Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

A series of lanthanide complexes including (Ind)3Sm(THF) (1), [(MeCp)2Sm(μ‐SPh)(THF)]2(2), [(MeCp)2Y(μ‐O‐i‐Pr)]2 (3), (MeCp)3Sm·θF (4), Sm(SPh)3(hmpa)3(5), [(MeCp)2Y‐(μ‐OCH2CF3)]2(6) and (OF3CH2O)3 Y(THF)3 (7) were synthesized and they have good activity for the oligomerization of phenyl isocyanate. Among them 5 shows the highest activity. The conversion is as high as 96.2%, with 1/2500 of the molar ratio of cat./ PhNCO. The main components in oligomer were characterized to be a cyclodimer and a cyclotrimer. The ratio of cyclodimer to cyclotrimer depends on the lanthanide complexes used. 7 gave 85.2% cyclotrimer with 1/300 of the molar ratio of cat./PhNCO at 40 °C for 0.5 h, while 5 gave 77.6% cyclodimer with 1/300 of the molar ratio of cat./PhNCO at 40 °C for 4 h.