Yttrium complexes mono compounds

Aryloxo-NHC-containing complexes could also be produced from amido precursors where the ligands also acted as internal base as shown by the Shen group. Hence, a hydroxyaryl-imidazolium ligand reacted with [LiY N(z-Pr2) 4] and BuLi at — 78 °C to give the NHC-yttrium complex [(NHQ3Y] 21 (Scheme 6.2). " From [LiYb N(z -Pr2) 4], a bis-substituted ytterbium compound [(NHC)2Yb N(z-Pr2) ] 22 was prepared. Of note, all attempts to prepare the mono-substituted complex were unsueeessful. 

Mono(guanidinate) complexes of lanthanum and yttrium have been synthesized as illustrated in Scheme 58.The lanthanum compounds were made starting from La[N(SiMe3)2]3 and dicyclohexylcarbodiimide. Both mono (guanidinate) derivatives are monomeric in the solid state with a four-coordinate La center. ... 

The only other class of compound that contains a lanthanide(III) ion and one [8]annulene ligand is the "mixed sandwich" complex, the [8]annulenelanthanate(III) cyclopentadienides. s This class of complexes can be made either by the addition of cyclopentadienide to the mono-[8]annulenelanthanide chlorides or by the addition of [8]annulene dianion to cyclopentadienyllanthanatedll) dichloride. The yttrium a and scandium members of this class have also been reported. 

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