Identification of Ge≡O Triple Bond in Ge 6 O - 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 Ge 6 O - cluster featuring a Ge≡O triple bond. The structural and chemical bonding properties of Ge 6 O -/0 are investigated using anion photoelectron spectroscopy and theoretical calculations. Two nearly degenerate isomers have been found for Ge 6 O - . The lowest-energy structure (6A) can be viewed as an O atom bonding with a tetragonal bipyramidal Ge 6 . The second one (6B) can be considered as an O atom interacting with a capped trigonal bipyramidal Ge 6 . Chemical bonding analyses reveal that Ge 6 O - (6A) can be viewed as a Ge≡O unit interacting with a σ antiaromatic C 2 v symmetric tetragonal pyramidal Ge 5 3- moiety. Comparisons of the chemical bonding in Ge 6 O - (6A) with that in Ge 5 CO - and Ge 5 MnO - indicate the similar behavior of Ge≡O to C≡O and Mn≡O in its bonding to the Ge 5 3- and Ge 5 4- moieties.