Rhenium in Complexes

Rhenium(iii) Complexes.—A pure sample of [Re(acac)3] has been prepared by heating a mixture of [Na(acac)] and [ReCl2(acac)2], or [ReCl2(acac)PPh3] for 24h at 175°C in vacuo dark-red crystals formed just outside the hot zone [Re(hfac)3] has also been obtained pure, and the compounds were characterized by i.r., electronic, and mass spectroscopy, and respective magnetic moments of 

Giusta, and P. Romiti, J. Inorg. Nuclear Chem., 1971, 33, 4093. 

The potential of the Re -Re couple in LiCl-KCl eutectic at 500 °C is — 0.358 V vs. the standard Pt electrode). 2 2 oxidizes [TcClg] directly to TCO4, but CI2 first produces technetium( v) which is then oxidized to pertechnetate. No oxidation of technetium(iv) by atmospheric oxygen in the presence of sunlight could be achieved. 

The reaction of ReClj with R4NCI (R = Et or Pr) (1 1) under anhydrous, oxygen-free conditions produces (R4N)[ReCl5]. The solubility, i.r. spectral, and magnetic properties of these air-stable salts suggest that the anions are polymeric, and they react with unidentate ligands [L = py, MeCN, H2O, DMF, 

Popova and L. G. Boiko, High Temp. High Pressures, 1971, 3, 237. 

---