Preferred bonding motif for indium aminoethanethiolate complexes: Structural characterization of (Me2NCH2CH 2S)2InX/SR (X = Cl, I; R = 4-MeC6H4, 4-MeOC6H4)

Article abstract of DOI:10.1021/ic061132h

The metathesis reaction of InCl₃ with Me₂NCH ₂CH₂SNa or the redox reaction of indium metal with elemental iodine and the disulfide (Me₂NCH₂CH ₂S)₂ yield the indium bis(thiolate) complexes (Me ₂NCH₂CH₂S)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-Me ₂C₆H₃) (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 (Me₂NCH ₂CH₂S)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.