C-13 AND PB-207 NMR-STUDIES OF SOME ORGANOLEAD COMPOUNDS

The 13C and 207Pb NMR spectra of several substituted aliphatic and aromatic organolead compounds of type R4-nPbXn have been obtained in order to determine how various factors are reflected in the NMR parameters. Carbon chemical shifts vary as expected, with the largest change observed for the carbon attached to lead. 1JCPb varies by a factor of greater than 10 in the compounds examined and depends on both substituent and solvent. A correlation between the s character of the orbitals in the carbon-lead bond and 1JCPb exists only if it is assumed that lead has a coordination number greater than 4 in many cases. A linear correlation exists between 1JCPb of aromatic lead compounds and the coordination number of lead where the coordination number is known from other studies, or can otherwise be reasonably ascertained. 207Pb chemical shifts vary over a 1000-ppm range and are dependent on substituent and solvent. It appears that both 1JCPb and 207Pb chemical shifts are sensitive probes for the solution structure of organolead compounds. © 1979.