Molecular conformation and supramolecular aggregation in four 2,3,4,5-tetrahydro-3,4-diphenylbenzothiazepines.

In (2RS,4RS)-1-acetyl-2,3,4,5-tetrahydro-2,4-diphenyl-1,5-benzothiazepine, C(23)H(21)NOS, (I), and (2RS,4RS)-1-chloroacetyl-2,3,4,5-tetrahydro-2,4-diphenyl-1,5-benzothiazepine,C(23)H(20)ClNOS, (II), the seven-membered rings have boat conformations, whereas in (2RS,4RS)-1-benzoyl-2,3,4,5-tetrahydro-2,4-diphenyl-1,5-benzothiazepine, C(28)H(23)NOS, (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 A, C.O = 3.268 (3) and 3.336 (3) A, and C-H.O = 150 and 152 degrees ]. In (II), the molecules are again linked by two C-H.O hydrogen bonds [H.O = 2.42 and 2.48 A, C.O = 3.295 (3) and 3.364 (2) A, and C-H.O = 153 and 154 degrees ], 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 A, C.O = 3.347 (2) and 3.295 (2) A, and C-H.O = 150 and 138 degrees ] 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-tetrahydro-2,4-diphenyl-1,5-benzothiazepine shows that the molecules are linked by three C-H.pi(arene) hydrogen bonds into a three-dimensional framework.