title: Photochemistry of monochloro complexes of copper(II) in methanol probed by ultrafast transient absorption spectroscopy.
abstract: Ultrafast transient absorption spectra in the deep to near UV range (212-384 nm) were measured for the [Cu(II)(MeOH)(5)Cl](+) complexes in methanol following 255-nm excitation of the complex into the ligand-to-metal charge-transfer excited state. The electronically excited complex undergoes sub-200 fs radiationless decay, predominantly via back electron transfer, to the hot electronic ground state followed by fast vibrational relaxation on a 0.4-4 ps time scale. A minor photochemical channel is Cu-Cl bond dissociation, leading to the reduction of copper(II) to copper(I) and the formation of MeOH·Cl charge-transfer complexes. The depletion of ground-state [Cu(II)(MeOH)(5)Cl](+) perturbs the equilibrium between several forms of copper(II) complexes present in solution. Complete re-equilibration between [Cu(II)(MeOH)(5)Cl](+) and [Cu(II)(MeOH)(4)Cl(2)] is established on a 10-500 ps time scale, slower than methanol diffusion, suggesting that the involved ligand exchange mechanism is dissociative.
authors: Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
authors: Andrey S
authors: AS
authors: Mereshchenko
authors: Suman K
authors: SK
authors: Pal
authors: Kanykey E
authors: KE
authors: Karabaeva
authors: Patrick Z
authors: PZ
authors: El-Khoury
authors: Alexander N
authors: AN
authors: Tarnovsky
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004583:Electrons; D007700:Kinetics; D008024:Ligands; D000432:Methanol / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D011789:Quantum Theory; D013057:Spectrum Analysis; D055672:Static Electricity; D013816:Thermodynamics; D013997:Time Factors; D014466:Ultraviolet Rays; D014732:Vibration
chemical_list: D002712:Chlorides; D008024:Ligands; D003300:Copper; D000432:Methanol