Synthesis, characterization, X‐ray crystal structure and in vitroantitumour activity of bis(1,2‐dicarba‐closo‐dodecaborane‐9‐carboxylato)di‐n‐butyltin

The 1 : 2 condensation of dibutyltin(IV) oxide with 1,2‐carborane‐9‐carboxylic acid resulted in bis(1,2‐dicarba‐closo‐dodecaborane‐9‐carboxylato)di‐n‐butyltin (1), the first carborane‐based organotin compound where the carborane cage is linked to the carboxylic moiety via a boron atom. The structure of 1, characterized by 1H, 11B, 13C, 119Sn NMR spectroscopy and X‐ray diffraction, was shown to correspond to bis(1,2‐dicarba‐closo‐dodecaborane‐9‐carboxylato)di‐n‐butyltin. Compound 1was screened in vitroagainst seven tumour cell lines of human origin and was found to be significantly more active than 5‐fluorouracil, cis‐platin and carboplatin but less active than methotrexate and doxorubicin. Copyright © 2003 John Wiley & Sons, Ltd.