THE DECEPTIVELY SIMPLE THERMOLYSIS OF TRIVALENT PERMETHYLTITANOCENE DERIVATIVES (ETA-5-C5ME5)2TIR - FORMATION OF A TETRAMETHYLFULVENE TITANIUM COMPOUND (ETA-6-C5ME4CH2)(ETA-5-C5ME5)TI AND RH, CATALYZED BY PERMETHYLTITANOCENE HYDRIDE, (ETA-5-C5ME5)2TIH

GA LUINSTRA, JH TEUBEN

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The complexes Cp*2TiR (Cp* = eta-5-C5Me5; R = Me, Et, n-Pr, C2H3, CH2CMe3, Ph) undergo thermolysis to yield the fulvene complex Cp*FvTi (Fv = eta-6-C5Me4CH2) and RH. Kinetic measurements and deuterium labeling studies show that the decomposition is catalyzed by Cp*2TiH, which is formed either by beta-hydrogen elimination from a titanium alkyl Cp*2TiCH2CH2R at low temperature or by hydrogenolysis of Cp*2TiR or Cp*FvTi, using dihydrogen eliminated from Cp*FvTi at elevated temperatures. Permethyltitanocene is not an intermediate. The rate of the catalyzed decomposition of Cp*2TiCH2CMe3 is linear in [Cp*2TiH]. For Cp*2TiMe it is proportional to [Cp*2TiH] and [CP*2TiMe] and inversely proportional to the starting concentration of Cp*2TiMe. This is explained in a kinetic scheme, where H-2, eliminated from Cp*2TiH to give Cp*FvTi, reacts with Cp*2TiR to regenerate Cp*2TiH and liberate RH. The model is supported by the reaction of (Cp*-d15)2TiD and Cp*2TiCH2CMe3 yielding Cp*2TiD and (Cp*FvTi-d29).

Original languageEnglish
Pages (from-to)3361-3367
Number of pages7
JournalJournal of the American Chemical Society
Volume114
Issue number9
Publication statusPublished - 22-Apr-1992

Keywords

  • NUCLEAR MAGNETIC-RESONANCE
  • C-H BONDS
  • MOLECULAR-STRUCTURE
  • ACTIVATION
  • COMPLEXES
  • CHEMISTRY
  • ZIRCONOCENE
  • LIGAND
  • PERMETHYLSCANDOCENE
  • ALKYL

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