Synthesis and Characterization of the 4,4′-Bipyridyl Dianion and Radical Monoanion. A Structural Study

The reaction of ethylenediamine solutions of 4,4′-bipyridine with varying stoichiometric amounts of sodium resulted in the isolation of the 4,4′-bipyridyl radical anion (44bipy•−) and the unprecedented 4,4′-bipyridyl dianion (44bipy2−). The radical was characterized by single-crystal X-ray diffraction in Na(44bipy)(en) (1) and Na2(44bipy)2(en)2 (2) and the dianion in Na2(44bipy)(en)2 (3), allowing for interesting correlations to be drawn between electronic structure and metric structural data. Further characterization of the solids by means of powder X-ray diffraction, electron paramagnetic resonance, and/or elemental analysis is also reported.