Solvothermal Approach to the Synthesis of Triangular Re(III) Iodide and Bromide Cluster Complexes

Abstract

Abstract: Crystalline Re3I9 (1) is formed in a quantitative yield upon the hydrothermal reaction of NaReO4 with concentrated HI at 200°C. The reaction of Re3I9 with HBr at 200°C results in complete replacement of iodide ligands with bromide ligands with retention of the cluster core. The addition of pyridine to the reaction mixture leads to crystallization of the pyridinium salt (PyH)2[Re3Br11(H2O)] · 4H2O (2). In the presence of phosphoric acid, (PyH)2[Re3Br9(PO4H)]·H2O (3) and (Et4N)2[Re3Br9(PO4H)]·2H2O (4) were isolated. The crystal structures of the compounds 2–4 were determined by single crystal X-ray diffraction. Complexes 1 and 4 were characterized by powder X-ray diffraction. The Re/halogen ratio for compounds 1–4 was determined by energy dispersive spectroscopy. Elemental analysis and 31P NMR spectroscopy data were obtained for compound 4, and vibrational spectra were measured for 1 (far-IR range) and 4 (near-IR range). The data for thermal stability in inert atmosphere were obtained for 1.