Identification of Ge≡O Triple Bond in GeO Cluster: Anion Photoelectron Spectroscopy and Theoretical Calculations.

Unlike C≡O, which is common in coordination chemistry and organometallic chemistry, little is known about Si≡O or Ge≡O compounds. Here we report a GeO cluster featuring a Ge≡O triple bond. The structural and chemical bonding properties of GeO are investigated using anion photoelectron spectroscopy and theoretical calculations. Two nearly degenerate isomers have been found for GeO. The lowest-energy structure (6A) can be viewed as an O atom bonding with a tetragonal bipyramidal Ge. The second one (6B) can be considered as an O atom interacting with a capped trigonal bipyramidal Ge. Chemical bonding analyses reveal that GeO (6A) can be viewed as a Ge≡O unit interacting with a σ antiaromatic symmetric tetragonal pyramidal Ge moiety. Comparisons of the chemical bonding in GeO (6A) with that in GeCO and GeMnO indicate the similar behavior of Ge≡O to C≡O and Mn≡O in its bonding to the Ge and Ge moieties.