Synthesis and Crystal Structure of a New Zn(II) Nitronyl Nitroxide Complex [Zn(NIT4Py)(PDA)(H2O)3]

1 INTRODUCTION Nitronyl nitroxides, independently or in combina- tion with metal ions, have been one of the most wi- dely studied systems in molecular magnetism for understanding radical-radical or metal-radical inte- ractions as well as for synthesizing organic ferroma- gnets and metal-radical magnetic materials[1～4]. Up to now, lots of metal-radical complexes have been reported[5～8]. On the other hand, cooperative inter- molecular interactions, such as coordination bonds, hydrogen bon…     

Synthesis,crystal structure and magnetic properties of a nickel(II) complex containing a 2-pyridyl-substituted nitronyl nitroxide

A new complex of formula [Ni(NIT2Py)₂Cl(H₂O)]Cl·2CH₃OH, where NIT2Py is 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, was synthesized and characterized structurally and magnetically. The structure consists of a [Ni(NIT2Py)₂Cl(H₂O)]⁺ ion, a chloride anion and two methanol molecules. The nickel(II) ion lies in a distorted octahedral environment; two nitrogen atoms and two oxygen atoms from NIT2Py ligands from the basal plane; one oxygen atom from a water molecule and one chloride anion occupy axial positions. Variable temperature magnetic susceptibility data show that there is strong antiferromagnetic coupling between the nickel(II) ion and nitronyl nitroxide radicals. The results suggest that the sign of the magnetic interaction depends on structural and ligand effects.     

Synthesis,structure and magnetic properties of a Pr(III) complex with chelating nitronyl nitroxide radicals

The synthesis and structure of Pr(III) complex with chelating nitronyl nitroxide radicals of formula [Pr(III)(NIT2Py)₂(NO₃)₃] (NIT2Py?=?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) is reported. Pr(III) is ten-coordinate with three bidentate nitrate anions and two radicals. The radical behaves as a bidentate chelating ligand through one oxygen atom of the nitronyl nitroxide group and one nitrogen atom of a pyridine ring. The electronic spectrum for the complex in THF and magnetic susceptibilities from 77–300?K are reported.     

Synthesis and Crystal Structure of a New One-dimensional Zn(II) Nitronyl Nitroxide Complex Bridged by Pyridine-2,4-dicarboxylate Anion

1 INTRODUCTION The synthesis and study of transition metal com- pounds incorporating organic free radicals directly bound to their coordination sphere are a major re- search aim in the field of molecular magnetism[1]. Exceptional stability, ease of chemical modification and versatility in their coordination properties have made nitroxide free radicals one of the most attrac- tive spin carriers for the design of molecular magne- tic materials[2, 3]. The structures and magnetic prope- rties …     

Two hetero-spin metal–radical complexes exhibiting strong antiferromagnetic interactions between the metal ions and nitroxide radicals

Two hetero-spin metal–radical complexes [Cu(NIT2Py)₂Cl] · ClO₄ · H₂O ( 1 ) and [Co(NIT2Py)₂(H₂O)(CH₃OH)] · (ClO₄)₂ ( 2 ) (NIT2Py = 2-(2′-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), were synthesized and characterized structurally and magnetically. The two complexes crystallize in mononuclear structures where two radical ligands coordinate to the metal ion through the nitroxide oxygen atoms directly via the bidentate chelating mode. The magnetic measurements show that two complexes exhibit strong antiferromagnetic interactions between the metal ions and the nitroxide radicals.     

Synthesis,crystal structure and magnetic properties of Co(NIT4Py)(H2PDA)(H2O)3

A Co(II)-pyridyl substituted nitronyl nitroxide complex Co(NIT4Py)(H₂PDA)(H₂O)₃ has been synthesized and structurally characterized (NIT4Py: 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and H₂PDA: 2,5-pyridine dicarboxylic acid). The compound is in the monoclinic space group P2(1)/c, a = 16.892(5) Å, b = 7.371(2) Å, c = 18.856(5) Å, β = 108.770(5)°, V = 2223.0(11) ų, Z = 4 and F(000) = 1064. The cobalt is in a distorted octahedral environment with one nitrogen from NIT4Py, one oxygen atom from H₂PDA, two oxygens from two water molecules in the basal plane and one nitrogen from H₂PDA and one water in the axial positions. The molecules are connected as a layered structure by intermolecular hydrogen bond interactions. Variable temperature magnetic susceptibility measurements reveal the occurrence of weak antiferromagnetic interactions in the compound.     

Synthesis,structures and magnetic properties of copper (II) and cobalt (II) complexes containing pyridyl-substituted nitronyl nitroxide and 3,5-dinitrobenzoate

Four new metal-radical complexes - [Cu(NIT3Py)₂(DTB)₂] 1, [Co(NIT3Py)₂(DTB)₂(CH₃OH)₂] 2, [Cu(NIT4Py)₂(DTB)₂(H₂O)₂] 3, [Co(NIT4Py)₂(DTB)₂(H₂O)₂] 4, (NIT3Py = 2-(3^′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], NIT4Py = 2-(4^′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], DTB = 3,5-dinitrobenzoic anion) have been synthesized by using transition metal ions, nitronyl nitroxide radicals as spin carriers, and incorporating 3,5-dinitrobenzoic acid (DTB) as a coligand.     

Synthesis,crystal structure and magnetic properties of a novel complex containing a diamagnetic metal ion and thiazole-substituted nitronyl nitroxide radicals

The synthesis, crystal structure and magnetic properties of a novel diamagnetic metal complex containing thiazole-substituted nitronyl nitroxide radicals, [HgCl₂(NIT2-thz)₂] (NIT2-thz?= 2-(2′-thiazole)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), is reported. The mercury(II) ion has distorted tetrahedral coordination involving two chloride atoms and two thiazole nitrogen atoms. Magnetic susceptibility data show that there are intramolecular antiferromagnetic interactions between the radicals in the complex.     

Ferromagnetic interactions in a Zn(II)–nitronyl nitroxide complex with dicyanoaurate(I) bridges

A two-dimensional Zn(II)-nitronyl nitroxide radical complex, Zn(NIT4Py)₂[Au(CN)₂]₂ (NIT4Py?=?2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) was synthesized and characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction methods. The complex is monoclinic, space group C2/c, with a?=?26.294(9), b?=?7.167(2), c?=?18.532(6) Å, β?=?111.758(5)°, V?=?3243.6(18) ų, Z?=?4, and R ₁ [I?>?2σ (I)]?=?0.0348, and has an infinite two-dimensional network motif. Magnetic studies showed ferromagnetic coupling between two radicals through Zn(II).     

A mercury(II)-radical complex with a 1D ladder structure

Interaction of HgI₂ with a new long rigid nitronyl nitroxide radical ligand, 2-[4-(2-pyridin-4-yl-vinyl)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (L), leads to the formation of the mercury-radical complex [Hg₂I₄L₂] _n (1). The single crystal structure analysis reveals that 1 exhibits a one-dimensional (1D) ladder structure. Magnetic susceptibility data of 1 were simulated by a uniform chain model composed of the NIT–NIT dimers, indicating that there exist an antiferromagnetic exchange between the nitroxides within the dimer (J ₁ = ?8.41 cm^?1) and a very weak interdimer antiferromagnetic interaction (J _c = ?0.39 cm^?1).     

A hydrogen-bonded,one-dimensional complex of cadmium(II) ions with 3,5-dinitrobenzoate and radicals: synthesis,characterization and crystal structure

A novel one-dimensional complex, [Cd(NIT4py)₂(DTB)₂(H₂O)₂] (1), (where NIT4py is 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and DTB is 3,5-dinitrobenzoate) has been synthesized and characterized by elemental analyses, IR and electronic spectra, single-crystal X-ray diffraction and magnetic measurements. The Cd(II) ion lies in a distorted octahedral environment with two nitrogen atoms from two NIT4py ligands and two oxygen atoms from two DTB molecules in the basal plane, and two oxygen atoms from two water molecules in axial positions. [Cd(NIT4py)₂(DTB)₂(H₂O)₂] units are connected to form one-dimensional chains by intermolecular hydrogen bonds. The complex exhibits intramolecular antiferromagnetic interactions.     

Synthesis,crystal structure and magnetic properties of a nickel(II) complex with pyridine-substituted nitronyl nitroxide radicals

The complex [Ni(NIT2Py)(PDA)(H₂O)]·(MeOH)(H₂O) [NIT2Py = 2-(2-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; PDA = 2,6-pyridine dicarboxylic acid] has been prepared and structurally characterized. The Ni^II ion is in a distorted octahedral environment: one nitrogen atom and one oxygen atom from the NIT2Py, one nitrogen atom from the PDA and one oxygen atom from the H₂O in the basal plane; two oxygen atoms from the PDA in the axial position. The units of [Ni(NIT2Py)(PDA)(H₂O)] were connected as a one dimension chain by intermolecular hydrogen bonds. The complex exhibits intramolecular antiferromagnetic interactions between the Ni^II ion and the NIT2Py.     

Syntheses,crystal structures,and magnetic properties of three one-dimensional metal–nitroxide complexes linked by 1,4-cyclohexanedicarboxylate ligands

Three one-dimensional metal–nitroxide complexes [Cu(NIT4Py)₂(1,4-chdc)] _n (1), {[Cu(IM4Py)₂(1,4-chdc)(H₂O)]·H₂O} _n (2) and {[Zn(IM4Py)₂(1,4-chdc)(H₂O)₂]·H₂O} _n (3) (NIT4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, IM4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and 1,4-chdc = 1,4-cyclohexanedicarboxylate anion) have been synthesized and characterized structurally as well as magnetically. All three complexes crystallize in neutral one-dimensional chains in which the nitroxide–metal–nitroxide units are linked by linear 1,4-cyclohexanedicarboxylate anions. The 1,4-chdc ligands only present the e,e-trans-configuration in these complexes, although there are both cis- and trans-isomers in the free ligand. Magnetic measurements show that complexes 1 and 2 both exhibit weak antiferromagnetic interactions between the copper atoms and nitroxide radicals.     

Synthesis, Crystal Structure and Optical Properties of a New Nd(Ⅲ) Nitronyl Nitroxide Complex [Nd(NIT2Py)2(NO3)3]

A new Nd(Ⅲ) nitronyl nitroxide complex [Nd(NIT2Py)2(NO3)3] (NIT2Py = 2-(2'-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized and structurally characterized by X-ray diffraction.It crystallizes in monoclinic, space group P21/n with a = 12.396(4), b =11.134(4), c = 23.360(7)(。A), β = 98.178(6)°, V= 3191.2(18)(。A)3, C24H32NgNdO13, Mr = 798.83, Dc =1.663 g/cm3, μ(MoKα) = 1.704 mm-1, F(000) = 1612, Z = 4, the final R = 0.0425 and wR = 0.0957for 6532 independentreflections with Rint = 0.0642 and 4552 observed reflections (I ＞ 2σ(I)).The complex exists as discrete mononuclear molecules and the neodymium(Ⅲ) ion is ten-coordinated with three bidentate nitrate anions and two radical ligands (NIT2Py) via bidentate chelating mode.The optical properties of the complex are discussed.     

Synthesis, Crystal Structure and Optical Properties of a New Nd(III) Nitronyl Nitroxide Complex [Nd(NIT2Py)_2(NO_3)_3]

1 INTRODUCTION Nitronyl nitroxides, independently or in combina- tion with metal ions, have been one of the most widely studied systems in molecular magnetism for understanding the radical-radical or metal-radical interactions as well as for synthesizing organic ferro- magnets and metal-radical magnetic materials[1～3]. Meanwhile, investigations on molecular coordina- tion compounds of lanthanide ions have also attrac- ted great attention due to their luminescence[4, 5] or magnetic propert…     

氮氧自由基-锌配合物[Zn(NIT3Py)2Cl2]的合成、结构和磁行为

A Zn(Ⅱ) complex with nitronyl nitroxide radicals [Zn(NIT3Py)₂Cl₂] (1) (NIT3Py=2-(3′-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized and structurally characterized by X-ray diffraction crystal structure determination method. The complex has a mononuclear-metal structure in which each Zn(Ⅱ) ion adopts a distorted tetrahedral geometry and is coordinated by two Cl^- anions and two pyridyl-N atoms from two NIT3Py radical ligands. The magnetic measurements show the weak antiferromagnetic interaction between the nitroxide radicals through the diamagnetic Zn(Ⅱ) ion. CCDC: 292363.     

Synthesis,structure, and properties of a 1-D copper(II) complex with nitronyl nitroxide radicals

A 1-D chain complex [Cu(NIT4Py)(IDA)]_∞ (NIT4Py = 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and IDA = iminodiacetate) has been prepared and characterized by single-crystal X-ray diffraction, IR, TGA, and magnetic analysis. Each Cu(II) is five-coordinate with distorted square pyramidal geometry. Each IDA bridges two Cu(II) ions via one carboxylate which occupies the axial site of Cu(II), leading to a chain structure composed of Cu(II)-radical cations and IDA anions. In the complex, there exist three magnetic exchange pathways, (i) interaction between units of (Cu(II)-NIT4Py) through IDA, (ii) Cu(II)-NIT4Py interaction, and (iii) NIT4Py-NIT4Py interaction through space. Compared with the first two magnetic interactions, the last magnetic exchange interaction should be too weak to be counted because of the large distance of the neighboring NIT4Py molecules (4.993 Å). Analysis of the magnetic properties was performed using the Bleany–Bowers (dimer) model, showing that the complex exhibited both weak antiferromagnetic interaction between the Cu(II) and NIT4Py, and between the units of (Cu(II)-NIT4Py) through IDA with exchange coupling parameters J = ?7.28 cm^?1 and zJ′ = ?0.40 cm^?1.     

四自旋氮氧自由基-锰(Ⅱ)配合物的合成、结构和磁性质

采用吡啶基取代的氮氧自由基4P4NIT与过渡金属锰(Ⅱ)离子进行配位,得到了1个双核的四自旋配合物{[Mn(hfac)2]2(4P4NIT)2}·CHCl3（其中,4P4NIT=2-(4′-(4″-吡啶基)苯基)-4,4,5,5-四甲基咪唑啉-3-氧化-1-氧基自由基,hfac=1,1,1,5,5,5-六氟乙酰丙酮阴离子)。 X射线单晶衍射分析表明,2个4P4NIT自由基作为桥联配体, 连接了2个Mn(hfac)2单元,形成双核四自旋配合物。 变温磁化率研究表明,配合物中过渡金属Mn(Ⅱ)离子和直接配位的氮氧自由基之间存在着强反铁磁相互作用。     

Crystal Structure and Magnetic Properties of A One-Dimensional Polymer [Mn(im2-py)(tp)(H2O)2]·1.25H2O

A new manganese(II) complex [Mn(im2-py)(tp)(H₂O)₂]·1.25H₂O (im2-py=2-(2'-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and tp=terephthalato dianion) has been synthesized and characterized structurally and magnetically. The crystal structure consists of neutral chains of manganese(II) ions linked by the terephthalate ligand. Variable temperature magnetic susceptibility data exhibit a weak antiferromagnetic coupling between the manganese(II) ion and the imino nitroxide radical.     

Syntheses,crystal structures and magnetic properties of a new thienyl-substituted nitronyl nitroxide and its copper(II) complex

A new building block for molecule-based magnetic materials???thiophene-substituted nitronyl nitroxide, NIT2-thp, [1, NIT2-thp?=?4,4,5,5-tetramethyl-2-(thiophenal-2-yl)imidazoline-1-oxyl-3-oxide] and its copper(II) complex [Cu(hfac)₂]₃(NIT2-thp)₂ (2) (hfac?=?hexafluoroacetylacetonate) have been synthesized and characterized structurally and magnetically. For 1, dimers were formed and arranged through intermolecular interactions, the shortest contact between nitroxide groups is 4.115?Å among adjacent dimers. In 2 two types of copper interaction with 1 give three colinear Cu(II) ions linked by two μ???1,4 bridging nitroxide ligands. The central metal ion is in a distorted octahedron, axially coordinated by two nitroxide oxygen atoms, while the two external metal ions are in distorted square-pyramidal environments with the nitroxide oxygen atom coordinated in the basal plane. Magnetic susceptibility data for 1 and 2 have been measured in the range 3–300?K. There are antiferromagnetic interactions (J?=??3.89?cm^?1) between the dimers of 1 and also ferromagnetic interactions in 2. The magnetic properties of 1 and 2 are discussed in connection with their crystal structures.