No abstract

Reaction of 1,3-dimesitylimidazolylidene (1) with p-functionalized phenyl azides 2 (a: H, b: OCH 3 , c: NO 2 ) afforded the respective imidazolylidene-triazenes 3 in good yields (65-99 %). Subsequent treatment with methyl iodide produced the corresponding methylated products 4 in near-quantitative yields (99 %). Analysis by NOESY 1D NMR spectroscopy and single-crystal X-ray diffraction revealed that the methylation reaction was regioselective and occurred at the nitrogen atom most distal from the heterocycle. Consistent with the formation of ionic salts, the 1 H NMR signals for the imidazole protons in 4 were shifted Ͼ 0.5 ppm downfield compared to 1, indicating the accumulation of positive charge.

the paper. The D SO4 values given in the text and Figure 2 remain correct. Thus, this correction does not change the basic conclusion of the paper, namely that an organic-solubilized cyclo [8]pyrrole may be used to extract sulfate effectively from a nitrate-rich aqueous solution. The value of log K′ exch value is still considered high as compared with that of the control, which is the simple anion exchanger acting independently. It may be noted that in the absence of 1 in Figure 1 (control system), the average value of D SO4 was found to be 0.0021, corresponding to log K′ exch (control) ) -6.0. Referring to Figure 2, this relatively small value implies a hypothetical control D SO4 value of 9.7 × 10 -9 for the corresponding system without the presence of 1 at 1 mM [NaNO 3 ]. By comparison, under these conditions, the measured value of D SO4 was 111 with 1 at 0.5 mM in the nitrate form in the organic phase. It therefore remains clear that 1 effects a remarkable enhancement relative to the feeble sulfate extraction possible by the simple anion exchanger acting independently. Supporting Information Available:Estimation of the values of log K′ exch and log K′ exch (control). This material is available free of charge via the Internet at http://pubs.acs.org.