Oxo-rhenium(V) compounds containing bis(3,5-dimethylpyrazol-1-yl)acetate scorpionate ligand

Ligand-exchange reactions of bidentate donor agents such as malonic acid (H₂mal) or 1,3-propanediol (H₂diol) with labile Re(O)(bdmpza)Cl₂ (bdmpza = bis(3,5-dimethylpyrazol-1-yl)acetate) precursors in the presence of triethylamine yield the mixed-ligand complexes Re(O)(bdmpza)(mal) (2) and Re(O)(bdmpza)(diol) (3), respectively. Compounds 2 and 3 can also be obtained starting directly from [Re(O)Cl₄][NBu₄], Libdmpza and the appropriate bidentate ligand in the presence of triethylamine. X-ray analyses of the two compounds show in both cases a distorted octahedral geometry around the rhenium atom comprising two pyrazolyl nitrogens and the bidentate ligand in the equatorial plane, and the oxo and the carboxylate oxygens on the apices. Differently from 2 and 3, X-ray diffraction analysis of the asymmetric precursor (OC-6-42)Re(O)(bdmpza)Cl₂ (1) reveals a slightly distorted octahedral geometry with the apical positions taken by the carboxylate oxygen and a chloride atom, and with the equatorial plane occupied by the nitrogens of the bis-pyrazolyl ligand, a chloride and the oxygen atom.