1991/06/19 by Otto Ermer, Lorenz Lindenberg · 3 citations
Chemistry · Materials Science · #Supramolecular Chemistry and Complexes #Porphyrin and Phthalocyanine Chemistry
paper · doi:10.1002/hlca.19910740417
Abstract The crystal structures of four inclusion compounds of 2,6‐dimethylideneadamantane‐1,3,5,7‐tetracarboxylic acid ( 4 ) are described, which involve the following guest species: ( a ) a mixture of 4‐methylpent‐3‐en‐2‐one, 2,6‐dimethylhepta‐2,5‐dien‐4‐one, and mesitylene (condensation products of acetone); ( b ) mesitylene; ( c ) a mixture of 4‐methylpent‐3‐en‐2‐one and mesitylene; ( d ) ( tert ‐butyl)benzene. In all four cases, the host architectures consist of two interpenetrating super‐diamond networks built up by the tetra‐acid molecules via pairwise H‐bonds between the tetrahedrally directed COOH groups. In the first three cases (tetragonal crystal symmetry), the two diamond‐like host lattices interpenetrate symmetrically, in the fourth case (monoclinic) asymmetrically. This asymmetry is brought about by the increased steric bulk of the ( tert ‐butyl)benzene guest molecules. Attempts to enforce an inclusion compound of 4 with a single, extremely hollow diamond‐like host lattice by offering still bulkier guest molecules have as yet not been met with success. The generally very high propensity of 4 to form inclusion compounds was envisaged and designed beforehand by appropriate evaluation and modulation of the crystal structure of the parent adamantane‐1,3,5,7‐tetracarboxylic acid, which represents a fivefold diamond‐like self‐inclusion compound. Crystals of the free, uncomplexed 4 appear to be extremely unstable and could so far not be obtained. On the other hand, from aqueous solution a very stable monohydrate of 4 may be crystallized ( 4 ‐H 2 O), which was also subjected to X‐ray analysis. The (triclinic) crystal structure of 4 ·H 2 O involves an interesting dichotomy inasmuch its pattern of H‐bonding may be rationalized either in terms of a double, cross‐linked super‐zincblende (sphalerite) architecture, or as a system of porous, puckered 4‐connected sheets, which interpenetrate each other pairwise and are cross‐linked by the H 2 O molecules. Various structure and (space group) symmetry characteristics of the supramolecular solid‐state complexes reported here are highlighted by pointing out analogies with comparable structures retrieved from the literature.