ON THE 5-THIA-(SUBSTITUTED)-1-OXA-4,6-DITHIA-5-STIBOCANES - SYNTHESISAND CHARACTERIZATION OF O(CH2CH2S)(2)SBS2P(OC2H5)(2) AND CRYSTAL AND MOLECULAR-STRUCTURE OF (CH2CH2S)(2)SB-SCH2CH2OCH2CH2S-SB(SCH2CH2)(2)O,A COMPOUND WITH 2 DIFFERENT 8-MEMBERED RING CONFORMATIONS

The stibocane O(CH2CH2S)(2)SbS2P(OC2H5)(2) (1) was prepared by reactin g O(CH2CH2S)SbCl and KS2P(OC2H5)(2), in anhydrous benzene, and charact erized by spectroscopic (IR, MS, H-1, C-13 and P-31{H-1} NMR) methods. The crystal and molecular structure of O(CH2CH2S)(2)Sb-SCH2CH2OCH2CH2 S-Sb(SCH(2)CH2)(2)O (2), obtained as a side product during the attempt s to grow crystals of the dithiophosphato derivative, was determined b y X-ray diffractometry. The compound is triclinic, space group P ($) o ver bar 1, a=7.994(1), b=10.495(1), c=14.562(2) Angstrom, alpha=77.90( 1), beta=85.50(1), gamma=69.02(1)degrees, V=1115.3(2) Angstrom(3), Z=2 . The molecule of 2 contains two SbS2C4O rings with different conforma tions, i.e. chair-chair for Sb(1) and boat-chair for Sb(2). In both he lerocyclic rings strong transannular Sb(1)... 0(1) (2.734(3) Angstrom) and Sb(2)... 0(3) (2.637(4) Angstrom) interactions are present. The 0 (2) atom of the bridging ligand also exhibits intramolecular Sb(1)... 0(2) (2.895(3) Angstrom) and Sb(2)... 0(2) (3.156(3) Angstrom) interac tions. In the crystal form 2 is associated in pairs through weak, inte rmolecular Sb(2)... S secondary interactions (3.733(1) Angstrom), thus resulting in different coordination polyhedra for the antimony atoms in the same molecule.