SOIL-STATE STRUCTURES OF TRIARYLANTIMONY DIHALIDES - THE ISOLATION OF SOME MIXED-HALIDE SPECIES AND CRYSTAL-STRUCTURES OF PH3SBL2 AND [PH4SB]L3

Fifteen compounds of stoichiometry R3SbX2 (R = Ph or substituted aryl; X2 = Br2, I2 or IBr) were synthesised and studied by Raman spectroscopy. The crystal structure of Ph3Sbl2 has been determined, which shows it to be a distorted trigonal-bipyramidal molecule. The distortion from regular trigonalbipyramidal geometry may be explained by a pseudorotation process towards a rectangular pyramid. Moreover, there are two independent molecules within the unit cell and its distoned structure is in direct contrast to the known Ph3SbX2 (X = Cl or Br) which both adopt regular trigonal-bipyramidal geometry. The interhalogen compounds R3SbIBr also have trigonal-bipyramidal geometry. In direct contrast to the molecules Ph3EI2 (E = P or As), which ionise in solution to form [Ph3EI]I, Ph3SbI2 is chemically changed in acetonitrile solution and forms the ionic [Ph4Sb]I3, there being no evidence for [Ph3Sbl]I. The crystal structure of [Ph4Sb]I3 has also been determined.