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

The title complex, [IrCl3(C4H8S)3], was prepared according to a literature method. A suitable crystal was obtained by diffusion of pentane into a di-chloro-methane solution and analyzed by single-crystal X-ray diffraction at 100 K. The title complex is isotypic with mer-tri-chlorido-tris-(tetra-hydro-thio-phene-κS)rhodium(III). However, the orientation of the tetra-hydro-thio-phene rings is different from an earlier report of mer-tri-chlorido-tris-(tetra-hydro-thio-phene-κS)iridium(III) deposited in the Cambridge Structural Database. The IrS3Cl3 core shows a nearly octa-hedral structure with various bond angles within 1-2° of the perfect 90 or 180° expected for an octa-hedron. The structure of the title compound is compared with the previous iridium complex as well as the rhodium and other octa-hedral metal tris-tetra-hydro-thio-phene 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.