New Plumbylenes and a Plumbylene Dimer with a Short Lead−Lead Separation,¹

The diarylplumbylene R2Pb: (3), R = 2-tBu-4,5,6-Me3C6H, and the rearranged alkylarylplumbylene RR‘Pb:, R = 2,4,6-tBu3C6H2, R‘ = CH2C(CH3)2-3,5-tBu2C6H3, were synthesized and characterized by NMR and UV/vis spectroscopy, as well as by X-ray crystallography. Treatment of 3 with the disilylplumbylene R‘‘2Pb:, R‘‘ = Si(SiMe3)3, furnished the heteroleptic plumbylene RR‘‘Pb: (8), which, in the solid state, forms the plumbylene dimer RR‘‘PbPbRR‘‘ (9). The X-ray structure analysis of 9 reveals a trans-bent angle of 46.5° and a Pb...Pb separation of 3.37 Å, the shortest observed so far between the lead atoms of two plumbylenes.