Reactions of the electron-rich triply bonded dirhenium(II) complexes Re 2X 4(μ-dppm) 2 (X=Cl, Br) with dioxygen Part III. The isolation and structural characterization of the dirhenium(V) complex Re 2(μ-O) 2(O) 2Cl 2(μ-dppm) 2

Abstract

The complex Re 2(μ-O)(O) 2Cl 4(μ-dppm) 2 converts to the closely related tetraoxo dirhenium(V) species Re 2(μ- O) 2(O) 2Cl 2(μ-dppm) 2 in dichloromethane in the presence of amines such as NEt 3 and pyridine. This reaction can be reversed upon reacting Re 2(μ-O) 2(O) 2Cl 2(μ-dppm) 2 with thionyl chloride. A structural analysis of Re 2(μ- O) 2(O) 2Cl 2(μ-dppm) 2 shows it to have an edge-sharing bioctahedral structure with a very long Re⋯Re distance (3.1237(7) Å). This is the first example of a structurally characterized (Re 2O 4] 2+ species in which there is a planar centrosymmetric ORe(μ-O) 2ReO unit. Crystal data for Re 2(μ-O) 2(O) 2Cl 2(μ-dppm) 2·4CH 2Cl 2 at −70 °C: triclinic space group P 1 (No. 2), a=9.769(3), b=12.269(4), c=13.128(6) Å, α=96.59(4), β=107.92(4), γ=93.09(3)°, V=1480(2) Å 3, Z=1. The structure was refined to R=0.040 ( R w=O.050) for 3388 data with I > 3σ( I).