Dynamic interligand hydrogen transfer in some η5-cyclopentadienylzirconium and -hafnium tetrahydroborates

Tobin J Marks, John R. Kolb

Research output: Contribution to journalArticle

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Abstract

The compounds (η5-C5H5)2Zr(BH 4)2, (η5-C5H5)2Hf(BH4)2, and (η5-C5H5)2Zr(H)BH4 exhibit exchange of C5H5 and BH4 hydrogens which is rapid on the proton NMR time scale at elevated temperatures. The process is found to be predominantly unimolecular, with free energies of activation (ΔG) for the above compounds of 21.3 ± 0.4, 19.4 ± 0.4, and 19.6 ± 0.4 kcal/mol (395°K), respectively. For (C5H5)2Zr(H)BH4, the hydrido hydrogen also appeal, to become involved in the exchange process at higher temperatures, with ΔG = 20.9 ± 0.5 kcal/mol (395°K). The intercha ige process also occurs for (C5H5)2Zr(BD4)2 in the solid state, but more slowly. The possible mechanisms of this prototropic rearrangement are discussed, and the likely importance of η1-C5H5 carbene-ylid complexes along the reaction coordinate is underscored.

Original languageEnglish
Pages (from-to)3397-3401
Number of pages5
JournalJournal of the American Chemical Society
Volume97
Issue number12
Publication statusPublished - 1975

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Hafnium
Hydrogen
Temperature
Free energy
Protons
Chemical activation
Nuclear magnetic resonance
hafnium tetrahydroborate
carbene

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Dynamic interligand hydrogen transfer in some η5-cyclopentadienylzirconium and -hafnium tetrahydroborates. / Marks, Tobin J; Kolb, John R.

In: Journal of the American Chemical Society, Vol. 97, No. 12, 1975, p. 3397-3401.

Research output: Contribution to journalArticle

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