Synthesis of sepulchrates and sarcophaginates

The [Co(sep)]Cl3 complex is obtained from Reaction 24 between cobalt(III) [Co(en)3]Cl3 tris-ethylenediaminate and dilute aqueous solutions of ammonia and formaldehyde in the presence of lithium carbonate with subsequent isolation of the product by lEC [94-96]  

Several variants of the first-developed procedure have been reported [97-100]. 

The corresponding macrobicyclic cobalt(II) [Co(sep)](ZnCl4) H20 complex was prepared by reduction of the [Co(sep)]Cl3 complex with zinc dust in aqueous HCl [95], A similar procedure was used for the synthesis of the dithionate [Co(sep)](S206) salt in the presence of Li2S206 [99], The optically active R- and S-isomers of cobalt sepulchrate were obtained from the optically active parent A-[Co(en)3]Cl3 and A-[Co(en)3]Cl3 complexes [94-95], 

The use of nitromethane instead of ammonia has resulted in the formation of the [Co(diNOsar)]Cl3 H20 sarcophaginate [94, 101]. 

A similar procedure was employed to obtain the [Co(diNOsar)]3 cation optically active isomers and salts of other anions [101]. A more rational approach to the synthesis of this clathrochelate was reported in Ref. 102. 

---

Goedken and Peng s idea to employ the reaction between the amino groups, bound to the metal ion, and formaldehyde for the synthesis of clathrochelates proved to be beneficial. It has served as a basis for later studies of Sargeson and coworkers on the synthesis of sepulchrates and sarcophaginates. 

---