Abstract
Relative signs of ^1^J(^207^Pb^13^C) and ^2^J(^207^Pb^1^H) were determined for numerous methyllead derivatives by observing the ^207^Pb satellites in two‐dimensional (2D) ^13^C/^1^H heteroscalar correlated NMR spectra. The compounds studied include the species [R~3~Pb]Li (R = Me, 1a, Et 1b), Me~3~PbSiMe~3~ (2), [Me~3~PbBH~3~]Li, several alkenyltri‐methyllead compounds and some heterocyclics. Together with the linear correlation between ^1^J(^207^Pb^13^C~Me~) and ^1^J(^119^Sn^13^C~Me~) for the corresponding tin compounds, this enables the prediction of the absolute sign of ^1^J(^207^Pb^13^C~Me~). An analogous linear correlation ^1^J(^207^Pb^13^C~C=~)/^1^J(^119^Sn^13^C~C=~) exists which explains some apparently anomalous values reported in the literature, e.g. for [Ph~3~Pb]Li and for an intramolecular‐base‐stabilized plumbylene. The two coupling constants, ^1^J(^207^Pb^13^C~Me~), for the Me~2~Pb group in a 2,5‐dihydro‐1,2,5‐azoniaplumbaboratole are of opposite sign, giving the first example of this type of behaviour for any dimethyl element fragment. In the case of 2 the negative sign of ^1^J(^207^Pb^29^Si) [reduced coupling constant ^1^K(^207^Pb^29^Si) > 0] has been deduced from the tilt of the ^207^Pb satellites in the 2D ^29^Si/^1^H heteroscalar correlated NMR spectrum. A positive sign of ^1^J(^207^Pb^11^B) follows from the consistent trend observed for the reduced coupling constants ^1^K(M^11^B) and ^1^K(M^13^C) (M = ^13^C, ^29^Si, ^119^Sn, ^207^Pb) in the series of compounds [Me~3~MBH~3~]Li and Me~4~M, respectively.