Chain ladder

The simple diols R2Si(OH)2 (R = Pr , Bul, c-C6Hn, and o-tolyl) form similar, but not identical, hydrogen-bonded chains. The structures of the Pr1 (305), Bu (40, 278), and c-C6Hn (292) compounds are very similar in that they comprise ladder chains of the general type 65, in which pairs of molecules are linked to form dimers and then further hydrogen bonds link the dimers to form the chains. [It has also been... 

In contrast, within (p-EPYNN)[Ni(dmit)2], first synthesized in 1996 [79], it has been proven that spin-ladder chains of the Ni(dmit)2 moiety coexist with the ferromagnetic one-dimensional chain of the p-EPYNN radical cation. Spin-ladders are of interest because of their potential applications in the area of quantum magnets and because it has been predicted that holes doped into even-leg ladders may pair and possibly superconduct [90-92]. 

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-... 

Note A ladder chain is a double-strand chain with adjacent constitutional units joined to each other through four atoms, two on one side and two on the other side of each... 

The high-temperature regime has been assigned to the spin-ladder chains of [Ni(dmit)2] anions, which become nonmagnetic at lower temperature (150 K),... 

Figure 9. Structure of (/)-EPYNN)[Ni(dmit)2], showing ID chain ofp-EPYNN and ID ladder chain of Ni(dmit)2 (dashed lines shows S S contacts between 3.2 and 3.7 A). [Drawn from the data available in (304).]...

Kossler et al. (349] described the cyclopolymerization of isoprene in the presence of EtAlCl2. They postulate simple diene addition to the propagating ladder chain... 

INTRODUCTTON Polymer molecules may have a variety of architectural structures such as linear, ring, star, branched, and ladder chains as well as three-dimensional network structures. The first synthetic cychc jxjlymers to be prepared and characterized were the poly(dimethylsiloxanes) (PDMS), which were reported in 1977. Since that time a number of other cychc pwlymers have been synthesized including cyclic polystyrene, cyclic poly(phenyhnethylsiloxane), cyclic poly(2-vinylpyridine), cyclic polybutadiene, and cychc poly(vinyhnethylsiloxane). ... 

FIGURE 8.4 The four different ways to arrange three poles (npper row) and dipoles (lower row) (a) three-ports circular or tangential, (b) two-ports chain ladder, (c) two-ports ladder chain, and (d) three-ports radial. The first three structures have three poles whereas the fourth one has four poles. 

Iodide complexes also adopt different structural types. The [Cu(S2CNBu2)2] [I3] complex polymeric with no anion-cation interactions (S) (320), while [Cu(S2CNEt2)2][l3] is also polymeric, but adopts structural type (W) to form infinite ladder chains in which bis(dithiocarbamate) units are separated by I3 anions (324). In contrast, [Cu(S2CNPt2)2][I5] adopts a type (X) structure in which the copper center is live coordinate, an is bound to the central atom of the 15 anion [Cu- I 3.665(4) A] (318). 

The stabilization process introduces significant volume reduction to the precursor fibers. The longitudinal shrinkage is resisted mechanically, but the diameter of the fibers is allowed to reduce. During that process, the orientation of PAN chains is largely preserved by the strong intermolecular interactions and by the newly-formed rigid ladder chain stmctuie. 

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