From a mercury(II) bis(yldiide) complex to actinide yldiides.

The bis(yldiide) mercury complex, (L-Hg-L) [L = C(PPh 3 )P(S)Ph 2 ], is prepared from the corresponding potassium yldiide and used to access the first substituted yldiide actinide complexes [(C 5 Me 5 ) 2 An(L)(Cl)] (An = U, Th) via salt metathesis. Compared to previously reported phosphinocarbene complexes, the complexes exhibit long actinide-carbon distances, which can be explained by the strong polarization of the π-electron density toward carbon.