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DOI: 10.1039/A605849C (Paper) Reference Section for: J. Chem. Soc., Dalton Trans., 1997, 951-956

Lithiated amidines: syntheses and structural characterisations

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James Barker, Donald Barr, Nicholas D. R. Barnett, William Clegg, Ian Cragg-Hine, Matthew G. Davidson, Robert P. Davies, Susan M. Hodgson, Judith A. K. Howard, Melvyn Kilner, Christian W. Lehmann, Isabel Lopez-Solera, Robert E. Mulvey, Paul R. Raithby and Ronald Snaith

Abstract

The reaction of a toluene solution of PhNC(Ph)NHPh (N,N′-diphenylbenzamidine) with n-butyllithium gave the toluene-solvated amidinolithium compound {Li[PhNC(Ph)NPh]}n1. Similarly the same reaction performed in the presence of the Lewis-base donors (Me2N)3PO (hmpa), Me2N(CH2)2NMe2 (tmen) or [Me2N(CH2)2]2NMe (pmdien) yielded the amidinolithium complexes {Li[PhNC(Ph)NPh·hmpa]}22, {Li[PhNC(Ph)NPh]·tmen} 3 and {Li[PhNC(Ph)NPh]·pmdien} 4 respectively. In addition the reaction of a toluene solution of the related amidine PhNC(Me)NHPh (N,N′-diphenylacetamidine) with LiBun in the presence of hmpa afforded {Li[PhNC(Me)NPh]·hmpa}25. The solid-state structures of 2–5, which have been resolved by single-crystal X-ray diffraction methods, show both similarities and differences. The complexes 3 and 4, which contain the di- and tri-dentate ligands tmen and pmdien respectively, are monomeric, whilst use of the unidentate Lewis base hmpa results in dimers 2 and 5. However, the way in which dimerisation is achieved differs. The co-ordination geometry about the lithium cation is clearly influenced by the choice of donor and as such shows how a change in the denticity of the donor ligand utilised can have a significant effect on the solid-state structure of the system.

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