UC Santa Cruz

Organometallic antimony(V) complexes were prepared as model compounds to better understand the interactions of chiral chelating diols with this metalloid. These complexes feature three aryl groups (meta-xylyl or para-tolyl) and a bidentate trans-2,3-butanediolate. The meta-xylyl and para-tolyl complexes of either enantiomerically pure 2R,3R-butanediolate or 2S,3S-butanediolate (compounds 1-4) crystallized in Sohncke space groups, as expected. In each case, though, pseudoinversion centers were present that mimic higher-symmetry space groups through global pseudosymmetry. We hypothesized that the crystallization of 1:1 mixtures of the enantiomeric complexes would produce crystals in the centrosymmetric space group approximated by the pseudosymmetry. The enantiomerically pure meta-xylyl complexes each crystallized in space group P1 (approximating P1̅), and the racemic compound did indeed crystallize in P1̅. The enantiomerically pure para-tolyl complexes each crystallized in space group P2₁ (approximating P2₁/c), but the racemic compound crystallized in P1̅. Although the enantiomerically pure and racemic compounds are not isostructural, there are similarities in their 3D structures that are analyzed.