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...

Structural Studies of the Chiral Lithium Amides [{PhC(H)Me}2NLi] and [PhCH2{PhC(H)Me}NLi.THF Derived from a-Methybenzylamine

Armstrong, D.R. and Henderson, K.W. and Kennedy, A.R. and Kerr, W.J. and Mair, F.S. and Moir, J.H. and Moran, P.H. and Snaith, R. (1999) Structural Studies of the Chiral Lithium Amides [{PhC(H)Me}2NLi] and [PhCH2{PhC(H)Me}NLi.THF Derived from a-Methybenzylamine. Journal of the Chemical Society, Dalton Transactions, 1999 (22). pp. 4063-4068. ISSN 0300-9246

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

Abstract

Reaction of (R,R)- or (S,S)-bis(1-phenylethyl)amine with nBuLi in hexane solution gave the chiral amide [{PhC(H)Me}2NLi] 1. Complex 1 crystallises with approximate D3 symmetry as a ring trimer (13) from hexane solution, as determined by X-ray crystallography. In direct contrast to the crystal structure of the related compound dibenzylamidolithium, [{(PhCH2)2NLi}3], no significant agostic Li· · ·C(H) contacts are present in 13. Solution 1H and 7Li NMR spectra of 1 in d8-toluene show the presence of two distinct aggregated species which have been assigned as a trimer and a monomer. The complex [PhCH2{PhC(H)Me}NLi·THF] 2·THF, was prepared by reaction of nBuLi with (R)-N-benzyl--methylbenzylamine in a hexane-THF solution and has been determined by X-ray crystallography to adopt a dimeric structure (22·2THF) in the solid state with C1 symmetry. As in 13, no short Li· · ·C(H) contacts are present in 22·2THF. The lack of Li· · ·C(H) interactions in both 13 and 22·2THF suggests that the rotameric conformations adopted for the benzyl groups in the complexes are governed mainly by steric effects. Using ab initio molecular orbital calculations (HF/6-31G*), the minimum energy structure for unsolvated monomeric 11 was determined to be a C2 symmetric molecule, I, where the faces of both phenyl groups are directed towards the metal, maximising the Li-aromatic interactions. The related C2 symmetric molecule with both methyl groups directed towards the metal is 8.68 kcal mol-1 less stable than I. Therefore, in the absence of aggregation and external solvation, significant stabilisation is achieved through Li· · ·C(H) benzyl interactions. The energy barrier to rotation for one benzyl sidearm for geometry I is 4.76 kcal mol-1, representing a significant lifetime for this conformer.