Synthesis, characterization and crystal structure of [(Hdmpz){HB(dmpz)3}VO(µ-η5-C 5H4CO2)Fe(η5-C5 H5)] (Hdmpz = 3,5-dimethylpyrazole)

Abstract

The complex [(Hdmpz){HB(dmpz) ₃ }VO(µ-η ⁵ -C ₅ H ₄ CO ₂ )Fe(η ⁵ -C ₅ H ₅ )] 1 (Hdmpz = 3,5-dimethylpyrazole) has been synthesized and its spectroscopic properties and crystal structure determined. It crystallizes in the triclinic space group P, with a = 10.563(2), b = 12.460(4), c = 13.028(5) Å, α = 95.16(3), β = 98.93(2), γ = 99.59(2)° and Z = 2. The vanadium(IV) ion is in a distorted-octahedral environment with nitrogen atoms of the borate ligand occupying three facial sites and the other sites by an oxo group, an oxygen atom from the ferrocenecarboxylate, and a nitrogen atom from a neutral Hdmpz. The cyclic voltammogram in CH ₂ Cl ₂ showed two oxidations at +0.70 and +1.41 V vs. Ag–AgCl, which are completely reversible at -30 °C. The first corresponds to oxidation of the ferrocenecarboxylate moeity, giving 1 ⁺ . The reversibility of 1 → 1 ⁺ has also been demonstrated by electronic absorption and EPR resonance spectroscopies. Complex 1 is EPR active giving spectra as expected from an isolated vanadium(IV) centre, whilst 1 ⁺ is EPR silent.