Asymmetry in the N-inversion of heteroarene imines: pyrimidin-4(3H)-imine, pyridin-2(1H)-imine, and 1H-purine-6(9H)-imine

The Journal of Organic Chemistry
Rainer GlaserStephanie Miller

Abstract

The uncatalyzed, thermal N-inversion reactions were studied of pyrimidin-4(3H)-imine (PMI), pyridin-2(1H)-imine (PYI), and 1H-purine-6(9H)-imine (PUI). Relevant regions of the potential energy surfaces were explored with second-order Moller-Plesset perturbation theory (MP2(full)/6-31G(d)) and with coupled cluster theory (CCSD/6-31G(d), CCSD/6-31+G(d)). The thermochemistry of stationary structures was evaluated at the MP2 level and their energies also were computed at the levels CCSD(T)/6-311+G(d,p) and CCSD(T)/6-311+G(2df,2p) and with structures optimized at lower CCSD levels. The best estimates for the (E)-preference free enthalpies DeltaG(298)(Z vs. E) are 2.6 (PMI), 2.3 (PYI), and 6.0 (PUI) kcal/mol and for the free enthalpies of activation DeltaG(298)(Z --> E) they are 21.6 (PMI), 21.1 (PYI) and 19.7 (PUI) kcal/mol. Nonplanar N-inversion transition state (ITS) structures occur along enantiomeric reaction paths and stationary structures for in-plane N-inversion correspond to second-order saddle points (SOSP) on the potential energy surface. The deformation energy DeltaE(def) = E(SOSP) - E(ITS) is less than 0.5 kcal/mol for PMI and PUI, but it is as high as DeltaE(def) approximately = 2 kcal/mol for PYI. The detailed study of...Continue Reading

References

Nov 28, 2001·The Journal of Organic Chemistry·J E JohnsonM A McAllister
Apr 1, 2004·Journal of the American Chemical Society·Rainer GlaserMartin Kaupp
Aug 12, 2005·Chemical Reviews·Jacopo TomasiRoberto Cammi
Jan 18, 2006·Journal of Molecular Modeling·Rainer GlaserFrancisca von Saint Paul
Jun 5, 2007·Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy·Teruyoshi KitamuraAkira Fujimoto
Aug 16, 2008·Science·P Metrangolo, G Resnati

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Citations

Aug 6, 2016·The Journal of Organic Chemistry·Sumit S ChourasiyaPrasad V Bharatam
Apr 30, 2011·The Journal of Organic Chemistry·Stephanie Coyle, Rainer Glaser
May 7, 2014·The Journal of Physical Chemistry. a·Kenneth M MerzJoao Bosco P da Silva

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