W0077

The Sextuple Phenyl Embrace as a Tool to Make Molecular Dimers. Thomas Steiner, Department of Stuctural Biology, Weizmann Institute of Science, Rehovot 76100 Israel

The sextuple phenyl embrace (SPE) is a concerted interaction of six phenyl rings in a close contact of two triphenyl or tetraphenyl groups (1). In this well-defined motif of intermolecular interactions, each of the six phenyl rings is involved in two edge-to-face phenyl-phenyl contacts of close to optimal geometry. This kind of interaction has been first described for tetraphenylphosphonium cations (1), but it also occurs with neutral central atoms. In principle, the central atom can be any atom allowing tetrahedral angles between the phenyl substituents, such as C, Si, P=O, etc. Heterodimers are formed if the two central atoms are different, i.e. -X(Ph)3...3(Ph)Y-, and homodimers are formed if if the central atoms are the same, i.e. -X(Ph)3...3(Ph)X-.

The SPE has been successfully used as a tool to form cocrystals, in which molecules of different kinds form heterodimers joined by SPEs between triphenyl groups. A published example is the binary crystal of triphenylsilyl- acetylene and triphenylphosphinoxide (2). Further examples will be presented, and also examples with homodimers will be shown. Disorder phenomena associated with the SPE will be discussed.

(1) Dance, I. and Scudder, M., Chem. Eur. J., 2, 1996, 481.

(2) Steiner, T., van der Maas, J., Lutz, B., J. Chem. Soc., Perkin Trans. 2,1997, 1287