Preferred bonding motif for indium aminoethanethiolate complexes: structural characterization of (Me2NCH2CH2S)2InX/SR (X = Cl, I; R = 4-MeC6H4, 4-MeOC6H4)

The metathesis reaction of InCl3 with Me2NCH2CH2SNa or the redox reaction of indium metal with elemental iodine and the disulfide (Me2NCH2CH2S)2 yield the indium bis(thiolate) complexes (Me2NCH2CH2S)2InX X = Cl (3) and I (4)], respectively. Compounds 3 and 4 may be further reacted with the appropriate sodium thiolate salts to afford the heteroleptic tris(thiolate) complexes (Me2NCH2CH2S)2InSR R = 4-MeC6H4 (5), 4-MeOC6H4 (6), and Pr (7)]. Reaction of 2,6-Me2C6H3SNa with 4 affords (Me2NCH2CH2S)2InS(2,6-Me2C6H3) (8), while no reaction is observed with 3, suggesting a greater reactivity for 4. All isolated compounds were characterized by elemental analysis, melting point, and Fourier transform IR and 1H and 13C{1H} NMR spectroscopies. X-ray crystallographic analyses of 3-6 show a bicyclic arrangement and a distorted trigonal-bipyramidal geometry for In in all cases. The two sulfur and one halogen (3 and 4) or three sulfur (5 and 6) atoms occupy equatorial positions, while the nitrogen atoms of the chelating (dimethylamino)ethanethiolate ligands occupy the axial positions. The metric parameters of the (Me2NCH2CH2S)2In framework were found to change minimally upon variation of the X/SR ligand, while the solubility of the corresponding compounds in organic solvents varied greatly. 1H NMR studies in D2O showed that 6 and 7 react slowly with an excess of the tripeptide l-glutathione and that the rate of reaction is affected by the pendant thiolate ligand -SR.