Title full: The electronic structure of nitrosyl and carbonyl supported metal-metal interactions. The photoelectron spectra of [η5-(C5H5)Fe(μ-NO)]2, [η5-(C5(CH3)5)Fe(μ-NO )]2, [η5-(C5H5)Ru(μ-NO)]2 and [η5-(C5(CH3)5)Co(μ-CO )]2. The valence photoelectron ionizations of[CpFe(μ-NO)]2, [Cp*Fe(μ-NO)]2, [CpRu(μ-NO)]2 and [Cp*Co(μ-CO)]2 (Cp = η5-C5H5 and Cp* = η5-C5(CH3)5) are examined in comparison to several theoretical calculations of the electronic structure and bonding in these complexes. The photoelectron spectra of this group of complexes, when collected together, allow identification of the eight valence metal-based ionizations. There is considerable disparity among the various calculations on the predicted order of these ionizations. The combination of Fenske-Hall calculations with experimental observations of ionization trends between isoelectronic first row complexes [Fe(NO) vs Co(CO)], between first and second row complexes (Fe vs Ru), and between complexes with ring methylation (Cp vs Cp*) allows a consistent assignment of the valence ionizations. The interplay of theory and experiment gives unique insight into the nature of bridging ligand coordination and clarifies the relative strengths of metal-ligand and metal-metal interactions, in each complex. It is found that as many metal-metal antibonding orbitals are occupied as metal-metal bonding orbitals, so that the formal metal-metal bond order is zero. The interactions are important in defining the bonding and stability of the complexes. These interactions lead to large ligand character in two of the valence ionizations.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry