Four mononuclear dysprosium complexes with neutral Schiff-base ligands: syntheses, crystal structures and slow magnetic relaxation behavior.

Four mononuclear 9-coordinate Dy-based complexes, [Dy(HL 1 ) 2 (NO 3 ) 3 (CH 3 OH)] (1Dy), [Dy(HL 2 ) 2 (NO 3 ) 3 (H 2 O)] (2Dy), [Dy(HL 3 ) 3 (NO 3 ) 3 ]·CH 3 CN (3Dy), and [Dy(HL 4 ) 3 (NO 3 ) 3 ] (4Dy), have been constructed by neutral Schiff-base ligands (1-[ N -(4-R)aminomethylidene-2( 1H )-naphthalenone, R = -Cl (HL 1 ), -NO 2 (HL 2 ), -OCH 3 (HL 3 ), -I (HL 4 )). By tuning the terminal substituent group of HL ligands, the number of HL ligands coordinated to the central Dy 3+ ion unexpectedly varies from 2 to 3, and the local symmetry around the Dy 3+ ion reduces from D 3h to C s . Magnetic measurements reveal that 2Dy can display single-ion magnet (SIM) behavior in zero dc field, while 1Dy, 3Dy and 4Dy show field-induced slow magnetic relaxation. Ab initio calculations were employed to elucidate magnetic anisotropy in the complexes, including g -tensors, averaged transition magnetic moments and magnetic easy axes. The difference in magnetic behaviors of the four complexes can be ascribed to the terminal substituent effect of neutral Schiff-base ligands.