Preparation and crystal structure of (2,2′-bibenzimidazole)dihalobis(triphenylphospine)rhenium(III) halides
摘要:
The reaction of ReOX3(PPh3)(2) (where X = Cl, Br) with 2,2'-bibenzimidazole (bibzimH(2)) in the presence of excess PPh3 yields the rhenium(III) cationic complexes [ReX2(PPh3)(2)(bibzimH(2))]X, in which the phosphines are trans to one another, whereas the plane perpendicular to this direction includes the chelating bidentate bibzimH(2) and two cis halogen ligands. The third halogen is a halide counter-ion. attached to the complex cation via a pair of N-(HX-)-X-... hydrogen bonds involving the two N-H groups of bibzimH(2). Crystallographic work on the chloro compound indicates that the departure from octahedral geometry is controlled by the bite of the bibzimH(2) ligand and that the presence of the phenylene groups does not introduce substantial steric hindrance. Despite the fact that the species is paramagnetic, the H-1 NMR spectra were fully assigned. (C) 2004 Elsevier Ltd. All rights reserved.