Hydridotris(thioxotriazolyl)borate (Tt), an ambidentate (N-3/S-3) tripodalligand. X-ray crystal structures of sodium, bismuth(III), tin(IV), and manganese(I) complexes

Treatment of the heterocycle 5-thioxo-4,5-dihydro-3,4-dimethyl-1,2,4-triazo le (thioxotriazole) with sodium tetrahydroborate at 210 degreesC provides t he new [N-3/S-3] ambidentate tripod ligand hydridotris(thioxotriazolyl)bora te (Tt) as its sodium complex salt. Complexes of this ligand with sodium, b ismuth(III), tin(IV), and manganese(I) have been synthesized and characteri zed by X-ray crystallography. The structures of these complexes illustrate the ambidentate character of the ligand with the softer metals bismuth and tin exhibiting sulfur coordination, while sodium and manganese(I) bond via the ligand nitrogen donors. In the [S-3] coordination mode the li-and creat es eight-membered chelate rings with the metal with the consequence that th e metal ligand unit adopts a propeller-type conformation with C-3-symmetry. However, in the [N-3] mode six-membered chelate rings are formed analogous to the familiar hydrotris(pyrazolyl)borate (Tp) ligand.