Solvent effects and excited-state dynamics in photochemical ligand substitution of the tungsten carbonyl complex W(CO)5L (L = piperidine, py)

Wavelength-Dependent Photochemistry of W(CO)4(en) (en = Ethylenediamine): Evidence for Distinct Chemical Reactivities from Singlet and Triplet Ligand Field Excited States

“…The quantum yield results for W(CO) 4 (en) reveal a 7-fold reduction when the lowest lying spin-forbidden LF state is populated directly compared to excitation of the corresponding spin-allowed LF level (see Table ). In contrast, the wavelength dependencies of W(CO) 5 (py) and W(CO) 5 (pip) are considerably lower and the quantum efficiencies are reduced much less (approximately 30−70%) as the excitation wavelength becomes longer …”

“…Currently, however, experimental evidence is emerging that portrays a more complicated picture of excited-state reactivity in M(CO) 6 and substituted metal carbonyl complexes. One illustration of this is the observation of wavelength-dependence behavior in the photosubstitutional quantum yields of W(CO) 5 (py) and W(CO) 5 (pip) (py = pyridine; pip = piperidine) …”

Wavelength dependence and solvent effects on the ligand field photochemistry: the ring closure process in the excited [Fe(CN)5(tn)]3− complex

“…When this competition can be related to properties of the solvent, one has an indication that the species will react on time scales sufficiently long to reach an equilibrium with the solvent environment. ~e s p i t e ' i t s simplicity, this model has been shown to be consistent with a significant number of the available experimental results, although the data from some particular systems do not fit within its conceptual framework (3,10,11,17).…”

Transition Metal Alkane Complexes†

“…Even this reaction with cyclohexane requires the extremely rapid dissipation of 3−4 quanta of excess energy into the CO modes, otherwise the cyclohexane would be immediately re-expelled (laser pulse of wavelength 532 nm corresponds to a photon energy of 225 kJ mol -1 ). However, it has also been suggested that the expelled cyclohexane may take some of the excess energy on dissociation, leaving the transition metal fragment vibrationally cooler 1 Ultrafast kinetic trace recorded following laser-induced dissociation of C 6 H 12 from Cr(CO) 5 (C 6 H 12 ), showing the reaction of “naked” Cr(CO) 5 with C 6 H 12 (IR detection at 1970 cm -1 ).…”