Molecular conformation and supramolecular aggregation in four 2,3,4,5-tetrahydro-3,4-diphenyl-benzothiazepines

In (2RS,4RS)-1-acetyl-2,3,4,5-tetrahydro-2,4-diphenyl-1,5-benzothiazepine, C23H21NOS, (I), and (2RS,4RS)-1-chloroacetyl-2,3,4,5-tetrahydro-2,4-diphenyl-1,5-benzothiazepine, C23H20ClNOS, (II), the seven-membered rings have boat conformations, whereas in (2RS,4RS)-1-benzoyl-2,3,4,5-tetrahydro2,4-diphenyl-1,5-benzothiazepine, C28H23NOS, (III), this ring has a conformation intermediate between the boat and twist-boat forms. The molecules of (I) are linked into isolated R-2(2)(16) dimers by two C-H...O hydrogen bonds [H...O=2.41 and 2.47 Angstrom, C...O=3.268 (3) and 3.336 (3) Angstrom, and C-H...O=150 and 152degrees]. In (II), the molecules are again linked by two C-H...O hydrogen bonds [H...O=2.42 and 2.48 AAngstrom, C...O=3.295 (3) and 3.364 (2) Angstrom, and C-H...O=153 and 154degrees], forming chains of alternating R-2(2)(18) and R-2(2)(22) rings. Two C-H...O hydrogen bonds [H...O=2.49 and 2.53 Angstrom, C...O=3.347 (2) and 3.295 (2) Angstrom, and C-H...O=150 and 138degrees] link the molecules of (III) into sheets containing alternating R-2(2)(22) and R-6(4)(30) rings. Re-examination of the published structure of (2RS, 4RS)-2,3,4,5-tetrahydro2,4-diphenyl-1,5-benzothiazepine shows that the molecules are linked by three C-H...pi(arene) hydrogen bonds into a three-dimensional framework.