Reactivity of Rare Earth Metal Alkyl Complexes with Nitriles or Isonitrile: Versatile Ways toward Multiply Functionalized β-Diketiminato, (Iso)indolyl, and Imidazolyl Chelating Rare Earth Metal Complexes.

The reactivity of the rare earth metal alkyl complexes L RE(CH 2 SiMe 3 )(THF) 2 ( 1 RE ) [RE = Y ( 1 Y ), Yb ( 1 Yb ), Lu ( 1 Lu ); L = 2,5-[(2-pyrrolyl)CPh 2 ] 2 ( N -methylpyrrole)] with various nitriles and isonitriles has been fully developed. Treatment of the yttrium monoalkyl complex ( 1 Y ) with 2 equiv of aromatic nitriles afforded the symmetric trisubstituted β-diketiminato yttrium complexes ( 2 Y(H) , 2 Y(Me) , and 2 Y(F) ) through successive cyano group insertion into the RE-C bond and 1,3-H shift or the unsymmetric trisubstituted β-diketiminato yttrium complex ( 3 Y ) unexpectedly via a 1,3-SiMe 3 shift when 4-(trifluoromethyl)benzonitrile was used in this reaction under the same conditions. By treating 1 Y with 2 equiv of tolyl acetonitrile, an activation of the sp 3 C-H bond occurred to form the corresponding β-aryl keteniminato complexes 4 Y( p -tol) and 4 Y( m -tol) . Remarkably, a heteroleptic cleavage of the CO-CN bond took place in the reaction of 1 Y with benzoyl nitrile, affording the unsymmetric trinuclear yttrium complex 5 Y bridged by three cyanide groups. Dinuclear ytterbium and lutetium complexes 6 Yb and 6 Lu containing a functionalized isoindole fragment were synthesized from the reactions of 1 with phthalonitrile by tandem insertion and cyclization. Further studies indicated that the temperature and stoichiometric ratio have a great influence on the reactivity patterns between the reactions of 1 RE with benzylisonitrile: two tetrasubstituted β-diketiminato complexes 8 and 9 were obtained at -30 °C, and tetrasubstituted imidazolyl yttrium and lutetium complexes 7 were isolated at elevated temperature, respectively. In addition, the tetrasubstituted β-diketiminato complexes 8 and 9 could be irreversibly converted to the cyclization products 7 by elevating the reaction temperature not only on the NMR scale but also on the preparative scale. Notably, when the phenyl isonitrile instead of benzyl isonitrile was reacted with 1 Yb , a 2,3-functionalized indolyl ytterbium complex 10 Yb was isolated.