Electronic spectra of protonated benzaldehyde clusters with Ar and N2: effect of ππ* excitation on the intermolecular potential.
Electronic spectra of the S(1)←S(0) transition of dimers of protonated benzaldehyde (BZH(+)) with Ar and N(2) are recorded by resonance-enhanced photodissociation in a tandem mass spectrometer. The S(1) origins observed are shifted to higher frequency upon complexation with Ar (ΔS(1) = 300 cm(-1)) and N(2) (ΔS(1) = 628 cm(-1)). Ab initio calculations at the CC2/aug-cc-pVDZ level suggest an assignment to H-bonded dimers of L = Ar and N(2) binding to the cis isomer of O-protonated BZH(+), yielding values of ΔS(1) = 242 and 588 cm(-1) for cis-BZH(+)-L(H). Electronic ππ* excitation results in a substantial increase of the proton affinity of BZH(+), which in turn destabilizes the intermolecular H-bonds to the inert ligands by 35%. The drastic effects of electronic ππ* excitation on the geometric and electronic structure as well as the strength and anisotropy of the intermolecular potential (H-bonding and π-bonding) are investigated.
Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
Alexander
A
Patzer
Max
M
Zimmermann
Ivan
I
Alata
Christophe
C
Jouvet
Otto
O
Dopfer
D001128:Argon / Q000737:chemistry*; D001547:Benzaldehydes / Q000737:chemistry*; D019281:Dimerization; D008024:Ligands; D009584:Nitrogen / Q000737:chemistry*; D010777:Photochemistry; D011522:Protons; D011789:Quantum Theory; D013057:Spectrum Analysis; D013816:Thermodynamics
D001547:Benzaldehydes; D008024:Ligands; D011522:Protons; D001128:Argon; D009584:Nitrogen