THEORETICAL-STUDY OF FE(CO)(N)(-)

The structures and CO binding energies are computed for Fe(CO)(n)(-) u sing a hybrid density functional theory (DFT) approach. The structures and ground states can be explained in terms of maximizing the Fe to C O 2 pi donation and minimizing Fe-CO 5 sigma repulsion. The trends in the CO binding energies for Fe(CO)(n)(-) and the differences between the trends for Fe(CO)(n)(-) and Fe(CO)(n) are also explained. For Fe(C O)(n)(-), the second, third, and fourth CO bonding energies are in goo d agreement with experiment, while the first is too small. The first C O binding is also too small using the coupled cluster singles and doub les approach including a perturbational estimate of the connected trip le excitations.