Higher Aggregate Lithium Amides

Treatment of 1,4-dimethylpiperazine (dmp) with lithium anilide LiNHPh gave [(LiNHPh)5(dmp)2]. It has a distorted ladder structure with five Li—N rings. However, it is U-shaped rather than stepped as shown by 4 [N = NHPh N(dmp) = 1,4-dimethylpi-peridine] from which it can be seen that the bridgehead lithium is bound to 

A number of hexameric lithium complexes are known.i Liss-iss example, there is a I--------------------------------------1,  

The largest known discrete lithium amide stracture, the tetradecameric [Lii4(O)(N(H)-(C5H9))i2] cage was synthesized in the presence of water it has a central oxo-anion. Fig. 2.2 highlights the Li 14N12O metal-heteroatom core. 

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Dimeric and higher aggregate lithium amides can generally be classified into the coordination motifs illustrated in Scheme 2.2. The four-membered (LiN)2 ring is ubiquitous in lithium amide chemistry and is observed both in discrete dimeric structures in either planar (Scheme 2.2, A) or non-planar (Scheme 2.2, B) geometries as well as in oligomeric and polymeric (ladder) frameworks (Scheme 2.2, C). Trimeric six-membered (LiN), ring... 

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