Tag: ligand

Ligand Influence on the Electronic Spectra of Dicationic Ruthenium-Bipyridine-Terpyridine Complexes

We report electronic spectra of a series of ruthenium polypyridine complexes of the form [(trpy)(bipy)RuII–L]2+ (bipy = 2,2′-bipyridine and trpy = 2,2′:6′,2″-terpyridine), where L represents a small molecular ligand that occupies the last coordination site. Species with L = H2O, CO2, CH3CN, and N2 were investigated in vacuo using photodissociation spectroscopy. All species exhibit bright metal-to-ligand charger transfer (MLCT) bands in the visible and near UV, but with different spectral envelopes and peak energies, encoding the influence of the ligand L on the electronic structure of the complex. Several individual electronic bands can be resolved for L = H2O and CO2, while the spectra for L = N2 and CH3CN are more congested, even at low ion temperatures. The experimental results are discussed in the framework of time-dependent density functional theory.

DOI: 10.1021/acs.jpca.6b02926

Shuang Xu†, James E. T. Smith‡, and J. Mathias Weber‡

† JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, United States
‡ JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0440, United States

Ligand influence on the electronic spectra of monocationic copper–bipyridine complexes

We present photodissociation spectroscopy and computational analysis of three monocationic Cu–bipyridine complexes with one additional ligand of different interaction strength (N2, H2O and Cl) in the visible and UV. All three complexes show similar ππ* bands with origins slightly above 4 eV and vibrational band contours that are due to bipyridine ring deformation modes. Experiments at low temperature show that excited-state lifetime is the limiting factor for the width of the vibrational features. In the case of Cl as a ligand, there is a lower lying bright ligand-to-ligand charge-transfer state around 2.75 eV. The assignment of the transitions was made based on equation-of-motion coupled-cluster calculations. While the nature of the ligand does not significantly change the position of the bright ππ* state, it drastically changes the excited-state dynamics.
 

DOI: 10.1039/C5CP05063D

Shuang Xu,a   Samer Gozem,b   Anna I. Krylov,b  Casey R. Christopherc and   J. Mathias Weber*c
 aJILA and Department of Physics, University of Colorado, Boulder, USA
bDepartment of Chemistry, University of Southern California, Los Angeles, USA
cJILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, USA
* weberjm@jila.colorado.edu