PYRIDOXAL THIOSEMICARBAZONATE MONOHYDRATE OF DIMETHYLTHALLIUM(III) - X-RAY STRUCTURE AND SPECTROSCOPIC PROPERTIES

The title compound, [TIMe2(HL) (H2O)] (HL = monoanion of pyridoxal thi osemicarbazone), crystallizes in the triclinic space group P (1) over bar (C-i(1), No. 2). The HL- anion coordinates to the thallium atom, i n an unusual mode through the S atom (Tl-S = 2.832(1) Angstrom), and a lso forms a weak bond with the metal atom of a neighbouring molecule t o make an asymmetric bridge (Tl'... S = 3.190(1) Angstrom. The acidic proton retained in the thiosemicarbazonato anion is located on the oxy gen of the phenolic hydroxyl group. The water molecule is only 2.630(4 ) Angstrom from the metal, suggesting a rather strong bond that contra sts with the long distance between the thallium and the phenolic oxyge n (Tl ... O(1)'=3.124(4) Angstrom). If both strong and weak intermolec ular interactions are taken in account, the metal has distorted octahe dral coordination with the methyl groups in apical positions. The soli d state IR spectrum and H-1, C-13 and Tl-205 NMR spectra in DMSO solut ion are also discussed.