Photoelectron Spectroscopy and Theoretical Studies of GeMnO Cluster with a Mn≡O Unit Interacting with a Double Aromatic Ge Ligand.

The structures and chemical bonding of GeMnO are investigated using anion photoelectron spectroscopy and theoretical calculations. The lowest energy structure of GeMnO is found to have a C symmetric structure with an O atom attached to a pentagonal bipyramidal MnGe. Chemical bonding analyses reveal that GeMnO can be considered as a [Mn≡O][Ge] complex with two unpaired 3d electrons on Mn. The Ge ligand is highly stable in GeMnO and exhibits double aromaticity with 10 delocalized σ electrons and 6 delocalized π electrons. Our calculations show that the Ge ligand could also form [Cr≡O][Ge] in NaGeCrO and [Fe≡O][Ge] in NaGeFeO. The results suggest the possibility of designing and synthesizing a series of stable high-valent metal oxide anionic species with the composition [M≡O][Ge] in the gas phase or in the salt-stabilized bulk solid materials.