Erbium Mixed-Ligand b-Diketiminato-Diamido Complex: Unusual Structure of Diamide Ligand

摘要

A novel mixed-ligand erbium complex [(NacNac)ErL(THF)] (1) containing two types of sterically hindered ligands - monoanionic N-mesityl substituted b-diketiminate (NacNac= (MesN-C(Me)CHC(Me)-NMes)-, Mes=2,4,6-Me3C6H2) and dianionic modified diamide ligand with mesityls as the N-aryl substituents (L=(MesN-C(H)(Me)-C(=CH2)-NMes)~(2-)) - was isolated from the salt metathesis reaction of [(NacNac)Er(THF)2] with potassium salt of doubly reduced diazabutadiene K2(DADMes~(2-) ) (DAD-Mes=MesN=C(Me)-C(Me)=NMes) prepared in situ. A solid-state structure of 1 was determined by single-crystal X-ray diffraction and revealed unusual asymmetrical diamide ligand with sp~3- and sp~2-hybridized carbon backbone atoms and exometallacyclic double carbon-carbon bond. In spite of the energy preference of symmetrical form of diamide ligand Lsym (Lsym=(MesN-C(Me)=C(Me)-NMes)~(2-)) calculated by DFT asymmetrical form L was found as minor product in the mixture of dipotassium salts obtained by reduction of DAD-Mes.