The reaction of nitro-1,2-diaminobenzenes with the [ReO]3+ core: isolation of oxo-free rhenium(V) complexes

The reaction of 2 equiv. of 3-nitro-1,2-diaminobenzene (H2L1) with trans-ReOCl3(PPh3)2 in ethanol gave the oxo-free rhenium(V) complex [ReCl(PPh3)(L1)2] (1) in good yield. IR, 1H NMR and X-ray crystallographic results indicate that the diamine ligand L1 coordinates in a dianionic bidentate diamido form to the metal, and that the complex has the unusual skew-trapezoidal bipyramidal geometry. With 4-nitro-1,2-diaminobenzene (H2L2) as ligand the complex [Re(L2)Cl3(PPh3)2] (2) was characterized, in which L2 coordinates in a dianionic monodentate imido form through one nitrogen only. Crystal data for 1·EtOH: C32H31ClN6O5PRe, monoclinic P21/c, a=14.937(11), b=15.017(8), c=15.394(12) Å, β=112.12(6)°, V=3198.7(38) Å3, Z=4, Dcalc=1.728 g cm−3, structure solution and refinement based on 3151 reflections converged at R=0.0807.