ISOLATION OF A SULFUR-RICH INDIUM POLYSULFIDE COMPLEX CONTAINING 2 DIFFERENT SX2- LIGANDS - SYNTHESIS AND STRUCTURE OF [INS10BR]2-

The reaction of InBr3 with K2S5 (or K2S4 and K2S6) and Ph4PBr afforded yellow (Ph4P)2[In(S4)(S6)Br] (I). Complex I crystallizes in the monoclinic space group P2(1)/c with a = 14.355(7), b = 17.723(4), c = 20.974(7) angstrom, beta = 108.5(1)degrees, V = 5060.6(4) angstrom 3 (at 23-degrees-C), Z = 4. The [In(S4)(S6)Br]2- anion features a trigonal bipyramidal indium centre coordinated by four sulphur atoms and one bromine atom. The latter occupies an axial position. The In3+ centre is chelated by two bidentate polysulphide S4(2-) and S6(2-) ligands. The S6(2-) ligand occupies two equatorial positions. The remaining one equatorial and one axial positions are OCCupied by the S4(2-) ligand. The average In-S distance is 2.535(35) angstrom. The In - Br distance is 2.615(3) A. Complex I shows no absorptions in the UV-vis spectrum. Two strong absorptions at 490 and 457 cm-1 in the IR spectrum are attributed to S - S vibrations.