mer-Trichloridotris(tetrahydrothiophene-κS)iridium(III): preparation and comparison with other mer-trichloridotris(tetrahydrothiophene-κS)metal complexes

Abstract

The title complex, [IrCl3(C4H8S)3], was prepared according to a literature method. A suitable crystal was obtained by diffusion of pentane into a dichloromethane solution and analyzed by single-crystal X-ray diffraction at 100 K. The title complex is isotypic with mer-trichloridotris(tetrahydrothiophene-κS)rhodium(III). However, the orientation of the tetrahydrothiophene rings is different from an earlier report of mer-trichloridotris(tetrahydrothiophene-κS)iridium(III) deposited in the Cambridge Structural Database. The IrS3Cl3 core shows a nearly octahedral structure with various bond angles within 1–2° of the perfect 90 or 180° expected for an octahedron. The structure of the title compound is compared with the previous iridium complex as well as the rhodium and other octahedral metal tris-tetrahydrothiophene compounds previously structurally characterized. DFT calculations were performed, which indicate the mer isomer is significantly lower in energy than the fac isomer by 50.1 kJ mol−1, thereby accounting for all compounds in the CSD being of the mer geometry. Powder X-ray diffraction of the bulk material showed that the preparation method yielded only the isomorph reported in this communication.

Keywords

• crystal structure
• iridium
• tetrahydrothiophene
• conformers