| Popis: |
The reaction of 5,14-dihydro-7,16-diethyl-( E ) or -( Z )-dipyrido[b,i][1,4,8,11]tetraazacyclotetradecine with chromium hexacarbonyl produced the corresponding oxochromium(IV) complexes. These compounds had intense bands in the infrared region at 985 cm −1 , which are attributed to the CrO stretching modes. The two complexes gave mass spectra with prominent parent and parent-O peaks. On the other hand the mass spectra for the nickel(II) complexes showed parent and parent-CH 3 peaks. The absorption bands appearing in the energy range greater than 19 000 cm −1 were attributable to the π→π* and CT transitions. Consistent with their diamagnetism, the oxochromium complexes gave well-resolved proton NMR and carbon-13 NMR spectra. The magnitude of downfield shifts for the oxochromium(IV) complex is much larger than that observed for the corresponding nickel(II) complex. This is due to the fact that the positive charge provided by chromium(IV) is greater in magnitude than that by nickel(II). |
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