Crystallographic studies of the molecular complexes ofE,E-1[p-dimethylaminophenyl]-5-[o-hydroxyphenyl]-penta-1,4-dien-3-one 9DHDK) with chloroform (1:0.4),m-dinitrobenzene (1:1) andp-dimethylaminobenzaldehyde (1:1); the Heilbron complexes

Abstract

Crystal structures are reported for the molecular complexes ofE,E-1-[p-dimethylaminophenyl]-5-[o-hydroxyphenyl]-penta-1,4-dien-3-one (DHDK) with chloroform,m-dinitrobenzene andp-dimethylaminobenzaldehyde. The three complexes (first reported by I. M. Heilbron and J. S. Buck [1] in 1921) have different structures. In DHDK·0.4 CHCl₃ (triclinic,a=12.086(6),b=10.323(5),c=8.015(4) Å, α=94.58(6), β=103.58(6), γ=110.10(6)^o,Z=2,P $\bar 1$ (assumed)), the host molecules are linked by two hydroxyl carbonyl hydrogen bonds to form centrosymmetric pairs, with the disordered CHCl₃ molecules contained in cavities left between the molecule pairs. The complex is a clathrate. In DHDK·m-dinitrobenzene (triclinic,a=21.787(9),b-13.850(5),c=7.759(4) Å, α=88.25(5), β=84.70(5), γ=88.86(5)^o,P $\bar 1$,Z=4) the DHDK molecules are linked in ribbons through head-to-waist hydroxyl-carbonyl hydrogen bonds. The guest molecules are contained in sinuous channels left between the DHDK ribbons; the host and guest molecules are approximately coplanar. Successive planes are mutually shifted so that the guest molecules are enclosed above and below by host molecules. This is a new structural type, with features resembling those of channel inclusion complexes. In DHDK·p-dimethylaminobenzaldehyde (monoclinic,a=22.331(9),b=12.238(5),c=8.904(4) Å, β=92.99(5)^o,Z=4,P2₁/n) the host molecules are arranged so as to leave channels of approximately rectangular cross-sections in which the guest molecules are accommodated. Additional stabilization is achieved by hydrogen bonding between host hydroxyl and guest carbonyl groups. This is a channel-inclusion complex. In the chloroform andp-dimethylaminobenzaldehyde complexes the host molecule has thes-trans, trans conformation but in them-dinitrobenzene complex its conformation iss-cis, trans.