| Six NITR nitroxide radicals have been synthesized,of which a novel nitroxide radical NITpt-BuPh(NITpt-BuPh=(2-(p-tert-phenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H -imidazolin-3-oxide-1-oxyl) has been determined by X-ray crystallographic method and ESR.A total of seven coordination complexes have been synthesized using transition metal ions and nitroxide radicals as spin carriers,meanwhile incorporating pyridine-2,4-dicarboxylate,fumarate,iminodiacetate,dicyanamide anion as bridging ligands. These complexes were characterized by X-ray crystallographic methods,element analyses,IR and variable-temperature magnetic susceptibility.Three coordination complexes incorporating pyridine-2,4-dicarboxylate bridging ligand have been synthesized.Complex[Mn(NIT4Py)(2,4-PDA)(H2O)2]2(1) is composed of dimeric unit.Two PDA bridge two Mn(Ⅱ) ions via two kinds of coordination modes:bidentate chelating and monodentate,respectively.A 2-D network structure is formed via intermolecular O-H…O hydrogen bonds alone ab plane.Complex 1 exhibits ferromagnetic coupling interaction through the direct Mn(Ⅱ)-radical bonds.{[Co(NIT4Py) (2,4-PDA)(H2O)2]}n(2) is an infinite 1-D chain structure with each PDA bridges two Co(Ⅱ) ion in bidentate chelating and monodentate mode,respectively.Furthermore,the complex forms a 2-D double-layer network structure via interchain hydrogen bonds.The Co(Ⅱ)-radical exhibits anti ferromagnetic coupling interaction.The structure of complex {[Zn(NIT4Py)(2,4-PDA)(H2O)2]}n(3) is similar to complex 2.Two complexes formed through fumarate as bridging ligand have been synthesized.In complex {[Zn(NIT4Py)(fum)(H2O)2]·H2O}n(4),the fumarate bridge two Zn(Ⅱ) ion in a bis-monodentate mode to generate an infinite 1-D chain structure.Furthermore,the chains are connected by O-H…O hydrogen bonds,forming a 2-D networks of double-layer.In complex {[Co2(NIT4Py)4(fum)2(H2O)4]·(H2O)2}n(5),the fumarate bridge two Co(Ⅱ) ion in a bis-monodentate mode to generate an infinite 1-D chain structure.Furthermore,the complex forms a 2-D network via interchain hydrogen bonds.Complex 5 exhibits antiferromagnetic interactions between the Co(Ⅱ) ion and the nitroxide radical. Complex[Cu(NIT4Py)(IDA)](6) incorporating iminodiacetate bridging ligand has been synthesized.In the neutral 1-D chain,Cu(Ⅱ)-nitroxide cation units are linked by iminodiacetate anion.Furthermore,the chains are connected by N-H…O hydrogen bonds, forming a 2-D networks structure.Complex Cu(NIT4Py)2[N(CN)2]2(H2O)2(7) consists of discrete molecules.Many coordination polymers made of transition metal and pyridyl-substituted nitroxide radicals incorporating different bridging ligands have been studied.Their magneto-structural correlations have been explored and the possible magnetic exchange mechanisms are explained.
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