Quenching of Emission and of Photochemistry of Pentacarbonyl-4-Cyanopyridinotungsten(O)

摘要

The complex W(CO)5L,L = 4 cyanopyridine, is found to emit in room temperature methycyclohexane solution. The emission is centered around 630 nm and is 105 plus or minus 10 nsec in lifetime, gamma, at 25 C. Added 0.1 M ethanol does not change the charcteristics, and in this medium 1/gamma = 2.61x10 to the 8th power exp(-1960/RT). The mission is quenched by anthracene, as is also the photosubstitution reaction whereby L is replaced by ethanol ( phi = 0.028 plus or minus 10% at room tmperature), Stern-Volmer plots of gamma/gamma and of phi/phi vs. quencher concentration are linear, the common slope giving a bimolecular quenching rate constant of 3.7x10 to the 9th power M sec. The charge transfer (CT) emitting state is clearly implicated in the photochemistry; between the emission spectrum and the anthracene triplet state energy, the energy of the CT state is bracketed as between 14.7 and 20 kk. (Author)