The role of chloro substituents in solid inclusion formation.: Crystal structures formed by a bulky hydroxy host with ethyl acetate (2:1) and cyclohexylamine (1:2) as guest

Two inclusion compounds of the 11-[bis(p-chlorophenyl)hydroxymethyl]-9,10-dihydro-9,10-ethanoan-thracene host (1) have been studied by X-ray diffraction in order to find an explanation of the exceptional clathrate formation ability of the present chloro-containing host as compared with that of closely related chlorine-free host analogues. Crystal data: 1 ethyl acetate (2:1), C29H22OCl2. 1/2(C4H8O2), M-w=501.45 P2(1)/c, a=8.9060(5), b=11.1109(6), c = 25.642(1) Angstrom, beta = 99.03(1)degrees, Z = 4, R = 0.047 for 2029 F values with I>2 sigma(I); 1 cyclohexylamine (1:2), 2[C29H22OCl2. 2(C6H13N)], M-w=1311.50, Pc, a=12.144(2), b=12.689(3), c=23.119(8)Angstrom, beta=91.68(1)degrees, Z=2, R=0.054 for 3073 F values with I>2 sigma(I). Although the two solid inclusion compounds differ in host-guest stoichiometry, space group symmetry and also in host-guest recognition mode, both co-crystals are held together by numerous C-H ... X(X=O, N or Cl) interactions, in which the chloro-substituents of 1 play a very active role. The observed frequent participation of chlorine in intermolecular interactions in these compounds suggests an ability of the (C-)Cl substituents to effectively enhance the crystal formation in the absence of more dominant forces.