15391-95-4Relevant academic research and scientific papers
Preparation, Structure and Reactivity of the Binuclear Di-μ-oxo-bis Complex
Ikari, Shinji,Ito, Tasuku,McFarlane, William,Nasreldin, Mohamed,Ooi, Bee-Lean,et al.
, p. 2621 - 2628 (1993)
The dark brown dirhenium(IV) complex Ba2*4.5H2O (H4edta = ethylenediamie-N,N,N',N'-tetraacetic acid), peak at 450 nm (ε = 7880 M-1 cm-1 per dimer), has been prepared.From X-ray crystallography, the compound crystallizes in a monoclinic space group C2/c with a = 15.867(3), b = 12.914(2), c = 9.686(2) Angstroem, β = 123.40(1) deg and Z = 4.The structure is centrosymmetric, with the Re atoms having distorted octahedral co-ordination, and each tetradentate edta(4-) ligand having two unco-ordinated -CH2CO2(1-) groups.The Re2O2 ring is planar and the short Re-Re distance of 2.362(2) Angstroem is consistent with multiple metal-metal bonding.The structure is that of the meso ΔΛ form.The (1)H and (13)C NMR spectra of the uncrystallised sodium salt in aqueous solution (pH 7.5) provide evidence for both meso ΔΛ and racemic ΔΔ or ΛΛ forms.The UV-VIS and CD spectra of the (R)-pdta analogue, where pdta(4-) is propylenediamine-N,N,N',N'-tetraacetate, are also reported.The edta complex exhibits irreversible electrochemical behaviour with an oxidation wave at +1.23 V vs. the normal hydrogen electrode at = 0.10 M.Kinetic studies on the oxidation of the Re(IV)2 complex to Re(VII) with the one-equivalent reagent cis-(1+) in 1 M H(1+) indicate a rate-determining first stage with no evidence for stable intermediate states.Effects of the product (2+) and H(1+) on the kinetics, and an unexpected difference in reactivity of isomeric forms of the Re(IV)2 complex are reported.
