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) A, 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) A, 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) A, 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.