Synthesis of crown ethers with the incorporated cobalt bis(dicarbollide) fragment

Abstract

A series of podands (acyclic analogues of crown ethers) related to 18-crown-6 was obtained by ring-opening reactions of the 1,4-dioxane derivative of nido-carborane [10-O(CH2CH2)2O-7,8-C2B9H11] with 1,2-S,S′- and O,O′-dinucleophiles (1,2-dimercaptoethane, 1,2-dimercaptobenzene, 1,2-dimercapto-ortho-carborane, 1,2-dihydroxy-ortho-carborane). By stepwise ring-opening reactions of the dioxane derivative with sulfur-containing nucleophiles the podand related to 15-crown-5 was prepared as well. The reactions of the obtained podands with CoCl2 result in the macrocyclic ring closure giving the corresponding crown ethers with the incorporated cobalt bis(dicarbollide) fragment K[8,8′-μ-S(OCH2CH2OCH2CH2)2-3,3′-Co(1,2-C2B9H9)2] and K[8,8′-μ-o-C6H4(OCH2CH2OCH2CH2S)2-3,3′-Co(1,2-C2B9H9)2]. The structure of Na[8,8′-μ-o-C6H4(OCH2CH2OCH2CH2S)2-3,3′-Co(1,2-C2B9H9)2] was determined by single crystal X-ray diffraction.