Nitrene and Carbene Transfer Catalyzed by Metalloporphyrins

Improvement of a biomimetic porphyrin catalytic system by addition of acids

The conditions of the use of the manganese/porphyrin/imidazole system needed to be improved in order to obtain larger amounts of models of metabolites. An increase of the oxidation yields and a better preservation of this catalytic system have been obtained on the examples of various alkanes, by an acid addition in the reaction mixture. Three manganoporphyrins were checked for evaluation of the reaction. These results were extended to molecules of therapeutical interest such as ibuprofen and phenylbutazone.

Hydrolysis, hydrosulfidolysis, and aminolysis of imido(methyl)rhenium complexes

The tris(imido)methylrhenium complex CH3Re(NAd)3 (1a, Ad = 1-adamantyl) reacts with H2O to give CH3Re(NAd)2O (2a) and AdNH2. The resulting di(imido)oxo species can further react with another molecule of H2O to generate CH3Re(NAd)O2 (3a). The kinetics of these reactions have been studied by means of 1H NMR and UV-vis spectroscopies. The second-order rate constant for the reaction of 1a with H2O at 298 K in C6H6 is 3.3 L mol-1 s-1, which is much larger than the value 1 x 10(-4) L mol-1 s-1 obtained for the reaction between CH3Re(NAr)3 (1b, Ar = 2,6-diisopropylphenyl) and H2O in CH3CN at 313 K. Both 1a and 1b react with H2S to produce the rhenium(VII) sulfide, (CH3Re(NR)2)2(mu-S)2 (4a, R = Ad; 4b, R = Ar), with second-order rate constants of 17 and 1.6 x 10(-4) L mol-1 s-1 in C6H6 and CH3CN, respectively. Complex 4b has been structurally characterized. The crystal data are as follows: space group C2/c, a = 30.4831 (19) A, b = 10.9766 (7) A, c = 18.1645 (11) A, beta = 108.268(1) degrees, V = 5771.5 (6) A3, Z = 4. The reaction between CH3Re(NAr)2O (2b) and H2S also yields the dinuclear compound 4b. Unlike 1b, 1a reacts with aniline derivatives to give mixed imido rhenium complexes.