CRYSTAL-STRUCTURES OF OPTICALLY-ACTIVE DIASTEREOMERIC TELLURONIUM ANDSELENONIUM SALTS - ANION-CATION INTERACTIONS IN THE CRYSTALLINE STATE

The tellurium atom in optically pure diastereomeric (R)-ethylmethylphe nyltelluronium (1S)-camphor-10-sulfonate ((R)(Te)-1) was found to inte ract with two oxygen atoms of the counter anions in the crystalline st ate, while that in the other diastereomeric isomer (S)(Te)-1 interacts with three oxygen atoms. This difference in interactions is considere d to be caused by steric factors (crystal packing) and not to be cause d by electronic effects, since the telluronium cations have the same s ubstituents and counter anions. The crystal packing structure of(R)(Te )-1 showed M-helix geometry through anion-cation interactions, while t hat of (S)(Te)-1 showed a 2D-sheet structure. The corresponding optica lly active selenonium salt (R)(Se)-2 showed crystal packing similar to that of(R)(Te)-1. (C) 1997 Elsevier Science S.A.