Synthesis and structures of antimony(III) halide complexes with oxa-thia and oxa-selena crowns

Abstract

Reaction of the oxa-thia macrocycle 1,10-dithia-4,7,13,16-tetraoxacyclooctadecane ([18]aneO4S2) in a 1:1:1mol ratio with SbCl3 and SbCl5 in MeCN gave [SbCl2([18]aneO4S2)][SbCl6] which contains an eight-coordinate cation. In the absence of SbCl5, the compounds [SbCl3([18]aneO4S2)], and [SbCl2([18]aneO4S2)]2[Sb3Cl11] form. Crystals of [SbCl2([18]aneO4Se2)]2[Sb3Cl11] ([18]aneO4Se2=1,10-diselena-4,7,13,16-tetraoxacyclooctadecane) were also obtained. The reaction of SbI3 with [18]aneO4S2 gave [SbI2([18]aneO4S2)][Sb2I7], which has a similar cation to the chloro-complexes. The smaller ring, 1,4-dithia-7,10,13-trioxacyclopentadecane ([15]aneO3S2) formed the discrete eight coordinate complex [SbCl3([15]aneO3S2)]. However, the small macrocycle 1,4,-dithia-7-oxacyclononane ([9]aneOS2) gave [SbCl3([9]aneOS2)] which is polymeric with a double chain structure involving exo-coordination of S-donors from two different ligands to the antimony and a long endo interaction (S2) with a third macrocycle. The neutral SbF3 complexes, [SbF3([18]aneO4S2)], [SbF3([18]aneO4Se2)] and [SbF3([15]aneO3S2)] are also described. X-ray crystal structures are reported for [SbCl2([18]aneO4S2)][SbCl6], [SbCl2([18]aneO4S2)]2[Sb3Cl11], [SbCl2([18]aneO4Se2)]2[Sb3Cl11], [SbI2([18]aneO4S2)][Sb2.5I9.5], [SbCl3([15]aneO3S2)], [SbF3([15]aneO3S2)] and [SbCl3([9]aneOS2)]. Comparisons are drawn with the Sb(III) complexes of crown-ethers and thia-macrocycles.