Crystal Structure And Magnetic Properties Of Heterobimetallic Assemblies Derived From Manganese (Ⅲ) Schiff Base Complexes And Anionic Cyanometallates

The molecular-based magnetic materials have been one of the most attractive fields in recent years. Mn(Ⅲ) ion can carry high spin(S=2) and apparent magnetic anisotropy due to Jahn-Teller distortion, which makes it promising candidate for application in the design of magnetic materials. In this dissertation, salen type Schiff base(SB), 1,1,2,2-tetramethylethylenediammine(tmen) and N-(2-hydroxybenzyl)salicylaldimine(H2La) as terminal ligands with [Fe(CN)6]3-, [Cr(CN)6]3-,[Fe(CN)5(NO)]2-, [Au(CN)2]- and [W(CN)8]3- as bridging ligands are applied to synthesize polynuclear complexes. The total of 23 polynuclear complexes are characterized by X-ray crystallography, magnetic measurements, IR, elemental analysis, UV-Vis and fluorescence spectra.Based on the coordination-acceptor building blocks [Mn(SB)]+, seventeen cyano-bridged complexes have been obtained:three binuclear complexes, eight trinuclear complexes, one tetranuclear complex, two pentanuclear complexes, two 1D chain complex and one 2D network. The structure of complex 2 consists of a two-dimensional layer containing as the repeating unit a cyclic dodecamer. The magnetic measurement of complex 2 indicates a molecular magnet behavior below 3.0 K. The strong frequency dependence of the ac susceptibility and the slow relaxation of the magnetization show that complex 4 behaves as a single-molecule magnet. In the novel 1D chain of complex 6, both Cr(Ⅲ) and Mn(Ⅲ) ions have two kinds of coordination mode. The magnetic measurements of complex 6 showed its metamagnetic behavior. The frequency dependence of the ac susceptibility shows that complex 7 may behave as a single-chain magnet. In complex 11, combination of a moderate zero-field splitting in Mn(Ⅲ) ions and an appropriate antiferromagnetic interaction between the Mn(Ⅲ) ions results in a typical spin-flop transition with a critical field of 20 kOe at 2.0 K. Dicyanoaurate(Ⅰ) anion acts as monodentate and bidentate ligand to form one binuclear complex 15 and two trinuclear complexes 16 and 17, respectively. To the best of our knowledge, this is the first report on discrete polynuclear complexes based on [Au(CN)2]- and [Mn(SB)]+Two cyano-bridged polynuclear complexes based on tmen, one di-μ-oxo bridged Mn(IV) dinuclear complex based on salen type Schiff base and three phenolate oxygen-bridged polynuclear complexes based on H2La have been prepaired and studied.