Lead structural studies

The crystal structure of the potassium salt of 1,3,5,7-tetramethylcyclootatetraene dianion has been determined by X-ray dififaction. ° The eight-membered ring is planar, with aromatic C—C bond lengths of about 1.41 A without significant alternation. The spectroscopic and structural studies lead to the conclusion that the cyclooctatetraene dianion is a stabilized delocalized structure. 

It is likely that the lead and sulfur atoms in most of the lead sulfarsenites and related minerals have the tercovalent argonic structures Pb—- and S y+, as in galena. Nowacki (1969) has published a valuable summary of results of structural studies of the so-called sulfosalt minerals, in relation to a system of classification of the structures that he has developed. Many structures of sulfide minerals have been determined by him and his coworkers. 

The biological profile of the optimized lead structure emerging from these studies, compound (15a), was extensively investigated both in vitro and in vivo. The in vitro pattern of activity was in general excellent inasmuch... 

First the primary combinatorial library of chiral ligands LI —L5 and chiral activators Al —A5 (Scheme 12) were studied in order to optimize the lead structure of the next generation of chiral ligands and activators.87,89... 

The coordination of the bis(benzimidazole) system 38 is of considerable interest. This leads to a dinuclear species [Fe2383](Cl04)4. Structural studies show that the bridging 38c molecules in [Fe2 38c3](C104)4 are arranged in a triple helix [45]. 

Recent comparisons of physicochemical properties of lead structures to drug molecules also enhanced the understanding of which criteria to apply for selecting a promising series. Those studies were reported by Oprea, Teague etal. [39-41] based on a dataset of 96 lead-drug pairs and a variety of calculated physicochemical properties. 

These studies consistently suggest that less complex lead structures are better to detect and exhibit a favorable optimization potential, which might influence attempts to design more leadlike [44] compound libraries for screening. They have also... 

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