Bis(pentafluorophenyl)mercury—a versatile synthon in organo-, organooxo-, and organoamido-lanthanoid chemistry

Diarylmercury(II) compounds, HgR2 (particularly bis(pentafluorophenyl)mercury), which are easily prepared and are stable to air and moisture, are attractive reagents for the synthesis of highly reactive lanthanoid organometallics and complexes. Thus, reactions of HgR2 (R=C6F5) with elemental lanthanoids in donor solvents generate organolanthanoid species that when subsequently treated with a protic reagent LH (e.g. C5R5H, ArOH, R2NH) eliminate volatile RH giving cyclopentadienyl-, aryloxo- and organoamido-lanthanoids, respectively. Combining these two steps in a convenient ‘one-pot’ reaction between Ln metal, HgR2 and LH provides a versatile synthetic method (redox transmetallation–ligand exchange) for a wide variety of lanthanoid complexes and exploits the high reactivity of the initially generated lanthanoidcarbon bond. The syntheses are possible even in instances where the intermediate organolanthanoid complex cannot be isolated or detected. The increasing scope of redox transmetallation–ligand exchange often makes it competitive with metathesis and its simplicity can make it superior. Previously unreported applications viz. to [Ln(C5H5)3(THF)] complexes, [Yb(C5H5)2(THF)2] and [Yb(C5Me5)2(THF)2] are included.