Observation of Confinement-Free Neutral Group Three Transition Metal Carbonyls Sc(CO) and TM(CO) (TM=Y, La).

Spectroscopic characterization of neutral highly-coordinated compounds is essential in fundamental and applied research, but has been proven to be a challenging experimental target because of the difficulty in mass selection. Here, we report the preparation and size-specific infrared-vacuum ultraviolet (IR-VUV) spectroscopic identification of group-3 transition metal carbonyls Sc(CO) and TM(CO) (TM=Y, La) in the gas phase, which are the first confinement-free neutral heptacarbonyl and octacarbonyl complexes. The results indicate that Sc(CO) has a C structure and TM(CO) (TM=Y, La) have a D structure.