| Abstract
| - The optimized geometries, adiabatic electron affinities, vertical electron affinities, vertical electrondetachment energies (for the anions), and IR-active vibrational frequencies have been predicted for thelong linear carbon chains HC2n+1H (n = 4−11). The B3LYP density functional combined with DZP andTZ2P basis sets was used in this theoretical study. These methods have been extensively calibrated versusexperiment for the prediction of electron affinities (Chem. Rev. 2002, 102, 231). The computed physicalproperties are discussed and compared with the even carbon chains HC2nH. The predicted electron affinitiesform a remarkably regular sequence: 2.12 eV (HC9H), 2.42 eV (HC11H), 2.66 eV (HC13H), 2.85 eV (HC15H),3.01 eV (HC17H), 3.14 eV (HC19H), 3.25 eV (HC21H), and 3.35 eV (HC23H). These electron affinities are asmuch as 0.4 eV higher than those for analogous even carbon chains. The predicted structures display anintermediate cumulene−polyacetylene type of bonding, with the inner carbons appearing cumulenic andthe outer carbons polyacetylenic.
|
