The photoelectron spectra of gaseous Re3Clg and Re3Br9 have been measured using both He(l) and He(ll) resonance lines for excitation. These have been assigned with the assistance of SCF-Xa-SW and Fenske-Hall molecular orbital calculations. For Re3Clg, it is found that the firsttwo ionizations are out of metal-metalV-bonding orbitals engaged in strong covalent interaction with the bridging and, to a lesser degree, the terminal chlorine atoms. The extent of Re-Cl interaction predicted by the calculations agrees well with the observed changes in intensity upon use of higher energy Fle(ll) ionization source, and is consistent with a greater degree of covalency in the Re-Cl bonding in Re3Clg than in [Re2Clg]2-. The correlation of intensity changes for Re3Br9 is not asconsistent as that in the nonachloride compound, although the calculations may be used as a guide in conjunction with the photoelectron spectra to construct a comprehensive picture of the bonding inthese trinuclear metal atom clusters that is consistent with the basic idea that there are double bonds between each pair of metal atoms. Finally, the electronic transitions for Re3Cl9 are calculated and the optical absorption spectra for the general class of Re3Cl9. 3L trimers are discussed and assigned. © 1980, American Chemical Society. All rights reserved.
