摘要
Three new diruthenium oxyanion complexes have been prepared, crystallographically characterized, and screened for their potential to photochemically unmask a reactive Ru - Ru=O intermediate. The most promising candidate, Ru 2 (chp) 4 ONO 2 (4, chp = 6-chloro-2-hydroxypyridinate), displays a set of signals centered around m/z = 733 amu in its MALDI-TOF mass spectrum, consistent with the formation of the [Ru 2 (chp) 4 O] + ([6] + ) ion. These signals shift to 735 amu in 4∗, which contains an 18 O-labeled nitrate. EPR spectroscopy and headspace GC-MS analysis indicate that NO 2 • is released upon photolysis of 4, also consistent with the formation of 6. Photolysis of 4 in CH 2 Cl 2 at room temperature in the presence of excess PPh 3 yields OPPh 3 in 173% yield; control experiments implicate 6, NO 2 • , and free NO 3 - as the active oxidants. Notably, Ru 2 (chp) 4 Cl (3) is recovered after photolysis. Since 3 is the direct precursor to 4, the results described herein constitute the first example of a synthetic cycle for oxygen atom transfer that makes use of light to generate a putative metal oxo intermediate.