Four closely related N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamides: order versus disorder, and similar molecular conformations but different modes of supramolecular aggregation, with a new disordered refinement of 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophene.

Abstract

Four closely related N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamides, bearing different substituents on the benzamide ring, have been synthesized and structurally characterized. In each of N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-3-fluorobenzamide, C22H18FNO2S, (I), N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-4-chlorobenzamide, C22H18ClNO2S, (II), N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2,6-difluorobenzamide, C22H17F2NO2S, (III), and N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-methoxybenzamide, C23H21NO3S, (IV), the last of which crystallizes with Z' = 2 in the space group P-1, the fused six-membered ring adopts a half-chair conformation. In each of (I)-(III), this ring is disordered over two sets of atomic sites having occupancies of 0.811 (6) and 0.189 (6) in (I), 0.645 (7) and 0.355 (7) in (II), and 0.784 (6) and 0.216 (6) in (III), such that the two disorder components of the ring are almost enantiomeric. Molecules of (I) are linked into chains by π-π stacking interactions, and those of (II) are linked into chains by a C-H...π hydrogen bond. A combination of two C-H...O hydrogen bonds and two C-H...π hydrogen bonds links the molecules of (III) into complex sheets, but the molecules of (IV) are linked by a combination of two hydrogen bonds, one each of the C-H...O and C-H...π types, to form centrosymmetric tetramers. The structures of (I)-(IV) are compared with that of the unsubstituted analogue N-(3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)benzamide and a new refinement of the parent amine 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophene, using the original data set, has found that here too the fused six-membered ring exhibits conformational disorder, with occupancies of 0.887 (9) and 0.113 (9). Comparisons are made with some related compounds.