Crown thioether chemistry of tin(IV): formation and crystal and molecular structures of 3SnCl4·2[9]aneS3 and 2SnCl4·[18]aneS6·MeCN ([9]aneS3= 1,4,7-trithiacyclononane; [18]aneS6= 1,4,7,10,13,16-hexathiacyclooctadecane)

Abstract

Reactions of tin(IV) chloride with selected thiacrown ligands in acetonitrile have been studied. With [9]aneS₃(1,4,7-trithiacyclononane) the yellow compound 3SnCl₄·2[9]aneS₃ has been isolated and structurally characterised by X-ray diffraction: orthorhombic, space group Pbca, a= 11.245(5)Å, b= 12.927(6)Å. c= 23.779(10)Å, Z= 4, at 230(2) K. The structure consists of six-co-ordinate [SnCl₃([9]aneS₃)]⁺ cations and [SnCl₆]^2– anions in the ratio 2 : 1. In the cation the thiacrown is chelated facially to a SnCl₃ unit with Sn–Cl 2.369(4)(mean), Sn–S 2.637(4)Å(mean). The [SnCl₆]^2– counter anions exhibit a regular octahedral geometry with Sn–Cl 2.448(4)(mean)Å. The reaction with [18]aneS₆(1,4,7,10,13,16-hexathiacyclooctadecane) provides yellow crystals of the adduct 2SnCl₄·[18]aneS₆·MeCN the structure of which has also been determined by X-ray diffraction; monoclinic, space group C2, a= 16.901 (5), b= 12.968(5), c= 7.284(3)Å, β= 100.50(3)°, Z= 2, at 240(2) K. The structure consists of two SnCl₄ units located at opposite ends of the ring cavity with one above and the other below the ring plane. Each tin atom is six-co-ordinate and is attached to the ring via cis chelation of two sulfur atoms.