Structure and Molecular-Packing Analysis of a Heptofuranosoimidazolidine-2-Thione

Abstract

1-(4-Bromophenyl)-3-ethyl-(3,5,6,7-tetra-0- acetyl-1,2-dideoxy-n-glycero-P-n-talo-heptofuranoso )-

* IUPAC name: 1-{6-acetoxy-3-bromophenyl-2-thioxo-2,3,3a,- 5,6,6a-tetrahydro-1H-furo[2,3-d]imidazol-5-yl }propane-1,2,3-triyl triacetate. 0108-2701/87/061134-05$01.50

[2,1-d]imidazolidine-2-thione, C24H 29BrN 209S, Mr = 601·46, orthorhombic, P2 12121, a= 15·634 (3), b=22·749(6), c=7·714(2)A, V=2743(I)Á 3, Z = 4, Dx = 1·46 Mg m-3, A.(Mo Ka)= 0·7107 Á, f.1. = 1·60 mm- 1 F(OOO) = 1240, room temperature, final wR = 0·052 for 1643 observed refiexions. The sugar ring adopts the 4E conformation and the dihedral angle in the bicycle system is 71·5 (7)0 • The crystal cohesion is mainly due to van der Waals interactions but sorne C-H···O intermolecular con­ tacts should be considered as weak hydrogen bonds. The lattice energy was computed in the atom-atom approach using van der Waals potential functions. The Coulombic term makes an important contribution to the lattice energy but no significant changes in structural parameters are obtained from its con­ sideration