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 RE(CHSiMe)(THF) () [RE = Y (), Yb (), Lu (); = 2,5-[(2-pyrrolyl)CPh](-methylpyrrole)] with various nitriles and isonitriles has been fully developed. Treatment of the yttrium monoalkyl complex () with 2 equiv of aromatic nitriles afforded the symmetric trisubstituted β-diketiminato yttrium complexes (, , and through successive cyano group insertion into the RE-C bond and 1,3-H shift or the unsymmetric trisubstituted β-diketiminato yttrium complex () unexpectedly via a 1,3-SiMe shift when 4-(trifluoromethyl)benzonitrile was used in this reaction under the same conditions. By treating with 2 equiv of tolyl acetonitrile, an activation of the C-H bond occurred to form the corresponding β-aryl keteniminato complexes and . Remarkably, a heteroleptic cleavage of the CO-CN bond took place in the reaction of with benzoyl nitrile, affording the unsymmetric trinuclear yttrium complex bridged by three cyanide groups. Dinuclear ytterbium and lutetium complexes and containing a functionalized isoindole fragment were synthesized from the reactions of 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 with benzylisonitrile: two tetrasubstituted β-diketiminato complexes and were obtained at -30 °C, and tetrasubstituted imidazolyl yttrium and lutetium complexes were isolated at elevated temperature, respectively. In addition, the tetrasubstituted β-diketiminato complexes and could be irreversibly converted to the cyclization products 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 , a 2,3-functionalized indolyl ytterbium complex was isolated.