Synthesis and characterization of phosphine adducts of thorium borohydride, Th(BH4)4: Crystal structures of Th(BH4) 4(PEt3)2 and Th(BH4) 4(Me2PCH2CH2PMe2) 2

Andrew C. Dunbar, John E. Gozum, Gregory S. Girolami

Research output: Contribution to journalArticlepeer-review

Abstract

Addition of tertiary phosphines to Th(BH4)4(Et 2O)2 yields the new Lewis base adducts, Th(BH 4)4(PMe3)2, Th(BH4) 4(PEt3)2, and Th(BH4) 4(dmpe)2, where dmpe = 1,2-bis(dimethylphosphino)ethane. If one considers the BH4- groups to occupy one coordination site, then Th(BH4)4(PEt3)2 adopts a trans-octahedral geometry, and Th(BH4)4(dmpe)2 adopts a trigonal dodecahedral geometry with the dmpe ligands bridging between the "inner" sites. In the PMe3 and PEt3 complexes, all four BH4- groups are κ3, whereas in the dmpe complex two of the BH4- groups are κ2 and two are κ3. In the dmpe complex, the Th⋯B distances to the κ2 and κ3 BH4- groups are 2.91 and 2.69 , respectively. All of the Lewis base adducts of Th(BH4)4 are volatile and may be sublimed in vacuum. They have been characterized by infrared and 1H, 11B, and 31P NMR spectroscopy. The results show that thorium complexes of unidentate phosphines can be made and are stable enough to isolate and characterize. 31P NMR coordination chemical shifts of thorium phosphine complexes are on the order of 30-45 ppm. The compound Th(BH4)4(dmpe)2 is the first thorium complex to contain κ2 BH4- groups.

Original languageEnglish (US)
Pages (from-to)2804-2808
Number of pages5
JournalJournal of Organometallic Chemistry
Volume695
Issue number25-26
DOIs
StatePublished - 2010

Keywords

  • Borohydride
  • Crystal structures
  • Phosphine
  • Tetrahydroborate
  • Thorium
  • Trialkylphosphine

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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