ELECTRONIC STRUCTURES OF LINEAR CARBON CHAIN MOLECULES

Photoelectron spectra of compounds having a linear carbon chain terminated by phenyl groups to stabilize the chain have been measured. The spectra consist of the contribution of phenyl groups and that of the chain part, which indicates small interaction between them. The highest occupied molecular orbital (HOMO) of these compounds derives from the carbon chain part. The longer the chain length becomes, the lower the binding energy of the HOMO. This fact implies the instability of a very long linear carbon chain. The spectra are well explained with the aid of semiempirical molecular orbital calculations.