Lanthanide Complexes for Oligomerization of Phenyl Isocyanate

A series of lanthanide complexes including (Ind) 3 Sm(THF) (1), [(MeCp) 2 Sm(μ‐SPh)(THF)] 2 (2), [(MeCp) 2 Y(μ‐O‐ i ‐Pr)] 2 (3), (MeCp) 3 Sm·θF (4), Sm(SPh) 3 (hmpa) 3 (5), [(MeCp) 2 Y‐(μ‐OCH 2 CF 3 )] 2 (6) and (OF 3 CH 2 O) 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.