References for 9

Catalytic two-electron reduction of dioxygen catalysed by metal-free [14]triphyrin(2.1.1)

“…A triplet fine structure EPR signal was observed as well as the typical anisotropic signals for HO 2 ˙ with the g || value of 2.0341, and isotropic signals for H 2 Trip˙ at 2.0030. 45 , 46 From the zero-field splitting value ( D = 230 G), the distance ( r ) between two unpaired electrons was determined using the relation D = 27 800/ r 3 47 to be 4.9 Å. This distance is consistent with the estimated distance between O 2 and H 3 Trip in the H 3 Trip/O 2 complex by DFT calculations ( Fig.…”

Oxygen Activation with Transition-Metal Complexes in Aqueous Solution

“…One might expect that the reactions between LMOO complexes and ROO • radicals will take place with rate constants that are between those for the self-reactions of individual couples. It was therefore surprising to find that the reaction between Cr aq OO 2+ ( k self ≤ 6 M −1 s −1 ) and (CH 3 ) 3 C(O)OO • ( k self ≈ 10 8 M −1 s −1 ) takes place with a rate constant 1.5 × 10 8 M −1 s −1 , as determined in laser-flash photolysis experiments. , …”

“…Formally, monometallic metal superoxo (LMOO, where L = ligand system and M = metal), hydroperoxo (LMOOH), and oxo (LMO) complexes are the respective analogues of alkylperoxyl radicals (ROO • ), alkyl hydroperoxides (ROOH), and alkoxyl radicals (RO • ). An abundance of kinetic and mechanistic data exists for the organic series. , Also, a number of studies have been carried out with metal complexes, but it has rarely been possible to examine different types of intermediates in the same metal−ligand system. Such a lack of systematic data is a serious impediment to the rational design of catalytic oxidation reactions.…”

“…While most of the parent alkyl radicals react in self-reactions at close to diffusion-controlled rates, alkylperoxyl radicals are greatly sensitive to steric factors, so that the rate constants for CH 3 OO • and (CH 3 ) 3 COO • differ by more than 5 orders of magnitude …”