Solvent and temperature induced switching between structural isomers of Rh(I) phosphinoalkyl thioether (PS) complexes.

To develop functional systems based on the weak-link approach (WLA), it is important to understand how solvent and ligand binding strength alter the coordination geometry of complexes formed from this method. A series of phosphinoalkyl thioether (PS) hemilabile ligands with varying electron donating abilities were synthesized and incorporated into homoligated RhI(PS)2Cl complexes to help understand the effects of solvent and ligand binding strength on the preferred coordination modes. The switching between closed and semiopen structural isomers of these RhI(PS)2Cl complexes was studied by variable temperature 31P NMR spectroscopy in different solvent mixtures of CH2Cl2 and tetrahydrofuran (THF) to obtain thermodynamic parameters (ΔG°, ΔH°, TΔS°, and Keq). The isomers differ in the position of the chloride counterion. In the closed isomer, the Cl− anion occupies the outer coordination sphere, while in the semiopen isomer, the Cl− has moved inner sphere and displaced one of the Rh−S bonds. The closed isomer...