IR spectra of C2H5(+)-N2 isomers: evidence for dative chemical bonding in the isolated ethanediazonium ion.

The potential energy surface (PES) of C(2)H(5)(+)-N(2) is characterized in detail by infrared photodissociation (IRPD) spectroscopy of mass-selected ions in a quadrupole tandem mass spectrometer and ab initio calculations at the MP2/6-311G(2df,2pd) level. The PES features three nonequivalent minima. Two local minima, 1-N(2)(H) and 1-N(2)(C), are adduct complexes with binding energies of D(0) = 18 and 12 kJ/mol, in which the N(2) ligand is weakly bonded by electrostatic forces to either the acidic proton or the electrophilic carbon atom of the nonclassical C(2)H(5)(+) ion (1), respectively.

Interaction of ionic biomolecular building blocks with nonpolar solvents: acidity of the imidazole cation (Im+) probed by IR spectra of Im+-Ln complexes (L = Ar, N2; n < or = 3).

The intermolecular interaction between the imidazole cation (Im+ = C3N2H4+) and nonpolar ligands is characterized in the ground electronic state by infrared photodissociation (IRPD) spectroscopy of size-selected Im+-Ln complexes (L = Ar, N2) and quantum chemical calculations performed at the UMP2/6-311G(2df,2pd) and UB3LYP/6-311G(2df,2pd) levels of theory. The complexes are created in an electron impact cluster ion source, which predominantly produces the most stable isomers of a given cluster ion. The analysis of the size-dependent frequency shifts of both the N-H and the C-H stretch vibrations and the photofragmentation branching ratios provides valuable information about the stepwise microsolvation of Im+ in a nonpolar hydrophobic environment, including the formation of structural isomers, the competition between various intermolecular binding motifs (H-bonding and pi-bonding) and their interaction energies, and the acidity of both the CH and NH protons.