Nitrogen anomalous behavior

Another notable example of the anomalous behavior of imidazole ligands is the kinetic tram effect observed for the rates of substitution of 02 for CO in the hemes Fe(TPP)02L ([29], M = Fe, X = 02, L = Py, Pip, or l-Melm) according to Eq.(4)and Table 8 30). One of the three nitrogen donors in question, l-Melm, stabilizes the dioxygen adduct in a manner not to be expected from its basicity. The substitution is clearly of the SN1 type, the elimination of the 02 molecule being the rate-determining step. 

N2 02, neopentane) in the zeolites A, X, L, mordenite, omega, and a synthetic offretite type have been determined from isotherms. These have been compared with the void volumes calculated from the known crystal structures. For most adsorbates the measured and calculated void volumes are in good agreement. However, helium and nitrogen exhibit anomalous behavior. A void volume-framework density relation for zeolites is given. 

The apparently anomalous behavior of the iron tetracarbonyl halides in terms of the inverse stability gradation iodide > bromide > chloride—the latter is labile above 0° C—which is the reverse sequence to that found with the nitrogen-base complexes L4FeX2 (L = NH3, pyridine, etc.), caused us... 

Where an imidazole nitrogen is substituted, as in 7- or 9-alkyl purines, the exchange rates for low and intermediate pH values are similar to those for purine. As pH increases, however, the rate of hydrogen abstraction does not decline, but accelerates dramatically (Fig. 2). Possible factors for this anomalous behavior are discussed in Section III,A,3. 

Oxoniachrysenes 67 are simultaneously 2-benzopyrylium and 1-benzopyrylium salts, but maintain a distinct chemical behavior. 5-Oxoniachrysene salts 67 are interesting mainly as precursors of ben-zo[c]phenantridine derivatives 132, as mentioned in Section II,C,6. However, in contrast to 2-benzopyrylium salts (cf. Section III,C,4,a), compounds 67 react with nitrogen nucleophiles to form stable adducts 131 or products of anomalous ring-opening, namely a-naphthols 66 and esters 70 (77KGS1176). 

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