HeI photoelectron spectroscopic (PES) studies of the electronic structure of Al(CH3)3, In(C2H5)3 and Cd(CH3)2 compounds

HeI photoelectron spectra (PES) of Al(CH3)3, In(C2H5)3 and Cd(CH3)2 compounds are recorded. The assignment of the PES bands is made on the basis of bandshape and ab initio SCF MO calculations using the 3-21G basis sets. Both PES experiment and theoretical calculation show that the characters of the HOMO [5e′ for Al(CH3)3, 12e′ for In(C2H5)3 and 3a2u for Cd(CH3)2] are mostly metal-carbon antibonding. The bond orders between the metal and carbon atoms for Cd(CH3)2, Al(CH3)3 and In(C2H5)3 are 0.9251, 0.7166 and 0.6957 respectively. The strength of metal-carbon bonding is Cd(CH3)2 > Al(CH3)3 > In(C2H5)3.