Novel Tetranuclear Heterometallic Mn[sub.3]Ni and Mononuclear Ni Complexes with an IONO/I Schiff Base Ligand: Synthesis, Crystal Structures, and Magnetic Properties

A mononuclear Ni(II) complex, [Ni(HL1)[sub.2] ], (1) and a novel tetranuclear heterometal Mn-Ni complex, [Mn[sub.3] Ni(L1)[sub.4] Cl[sub.2] (EtOH)[sub.2] ], (2) [H[sub.2] L1 = N-(2-hydroxymethylphenyl)salicylideneimine], have been synthesized and characterized via X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the tridentate ligand, H[sub.2] L1, coordinates in a facial mode for Ni and a mer mode for Mn, respectively. Complex 2 includes Mn(II)Mn(III)[sub.2] Ni(II) tetranuclear metal core bridged by μ-phenoxo and μ-alkoxo oxygens. Magnetic measurements for 2 indicate that weak ferromagnetic interactions (J[sub.Mn(III)Ni(II)] = 2.23, J[sub.Mn(III)Mn(II)] = 0.46, J[sub.Mn(II)Ni(II)] = 1.78, and J[sub.Mn(III)Mn(III)] = 0.58 cm[sup.−1] ) dominate in the tetranuclear core. Additionally, in alternating current (AC) magnetic measurements, frequency-dependent out-of-phase responses were observed.