Syntheses of {(MeC₅H₄)₂Ln(THF)[O CN(i-Pr)₂ NPh]} (Ln = Y, Er, Yb) and the X-ray Crystal Structure of the Yttrium Complex:  The Active Species for Polymerization of Phenyl Isocyanate by (Diisopropylamido)bis(methylcyclopentadienyl)lanthanides

Insertion of phenyl isocyanate into the Ln−N σ bond of (MeC5H4)2Ln(i-Pr)2(THF) (Ln = Y (1), Er (2), Yb (3)), which were synthesized by reactions of (MeC5H4)2LnCl(THF) with LiN(i-Pr)2, led to the isolation of {(MeC5H4)2Ln(THF)[O CN(i-Pr)2 NPh]} (Ln = Y (4), Er (5), Yb (6)). The latter is the active species for phenyl isocyanate polymerizations. The X-ray structure analysis of 4 shows that Y is coordinated to two methylcyclopentadienyl groups and one bidentate anion [O CN(i-Pr)2 NPh]- via a partial single bond, partial donor bond interaction with N1 and O1 atoms.