OctacoordinateMetal Carbonyls of Lanthanum and Cerium:Experimental Observation and Theoretical Calculation.

Theoctacoordinate metal carbonyls La(CO)8+andCe(CO)8+were observed in laser vaporizationof La and Ce in pure CO gas. The peak intensities in the mass spectra,the infrared photodissociation spectra, and the theoretical calculationsindicate that all CO ligands in these two complexes are bonded withthe central metal atoms. The CO stretching frequencies in La(CO)8+and Ce(CO)8+are determinedto be 2110 and 2108 cm–1, respectively. Theoreticalstudies indicate that the most stable structures for La(CO)8+and Ce(CO)8+are an Ohgeometry at its triplet state and aslightly distorted Ohgeometry at its quartet state, respectively. These two complexesrepresent new octacoordinate metal carbonyls after previously determinedU(CO)8+and Y(CO)8+. [ABSTRACT FROM AUTHOR]