On the bonding in Fe2(CO)9

This is the authors' abstract. We don't add key points for this paper.

The bonding in Fe2(CO)9 is analyzed using an SCF wave function for a large basis set. There is no direct Fe–Fe metal–metal bond. The bridging CO’s hold the two Fe(CO)3 fragments together by σ donation into the empty Fe–Fe dπ orbital and metal donation from the dπ* orbital into the CO 2π* orbital. The bonding of the terminal CO’s is similar to that in Ni(CO)4 and the equatorial CO groups in Fe(CO)5.