CONCERTED SUPRAMOLECULAR MOTIFS - INVERTED SEXTUPLE ARYL EMBRACES IN CRYSTALLINE TRIS(9-ANTHRACENYL)PHOSPHINE

Crystalline tris(9-anthracenyl)phosphine 1 contains an unusual supramo lecular motif, an inverted sextuple aryl embrace (ISAE) of a pair of p hosphines. This embrace, which is maintained by six intermolecular edg e-to-face interactions between anthracenyl groups, differs from the no rmal sextuple phenyl embraces (SPE) of Ph3P in that the phosphines are inverted relative to each other. The P-C vectors are directed away fr om the interaction zone in the ISAE, rather than into the interaction zone as in the SPE, The ISAE has (3) over bar symmetry. The net attrac tive energy of this concerted supramolecular motif is calculated to be 165 kJ mol(-1) for the ISAE pair. Each molecule of 1 is also involved in three quadruple anthracenyl embraces with three other neighbouring molecules, in geometry comparable with the parallel quadruple phenyl embraces of Ph3P and Ph(4)p(+). (C) 1997 Elsevier Science Ltd.