Double proton transfer in crystals of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a] pyrimidine (hppH): C-13 and N-15 CPMAS NMR study of (hppH)(2)

Coles, Martyn P, Khalaf, Majid S, Claramunt, Rosa M, Garcia, M Angeles, Alkorta, Ibon and Elguero, Jose (2010) Double proton transfer in crystals of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a] pyrimidine (hppH): C-13 and N-15 CPMAS NMR study of (hppH)(2). Journal of Physical Organic Chemistry, 23 (6). ISSN 0894-3230

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Abstract

In this paper, we report an example of intermolecular solid-state proton transfer in the bicyclic guanidine, hppH. A combination of X-ray crystallography, CPMAS NMR (C-13 and N-15) and theoretical calculations allows us to determine that a double proton transfer takes place in the (hppH)(2) dimer with an activation energy of about 50 kJ mol(-1). According to the B3LYP/6-311++G(d,p) calculations, the double proton transfer occurs non-symmetrically through a zwitterion.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Martyn Coles
Date Deposited: 06 Feb 2012 18:56
Last Modified: 02 May 2012 13:41
URI: http://sro.sussex.ac.uk/id/eprint/18971
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