Mononuclear and trinuclear Dy SMMs with Schiff-base ligands modified by nitro-groups: first triangular complex with a N-N pathway

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 48; no. 46; pp. 17331 - 17339
• Main Authors: Cheng, Li-Wei, Zhang, Chi-Lung, Wei, Jun-Yu, Lin, Po-Heng
• Format: Journal Article
• Published: 26.11.2019
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c9dt02646k

Using two Schiff-base ligands containing an electron-withdrawing group (NO 2 ), we obtained two mononuclear and two trinuclear complexes with the general formula [Dy(hni)(NO 3 )(DMF) 2 ]·DMF ( 1 ·DMF), [Dy(hni) 2 (H 2 O) 2 ]·NO 3 ·EtOH ( 2 ·NO 3 ·EtOH), [Dy 3 (hnc) 3 (DMF) 6 ] ( 3 ) and [Gd 3 (hnc) 3 (DMF) 6 ] ( 4 ) ( H-hni : 2-(hydroxyl-3-methoxy-5-nitrophenyl)methylene(isonictino)hydrazine and H 3 -hnc : 1,5-bis(2-hydroxy-3-methoxy-5-nitrobenzylidene)carbonohydrazide). Four complexes were confirmed by infrared spectroscopy and single-crystal X-ray diffraction. The crystal structure of complex 3 reveals that the modified Schiff-base ligand provides two different tridentate coordination pockets (ONN and ONO) to encapsulate Dy III with a unique N-N pathway. The magnetic properties of all four complexes have been investigated using dc and ac susceptibility measurements. The frequency-dependent ac susceptibility is indicative of single-molecule magnetic behavior without and/or with an optimum dc field with a relaxation barrier U eff = 34 K (400 Oe), 19 K (0 Oe) and 80 K (0 Oe) for complexes 1 , 2 and 3 , respectively. Three Dy III SMMs were obtained with Schiff-base ligands containing nitro-groups. The triangular complex supported by the cis - trans form of the hnc 3− ligand displayed the first air-stable triangular complex with a N-N pathway.