Interpenetrating non-molecular and supramolecular (10,3)-a nets occurring with chiral recognition in crystalline (Ph3MeP)2[NaCr(ox)3]

Abstract

This report describes the high symmetry cubic crystal structure of (Ph3MeP)2[NaCr(ox)3], in which there is a three-dimensionally non-molecular anionic net of [M(ox)3] sites, interpenetrated by a three-dimensionally supramolecular net of cations, and the enantiospecific relationships between these nets. The anion array is a (10,3)-a net formed by covalent bridging of CrIII and NaI by oxalate anions. The cation array is also a (10,3)-a net where cations are linked by a novel embrace involving phenyl and methyl groups. There are threefold embraces between the cations and anions, with a calculated attractive energy of 125 kJ mol-1 per Ph3MeP+/[M(ox)3] pair. These embraces are homochiral and provide the chiral recognition between the cation and anion lattices. (Ph3MeP)2[NaCr(ox)3] is distinctive in being the only oxalate-bridged three-dimensional (10,3)-a lattice formed by a monopositive cation. Relationships between (Ph3MeP)2[NaCr(ox)3] and comparable crystals containing [M(bipy)3] or [M(phen)3] cations are described. Amongst crystals with interpenetrating (10,3)-a nets, (Ph3MeP)2[NaCr(ox)3] is a chiral intermediate type with non-molecular..supramolecular nets, between racemic non-molecular..non-molecular nets and racemic supramolecular..supramolecular nets