Divalent organo compounds

Competitive adsorption on sepiolite clay of a monovalent dye (e.g., methyl green or methyl blue) and of the divalent organo-cationic herbicides diquat and paraquat was studied by Rytwo et al. (2002). To evaluate a possible competitive adsorption between the two organic compounds, separate aqueous solutions of each cation were used and adsorption isotherms were obtained. Fig. 8.27 shows the amount of diquat, paraquat, and methyl green adsorbed on sepiolite as a function of total added divalent cation. It may be observed that, when the added amounts were lower than the cation exchange capacity of the sepiolite (O.Mmol kg ), aU cations were completely adsorbed. 

Organic tellurium compounds with one Te—C bond containing divalent, tetravalent, or hexavalent tellurium have been prepared. The most widely investigated and best characterized compounds are the diorgano ditellurium derivatives and the organo tellurium trihalides. Pentafluoroethyl tellurium chloride tetrafluoride is the only known example of a hexavalent tellurium compound with one Te-C bond in the molecule. 

While the inorganic chemistry of divalent tin and lead is well established, there are few well-characterized divalent organotin and organo-lead compounds. The R2Sn formulation seen in the older literature has proved to be an empirical formula, the formally divalent stannylene actually being an oligomeric linear or cyclic organostannane. Neumann has commented on this point several times (1-3). 

---