Synthesis and crystal structures of two (cyclopentadienyl)titanium(III) hydroborate complexes, [Cp*TiCl(BH4)]2 and Cp2Ti(B3H8)

Do Young Kim, Yujian You, Gregory S. Girolami

Research output: Contribution to journalArticlepeer-review

Abstract

Treatment of Cp*TiCl3 and Cp2TiCl2 with NaB3H8 affords the titanium(III) hydroborate compounds [Cp*TiCl(BH4)]2 and Cp2Ti(B3H8), respectively. The former compound arises by means of a new reaction, the metal-induced fragmentation of the B3H8 anion, and can also be made by treating Cp*TiCl3 with LiBH4. The latter compound has been previously described, but not characterized crystallographically. Both compounds have been studied by single crystal X-ray diffraction. Dimeric [Cp*TiCl(BH4)]2 has bridging chloride ligands and terminal Cp* and BH4 ligands. The Ti-Ti distance is 3.452(1) Å, which indicates that there is no metal-metal bonding interaction. The Ti-Cl distances are 2.440(2) Å and the Ti-Cl-Ti and Cl-Ti-Cl angles of 89.97(8) and 90.03(8)° so that the Ti2Cl2 unit is nearly a perfect square. The BH4 groups are each tridentate, with a Ti-B distance of 2.220(9) Å and an average Ti-H distance of 1.98(5) Å. In Cp2Ti(B3H8), the B3H8 ligand is bidentate, as is usually seen, and the Ti-B and Ti-H distances are 2.600(3) and 1.96(2) Å. The dihedral angle between the Ti-B(1)-B(2) plane and the B(1)-B(2)-B(3) plane is 123.4°. The Ti-B distances are 0.04 Å longer than those in niobium analog, Cp2Nb(B3H8), despite the fact that the single bond metallic radius of Ti is 0.02 Å smaller than that of Nb. This lengthening of the bond is probably a consequence of the presence of one fewer skeletal bonding electron in Cp2Ti(B3H8).

Original languageEnglish (US)
Pages (from-to)981-986
Number of pages6
JournalJournal of Organometallic Chemistry
Volume693
Issue number6
DOIs
StatePublished - Mar 15 2008

Keywords

  • Borohydride
  • Crystal structure
  • Cyclopentadienyl
  • Hydroborate
  • Pentamethylcyclopentadienyl
  • Titanium

ASJC Scopus subject areas

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

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