Synthetic and Spectroscopic Studies of Some Nitrato–Lanthanide(III) Hydrazone Complexes of Higher Coordination Number

The reactions of the lanthanide(III) ions Y, La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, and Yb, with pyridine‐2‐carboxaldehyde‐4‐chlorobenzoylhydrazone (PpClBH) leads to the formation of complexes corresponding to the formulae [Ln(PpClBH)2(NO3)3], (Ln = La, Ce, and Pr) and [Ln(PpClBH)2(NO3)2]NO3 (Ln = Y, Nd, Eu, Gd, Tb, Dy, Ho, Er, and Yb). Twelve new compounds have been prepared. The complexes were characterized by means of elemental analyses, conductivity measurements, magnetic moments, and spectroscopic studies (IR, UV‐VIS, and 1H NMR). The coordination number of 12 have been proposed for the La, Ce, and Pr complexes, while for the Y, Nd, Eu, Gd, Tb, Dy, Ho, Er, and Yb compounds the coordination number is reduced to 10. This change in coordination number is consistent with the lanthanide contraction. Complexes having coordination numbers greater than ten appear to be limited to the lighter lanthanides. PpClBH has been characterized by elemental analysis, IR, UV, and 1H NMR.