The digallane molecule, Ga2H6: experimental update giving an improved structure and estimate of the enthalpy change for the reaction Ga2H6(g) → 2GaH3(g)

A.J. Downs, T.M. Greene, E. Johnsen, C.R. Pulham, H.E. Robertson, D.A. Wann

Research output: Contribution to journalArticlepeer-review

Abstract

Improved methods of analysis and new quantum chemical calculations have been applied to the results of earlier gas-phase electron diffraction (GED) studies of digallane to give what is judged to be the most realistic structure available to date. The principal distances (ra3,1 in pm) and interbond angles (∠a3,1 in deg) are as follows (t = terminal, b = bridging): r(Ga⋯Ga) 254.9(2), r(Ga-Ht) 155.0(6), r(Ga-H b) 172.3(6), ∠Ga-Hb-Ga 95.4(5), and ∠H t-Ga-Ht 128.6(9). Scrutiny of the IR spectra of solid Ar matrices doped with the vapour above solid samples of gallane at temperatures in the range 190-220 K reveals the presence of not only Ga2H 6 as the major component, but also a significant fraction of the monomer GaH3. Analysis of the relative proportions of the two molecules evaporating from the solid at different temperatures has led to a first experimental estimate of 59 ± 16 kJ mol-1 for the enthalpy change associated with the reaction Ga2H6(g) → 2GaH3(g). Together with a value of 52 kJ mol-1 delivered by fresh calculations at the MP2 level, this implies that the stability of the dimer with respect to dissociation has been overrated by earlier theoretical treatments. © 2010 The Royal Society of Chemistry.
Original languageEnglish
Pages (from-to)5637-5642
JournalDalton Transactions
Volume39
Issue number24
DOIs
Publication statusPublished - 2010

Bibliographical note

Cited By (since 1996):3

Export Date: 1 October 2013

Source: Scopus

doi: 10.1039/c000694g

Language of Original Document: English

Correspondence Address: Downs, A. J.; Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom; email: tony.downs@chem.ox.ac.uk

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Keywords

  • Enthalpy change
  • Gallanes
  • Gas-phase electron diffraction
  • Improved methods
  • IR spectrum
  • MP2 levels
  • Quantum chemical calculations
  • Solid samples
  • Theoretical treatments
  • Enthalpy
  • Quantum chemistry
  • Gallium

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