622854-65-3Relevant academic research and scientific papers
Diphenylthallium(III) thiosemicarbazonates: Flexibility of coordination in the solid state and polymorphism in chloroform solution
Lobana, Tarlok S.,Casas, José S.,Casti?eiras, Alfonso,García-Tasende, María S.,Sánchez, Agustín,Sordo, José
, p. 23 - 32 (2003)
The reactions of diphenylthallium(III) hydroxide in water-ethanol at room temperature with thiosemicarbazones HL=R=N(3)-N(2)H-C(1)(S)-N(1)H2 (RO=cyclopentanone, benzaldehyde, 2-hydroxybenzaldehyde, 4-methoxybenzaldehyde, acetophenone, furan-2-carbaldehyde, pyridine-2-formaldehyde and pyridine-2-acetaldehyde) afforded novel diphenylthallium(III) thiosemicarbazonates of stoichiometry [TlPh2(L)] (compounds 1-8, respectively) that were characterised with the help of analytical data, physical properties, IR spectrometry, multinuclear (1H, 13C and 205Tl) NMR spectroscopy and X-ray studies of 1, 7 and 8. In crystals of 1 (and probably also in those of 2, 4, 5 and 6), Tl(III) is bound to two phenyl carbons and to the N(3) and S atoms of the monodeprotonated thiosemicarbazone in a distorted trigonal bipyramidal coordination polyhedron with one vacant site in the equatorial plane. In 3 the metal atom is S,N(3),O-coordinated. In 7 and 8 there are three independent molecules: all three have distorted trigonal bipyramidal coordination with Tl coordinated to two carbon atoms and to the N(Py), N(3) and S atoms of the deprotonated thiosemicarbazones, but they differ significantly in their bonding parameters. The 205Tl NMR spectra suggest that for 1-6 more than one coordination mode is present in solution in chloroform, whereas for 7 and 8 there is only one species. Low temperature proton NMR studies of 7 and 8 showed that the energy barrier to rotation of the amino groups about the C1-N1 bond correlated with the bonding parameters of the thioamide group in the solid state; in both cases the barrier is somewhat higher than in thiosemicarbazonates of PhHg(II).
