17-Crown-5 ether condensed with 11-vertex nido-carborane

Abstract

The reaction of easily accessible nido carborane [nido 7,8 (HOCH 2 ) 2 7,8 C 2 B 9 H 10 ] -with tetraethylene glycol tosylate produces nido carborane sodium salt condensed with 17 crown 5 ether, Na[nido 7,8 O(CH 2 СH 2 OCH 2 CH 2 OCH 2 ) 2 7,8 C 2 B 9 H 10 ]. The structures of solvate complexes of this crown ether with acetone, ethanol, and water were studied by X ray diffrac tion analysis.Anionic polyhedral boron compounds attract atten tion of researchers due to their unique ability to extract highly toxic radioactive metal cations (primarily, 137 Cs + and 90 Sr 2+ ) from solutions of spent nuclear fuel. 1,2 To enhance efficiency and selectivity of extraction, polyhe dral anions are often bound to molecules of other com plexing agents, such as podands, crown ethers, and calix arenes. As a rule, these substituents are introduced by nu cleophilic opening of dioxane derivatives 3 of cobaltacar boranes. 4-7 In addition, alkylation of amino 8 and thio substituted 9-11 polyhedral anions is used sometimes. In this work, we propose an alternative approach to the syn thesis of carborane crown ethers based on the conden sation of easily accessible 1,2 bis(hydroxymethyl) ortho carborane.The cleavage of 1,2 bis(hydroxymethyl) ortho carbo rane by an ethanolic solution of KOH gives an 11 vertex monoanion [nido 7,8 (HOCH 2 ) 2 7,8 C 2 B 9 H 10 ] -(1), which was isolated as a salt with the Me 3 NH + cation in 82% yield. The subsequent interaction of 1 with tetra ethylene glycol tosylate in the presence of NaH affords sodium salt of nido carborane anion [2] -con taining the 17 crown 5 ether fragment in 64% yield (Scheme 1). The high yield of the cyclic pro duct is related, most likely, to the template effect of sodi um ion.