Formamidine-formamide dimer

Sponer, J. and Hobza, P. (2000) Interaction energies of hydrogen-bonded formamide dimer, formamidine dimer, and selected DNA base pairs obtained with large basis sets of atomic orbitals, J. Phys. Chem. A 104, 4592-4597. 

The other dimers in Fig. 29.7 show asymmetry. If the proton transfer potential is asymmetric, there will be no synchronous transfer and at most accidental level splittings. In the formamide dimer [44] the two hydrogen bonds are the same but the donor and acceptor groups are different. The available calculations indicate that the structure of the equilibrium configuration is intermediate between the equilibrium configurations of dimeric formic acid and dimeric formamidine, as... 

The MCSCF method has been used to calculate the intermolecular spin-spin coupling constants in formamide-formamide and formamide-formamidine dimers, modelling the hydrogen bond in peptides and adenine-tymine (or adenine-uracil) pair in a nucleic acid, respectively. The obtained hydrogen-bond-transmitted coupling constants are visualized in Fig-... 

Fig. 1. The hydrogen-bond-transmitted coupling constants calculated at the MCSCF level for formamide-formamide and formamide-formamidine dimers Asterix denotes the numbers for which SD terms are omitted.

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