Insertion Reaction of Phenyl Isocyanate into the Ln−C σ-Bond of Organolanthanide Complexes:  Synthesis, Characterization, and Crystal Structures of {(C<INF>5</INF>H<INF>4</INF>CH<INF>3</INF>)<INF>2</INF>Ln[μ-η<SUP>1</SUP>:η<SUP>3</SUP>-OC(R)NPh]}<INF>2</INF> (Ln = Sm, Dy, Er, Ho; R = n-butyl, α-naphthyl)

Cp‘<INF>2</INF>LnR(THF) (Cp‘ = C<INF>5</INF>H<INF>4</INF>CH<INF>3</INF>) reacted with phenyl isocyanate to form the PhNCO insertion products [Cp‘<INF>2</INF>Ln(OC(R)NPh)]<INF>2</INF> [R = n-butyl, Ln = Sm (<BO>1</BO>), Dy (<BO>2</BO>), Er (<BO>3</BO>); R = α-naphthyl, Ln = Dy (<BO>4</BO>)]. It was found that an excess of PhNCO did not affect the nature of the final complexes, a single insertion only being observed and excess PhNCO forming a cyclotrimer (<BO>5</BO>). The reaction of Cp‘HoCl<INF>2</INF>(THF)<INF>3</INF> with BuⁿLi and subsequently with 2 equiv of PhNCO in THF gave Ho[OC(Buⁿ)NPh)]<INF>3</INF> (<BO>6</BO>) and [Cp‘<INF>2</INF>Ho(OC(Buⁿ)NPh)]<INF>2</INF> (<BO>7</BO>), which can be rationalized by the rearrangement reaction of the di-insertion product Cp‘Ho[OC(Buⁿ)NPh]<INF>2</INF>(THF)<INF>x</INF><INF></INF>. The structures of <BO>1</BO>, <BO>4</BO>·THF, <BO>5</BO>·THF and <BO>7</BO> were determined by X-ray diffraction, revealing an unusual bonding mode of the amido groups arising from the insertion of PhNCO into the Ln−C σ-bonds and that the O&bondDotb;C&bondDotb;N fragment of the OC(R)NPh ligand acts as both a bridging and side-on chelating group.