| Abstract
| - The reactions of a triphosphacyclohexadienyl anion, [MeP3C3But3]-, toward a series of group 13 and 14 halide complexes have been investigated. These have given rise to a range of homo- and heteroleptic diphospholyl complexes via facile, metal-mediated phosphinidene elimination reactions. In addition, several phosphaorganometallic cage compounds (e.g., see picture) have been formed via rearrangements of the triphosphacyclohexadienyl anion within the coordination sphere of group 14 metals.
- The reactivity of the lithium triphosphacyclohexadienyl complex Li[1,3,5-MeP3C3But3] toward a rangeof group 13 and 14 halide complexes has been investigated. The heterocycle reacts with MX (M = Ga,In, or Tl; X = Cl or I) to give the diphosphacyclopentadienyl (i.e., diphospholyl) complexes [M(η5-1,3-P2C3But3)] in good yield via phosphinidene, PMe, elimination reactions. One complex, M = Tl, has beenstructurally characterized and found to exist as a one-dimensional polymer in the solid state. Similarly,the reactions of Li[MeP3C3But3] with MCl2 (M = Sn or Pb) have given the tetraphosphametallocenes[M(η5-1,3-P2C3But3)2], which have been structurally characterized. These exhibit fluxional behavior insolution, which has been examined by variable-temperature NMR studies. The monomeric guanidinato−tin chloride complexes [LSnCl] (L = Cy2NC(NAr)2- or (cis-2,6-Me2C5H8N)C(NAr)2-, Cy = cyclohexyl,Ar = C6H3Pri2-2,6) have been prepared, structurally characterized, and treated with Li[MeP3C3But3].Again, this has yielded diphospholyl complexes [LSn(η1-1,3-P2C3But3)] via phosphinidene eliminationprocesses. In contrast, the reactions of Ph3ECl, E = Sn or Pb, do not proceed via phosphinidene eliminationreactions, but instead by triphosphacyclohexadienyl rearrangement processes that eventually lead tocomplexes [Ph3M(η2-P,P-MeP3C3But3)], containing five-coordinate metal centers that are P,P-chelatedby an anionic bicyclic ligand. In the case of the tin complex, a reaction intermediate has been isolatedand shown to contain the first structurally characterized example of a 1,2-diphosphabicyclo[1.1.0]butanefragment. A mechanism for the formation of this intermediate has been proposed.
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