Diastereoisomeric proton-bound complexes of 1,5-diaza-cis-decalin with butan-2-amine are studied by means of the DFT calculations and mass spectrometry. The homochiral complex is favored by about 4 kJ/mol over the heterochiral complex.
For a more loosely bound ion-pair complex of the protonated bases 1 and 2 with an iodine counterion the energy difference drops to about 2 kJ/mol.