Crystal Structures of the Chiral Diamine (<i>R,R</i>)-TMCDA with the Commonly Used Alkyllithium Bases Methyllithium, <i>iso</i>-Propyllithium, and <i>sec-</i>Butyllithium

(R,R)-N,N,N‘,N‘-Tetramethyl-1,2-diaminocyclohexane [(R,R)-TMCDA] coordinated alkyllithiums crystallize as dimeric [MeLi·(R,R)-TMCDA]2 and [i-PrLi·(R,R)-TMCDA]2 and monomeric s-BuLi·(R,R)-TMCDA. s-BuLi·(R,R)-TMCDA is the first structurally characterized Lewis base coordinated adduct of s-BuLi. The high reactivity of s-BuLi·(R,R)-TMCDA in deprotonation reactions results from the monomeric structure.