不對稱配基之新直線型五核鎳金屬串錯合物 的合成與性質研究

Abstract

Two series of the complex, which contain the novel linear pentanickel metal string complexes and a trinickel metal string complex, have been studied. The asymmetric 2-(Phenylpyridyldiamino)- 1,8-naphthyridine (H2phpdany) ligand and its pentanickel metal string complex, (4,0)-[Ni5(phpdany)4Cl](PF6) (1) are synthesized. According to X-ray crystallography analysis, the metal ions of complex 1 are surrounded by four unsymmetrical ligands with (4,0) stereoisomer. Because of the steric hindrance of the bulky phenyl groups, there is only one axial ligand Cl-, which is coordinated to terminal naphthyridyl groups’ nickel ion. Magnetic measurements show that complex 1 is paramagnetic. The terminal naphthyridyl groups’ Ni2+ ion possess S = 1 and the others Ni ions are diamagnetic. Complex 1 undergoes redox reaction, which lead one-electron oxidation and reduction complexes (4,0)-[Ni5(phpdany)4Cl](PF6)2 (2) and (4,0)-[Ni5(phpdany)4Cl] (3). Complexes 2 and 3 are characterized by magnetism, EPR and UV/Vis-NIR spectra and compare with complex 1. In the second part, by using the precursor [Ni3(dpa)4Cl2] with nitrosonium tetrafluoroborate in acetonitrile, the reaction proceeded with nitration instead of originally proposed oxidation. [Ni3(dpa(NO2)2)4Cl2] has been synthesized successfully and studied. The nitropyridine formed in the reaction of pyridine with nitronium ion (NO2+). A linear trimetallic string of nickel(Ⅱ) atoms wrapped by dpa- ligand with two NO2 groups at the 3-positions of each pyridyl group. Magnetic measurements show that it exhibits antiferromagnetic coupling ( J = -196.25 cm-1 ). The terminal Ni2+ and center Ni2+ are S = 1 and S = 0 respectively.