Picture of a black hole

Strathclyde Open Access research that creates ripples...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of research papers by University of Strathclyde researchers, including by Strathclyde physicists involved in observing gravitational waves and black hole mergers as part of the Laser Interferometer Gravitational-Wave Observatory (LIGO) - but also other internationally significant research from the Department of Physics. Discover why Strathclyde's physics research is making ripples...

Strathprints also exposes world leading research from the Faculties of Science, Engineering, Humanities & Social Sciences, and from the Strathclyde Business School.

Discover more...

Developing a hetero-alkali-metal chemistry of 2,2,6,6-tetramethylpiperidide (TMP): stoichiometric and structural diversity within a series of lithium/sodium, lithium/potassium and sodium/potassium TMP compounds

Armstrong, David R. and Kennedy, Alan R. and Mulvey, Robert E. and Robertson, Stuart D. (2011) Developing a hetero-alkali-metal chemistry of 2,2,6,6-tetramethylpiperidide (TMP): stoichiometric and structural diversity within a series of lithium/sodium, lithium/potassium and sodium/potassium TMP compounds. Chemistry - A European Journal, 17 (32). pp. 8820-8831. ISSN 0947-6539

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

Studied extensively in solution and in the solid state, Li(TMP) (TMP=2,2,6,6-tetramethylpiperidide) is an important utility reagent popular as a strongly basic, weakly nucleophilic tool for C-H metallation. Recently, there has been a surge in interest in mixed metal derivatives containing the bulky TMP anion. Herein, we start to develop hetero (alkali metal) TMP chemistry by reporting the N,N,N',N'-tetramethylethylenediamine (TMEDA)-hemisolvated sodium-lithium cycloheterodimer [(tmeda)Na(mu-tmp)(2)Li], and its TMEDA-free variant [{Na(mu-tmp) Li(mu-tmp)}infinity], which provides a rare example of a crystallographically authenticated polymeric alkali metal amide. Experimental observations suggest that the former is a kinetic intermediate en route to the latter thermodynamic product. Furthermore, a third modification, the mixed potassium-lithium-rich cycloheterotrimer [(tmeda) K(mu-tmp) Li(mu-tmp) Li( mu-tmp)], has also been synthesised and crystallographically characterised. On moving to the bulkier tridentate donor N,N,N',N '',N ''-pentamethyldiethylenediamine (PMDETA), the additional ligation forces the sodium-lithium and potassium-dilithium ring species to open giving the acyclic arc-shaped complexes [(pmdeta)Na(mu-tmp)Li(tmp)] and [(pmdeta)K(mu-tmp)Li(mu-tmp)Li(tmp)], respectively. Completing the series, the potassium-lithium and potassium-sodium derivatives [(pmdeta)K(mu-tmp)(2)M] (M=Li, Na) have also been isolated as closed structures with a distinctly asymmetric central MN2K ring. Collectively, these seven new bimetallic compounds display five distinct structural motifs, four of which have never hitherto been witnessed in TMP chemistry and three of which are unprecedented in the vast structural library of alkali metal amide chemistry.