Crystal structures of (MeC5H4)4U2(μ-NR)2. Unsymmetrical bridging, R = Ph, and symmetrical bridging, R = SiMe3, organoimide ligands in organoactinide compounds

John G. Brennan, Richard A. Andersen, Allan Zalkin

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48 Scopus citations

Abstract

The tetravalent uranium complexes with bridging organoimide ligands, (MeC5H4)4U2(μ-NR)2, have been prepared by the valence conproportionation reaction of (MeC5H4)3U•thf and (MeC5H4)3UNR. X-ray crystallographic study of R = Ph and SiMe3 shows that the NPh group asymmetrically bridges the two uranium fragments, whereas the NSiMe3 group symmetrically bridges the two uranium fragments. Crystals of (MeC5H4)4U2(NPh)2 are monoclinic, P21/n, with a = 14.738 (3) Å,b- 9.933 (2) Å, c = 10.612 (2) Å, β = 102.11 (2)° at 23 °C. For Z = 2 (dimers) the calculated density is 2.13 g/cm3. The structure was refined by full-matrix least-squares to a conventional R factor of 0.029 [1600 data, F2 > 2σ(F2)]. Crystals of (MeC5H4)4U2(NSiMe3)2 also are monoclinic, P21/n with a = 15.761 (6) Å, b = 9.389 (4) Å, c = 11.052 (4) Å, β = 101.36 (3)° at 23 °C. For Z = 2 (dimers) the calculated density is 2.00 g/cm3. The structure was refined by full-matrix least-squares to a conventional R factor of 0.023 [2544 data, F2 > 2σ(F2)]. Both complexes are dimers in which the two (MeC5H4)2U fragments are bridged by the organoimide group so that an inversion center is located in the center of the U2N2 ring. The bridging U-N distances are 2.156 (8) and 2.315 (8) Å in the NPh complex and 2.217 (4) and 2.230 (4) Å in the NSiMe3 complex.

Original languageEnglish (US)
Pages (from-to)4554-4558
Number of pages5
JournalJournal of the American Chemical Society
Volume110
Issue number14
DOIs
StatePublished - Jul 1 1988
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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