Ring-laddering

Alkali metal organonitrogen chemistry is a fertile field of research boasting an ever-burgeoning variety of structural types, including not just clusters in the traditional sense but also rings, ladders, chains, etc. Even to review clusters alone would be a substantial task and not feasible to complete in a chapter of this limited size. Therefore what follows in the next section is firstly an introduction to commonly observed cluster motifs in metal nitrogen compounds, chosen because they illus-... 

III. Simple Lithium Amides (Amidolithiums) and Their Complexes Ring Laddering... 

Fig. 4 (a), Two-dimensional [NTIytSOUCHeOLf, XIII, formed by the sinusoidal chains which, in turn, consist of hexameric units from ref. 66, (b) (0-T) two-dimensional cadmium sulfate of [Cdj(S04)3(H20)2]2 in XIV, redrawn from ref. 35. Note the fusion of the four-membered ring ladders to form the layered structures. 

While the puckered (LiN)3 ring is the central structural unit in these unsolvated amides, a ring-ladder interconversion may be observed upon addition of coligand to the lithium amides. This structural rearrangement follows the same pattern as observed in the chemistry of monofunctional... 

Supramolecular self-assembly of lithium amides can occur by a process known as ring-laddering [71] by which ladder structures are generated. An illustrative recent example is octameric [LiNHBu ]g, 126, (Figure 6.7) [109]. 

During the stabilization process, dehydrogenation, oxidation, and nitrile cy-clization reactions result in the formation of a condensed pyridine ring ladder structure that is suitable for subsequent carbonization (29). The general mechanism is shown in Figure 7. The details of the stabilization mechanism are highly... 

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