Pyridine Nitrogen Oxide And Thiocyanate Ligand Cu (ii), Co (ii), Ni (ii) Coordination Polymer Synthesis, Characterization And Magnetic Study

In this dissertation three novel coordination polymers have been designedand synthesized and the three complexes include the one-dimensional Cu(Ⅱ)complex [Cu₂(μ_1,3-SCN)2(μ′_1,3-SCN)₂(L1)₂]_n, the one-dimensional Co(Ⅱ) complex[Co(μ_1,3-SCN)(μ₂-L1)(SCN)(CH3OH)]_n and the two-dimensional Ni(Ⅱ) complex[Ni(μ_1,3-SCN)₂ (μ₂-L1)]_n, in which the Cu(Ⅱ) complex was constructed withthiocyanate as bridging ligand and 4-methylpyridine N-oxide (L1) as capped ligand,whereas the Co(Ⅱ) and Ni(Ⅱ) complexes deal with thiocyanate and4-methylpyridine N-oxide as mixed bridging ligands. The three complexes werecharacterized with infrared spectra, elemental analysis and X-ray crystallographicanalysis. The Cu(Ⅱ) complex was studied with ESR;the variable temperaturemagnetic susceptibilities (4-300 K) were measured for the three complexes. Forthe Cu(Ⅱ) complex a binuclear fitting formula was used and the magnetic couplingconstant 2J = -216 cm^-1 was obtained through the fitting, then density functionalcalculations have been carried out for the binuclear unit and it gave the magneticcoupling mechanism and a similar singlet-triple splitting value J = -326.10 cm^-1,and the error that are from the fitting and the calculations was analyzed. For theCo(Ⅱ) and Ni(Ⅱ) complexes the calculation models were first constructed throughthe analyzing the characters of the two crystal structures, then density functioncalculations were performed on the two model complexes, respectively;thecalculations gave the magnetic coupling mechanism and the magnetic couplingconstants;Based on the calculations the fitting formulae were selected and thefittings were accomplished;the fittings gave the experimental magnetic couplingconstants, and the errors dealing with the calculations and the experimental werestudied. The structural factors that affect the magnetic coupling were studied forthe three complexes.The special advantages and contributions of this dissertation are as follows:1. The Cu(Ⅱ) complex exhibit maximum magnetic coupling in the complexes withthiocyanate as bridging ligand to date;The ESR spectra of the complexdisplays a very unusual interesting phenomenon that deal with the relationshipof peak width with the intensity of magnetic coupling, and which have not beenreported in the published papers of Cu(II) complexes.2. A new method, namely, the combination of theoretical calculations andexperimental fitting, was first suggested and used to study the magneticinteraction for the complexes with mixed bridging ligands.The results of this dissertation will benefit the synthesis of idealmolecular-magnets and it also benefits the understanding for the bio-functionof bridged metallic ions in metallic proteins.