Rigid NO-Pentadentate Ligand-Assisted Octacoordinate Mononuclear Ln(III) Complexes: Syntheses, Characterization, and Slow Magnetization Relaxation.

A series of air-stable mononuclear octacoordinate Ln(III) complexes, [(L)Ln(TPPO)]OTf (Ln = Y (); Gd (); Tb (); Dy (); Ho (); and Er ()) and [(L)Ln(TPPO)(NO)] (Ln = Y () and Dy ()), are synthesized employing a rigid NO-pentadentate chelating ligand as the basis ligand and meridional ancillary ligands (where HL = 2,6-diacetylpyridine -benzoylhydrazone, TPPO = triphenylphosphine oxide, and OTf = trifluoromethanesulfonate). All the complexes are synthesized under aerobic conditions and characterized comprehensively by spectroscopic and X-ray crystallographic techniques. Magnetic property investigation on the polycrystalline solid samples of (Ln = Gd, Tb, Dy, Ho, and Er) and are reported. A field-induced single-molecule magnet behavior was observed for the Dy derivatives. exhibits the highest effective energy barrier of magnetization reversal, / = 47 K under = 1 kOe among the complexes presented herein.