Intermediate between structures

Fig. 3. Types of traps for tar sand deposits, where O represents a stratigraphic trap, x, an intermediate between stratigraphic traps H, a structural/stratigraphic trap , an intermediate between structural/stratigraphic and structural traps and...

Bonds with characteristics intermediate between ionic and covalent can also be represented by, for example, two imaginary structures, I and II both of which contrihute to the true structure III. Consider gaseous hydrogen chloride ... 

Carbon dioxide has a linear structure. The simple double-bonded formula, however, does not fully explain the structure since the measured carbon-oxygen bond lengths are equal but intermediate between those expected for a double and a triple bond. A more accurate representation is, therefore, obtained by considering carbon dioxide as a resonance hybrid of the three structures given below ... 

Solid cadmium(II) iodide Cdlj has a layer lattice —a structure intermediate between one containing Cd " and P ions and one containing Cdl2 molecules—and this on vaporisation gives linear, covalent I—Cd—I molecules. In solution, iodo-complexes exist, for example... 

The hexagonal-close-packed (hep) metals generally exhibit mechanical properties intermediate between those of the fee and bcc metals. For example Zn encounters a ductile-to-brittle transition whereas Zr and pure Ti do not. The latter and their alloys with a hep structure remain reasonably ductile at low temperatures and have been used for many applications where weight reduction and reduced heat leakage through the material have been important. However, small impurities of O, N, H, and C can have a detrimental effect on the low temperature ductihty properties of Ti and its alloys. 

Whereas the glass transition of a copolymer is usually intermediate between those of the corresponding homopolymers this is not commonly the case with the melting points. Figure 4.12 shows the effect of copolymerising hexamethylenesebacamide with hexamethyleneterephthalamide. Only when the monomer units are isomorphous, so that the molecules can take up the same structure, is there a linear relationship between melting point and composition (as with hexamethyleneadipamide and hexamethyleneterephthalamide). 

In 1991 MMM announced Fluorel II, a terpolymer of tetrafluoroethylene, vinylidene fluoride and propylene. As might be expected from the structure, this is intermediate between FKM and Aflas, having better resistance to many newer automotive oils, lubricants and transmission fluids than the former but better heat resistance than the latter. 

One of the structural implications of the delocalization of the negative charge, the identity of the two C—O bond lengths, intermediate between those of single and double bonds, has been verified by many crystal structure determinations. 

Prepolymer An intermediate chemical structure between that of a monomer and the final resin. 

Similar results were found by Bacsa el al. [26] for cathode core material. Raman scattering spectra were reported by these authors for material shown in these figures, and these results are discussed below. Their HRTEM images showed that heating core material in air induces a clear reduction in the relative abundance of the carbon nanoparticles. The Raman spectrum of these nanoparticles would be expected to resemble an intermediate between a strongly disordered carbon black synthesized at 850°C (Fig. 2d) and that of carbon black graphitized in an inert atmosphere at 2820°C (Fig. 2c). As discussed above in section 2, the small particle size, as well as structural disorder in the small particles (dia. —200 A), activates the D-band Raman scattering near 1350 cm . ... 

A number of bridged crown ethers have been prepared. Although the Simmons-Park in-out bicyclic amines (see Sect. 1.3.3) are the prototype, Lehn s cryptands (see Chap. 8) are probably better known. Intermediates between the cryptands (which Pedersen referred to as lanterns ) and the simple monoazacrowns are monoazacrowns bridged by a single hydrocarbon strand. Pedersen reports the synthesis of such a structure (see 7, below) which he referred to as a clam compound for the obvious reason . Although Pedersen appears not to have explored the binding properties of his clam in any detail, he did attempt to complex Na and Cs ions. A 0.0001 molar solution of the clam compound is prepared in ethanol. The metal ions Na and Cs are added to the clam-ethanol solutions as salts. Ultraviolet spectra of these solutions indicate that a small amount of the Na is complexed by the clam compound but none of the Cs . 

In all chemical reactions, the reacting atoms or molecules pass through a state that is intermediate in structure between the reactant(s) and the product(s). Consider the transfer of a proton from a water molecule to a chloride anion ... 

CrS has a unique monoclinic structure intermediate between NiAs and PtS types. 

Five-coordinate complexes are far more common than was once supposed and are now known for all configurations from d to d. Two limiting stereochemistries may be distinguished (Fig. 19.4). One of the first authenticated examples of 5-coordination was [VO(acac)2] which has the square-pyramidal 4 structure with the =0 occupying the unique apical site. However, many of the complexes with this coordination number have structures intermediate between the... 

B Benzene is a resonance hybrid whose structure is intermediate between two line-bond structures. 

One way to explain this situation is to assume that each of the bonds in S02 is intermediate between a single and a double bond. To express this concept, two structures, separated by a double-headed arrow, are written... 

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