Syntheses and x-ray structures of (diphenylpyridylmethyl)lithium, -sodium, and -potassium in comparison with the triphenylmethyl derivatives

The crystal structures of PhzCPyLi-20Et2, PhzCPyNa-BTHF, and PhzCPyK-PMDTA/THF (Py = pyridyl, THF = tetrahydrofuran, PMDTA = (MezNCH2Chz)zNMe) have been determined low-temperature X-ray analysis. Whereas the potential energy surface of the triphenylmethyl alkali metal derivatives seems to be quite flat, that of the diphenylpyridylmethyl alkali metal compounds seems to have quite a distinct minimum. Structural features confirm the hypothesis the negative charge is almost exclusively located at the nitrogen atom. Moreover, the results of the present study emphasize structural trends already established in the heavier triphenylmethyl alkali metal compounds.