METAL-MEDIATED COUPLINGS OF A DIPHOSPHASTIBOLYL RING ANION, [1,4,2-P2SBC2BU2T](-) - SYNTHESIS AND CHARACTERIZATION OF NOVEL ANTIMONY-CONTAINING CAGE COMPOUNDS

Two equivalents of the diphosphastibolyl ring anion, [1, 4, 2-P2SbC2Bu 2t](-) reacted with FeCl3 to produce an antimony-containing cage compo und, P4Sb2C4Bu4t, via an oxidative coupling mechanism. This cage under went an intramolecular rearrangement reaction when treated with [W(CO) (5)(thf)] (thf = tetrahydrofuran) to produce the complex [{W(CO)(5)}P4 Sb2C4Bu4t], which X-ray crystallography shows to contain a three-membe red PPC 'diphosphirane' ring. Treatment of cis-[PtCl2(PEt3)(2)] with 1 equivalent of [1, 4, 2-P2SbC2Bu2t](-) yielded the first example of a complex, trans-[PtCl(PEt3)(2)(eta(1)-P2SbC2Bu2t)], containing a solely eta(1)-co-ordinated diphosphastibolyl ring. The crystal structure of this compound shows the heterocyclic ring to retain its aromaticity af ter co-ordination. Treatment of cis-[PtCl2(PEt3)(2)] with 2 equivalent s of [1, 4, 2-P2SbC2Bu2t](-) initiated a ring-coupling reaction at the metal to give the novel cage complex cis-[Pt(PEt3)(2)(eta(2)-P4Sb2C4B u4t]. The molecular structure of the cage shows it to contain a highly strained, dianionic ligand, [P4Sb2C4Bu4t](2-), which chelates the pla tinum through antimony and phosphorus atoms. Unusual features in the P -31-{H-1} NMR Spectrum of the complex are described.