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 ore-free rhenium(V) complex [ReCl(PPh3)(L-1)(2)] (1) in good yield. IR, H-1 NMR and X-ray crystallographic results indicate that the diamine ligand L-1 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(L-2)Cl-3(PPh3)(2)] (2) was characterized, in which L-2 coordinates in a dianionic monodentate imido form through one nitrogen only. Crystal data for 1-EtOH: C32H31CIN6O5PRe, monoclinic P2(1)/c, a = 14.937(11), b = 15.017(8), c = 15.394(12) Angstrom, beta = 112.12(6)degrees, V = 3198.7(38) Angstrom(3), Z = 4, D-calc = 1.728 g cm(-3), structure solution and refinement based on 3151 reflections converged at R = 0.0807. (C) 2000 Elsevier Science S.A. All rights reserved.