The synthesis of soft tripodal ligands: restrictions on the preparation of hydrotris(thiazolyl)borate anions from borohydride melts

The syntheses of two new, soft, tripodal anions, hydrotris(mercaptothiazolyl)borate (Tz) and hydrotris(mercaptobenzothiazolyl)borate (Tbz), are reported. These species not only extend the series of thiazolylborate anions which can be generated using the protocol of Trofimenko, but analysis of the respective thione melting points and pKa values, enables the prediction of which thiazolylborate anions can be produced using borohydride melts. Both of the products are converted into their thallium complexes, which can be used as convenient ligand transfer reagents. The X-ray crystal structure of thallium(I) hydrotris(2-mercapto-benzothiazolyl)borate, [Tl(Tbz)]∞, is reported. The ligand complexes to Tl as a C3 tridentate species, while a bridging thione links Tl(Tbz) units into zigzag one-dimensional polymeric chains.