Site-specific interaction between hydrocarbon cations and inert ligands: IR spectra of isomeric C3H3+-L dimers (L = Ne,Ar,O-2,N-2,CO2)

Infrared (IR) photodissociation spectra of isomeric C3H3+-L dimers with the inert ligands L=Ne, Ar, O-2, N-2, and CO2 are recorded in the spectral range of the C-H stretch fundamentals. At least two C3H3+ isomers are generated by electron impact ionization of allene (H2CCCH2) in the cluster ion source, namely the cyclopropenyl (c-C3H3+) and propargyl (H2CCCH+) cations. Both C3H3+ ions form weakly-bound adducts with all ligands considered and the attraction in these ion ligand complexes is dominated by induction and electrostatic forces. In general, the intermolecular interaction in both c-C3H3+-L and H2CCCH+-L increases in the order Ne