DIANIONIC RHENIUM CARBONYL HALIDES

The dinegative rhenium carbonyl halide anions Re(CO)3X2-3 (X = Cl, Br, I) and Re2(CO)6X2-4 (X = Cl, Br) have been obtained as their tetraethylammonium salts from the reaction of [(C2H5)4N] [Re2(CO)6L3] (L = H, C2H5O, i-C3H7O) with the hydrohalic acids. With the exception of the dimeric bromo complex, they can also be prepared by the action of halide ions on the appropriate halogenopentacarbonylrhenium. An isothiocyanato complex, Re(CO)3(NCS)2-3 results from treating any of the dianions with SCN-. Infrared spectra were determined, and the CO and ReX stretching frequencies were identified. The results are consistent with cis(C3v) octahedral geometry for Re(CO)3X32- and with a doubly halogenbridged dimeric arrangement for Re2(CO)6X2-4. The ReX stretching frequencies of Re(CO)5X (X = Cl, Br, I), Re(CO)4X-2 (X = Br, I), Re2(CO)8X2 (X = Cl, Br, I), and Re2(CO)7X3- (X = Cl, Br) are also reported and used to indicate probable structures. © 1969, American Chemical Society. All rights reserved.