Complex Ions and chelate compounds

Lead complexes play a dominant role In Its separation and determination. The most important nonorganlc lead complexes are those formed with halides and the hydrolyzed complexes formed in alkaline solution. 

Lead is only slightly soluble in dilute acidic chloride solutions but as the chloride ion concentration Increases the solubility becomes greater. The solubility of lead chloride 

PbNOg j has been established (H8). That formation of negatively charged nitrate complexes does not take place to any considerable extent la Indicated by the failure of lead nitrate to Increase In solubility with Increasing nitrate concentration (S4). Uie absence of such complexes Is also shown by the failure of lead nitrate to absorb appreciably on anion exchange resins from nitric acid or ammonium nitrate solutions (N2) and by the non-extractablllty of lead Into diethylether from nitrate solutions (Bl). 

The formation of plumblte Ions HPb02 In strongly alkaline solutions has already been noted in section IV-4. This complex plays an Important role In some separation processes. A few other Inorganic complexes such as the selenocyanates, Pb(CNSe)2 and Pb(CNSe)g are known (G1)(G2) but have not been Important for lead analysis. 

Llgend Abbreviated Fomula Metal Chelate Temp c Ionic Btreng  

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