Rhenium complexes of P,P,P’,P’-tetrakis(o-hydroxyphenyl)diphosphinoethane

Preparation of the hydrochloride salt of a new potentially hexadentate ligand precursor P,P,P’,P’-tetrakis(o-hydroxyphenyl)diphosphinoethane dihydrochloride (abbreviated H4P2O4 . 2HCl) is described. From H4P2O4 . 2HCl, neutral [Re2O2Cl2(PPh(3))(2)(mu-P2O4)] and dianionic [Re2O2Br4(mu-P2O4)](2-) dinuclear rhenium(V) complexes were synthesized. The complexes have been characterized by elemental analysis, infrared spectroscopy, mass spectrometry, and (HP)-H-1-P-31{H-1} NMR spectra. P-31{H-1} NMR revealed that only one isomer, presumably the anti, was present for [Re2O2Cl2(PPh(3))(2)(mu-P2O4)], and that two isomers, both anti and syn isomers, were observed for [Re2O2Br4(mu-P2O4)](2-). The coligands (PPh, for the former, Br- for the latter) of both complexes underwent ligand exchange with pyridine.