Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2012

• A highlight in organolanthanide chemistry was the synthesis of the first molecular complexes of holmium(2+) and erbium(2+).
• The direct P4 activation using Sc and Y complexes has been achieved for the first time under mild conditions.
• Complexation of endohedral Ln metallofullerenes with TiCl4 provides an efficient route for separation from empty fullerenes.
• (C5Me4H)3U reacts with 1 equiv. of NO to form the first f-element nitrosyl complex, (C5Me4H)3UNO.

This review summarizes the progress in organo-f-element chemistry during the year 2012. A continuing trend in organolanthanide research is a strong emphasis on applications of organolanthanide complexes in homogeneous catalysis and materials science. Reactive lanthanide alkyl complexes supported by ligands other than cyclopentadienyl rings also continue to attract continuing interest. Currently, the study of organo-rare-earth-based SMMs is another exciting topic in organolanthanide chemistry. Notable among the highlights in organolanthanide chemistry is the synthesis of the first molecular complexes of holmium and erbium in the +2 oxidation state which have been generated by reducing Cp′3Ln (Cp′ = C5H4SiMe3; Ln = Ho, Er) with KC8 in the presence of 18-crown-6 in Et2O at −35 °C. The direct P4 activation using scandium and yttrium complexes has been achieved for the first time under mild conditions. Two novel Pn-containing products, [(NNfc)Sc]4P8 and [(NNfc)Sc]3P7, were isolated from reactions of P4 with the scandium arene complexes (μ-naphthalene)[(NNfc)Sc]2 and (μ-anthracene)[(NNfc)Sc]2 (NNfc = 1,10′-fc(NSitBuMe2)2, fc = ferrocenylene). A steady increase in research activities focussed on endohedral lanthanide metallofullerenes has been observed in 2012. Highly remarkable in this field was the discovery that complexation of endohedral metallofullerenes with TiCl4 can provide an efficient route for separation and purification of lanthanide metallofullerenes from empty fullerenes in large scale. Ca. 24% of all relevant papers published in 2012 were in the area of organoactinide chemistry, which continues to produce exciting results. A major achievement in organoactinide chemistry was the finding that (C5Me4H)3U reacts with 1 equiv. of NO to form the first f-element nitrosyl complex, (C5Me4H)3UNO, as a dark brown solid.