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Two Mn(II) complexes based on two nitronyl nitroxide radicals with different substituent R groups have been synthesized, and characterized structurally and magnetically: [[Mn(hfac) 2 ] 3 (NITPyOMe) 2 ] ( 1 ) (hfac = hexafluoroacetylacetonate, NITPyOMe = 2-(5′-(2″-methoxy)pyridyl)-4,4,5,5-tetramethylimidazozoline-1-oxyl-3-oxide) and [[Mn(hfac) 2 ] 3 (NITPhOEt) 2 ] ( 2 ) (NITPhOEt = 4′-ethoxyphenyl-4,4,5,5- tetra-methylimidazoline-1-oxyl-3-oxide). The X-ray crystal structure analyses show that modifying the substituent R groups with a donor N atom helps to get the one-dimensional Mn(hfac) 2 -bridged [Rad–Mn(hfac) 2 ] 2 chain complex 1 , while the large steric hindrance of the NITPhOEt radical induces complex 2 to be a mononuclear tri-spin compound, in which the central Mn(II) ion is coordinated by two hfac and two NITPhOEt radicals. Variable temperature magnetic susceptibility studies reveal that there are antiferromagnetic interactions between the Mn(II) ions and the radical through the N–O group in both of the two complexes. [ABSTRACT FROM AUTHOR]

Abstract: Four new copper(II) complexes containing different nitronyl nitroxide radicals have been synthesized, characterized structurally and magnetically: [(Cu(hfac)2)3(NITPh-3-Br-4-OMe)2] (1), [(Cu(hfac)2)3(NITPyOMe)2] (2), [Cu(hfac)2(2-QNNN)] (3) and [Cu(hfac)2(NITmNO2)2] (4) (hfac=hexafluoro-acetylacetonate; and NITPh-3-Br-4-OMe=2-3′-Br-4′-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NITPyOMe=2-4′-methoxy-3′-pyridyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, 2-QNNN=2-2′-quinolyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NITmNO2 =2-(3-nitrophenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). The X-ray crystal structure analyses show that complexes 1 and 2 have similar centrosymmetric five-spin structures built by three Cu(hfac)2 units bridged by two nitroxide ligands through their NO groups. While complex 3 consists of isolated molecule where the nitronyl nitroxide radical acts as chelating ligand towards copper(II), and complex 4 is a rare mononuclear tri-spin compound, in which central Cu(II) ion is coordinated by two hfac and two NITmNO2 radicals. The variable-temperature magnetic susceptibility studies reveal strong antiferromagnetic interactions between Cu(II) ions and radicals in complexes 1–2, practically diamagnetic in complex 3 and weak ferromagnetic interaction in complex 4. [Copyright &y& Elsevier]

Abstract: Five novel Ln(III) complexes based on a new nitronyl nitroxide radical have been synthesized, characterized structurally and magnetically: [Ln(hfac)3(NITPh-3-Br-4-OMe)2] (Ln(III)=Eu(1), Gd(2), Tb(3), Dy(4), Ho(5); hfac=hexafluoroacetylacetonate; and NITPh-3-Br-4-OMe=2-3′-Br-4′-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). The single-crystal structures analyses show that these complexes have similar mononuclear tri-spin structures, in which central Ln(III) ions are all eight coordinated by three hfac molecules and two NITPh-3-Br-4-OMe radicals. The variable-temperature magnetic susceptibility studies reveal the antiferromagnetic interactions between the paramagnetic ions (Ln(III) and radicals) in complexes 1, 2, 3 and 5 and ferromagnetic interaction in complex 4. The luminescence characterizations of complexes Eu(1), Tb(3) and Dy(4) are also studied in this paper. [Copyright &y& Elsevier]

Abstract: Three new lanthanide complexes based on a novel nitronyl nitroxide radical [Ln(hfac)3(NITPhiPr)2] (Ln=Gd(1), Tb(2), Dy(3); hfac=hexafluoroacetylacetonate, NITPhiPr=4′-isopropyl-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been successfully synthesized, characterized structurally and magnetically, which all display radical-Ln(III)-radical tri-spin structures. The magnetic studies reveal the ferromagnetic interactions between the Gd(III) ion and radicals and the antiferromagnetic interaction between two radicals in the complex 1. And both Ln(III)–radical ferromagnetic interactions exist in complexes 2 and 3. [Copyright &y& Elsevier]

Two new lanthanide–radical complexes, [Tb(hfac)3(EtVNIT)2] (1) and [Dy(hfac)3(EtVNIT)2] (2) (EtVNIT = 2-(4′-ethoxy-3′-methoxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate), were synthesized; both display radical–Ln(III)–radical (Ln=Tb (1), Dy (2)) tri-spin structures. Magnetic studies reveal that interactions between the lanthanide ions and radicals are ferromagnetic. [ABSTRACT FROM PUBLISHER]

Abstract: Three new lanthanide-radical complexes containing the same radical ligand were successfully synthesized, which all display radical-Ln(III)-radical (Ln=Pr (1), Gd (2), Ho(3)) tri-spin structures. The magnetic studies revealed that, for complex 2, the interactions between the Gd(III) ion and radical are ferromagnetic, while the interaction between two radicals is antiferromagnetic. In complexes 1 and 3, antiferromagnetic couplings exist between the lanthanide ions and radicals. [Copyright &y& Elsevier]

Two heterospin complexes [Cu(NIT3Py)(cda)H2O] ·H2O ( 1) and [Cu(NIT2Py)(cda)H2O] ·H2O ·CH3OH ( 2) with CuII ions and pyridyl-substituted nitronyl nitroxide radicals (NIT xPy = 2-( x′-pyridyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide, x = 3, 2; H2cda = 4-hydroxy-pyridine-2,6-dicarboxylic acid) were synthesized and characterized structurally and magnetically. The single crystal structures show that the two complexes are both two-spin complexes, in which the different radicals make the two complexes have different hydrogen bonding interactions to form 2D and 1D supramolecular network for complexes 1 and 2, respectively. The magnetic measurements indicate that complexes 1 and 2 both exhibit antiferromagnetic interactions between CuII and radicals. [ABSTRACT FROM AUTHOR]