Parallel Metallocenes of Germanium, Tin, and Lead

The reaction of 2 equiv of LiCps (Cps = C5Me4(SiMe2But)) with GeCl2?diox, SnCl2, or PbCl2 in ethereal solvents affords the metallocenes [M(n5-Cps)2] (M = Ge, 1; M = Sn, 2; M = Pb, 3) in 96, 89, and 84% yields, respectively. A single-crystal X-ray structural analysis of each reveals that, for the first time, the cyclopentadienyl rings are parallel for all three metallocenes. Both solid- and solution-state multinuclear NMR spectroscopic data for 2 and 3 are reported. An examination of 1-3 using DFT has also been performed, and in the case of 1 a comparison with its C5H5 analogue has been carried out.