Determination of ligand-field parameters and f-electronic structures of hetero-dinuclear phthalocyanine complexes with a diamagnetic yttrium(III) and a paramagnetic trivalent lanthanide ion

Ligand-field parameters of the f-electronic systems in a series of dinuclear lanthanide phthalocyaninato complexes have been determined. To study the systems without intermetallic interactions, new asymmetric hetero-dinuclear lanthanide phthalocyaninato complexes, PcYPcLnPc* (Pc = dianion of phthalocyanine, Pc* = dianion of 2,3,9,10,16,17,23,24-octabutoxyphthalocyanine and Ln = Tb, Dy, Ho, Er, Tm, and Yb), were prepared. The synthesis of the dinuclear complexes were achieved by the reaction of Pc2Y, H2Pc*, and Ln-(acac)(3).n(H2O). Measurements of magnetic susceptibility of powder samples of PcYPcLnPc* were carried out over the temperature range from 1.8 to 303 K. Using the multidimensional simplex minimization method, we obtained a set of ligand-field parameters that reproduces both the H-1 NMR paramagnetic shifts and the magnetic susceptibility data. Ligand-field-splitting structure of the ground-state multiplets of the six lanthanide systems has been elucidated. A new computational approach to obtain ligand-field parameters is proposed for the situations in which sharp emission or absorption bands or both are not available.