The thermal stability of tris(methimazolyl)borates and their germanium complexes

Dawn Wallace, Kirsten Chalmers, Christopher A. Dodds, Iain A. Stepek, David R. Armstrong, Leonard E.A. Berlouis, John Reglinski*, Mark D. Spicer*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

A series of methimazole-based soft scorpionate anions ([RTmMe]–, R = H, Ph, Me, nBu) bearing substitution at the bridgehead boron have been used to produce a series of germanium complexes of general formulae [Ge(RTmMe)2]I2.
Structural analyses of the germanium complexes by X-ray crystallography reveal that they all contain an octahedral S6 coordination sphere. The scorpionate anions (as their Li or Na salts) and their germanium complexes have been studied by thermogravimetric analysis. This analysis suggests that the degradation pathway for the free scorpionate anions differs from that of the complexes. Both pathways involve the loss of a methimazole ring thereby supporting the view that cleavage of the boron–nitrogen bonds can occur under thermally aggressive conditions. As expected, the presence of the germanium alters the degradation profile of the anion. In contrast to the free anions, the four complexes all display a similar mechanism for degradation. Although the presence of the germanium enforces a conformational change in the anions, its presence does not significantly increase the stability of the boron–nitrogen bonds.
Original languageEnglish
Pages (from-to)2569-2575
Number of pages7
JournalEuropean Journal of Inorganic Chemistry
Volume2014
Issue number15
Early online date8 Apr 2014
DOIs
Publication statusPublished - 20 May 2014

Fingerprint

Germanium
Borates
Anions
Thermodynamic stability
Methimazole
Degradation
Bearings (structural)
Boron
X ray crystallography
Thermogravimetric analysis
Substitution reactions
Salts

Keywords

  • germanium
  • soft scorpionate ligands
  • thermogravimetric analysis
  • degradation
  • density functional calculations

Cite this

Wallace, D., Chalmers, K., Dodds, C. A., Stepek, I. A., Armstrong, D. R., Berlouis, L. E. A., ... Spicer, M. D. (2014). The thermal stability of tris(methimazolyl)borates and their germanium complexes. European Journal of Inorganic Chemistry, 2014(15), 2569-2575. https://doi.org/10.1002/ejic.201301588
Wallace, Dawn ; Chalmers, Kirsten ; Dodds, Christopher A. ; Stepek, Iain A. ; Armstrong, David R. ; Berlouis, Leonard E.A. ; Reglinski, John ; Spicer, Mark D. / The thermal stability of tris(methimazolyl)borates and their germanium complexes. In: European Journal of Inorganic Chemistry. 2014 ; Vol. 2014, No. 15. pp. 2569-2575.
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Wallace, D, Chalmers, K, Dodds, CA, Stepek, IA, Armstrong, DR, Berlouis, LEA, Reglinski, J & Spicer, MD 2014, 'The thermal stability of tris(methimazolyl)borates and their germanium complexes', European Journal of Inorganic Chemistry, vol. 2014, no. 15, pp. 2569-2575. https://doi.org/10.1002/ejic.201301588

The thermal stability of tris(methimazolyl)borates and their germanium complexes. / Wallace, Dawn; Chalmers, Kirsten; Dodds, Christopher A.; Stepek, Iain A.; Armstrong, David R.; Berlouis, Leonard E.A.; Reglinski, John ; Spicer, Mark D.

In: European Journal of Inorganic Chemistry, Vol. 2014, No. 15, 20.05.2014, p. 2569-2575.

Research output: Contribution to journalArticle

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T1 - The thermal stability of tris(methimazolyl)borates and their germanium complexes

AU - Wallace, Dawn

AU - Chalmers, Kirsten

AU - Dodds, Christopher A.

AU - Stepek, Iain A.

AU - Armstrong, David R.

AU - Berlouis, Leonard E.A.

AU - Reglinski, John

AU - Spicer, Mark D.

PY - 2014/5/20

Y1 - 2014/5/20

N2 - A series of methimazole-based soft scorpionate anions ([RTmMe]–, R = H, Ph, Me, nBu) bearing substitution at the bridgehead boron have been used to produce a series of germanium complexes of general formulae [Ge(RTmMe)2]I2.Structural analyses of the germanium complexes by X-ray crystallography reveal that they all contain an octahedral S6 coordination sphere. The scorpionate anions (as their Li or Na salts) and their germanium complexes have been studied by thermogravimetric analysis. This analysis suggests that the degradation pathway for the free scorpionate anions differs from that of the complexes. Both pathways involve the loss of a methimazole ring thereby supporting the view that cleavage of the boron–nitrogen bonds can occur under thermally aggressive conditions. As expected, the presence of the germanium alters the degradation profile of the anion. In contrast to the free anions, the four complexes all display a similar mechanism for degradation. Although the presence of the germanium enforces a conformational change in the anions, its presence does not significantly increase the stability of the boron–nitrogen bonds.

AB - A series of methimazole-based soft scorpionate anions ([RTmMe]–, R = H, Ph, Me, nBu) bearing substitution at the bridgehead boron have been used to produce a series of germanium complexes of general formulae [Ge(RTmMe)2]I2.Structural analyses of the germanium complexes by X-ray crystallography reveal that they all contain an octahedral S6 coordination sphere. The scorpionate anions (as their Li or Na salts) and their germanium complexes have been studied by thermogravimetric analysis. This analysis suggests that the degradation pathway for the free scorpionate anions differs from that of the complexes. Both pathways involve the loss of a methimazole ring thereby supporting the view that cleavage of the boron–nitrogen bonds can occur under thermally aggressive conditions. As expected, the presence of the germanium alters the degradation profile of the anion. In contrast to the free anions, the four complexes all display a similar mechanism for degradation. Although the presence of the germanium enforces a conformational change in the anions, its presence does not significantly increase the stability of the boron–nitrogen bonds.

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KW - soft scorpionate ligands

KW - thermogravimetric analysis

KW - degradation

KW - density functional calculations

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Wallace D, Chalmers K, Dodds CA, Stepek IA, Armstrong DR, Berlouis LEA et al. The thermal stability of tris(methimazolyl)borates and their germanium complexes. European Journal of Inorganic Chemistry. 2014 May 20;2014(15):2569-2575. https://doi.org/10.1002/ejic.201301588