Department of Physics Periyar University^* Department of Physics, Bangalore University,Bangalore-560 056, India.^** Sabinsa Corporation, Deerpark Drive Suit, Monmouth Junction, NJ 00852, USA.^***
○A.David Stephen^* K. A. Nirmala^** N. Kalyanam^*** P. Kumaradhas^*

The title compound [C₁₈H₁₇NO₅S] is a (+) form of cis(±) mixture¹ and it is a diltiazem² related compound. Diltiazem is a benzothiazepine calcium-channel blocking agent. This is a part of our work on a series of 1, 5-benzothiazepine compounds to understand the geometrical effect and the nature of hydrogen bonding interaction by varying the different substituents with parent skeleton using x-ray analysis. The title compound crystallizes in orthorhombic space group P2₁2₁2₁ with a = 9.271(1) Å, b = 11.838(1) Å, c = 15.836(2) Å, Z = 4, V = 1738.0(3) ų and F(000) = 752. The structure has been determined using SHELX-97 program suit. The least-square refinement gave residual index R(F) = 0.042, wR(F²)= 0.111 for 1733 observed reflections. The molecular packing is stabilized by hydrogen bonding. The amide group forms strong hydrogen bond with the symmetrically sitting neighboring molecules in the crystal. The molecules are linked into an infinite chain through hydrogen bonds. The seven-membered ring is distorted showing twist-boat conformation. The methoxyphenyl group significantly deviated from planarity.

[1] Kumaradhas, P. and Nirmala, K.A. Acta Cryst. (1996), C52, 1259.
[2] Kojic-Prodic, B., Ruzic-Toros, Z. and Sunjic,V. Helv. Chim. Acta. (1984), 67, 916.