Issue 7, 1983

Azomethine derivatives. Part 20. Crystal and molecular structures of the lithioketimine [{Li(N[double bond, length half m-dash]CBut2)}6] and lithioguanidine [{Li[N[double bond, length half m-dash]C(NMe2)2]}6]; electron-deficient bridging of Li3 triangles by methyleneamino-nitrogen atoms

Abstract

The lithioketimine Li(N[double bond, length half m-dash]CBut2)(1) and lithioguanidine Li[N[double bond, length half m-dash]C(NMe2)2](2) have remarkably similar hexameric structures [{Li(N[double bond, length half m-dash]CR2)}6](R = But or NMe2) in the crystal phase, based on slightly folded chair-shaped Li6 rings held together by triply-bridging methyleneamino-groups, N[double bond, length half m-dash]CR2, thus providing examples of electron-deficient bridging by the nitrogen atoms of organonitrogen ligands. The mean distance between adjacent metal atoms in the Li6 rings is 2.35(2)Å in (1), and 2.445(2)Å in (2), and the mean dihedral angles between Li6 chair seats and backs are 85 and 78° respectively. The nitrogen atoms of the bridging methyleneamino-groups are approximately equidistant from the three bridged metal atoms, the mean Li–N distance being 2.06(1)Å in (1) and 2.00(1)Å in (2). The N[double bond, length half m-dash]C distances of 1.30(1) and 1.244(3)Å respectively lie within the range expected for carbon–nitrogen double bonds. Features of these structures are compared with those of related compounds, and some bonding implications are discussed.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1983, 1309-1317

Azomethine derivatives. Part 20. Crystal and molecular structures of the lithioketimine [{Li(N[double bond, length half m-dash]CBut2)}6] and lithioguanidine [{Li[N[double bond, length half m-dash]C(NMe2)2]}6]; electron-deficient bridging of Li3 triangles by methyleneamino-nitrogen atoms

W. Clegg, R. Snaith, H. M. M. Shearer, K. Wade and G. Whitehead, J. Chem. Soc., Dalton Trans., 1983, 1309 DOI: 10.1039/DT9830001309

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