Solid state structures of the chiral lithium amide complexes (S>[(Ph(Me)CH)(PhCH2)NLHhf]2 and (A)-[(Ph(Me)CH)(PhCH2)NLi-pmdta]t

Two chiral lithium amide complexes derived from a-(methylbenzyl)benzylamine have been synthesised and structurally characterised in the solid state by X-ray crystallography. Complexation of (5)-{[Ph(Me)CH][PhCH2]NLi} with thf results in the dimer (5)-{[Ph(Me)CH][PhCH2]NLi-thf}2 (space group />432,2). The dimer is composed of a central four membered (NLi)2 ring with the Ph(Me)C and Ph(CH2) moieties adopting a cis orientation relative to the ring rather than the more usual trans. The reaction of (Ä)-{[Ph(Me)CH][PhCHJNLi} with the tridentate N donor, pmdta, (Ar,Ar,Ar',Ar',Ar-pentamethyldiethylenetriamine) results in the monomer CK)-{[Ph(Me)CH][PhCH2]NLi'pmdta} (space group, P2,). In both structures the amido moiety adopts a similar 'butterfly-in-flight' conformation. Heating either the solution or crystals of the monomer results in the loss of H2 at the benzylic carbons and conversion to an aza-allyl structure, as evidenced by NMR.