MS32-P03 The impact of stereogenic center on the architecture of the water framework: 2-methylpyrrolidine and sec-butylamine hydrates Patryk Rzepiński (Chemistry Department, University of Warsaw, Warsaw, Poland) Łukasz Dobrzycki (Chemistry Department, University of Warsaw, Warsaw, Poland) Michał Cyrański (Chemistry Department, University of Warsaw, Warsaw, Poland) Roland Boese (Chemistry Department, University of Warsaw, Warsaw, Poland)email: przepinski@chem.uw.edu.pl
sec-Butylamine and 2-methylpryrrolidine are primary aliphatic and secondary cyclic amines, respectively. They can exist in enantiopure form or as a racemic mixture. In both cases they can interact with water molecules forming hydrates of rather differentiated architecture. Their analyses shed light on the influence of stereogenic center on crystal packing and, in consequence, on the transfer of chirality to water frameworks and on their complexity.
Using the in situ crystallization technique [1] assisted by IR laser focused radiation we were able to obtain crystals of racemic amines, (R)-2-methylpyrrolidine and (S)-sec-butylamine. For each case we obtained also hydrates. As expected, racemic 2-methylpyrrolidine or sec-butylamine crystallize in centrosymmetric group (monoclinic P21/n or orthorhombic Pccn, respectively), whereas (R)-2-methylpyrrolidine and (S)-sec-butylamine in non-centrosymmetric ones (P21, or P21212, respectively). In the case of hydrates the amine molecules are incorporated to 3D water network. Racemic mixture and R isomer of 2-methylpyrrolidine lead to 7 hydrate but they differ in crystallographic systems (P21/n or P212121, respectively). The case of sec-butylamine is different because the presence of stereogenic center dramatically changes the symmetry. Racemic mixture of sec-butylamine and water leads to 71/3 hydrate (P21/c space group) while the mixture of S isomer and water gives 6 hydrate (P212121 space group).
It is worth to mention that hydrogen atoms for 2-methylpyrrolidine hydrate (both racemic and enantiopure) are ordered whereas in the case of sec-butylamine hydrate they are disordered.

Acknowledgements The work has been supported by the National Science Center grant (NCN 2011/03/B/ST4/02591)
References:

[1] Boese, R. (2014) Z. Krystallogr., 229, 595
Keywords: chirality, hydrates, in situ crystallization