Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies

D R Armstrong, W Clegg, L Dunbar, S T Liddle, M MacGregor, Robert Mulvey, D Reed, S A Quinn

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

A series of alkali metal-1-azaallyl complexes, [{CH3CH2CH2C(H)C(Bu-t)N(H)Li . HMPA}(2)], 1, [{CH3CH2CH2C(H)C(Bu-t)N(H)Na . 2HMPA}(2)] 2 and [{CH2C(Bu-t)N(H)Li . HMPA}(2)] 3, has been synthesised by treating each appropriate metal alkyl reagent (n-butyllithium, n-butylsodium or methyllithium, respectively) with tert-butyl cyanide in the presence of the Lewis base HMPA [hexamethylphosphoramide, (Me2N)(3)P=O]. X-Ray crystallographic studies have established that each structure is dimeric and built around a precisely or approximately centrosymmetric rhomboidal (N-M)(2) ring. However, the nature of the azaallyl-metal bonding differs with 1 and 2 displaying a terminal eta(1)-N arrangement, while 3 displays a chelating eta(3)-NCC arrangement. H-1 and C-13 NMR spectroscopic studies suggest that these distinct bonding modes an retained in [H-2(8)]toluene solution. Long-range ((4)J) "W" coupling (2.4 Hz) is observed for 3 between the NH and one of the alpha-CH2 protons, consistent with the trans orientation of the NH and Cchemical anionC linkages seen in the solid state. The preference for this geometry is confirmed by ab initio MO calculations on models of 3, which examine the energetics of the ketimide-azaallyl isomerism involved in the formation of 1-3.

Original languageEnglish
Pages (from-to)3431-3436
Number of pages6
JournalJournal of the Chemical Society, Dalton Transactions
Issue number20
DOIs
Publication statusPublished - 21 Oct 1998

Keywords

  • molecular orbital methods
  • basis sets
  • aza-allyl
  • metal
  • LITHIUM
  • ions
  • crystal structures

Fingerprint Dive into the research topics of 'Alkali metal-1-azaallyl complexes: X-ray crystallographic, NMR spectroscopic and ab initio calculational studies'. Together they form a unique fingerprint.

  • Cite this