Rhenium Tris(pyrazolyl)borate Complexes with O -Donor Ligands: Synthesis and Structures

Abstract The reaction of TpReOCl 2 (Tp is the tris(pyrazolyl)borate anion) with methanol in the presence of triethylamine affords new rhenium alkoxide complex TpReO(OMe) 2 ( I ). Unlike the starting complex resistant to hydrolysis, complex I reacts with water in toluene to form the dimeric complex [TpReO(μ-O)] 2 ( II ). The action of a large amount of water in acetone also leads to the decomposition of some Tp ligands and formation of the cationic complex [(TpReO) 2 (μ-O)(μ-C 3 H 3 N 2 )]ReO 4 ( III ) with the pyrazolate bridging ligand and perrhenate anion on the external sphere. The treatment of complex I with acetic anhydride gives the rhenium tris(pyrazolyl)borate complex bearing terminal acetate substituents TpReO(OAc) 2 ( IV ). The synthesized complexes are characterized by IR and NMR spectroscopy, and their structures are determined by X-ray diffraction (CIF files CCDC nos. 2081834 ( I ), 2081835 ( II ), 2081836 ( III ), 2081837 ( IV )).