title = An ab initio investigation of structure and inversion barrier of triisopropylamine and related amines and phosphines | url = | journal = Theor. Chim. Acta. | volume = 82 | issue = 3-4| pages = 271–284 | doi = 10.1007/BF01113258 }}</ref> Consequently, amines of the type RR′R"N are not optically stable (enantiomers racemize rapidly at room temperature), but [[P-Chiral phosphine|P-chiral phosphines]] are. Appropriately substituted [[sulfonium]] salts, sulfoxides, [[arsine]]s, etc. are also optically stable. [[Steric effects
==References==
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