Substituent effects in ditetrel alkyne analogues: Multiple vs. single bonded isomers.

Yang Peng, Roland C. Fischer, W. Alexander Merrill, Jelena Fischer, Lihung Pu, Bobby D. Ellis, James C. Fettinger, Rolfe H. Herber, Philip P. Power

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The synthesis and characterization of a series of digermynes and distannynes stabilized by terphenyl ligands are described. The ligands are based on the Ar' (Ar' = C6H3-2,6(C6H3-2,6-iPr2)2) or Ar* (Ar* = C6H3-2,6(C6H2-2,4,6-iPr3)2) platforms which were modified at the meta or para positions of their central aryl rings to yield 4-X-Ar' (4-X-Ar' = 4-X-C6H2-2,6(C6H3-2,6-iPr2)2, X = H, F, Cl, OMe, tBu, SiMe3, GeMe3) and 3,5-iPr2-Ar' or Ar* and 3,5-iPr2-Ar*. The compds. were synthesized by redn. of the terphenyl germanium(II) or tin(II) halide precursors with a variety of reducing agents. The precursors were obtained by the reaction of one equiv. of the lithium terphenyl with GeCl2 dioxane or SnCl2. For germanium, their x-ray crystal structures showed them to be either Ge-Ge bonded dimers with trans-pyramidal geometries or V-shaped monomers. In contrast, the terphenyl tin halides had no tin-tin bonding but existed either as halide bridged dimers or V-shaped monomers. Redn. with a variety of reducing agents afforded the digermynes ArGeGeAr (Ar = 4-Cl-Ar', 4-SiMe3-Ar' or 3,5-iPr2-Ar*) or the distannynes ArSnSnAr (Ar = 4-F-Ar', 4-Cl-Ar', 4-MeO-Ar', 4-tBu-Ar', 4-SiMe3-Ar', 4-GeMe3-Ar', 3,5-iPr2-Ar', 3,5-iPr2-Ar*), which were characterized structurally and spectroscopically. The digermynes display planar trans-bent core geometries with Ge-Ge distances near 2.26 Å and bending angles near 128° consistent with Ge-Ge multiple bonding. In contrast, the distannynes had either multiple bonded geometries with Sn-Sn distances that averaged 2.65 Å and an av. bending angle near 123.8°, or single bonded geometries with a Sn-Sn bond length near 3.06 Å and a bending angle near 98°. The 3,5-iPr2-Ar*SnSnAr*-3,5-iPr2 species had an intermediate structure with a longer multiple bond near 2.73 Å and a variable torsion angle (14-28°) between the tin coordination planes. Moessbauer data for the multiple and single bonded species displayed similar isomer shifts but had different quadrupole splittings. [on SciFinder(R)]
Original languageEnglish
Pages (from-to)461-468
Number of pages8
JournalChemical Science
Volume1
Issue number4
DOIs
Publication statusPublished - 2010

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    Peng, Y., Fischer, R. C., Merrill, W. A., Fischer, J., Pu, L., Ellis, B. D., ... Power, P. P. (2010). Substituent effects in ditetrel alkyne analogues: Multiple vs. single bonded isomers. Chemical Science, 1(4), 461-468. https://doi.org/10.1039/c0sc00240b