Observation of Confinement‐Free Neutral Group Three Transition Metal Carbonyls Sc(CO)7 and TM(CO)8 (TM=Y, La)

Abstract

AbstractSpectroscopic 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)7 and TM(CO)8 (TM=Y, La) in the gas phase, which are the first confinement‐free neutral heptacarbonyl and octacarbonyl complexes. The results indicate that Sc(CO)7 has a C2v structure and TM(CO)8 (TM=Y, La) have a D4h structure. Theoretical calculations predict that the formation of Sc(CO)7 and TM(CO)8 (TM=Y, La) is both thermodynamically exothermic and kinetically facile in the gas phase. These highly‐coordinated carbonyls are 17‐electron complexes when only those valence electrons that occupy metal−CO bonding orbitals are considered, in which the ligand‐only 4b1u molecular orbital is ignored. This work opens new avenues toward the design and chemical control of a large variety of compounds with unique structures and properties.