Influence of a Lanthanide Ion on the Ni Site of a Heterobimetallic 3d-4f Mabiq Complex.

This work presents the synthesis and characterization of a 3d-4f bimetallic complex based on the redox-active macrocyclic biquinazoline ligand, Mabiq. The mixed Yb-Ni complex, [(Cp*)Yb(Mabiq)Ni]BArF (), was synthesized upon reaction of [Ni(Mabiq)]BArF () with (Cp*)Yb(OEt). The molecular structures of and its sister complex, [(Cp*)Yb(Mabiq)Ni][(Cp*)Yb(OTf)] (), confirmed the presence of a Yb(III) center and a reduced Ni-Mabiq unit. Spectroscopy (absorption and NMR), cyclic voltammetry, and magnetic susceptibility studies were employed to analyze the electronic structure of , which is best described by the [(Cp*)Yb(Mabiq)Ni] formulation. Notably, the ligand-centered radical is delocalized over both the diketiminate and bipyrimidine units of the Mabiq ligand. The magnetic susceptibility and variable temperature NMR studies for denote coupling between the Ni-Mabiq site and the peripheral Yb center-previously unobserved in 3d-3d Mabiq complexes. The complex nature of the exchange interactions is highlighted by the multiconfigurational ground state for , comprising nearly degenerate singlet and triplet states.