207Pb-NMR

Cp PbCp 13C and 207Pb NMR, CP-MAS-NMR, IR, Raman, MS and powder XRD.a A Pb(II) compound. Parallel staggered conformation proposed for decaphenyl-plumbocene. 150, 151a... 

Mes3PbCOR, R = Me, Ph H, 13C and 207Pb NMR and XRD. First stable acylplumbanes ever synthesized. 151b... 

Me3Pb)3N 1H, 15N and 207Pb NMR. The value and sign of coupling constants were determined ( Pb N) the largest value for this constant published so far, VC H). 153... 

TABLE 13. 207Pb NMR chemical shifts and J couplings of phenyl-substituted Pb anionsa... 

Examples of the use of 207Pb NMR spectroscopy for the study of coordination and stability of lead-containing five-membered heterocycles are rare. For instance, the differences in coordination number for different macrobicyclic... 

A dianionic compound with trigonal-planar coordinated lead was obtained from the reaction of disodium decacarbonyldichromate with lead nitrate (equation 65)81. The authors found that its 207Pb NMR signal (5 7885 ppm) supports an unsaturated character. The it system was also chemically evident. Below 213 K, in the presence of PMej, a pyramidal adduct is formed quantitatively, the structure of which confirms coordination of the Lewis base PMe3 to the coordinatively unsaturated lead center (Pb-P 2.84 A). 

TABLE 19. 207Pb NMR data for transition metal lead complexes... 

Blinc et al.71 have carried out 207Pb NMR in an electric field. They have observed separately the anisotropic 207Pb spectra of FE like polar clusters and isotropic spectra of spherical glass matrix into which the polar clusters are embedded, confirming the model proposed by Bums and Dacol. They concluded that PMN to be an incipient FE. 

Pb NMR Spectroscopic Data of Plumbylium Ions and Related Species... 

Pb NMR Chemical Shifts for Plumbyl Cationic Compounds... 

The closely related lead analogue 81 shows essentially the same structural features, but the lead atom in 81 is less pyramidalized (355.7°, see Table XIV), which indicates weaker coordination. The NMR spectroscopic parameters for 81, such as 207Pb NMR chemical shift and scalar Pb-C(sp) coupling constants (see Section III.B.3) clearly demonstrate however the side-on complexation of the plumbyl cation by the C = C triple bond in zwitterions 81.161... 

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