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

Abstract

The diarylplumbylene R 2 Pb: (3), R ) 2-tBu-4,5,6-Me 3 C 6 H, and the rearranged alkylarylplumbylene RR′Pb:, R ) 2,4,6-tBu 3 C 6 H 2 , R′ ) CH 2 C(CH 3 ) 2 -3,5-tBu 2 C 6 H 3 , were synthesized and characterized by NMR and UV/vis spectroscopy, as well as by X-ray crystallography. Treatment of 3 with the disilylplumbylene R′′ 2 Pb:, R′′ ) Si(SiMe 3 ) 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.

Synthesis, Structure, and Reactivity of Lewis Base Stabilized Plumbacyclopentadienylidenes

“…3.05 ). [34,35] Because of the NMR spectra of 7 being similar to those of 3 a in [D 6 ]benzene, dimer 7 is also considered to dissociate into 4 and 6 in benzene. Remarkably, the dimer 7 is relatively unstable in solution, and gradually decomposed to spiroplumbole 10 [28] (after 54 h, 50 % of 7 converted into 10; Scheme 5).…”

Heavy Analogs of Carbenes: Silylenes, Germylenes, Stannylenes and Plumbylenes

“…As a consequence, the 207 Pb NMR resonance of 37 was observed in the extremely low-field region of 10050 ppm. 186 Heteroleptic plumbylene 39 revealed a more NMR-shielded and less crowded situation around the carbene center (compared with that of diarylplumbylene 38) • • 5067 ppm ( 207 Pb NMR) and 94.8 • (C-Pb-C bond angle). On the other hand, reaction of PbCl 2 with Mes*MgBr resulted in the unexpected formation of heteroleptic aryl(alkyl)plumbylene 39, believed to be produced through the isomerization of the initially formed homoleptic diarylplumbylene Mes* 2 Pb • • 40.…”

“…185 Similarly to stannylene 23, plumbylene 37 featured long intermolecular nonbonding Pb· · ·Pb contacts of 8.91Å and a wide C-Pb-C bond angle of 117.1 • , indicative of its monomeric form in the crystalline state. 186 The spectral and structural data of 38 were typical for diarylplumbylenes: 6927 ppm ( 207 Pb NMR), 490 nm (UV-Vis), 103.0 • (C-Pb-C bond angle). 186 The spectral and structural data of 38 were typical for diarylplumbylenes: 6927 ppm ( 207 Pb NMR), 490 nm (UV-Vis), 103.0 • (C-Pb-C bond angle).…”

MOLECULAR STRUCTURE OF ORGANOSILICON COMPOUNDS WITH Si-M (M = Ge, Sn, Pb, Ti, Zr, Hf) BONDS

“…6 The Si-Pb bond lengths (2.700 and 2.704 A) are only slightly longer than those in compound 33 with tetravalent lead atoms. Plumbylenes bearing one mesityl [57] (or 2,4,6-tris(trifluoromethyl)phenyl [51]) and one tris(trimethylsilyl)silyl substituent at the lead as in stannylene 27 [R=2 1 4 1 6-(CF 3 The lead (II) compound 35 [54] is isostructural with silylstannylene 31 [54] and the molecular geometric parameters for these derivatives are very similar, only for M=Pb the SiPb bond is longer (2.776 A) and the SiPbSi angle, narrower (105.8°) than the SiSnSi one (106.8°).…”