Novel rhenium(V) oxo complexes containing bis(pyrazol-1-yl)acetate and bis(pyrazol-1-yl) sulfonate as tripodal N,N,O-heteroscorpionate ligands

Reactions of [NBu4][Re(O)Cl4] with bis(pyrazol-1-yl)methane (bpzm), bis(pyrazol-1-yl)acetate (Hbpza) and with the lithium salts Li[bis(3,5-dimethylpyrazol-1-yl)acetate] (Libdmpza), and Li[bis(3,5-dimethylpyrazol-1-yl)methanesulfonate] (Libdmpzs) produce a series of new compounds containing either a k2-N,N bidentate pyrazolyl ligand [Re(O)(bpzm)Cl3 1, Re(O)(bpzm)(OMe)Cl2 2, Re(O)(bpzaOMe)(OMe)Cl2 4] or a k3-N,N,O heteroscorpionate [Re(O)(bpza)Cl2 3, Re(O)(bdmpza)Cl2 isomers 5 and 6, Re(O)(bdmpza)(OMe)Cl 7, Re(O)(bdmpza)(OEt)Cl 8, Re(O)(bdmpzs)(OMe)Cl 9, Re(O)(bdmpzs)(OEt)Cl 10]. X-ray analyses of 1 and 3 show in both cases a distorted octahedral environment around the rhenium atom. The nature and the geometry of the products are strongly determined by the reaction solvent and by the heteroscorpionate ligand itself. When scorpionates bear methylated pyrazolyl rings mixed heterocomplexes Re(O)(bdmpza)(glycol) 11 and Re(O)(bdmpzs)(glycol) 12 are obtained (H2glycol = ethylene glycol). Also 11 shows an octahedral geometry as assessed by X-ray study.