Abstract: | Capability of ReIII(tu-S)6]Cl3, where tu = thiourea, as a precursor to other ReIII complexes by ligand substitution in aqueous medium is studied. For the decomposition of Re(tu-S)6]Cl3, experiments suggest pseudo first order kinetics and observed rate constants vary from 1.3 × 10–2 to 9.6 × 10–2 min–1 in the pH range 2.80–5.04. Experiments in presence of incoming ligand (ethylendiaminetetraacetic acid or diethylentriaminepentaacetic acid) show that ligand substitution is significantly slower than decomposition of the precursor, even when pH and temperature are modified. Similar results were obtained working with ReIII(Metu-S)6]Cl3, where Metu = N-methylthiourea. Molecular structure of ReIII(Metu-S)6](PF6)3 · H2O was determined by single crystal X-ray diffractometry. The coordination polyhedron around the Re ion is a distorted octahedron. The six methylthiourea ligands are bonded to the metal through the sulfur atoms bond lengths range from 2.409(2) to 2.451(2) Å]. |