An investigation into the properties of various types of coordination compounds of thallium

Abstract

A number of complexes of thallium (III) were prepared and several of their properties, including infra-red, visible and ultra-violet spectra, magnetic susceptibility and conductivities were investigated. Compounds of the type M3T1X6 (M = alkali metal orammonium ion and X = Cl; and M = Rb and X = Br), T1T1X4,Tl3TlX6 (X = Cl and Br), R4NTIX4 (R = CH3, C2H5 and X = Cl,Br and I), R4NX (R = CH3, C2H5 and X = Cl, Br and I), [TlOrg2X2]TlX4 and [TlOrg2X2]X' (Org = 2-2' bipyridine,1:10 phenanthroline and X = Cl, Br and I and X' =I) wereprepared and a systematic study of their diamagneticproperties was made. Anionic susceptibility values for theanions TlX6 and TlX4 were found and used in ascertaining the structure of the intermediate compounds, TITIX4 and Tl3TlX6 and of the 2-2' bipyridine and 1:10 phenanthroline complexes, [TlOrg2X2]TlX4 and [TlOrg2X2]X. For the intermediate compounds a lowering of diamagnetism due to bond shortening was noted and the magnetic evidence for the dimeric structure of the 2-2' bipyridine and 1:10 phenanthroline complexes was established. Theoretical diamagnetic susceptibility calculations for the above anions were furthermore made and compared with the experimental values.The preparation of new complexes of thallium (III) halides with quaternary ammonium cations of the typeR4NTIX4(R = CH3, C2H5, C6H5(CH3)3 and C4H9 and X = Cl,Br and I) and of mixed halide complexes of the type R4NTlX'X3 (R = CH3, C2H5 C6H5(CH3)3 and C4H9, X and X' =Cl, Br or I) was carried out and some of these compounds were studied from an analytical point of view. The tetra-n-butyl and trimethyl phenyl ammonium tetra iodothallates are recommended as promising reagents for the gravimetric determination of thallium in the tervalent state.Compounds of the type R4NTIX4, R4NTIX3X', [T10rg2X2]X and [T10rg2X2]X were shown to behave as uni-univalent electrolytes in organic solvents.The infra-red spectra of the 2-21 bipyridine and 1:10 phenanthroline halogeno complexes in the range 2000-500cm1 were investigated. Evidence for the cis configuration of the compound [Tlbipy2I2]TlI4 was found. The infra-red spectra of the mono, bis and tris complexes of thallium (III) nitrate of 2-2' bipyridine and 1:10 phenanthroline have been studied and evidence for their structures is provided. These infra-red results were found to be in agreement with those of conductivity measurements.The ultra-violet and visible absorption spectra of the R4NTIX4 (X = Cl, Br or I) in ethanol and acetonitrile solutions were examined. The characteristic TlCl4 and TlBr4 bands have been assigned and suggestions made as to the origin of the bands observed in the spectra of the tetraiodothallates. In the case of the intermediate compounds the ultra-violet absorption bands observed were found to arise mainly from thallium (I) transitions. The ultraviolet absorption spectra of the 2-2' bipyridine and 1:10 phenanthroline halogeno complexes in organic solvents were furthermore studied and the characteristic ligand bands observed in each case.Stability constants of the mono, bis and tris thallium (III):phenanthroline cations were determined in aqueous perchlorate solutions using the method of competitive reactions and a modified continuous variations technique. Further study was carried out in the ultra-violet region using Job's method and a comparison was made with available literature data.