Photochemical Dynamics of Co(CO)₃NO:
Collaboration with Karma Sawyer and Charles Harris

Owing to its unique σ and π^* orbital interactions, the nitrosyl ligand can exist in four distinct configurations when bonded to transition metal centers.

In collaboration with Karma Sawyer and the experimental spectroscopy group of Charles Harris at Berkeley, the photochemical dynamics of the excited states of Co(CO)₃NO were investigated. Their experiment provides time-resolved vibrational spectra, which tracks the changes in the force constant of the nitrosyl bond. Two bent nitrosyl structures were observed in the excited state, and state-to-state dynamics were elucidated. After initial photoexcitation to a high-lying state, fast (sub-ps) conversion to a bent triplet occurs (T₂ or T₃). Subsequent relaxation to T₁—a species with even greater NO bending—occurs with a time constant of 350 ps. Slow conversion to the linear, ground singlet state occurs on a timescale longer than the experiment (>1 ns).

Reference:
"Direct observation of photoinduced bent nitrosyl excited-state complexes"
K. R. Sawyer, R. P. Steele, E. A. Glascoe, J. F. Cahoon, J. P. Schlegel, M. Head-Gordon, C. B. Harris. J. Phys. Chem. A 112 8505–8514 (2008).