STRUCTURAL AND CONFORMATIONAL-ANALYSIS OF 6-MEMBERED, 7-MEMBERED, AND8-MEMBERED CYCLOALKANES IN TRIS(5-ACETYL-3-THIENYL)METHANE INCLUSION-COMPOUNDS

Tris(5-acetyl-3-thienyl)methane (TATM) forms inclusion compounds with cyclohexane, -heptane, and -octane in a host/guest ratio of 2:1. The c lathrate compounds have been studied by X-ray crystallography. The inc lusion compound with cyclohexane crystallizes in two distinct triclini c unit cells of space group P $$($) over bar 1: in the A form, the uni t cell dimensions are a = 8.622(2), b = 10.194(2), c = 12.795(2) Angst rom, alpha = 79.09(1)degrees, beta = 72.74(1)degrees, gamma = 84.89(1) degrees, V = 1053.9(4)Angstrom(3) (220 K); for the B form, a = 11.668( 4), b = 13.729(3), c = 14.227(4) Angstrom, alpha = 89.40(3)degrees, be ta = 77.20(4)degrees, gamma = 76.24(4)degrees, V= 2157(1) Angstrom(3) (room temperature). In the A form the cavity is of the channel type bu t the guest molecule is located on a centre of inversion while in the B form the cavity is also of the channel type but the guest molecule i s in a general position. The inclusion compounds of cycloheptane and c yclooctane crystallize only in the B form. The guest molecules in the B form are disordered. Conformational analyses of the guest molecules have also been performed by a combination of molecular dynamics and en ergy minimization.