Lead compounds complexity

The mixture of diastereomers has been separated into its two principal components by Izatt, Haymore, Bradshaw and Christensen who had previously identified the two principal diastereomers as the cis-syn-cis and cis-anti-cis isomers. Their previous separation technique involved a protracted chromatography on alumina but the new method relied upon the difference in water solubility between the lead perchlorate and hydroniur perchlorate complexes. The lead perchlorate complex is essentially insoluble in aqueous solution and precipitates from it. Using this method, one may obtain 39% of the high-melting polymorph (mp 83—84°) and 44% of the low-melting compound (mp 62—63°). Note that the former also exists in a second crystalline form, mp 69—70°. 

The metaboHsm of animal cells is rather complex and this leads to complex growth requirements compared to bacterial cells. Therefore, cells were grown in undefined biological fluids for a long time. Eagle [11] was the first to reduce the number of defined compounds to those shown to be essential for cell growth. 

Several tri(cyclopentadienyl)tin(ll) and lead(ll) complexes have been prepared with alkali metal cations. The arrangement of Cp rings around the metal is in a paddle wheel configuration the alkali cation is bound to Cp and not Sn or Pb, further supporting the view of a weak alkali metal group 14 bond. Representative examples of these compounds include (77S-Cp)2E(/r-Cp)-Na(PMDTA) (E = Sn 230, Pb 231).239 240... 

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