Lithium bis(amido)cuprates are an important class of bimetallic base, which can
chemo- and regioselectively metalate aromatic compounds, via directed ortho
cupration (DoCu). This thesis begins with an introduction to aspects of the chemistry
of organolithium compounds, group 11 organometallic compounds and their
lithium 'ate complexes. Examples of such synergic bases are presented and the
introduction is concluded with a discussion of lithium bis(amido)cuprate bases,
which along with their silver congeners, are the subject of this dissertation. In
general, syntheses involve the addition of a lithium amide to a group 11 salt,
resulting in the formation of a lithium bis(amido)cuprate or argentate.
Structurally focussed work commences with the use of new amide ligands to develop
heteroleptic bis(amido)cuprate systems. The reaction of mixtures of lithium
amides with CuBr provides a series of novel Lipshutz-type and Gilman cuprates.
Interesting structural features are uncovered, which are rationalised in terms of
altered steric demands in the newly introduced amide ligands in these systems.
CuSCN and CuOCN are investigated as inexpensive and safer alternatives to
CuCN in cuprate formation. In the solid state, a series of Lipshutz-type cuprates
(TMP)2Cu(SCN)Li2(L) (L = Et2O, THF, THP) are revealed, whose molecular
conformations are infuenced by the identity of the Lewis base. However, in benzene
solution, in situ conversion of Lipshutz-type to Gilman cuprate is found to
occur. Moving to the synthetic setting, derivatisation of chloropyridines is attempted
and gives functionalised halopyridines in 51-71 % yield. CuOCN is found
to behave quite differently when reacted in the same way as CuSCN, whereby
X-ray crystallography reveals structures in which Cu-Li substitution is apparent. The unique reactivity of CuOCN is interpreted with the aid of multinuclear NMR
spectroscopy. A new route to Lipshutz-type cuprates is explored by the synthesis
of (TMP)2Cu(OCN)Li2(THF) from Gilman cuprate and LiOCN. This avoids
Cu-Li substitution. Meanwhile, reaction of lithium N,N-diisopropylamide with
CuOCN also avoids metal disorder, to give a novel lithium cuprate-lithium amide
adduct.
Further advances in our understanding of group 11 'ate complexes are made
by introducing silver as a spectroscopically active nucleus in the lithium argentates
(TMP)2AgLi and (TMP)2Ag(CN)Li2(THF). In the solid state, these parallel
the structures known for Gilman cuprate (TMP)2CuLi and Lipshutz cuprate
(TMP)2Cu(CN)Li2(THF), respectively. In solution, NMR spectroscopy reveals
features consistent with retention of these structures. Lastly, the formation of
mixed Cu-Li aggregates from combining TMPLi and TMPCu in aromatic solvent
are investigated. Surprising reactivity is uncovered, in which the aromatic solvent
is metalated and incorporated into mixed-metal aggregates.
This thesis concludes with a summary of the findings and suggestions for future
work, including how the findings presented herein may be transformed into practical
improvements to cuprate systems. In particular, the possibility that Gilman
cuprate may be activated towards the metalation of aromatic substrates by the
addition of sub-stoichiometric or catalytic amounts of a lithium salt additive is
explored.EPSRC grant EP/J500380/