Glycolate complexes structures

Fig. 20. Molecular structure of the glycolate complex anion [Be6(0CH2C02)8]4. Reproduced with permission from Ref. (182). Copyright 1992, Verlag der Zeitschrift fur Naturfors chung.

The blue PVA-Iodine complex was first found by Herrmann et al [5] who first synthesized PVA, and by Staudinger et aL [6] as early as 1927. Since then, the complex has attracted the interest of many researchers, and many studies have been done from different points of view. Some studied the complex formed in PVA solutions, while others studied the complex formed in bulk (film and fibers) PVA. Some concentrated their attentions on the effects of the PVA molecular structure on the complex formation, i.e. the 1,2 glycol hetero structure content of the chain backbone [10-12], the stereoregularity [10,11,13-15], the degree of saponification [16-18] and the chemical modification such as formalization [18-20]. 

Similar calculations were conducted also for the analogous glycolate complexes, using the hydrido complex 74 as model (Figure 9)30a. The calculations confirmed the ground state structure (I) established for similar compounds in the solid state. The diastereomeric TBP structures II and III, as well as the distorted SP structures IV and V, were calculated... 

The literature contains numerous observations on the properties of polysaccharides in cuprammonium solutions the work on cellulose is especially voluminous. Viscometric measurements in cuprammonium solution are regularly employed to determine the size of cellulosic molecules. However, before the spatial requirements for complexing with cuprammonium became known the properties of the complexes of polysaccharides could not be interpreted in terms of the structure of their monosaccharide units. With the present understanding of cupram-monium-glycol complexing, some of the earlier observations will be reexamined. 

Specific rotations in cuprammonium are based upon the weight of the glycol-containing molecule, not upon the weight of the copper glycol complex. This provision is necessary since the structures and molecular weights of the complexes are unknown. The optical rotations are the result of a reversible reaction, hence they are particularly dependent upon the concentrations of the reactants. The composition of the... 

Fig. 9 a, b. Complex formation of polyelectrolytes with rigid polymer chains such as polysaccharides. (a) pH Dependence of the composition of the complex. (1) Theoretical values assuming stoichiometry (2) Experimental values (b) Schematic representation of a ladder-like complex structure of one part of SCS and two parts of GC SCS = Sulfated cellulose, GC = glycol chitosan... 

Note Type of monomer used can vary from basic ethylene glycol mono- or di-methacrylates to complex structures that are beyond the scope of this book. Type of stabilisers, initiators, promoters, colorants, fillers, rubbers and thixotropic agents are propriety to adhesive manufacturing companies. 

The crystal structure of tetraethylene glycol complex of sodium tetraphenylborate, T. Ueda and N. Nakamura, Bull. Chem. Soc. Jpn., 1992, 65, 3180. 

In contrast, metal clusters have several active centers or can form multi-electron systems. Metal clusters such as Rh (CO)i6, Rh4(CO)i2, It4(CO)i2, Ru3(CO)i2, and more complex structures have been successfully tested in carbonylation reactions. Rhodium clusters catalyze the conversion of synthesis gas to ethylene glycol, albeit at very high pressures up to now. 

One of the most complex types of step-growth reaction is that between a di-glycol, HOROH, and a di-isocyanate, 0=C=NR N=C=0, to produce a polyurethane, which contains the structural unit —O—R O—(C=0)—(NH)—R (NH)—(C=0)—. Several subsidiary reactions can also take place and, although all of the possible reaction products are unlikely to be present simultaneously, polyurethanes usually have complex structures. Thermoplastic polyurethanes are copolymers that usually incorporate sequences of polyester or polyether segments. 

Rogers, R.D. Bauer, C.B. Structural Chemistry of Metal-Crown Ether and Polyethylene Glycol Complexes Excluding Groups 1 and 2. In Comprehensive Supramolecular Chemistry, Atwood, J.L., Davies, J.E.D., MacNicol, D.D., Vogtle, R, Eds. Elsevier Science Oxford, UK, 1996 Vol. 1, 315-355. 

Laser action in organic dyes was discovered independently by Sorokin et al. [8.45] and Schafer et al. [8.46] in 1966. Since then, several hundreds of dyes have been shown to have suitable properties, to greater or lesser degrees, for use as laser media. One of the most common laser dyes is Rhodamine 6G dissolved in methanol or ethylene glycol. The complex structure of organic dyes is illustrated in Fig.8.18, where the formula for Rhodamine 6G is shown. 

The IR spectra of PEO in the liquid state or in solution may be interpreted by comparing them with the assigned bands in the vibrational spectra of crystalline PEO [20, 26, 27] and structurally related compounds such as 1,2-dichlorethane, [19, 21-23]. ethylene chlorohydrin [30], metal-ethylenediamine complexes [31, 32] ester and ether derivative of ethylene glycol [33], crystalline polyesters [34], and metal-ethylene glycol complexes [35]. 

The materials shown and described above were generally prepared from the nucleophilic phenoxide or alkoxide and the appropriate bromide. The syntheses of a variety of such compounds were detailed in a report which appeared in 1977. In the same report, complex stability and complexation kinetics are reported. Other, detailed studies, of a similar nature have recently appeared" . Vogtle and his collaborators have also demonstrated that solid complexes can be formed even from simple polyethylene glycol ethers . Crystal structures of such species are also available... 

Erbium, tris(2,2,6,6-tetrametbyl-3,5-hep tanedione) structure, 1, 65, 66 Erbium complexes acetylacetone, 2, 374 Erhium(ill) complexes glycolic acid, 2, 472 Eriochalcite, 6, 855 Eriochrome black T metallochromic indicators, 1, 555 Eriochrome blue black R metallochromic indicators, I, 556 Eriochrome cyanine R metallochromic indicator, 1, 556 Erythrocruorin, 6, 689 dioxygen transport, 6,683 stability... 

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