Ligand-mediated metal-metal interactions in ( ν5: ν5-fulvalene) bis (dicarbonylcobalt) and rhodium complexes

Abstract

Gas phase photoelectron spectroscopy (PES) is used to investigate the bonding and electronic structure in (fv) [M(CO) 2] 2 (fv = fulvalene, η 5: η 5-C 10 H 8 2−; M = Co, Rh). The results for these bimetallic complexes are also compared to those for the analogous monometallic complexes CpM(CO) 2 (Cp = η 5−C 5H 5 −; M = Co, Rh) which have been reported previously. The low valence ionization patterns observed for CpCo(CO) 2 and (fv)[Co(CO) 2] 2 are very similar, indicating that there is little electronic interaction between the two metals of the dicobalt complex. The spectrum of (fv)[Rh(CO) 2] 2 also is very similar to the spectrum of CpRh(CO) 2, except that the first metal ionizations in the bimetallic rhodium compound show a significant splitting (0.45 eV). This splitting is due to electronic interaction between the two metal centers which occurs via communication through the fulvalene π system. The differences in electronic structure are compared to the differences in electrochemical behavior of the Co and Rh fulvalene complexes.