Multiple Bonding Between Group 3 Metals and Fe(CO)3

Heteronuclear Group 3 metal/iron carbonyl anion complexes ScFe(CO)3−, YFe(CO)3−, and LaFe(CO)3− are prepared in the gas phase and studied by mass‐selective infrared (IR) photodissociation spectroscopy as well as quantum‐chemical calculations. All three anion complexes are characterized to have a metal–metal‐bonded C3v equilibrium geometry with all three carbonyl ligands bonded to the iron center and a closed‐shell singlet electronic ground state. Bonding analyses reveal that there are multiple bonding interactions between the bare group‐3 elements and the Fe(CO)3− fragment. Besides one covalent electron‐sharing metal–metal σ bond and two dative π bonds from Fe to the Group 3 metal, there is additional multicenter covalent bonding with the Group 3 atom bonded to Fe and the carbon atoms. Vier gewinnt: Die heteronuklearen anionischen Gruppe‐3‐Metall/Eisencarbonyl‐Komplexe ScFe(CO)3−, YFe(CO)3−, and LaFe(CO)3− wurden in der Gasphase hergestellt und durch massenselektive Infrarot‐Photodissoziationsspektroskopie sowie quantenchemische Berechnungen untersucht. Die Ergebnisse zeigen eine beispiellose Vierfachbindung zwischen den beiden Metallatomen auf.