Cocrystallized mixtures and multiple geometries: Syntheses, structures, and NMR spectroscopy of the Re6 clusters [NMe4]4[Re6(Te(8-n)Se(n))(CN)6] (n = 0-8)

Yuri V. Mironov, Jason A. Cody, Thomas E. Albrecht-Schmitt, James A Ibers*

*Corresponding author for this work

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Abstract

The mixed tellurium/selenium Re6 clusters [NMe4]4[Re6(Te(8-n)Se(n))(CN)6] (n = 0-8) have been prepared from the reactions of Re6Te15 with the appropriate stoichiometry of NaCN and Se at 600°C, followed by cation exchange with NMe4Br. A typical anion comprises an Re6 octahedron with its eight faces capped by μ3-chalcogen atoms to form a pseudocube, and each Re atom has a terminal cyanide ligand. These anions have essentially idealized cubic symmetry. In the [Re6Te8(CN)6]4- anion, Re-Re bond distances range from 2.673(1) to 2.690(1) Å and Re-(μ3-Te) distances range from 2.683(1) to 2.705(1) Å. In the [Re6Se8(CN)6]4- anion the Re-Re and Re-(μ3-Se) distances range from 2.622(2) to 2.638(2) Å and 2.520(3) to 2.550(3) Å, respectively. The '[Re6Te4.34Se3. 66(CN)6]4-' anion, with disordered Se/Te positions, displays intermediate bond distances with Re-Re distances ranging from 2.653(1) to 2.665(1) Å and Re-(μ3-Q) (Q = Se, Te) distances ranging from 2.581(1) to 2.673(1) Å. Whereas single-crystal X-ray diffraction results provide the barest indication of the complicated nature of the mixed Te/Se crystalline products, NMR spectroscopy indicates that they comprise cations and mixtures of geometric isomers of [Re6(Te(8-n))Se(n))(CN)6]4- anions (125Te NMR (δ, ppm): [NMe4]4[Re6Te8(CN)6], -1112; [NMe4]4[Re6Te7Se(CN)6], ≤10 peaks, -643 to -1231; [NMe4]4[Re6Te4Se4(CN)6], ≤18 peaks, -705 to -1234; [NMe4]4[Re6TeSe7(CN)6], ≤12 peaks, -648 to -1114. 77Se NMR (δ, ppm): [NMe4]4[Re6TeSe7(CN)6], ≤8 peaks, 928 to 966; [NMe4]4[Re6Se8(CN)6]·3 1/3H2O, 933).

Original languageEnglish (US)
Pages (from-to)493-498
Number of pages6
JournalJournal of the American Chemical Society
Volume119
Issue number3
DOIs
StatePublished - Jan 22 1997

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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