Crystal Structures of Tetramesityl‐Substituted Tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene

Crystal structures of tetramesityl‐substituted tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP) derivative were determined for crystals containing different solvents, CHCl3, CH2Cl2, acetone, and benzene at different temperatures to discuss the conjugation modes in the antiaromatic system, i. e., whether it adopts a D2h structure consisting of local aromatic sextets and quinodimethane substructures or a D4h double annulenenoid structure. The structures of the TCPTP core in all crystals determined at 113 K or 93 K resemble those of the theoretical D2h geometry, whereas the bond lengths at room temperature (293 K) adopt averaged values of the theoretical D2h and D4h geometries. These results are interpreted in terms of disorder of two perpendicularly oriented D2h structures at room temperature and support the theoretical prediction which favours the D2h geometry. The slightly different bond length distributions in the crystals are ascribed to the different space in the vicinity of the molecule which allows the molecule to adopt the two orientations in different occupancies. X‐ray crystallographic analyses of a tetracyclopentatetraphenylene derivative were performed for four different crystals containing different solvents at 113 K or 73 K and at 293 K. The low temperature analyses confirmed that the D2h structure of the π core consisting of local aromatic sextets and quinodimethane substructures. The D4h‐like geometry observed at room temperature was ascribed to disorder of two orthogonally oriented D2h structures.