Pasteur's tartaramide/malamide quasiracemates: new entries and departures from near inversion symmetry

Abstract

This investigation explores Pasteur's 1853 (+)-tartaramide/(−)-malamide quasiracemate, extends this system to the crystallization behavior of methyl and butyl derivatives, and challenges the well-known notion that pairs of quasienantiomers assemble without exception to give near centrosymmetric crystal packing motifs. Each of the structures included in this study exhibits an extensive set of N/O–H⋯O contacts with component alignment in the quasiracemates defined by inversion and/or glide symmetry. Solid-state density functional theory calculations were applied to quantify the crystal stabilization and rationalize the observed packing tendencies.