A Chain Aggregate of Methyllithium Tetramers

The reactions of 1,3,5-trimethyl-1,3,5-triazacyclohexane, TMTAC,
with methyllithium (MeLi) in the absence or presence of the Lewis
acid trimethylaluminum (AlMe3) give different kinds of
adducts but do not lead to deprotonation of the heterocycle. With
MeLi, an aggregation motif of endless linear chains of MeLi tetramers
is obtained, in which the three nonconnected lithium atoms are saturated
by binding to only one of the three nitrogen atoms of the tridentate
terminal TMTAC ligands; in contrast, in the presence of AlMe3, methyllithium is completely disaggregated to give a [Li(TMTAC)2][AlMe4] salt with six-coordinated lithium atoms.