Synthesis,structure, and magnetic properties of nickel(II), copper(II), cobalt(II), and zinc(II) 2,2,5,5-tetramethyl-3-imidazolin-1-oxyl-4-(1′-butylidene-2′-oxylates)

Syntheses are reported for the coordination compounds of nickel(II), copper(II), cobalt(II), and zinc(II) with 4-(2 -oxobutylidene)-2,2,5,5-tetramethyl-3-imidazolin-1-oxyl (LH) with the formula NL₂. The central atom in solid NiL₂ has square coordination, while in solution, this atom has distorted tetrahedral coordination. The coordination of the central atom in the other ML₂ is distorted tetrahedral both in the solution and in the solid phase. CuL₂ and CoL₂ in the solid phase feature exchange clusters with ferromagnetic exchange interaction between the unpaired electrons of the paramagnetic sites.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 669–675, March, 1990.The authors thank L. B. Volodarskii for providing a sample of 1-hydroxy-2,2,5,5-tetramethyl-3-imidazoline and a consultation in planning the synthesis of LH, A. M. Atskanov for taking the PMR spectra, E. G. Boguslavskii for taking the EPR spectra, and K. M. Indrichan for taking the mass spectra.     

Crystal Structure of Copper(II) and Cobalt(II) Hexafluoroacetylacetonate Complexes with 2,2,5,5-Tetramethyl-4-phenyl-3-imidazoline-1-oxyl-3-oxide

The crystal structures of the copper(II) and cobalt(II) hexafluoroacetylacetonate complexes with the nitroxide 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-1-oxyl-3-oxide (PhImOx) Cu(hfac)₂(PhImOx), Co(hfac)₂(PhImOx), and Co(hfac)₂(PhImOx)₂ have been determined. The former two are chain type complexes, whereas the latter has a molecular structure. The coordination polyhedra of the copper and cobalt atoms are tetragonally distorted octahedra. In the two chain type compounds, the octahedra are formed from the hfac anion, nitroxyl, and N-oxide O atoms; in the molecular complex, the O atoms of the NO groups are not coordinated to the metal atoms. In the structure of Cu(hfac)₂(PhImOx), F...F contacts equal to 2.805 have been found.     

Crystal structure of bis[2,2,5,5-tetramethyl-3-imidazoline-1-oxyl-4-(1′-propenyl-2′-oxyato)]nickel(II), Ni(C10H16N2O2)2

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 112–117, March–April, 1992.     

Acyl chlorides of 2,2,5,5-tetramethyl-3-imidazolin-1-oxyl-4-0-acylhydroximic acids

Acylation of nitroenamine derivatives of imidazolidin-1-oxyl with carboxylic acid chlorides leads to 0-acylhydroximic acid chloride derivatives of 3-imidazolin-1-oxyl. The reaction proceeds apparently through a nitrile oxide. It was shown for the 0-benzoyl derivative that reaction of the obtained acyl chlorides with nucleophilic reagents usually gives products of chlorine atom substitution with simultaneous cleavage of the acyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 444–450, February, 1991.     

Synthesis and magneto-optical properties of a series of bis(β-diketonato) Co(II) complexes with imino nitroxide radical chelate

A series of bis(4,4,4-trifluoro-1-R-1,3-butanedinato) Co(II) complexes with imino nitroxide radical(IM2py), [Co(Rtfc)₂(IM2py)] (R = trifluoromethyl, phenyl, naphthyl, thienyl), was prepared and characterized by the X-ray analysis which demonstrated the stereospecific formation of the trans(CF₃)-isomer with the trans disposition of the CF₃ groups. The significant substituents effect on the UV–Vis spectra and magnetic properties were discussed in consideration of the inversion of the d_π(t_2g) orbital levels leading to the orbital orthogonality or overlap with the SOMOπ¹ of IM2py in terms of the AOM parametrizations or spin-paring energy.     

Strong intramolecular ferromagnetic couplings in nickel(II) and copper(II) complexes chelated with tert-butyl 5-methoxy-2-pyridyl nitroxide

We successfully isolated a new paramagnetic bidentate ligand tert-butyl 5-methoxy-2-pyridyl nitroxide (meopyNO). Complexation of nickel(II) and copper(II) perchlorates with meopyNO gave the corresponding ML₂-type bis-chelated compounds. The magnetic studies showed that they were ground high-spin molecules with 2J/k_B = +288(5) and +178(3) K for [M(meopyNO)₂(H₂O)₂] · (ClO₄)₂ (M = Ni and Cu, respectively), where the spin Hamiltonian is defined as H = ?2J(S₁ · S₂ + S₂ · S₃). From the crystallographic analysis, the torsion angles (?) around M–O–N–C_2py were 4.2(3)° and 6.87(19)°, respectively, being so small that the orthogonality between the magnetic radical π1 and the metal dσ orbitals would be guaranteed.     

Synthesis and spectral studies of cobalt(II), nickel(II) and copper(II) complexes of 1-(2-hydroxy-1-naphthyl)-3-(4-X-phenyl)-2-propen-1-ones and their pyridine adducts

Transition Metal Chemistry - Metal(II) chelates of the type ML2nB [M = CoII, NiII and CuII; L = 1-(2-hydroxy-1-naphthyl)-3-(4-X-phenyl)-2-pro-pen-1-one, (X = H, Cl or Me); B = H2O or Py; n = 0, 2]...     

Cobalt(II), nickel(II) and copper(II) complexes of 4-(sulfonylazido)phenylazopyrazolones

Transition metal complexes of Co^II, Ni^II and Cu^II with 4-(4-azidosulfophenylazo)-5-phenyl-3,4-dihydro-2H-pyrazol-3-oneHL¹, 4-(4-azidosulfophenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL² and 4-(3-azidosulfo-6-methoxyphenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL³ were prepared and characterized by elemental analyses, molar conductances and magnetic susceptibilities and by i.r., electronic and e.s.r. spectral measurements as well as thermal (d.t.a and t.g.a.) analysis. The i.r. spectra indicate that HL acts as a bidentate ligand coordinating via the azo and enolic-oxygen linkages. The electronic spectral data and magnetic moments suggest a tetragonally distorted octahedral geometry for the complexes having the formula ML₂·2H₂O, (M = Co^II, Ni^II and Cu^II), square pyramidal geometry for CuL ₂ ³ H₂O and tetrahedral geometry for CoL ₂ ³ . The X-band e.s.r. spectra of the copper(II) complexes reveal anaxial symmetry for both CuL ₂ ² 2H₂O and CuL ₂ ³ H₂O while CuL ₂ ¹ O is isotropic in the solid state at room temperature. The d.t.a. curves show two exothermic peaks for all three complexes CoL ₂ ³ ,NiL ₂ ³ 2H₂O and CuL ₂ ³ H₂O and one endothermic peak for the latter two aqua complexes.     

Cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin

A new series of hexacoordinate cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin HL having formulae [LM(OAc)(H₂O)₂] · nH₂O (M = Co^II, Cu^II and Ni^II), [LMCl(H₂O)₂] · nH₂O (M = Co^II and Ni^II), [LCuCl(H₂O)]₂ · 2H₂O, [LCu(H₂O)₃](ClO₄) and [LCu(HSO₄)(H₂O)₂] were isolated and characterized by elemental analyses, molar conductivities and magnetic susceptibilities, and by i.r., electronic and e.s.r. spectral measurements, as well as by thermal (t.g. and d.t.g.) analyses. The i.r. spectra indicate that the ligand HL behaves as a monobasic tridentate towards the three divalent metal ions via an azo-N, carboxylate-O and thiohydantoin-O atom. The magnetic moments and electronic spectral data suggest an octahedral geometry for Co^II complexes, distorted octahedral geometry for both Ni^II and Cu^II complexes with a dimeric structure for [LCuCl(H₂O)]₂ · 2H₂O through bridged chloro ligands. The X-band e.s.r. spectra reveal an axial symmetry for the copper(II) complexes with unsymmetrical M_s = ± 1 signal and G-parameter less than four for the dimeric [LCuCl(H₂O)]₂ · 2H₂O. The thermogravimetry (t.g. and d.t.g.) of some complexes were studied; the order and kinetic parameters of their thermal degradation were determined by applying Coats–Redfern method and discussed.     

Strong ferromagnetic exchange couplings in copper(II) and nickel(II) complexes with a paramagnetic tridentate chelate ligand, 2,2'-bipyridin-6-yl tert-butyl nitroxide

A paramagnetic ligand 6bpyNO (2,2'-bipyridin-6-yl tert-butyl nitroxide) is a newcomer in the field of metal-radical hybrid magnetic materials. Complexes [CuII(6bpyNO)Cl2] and [NiII(6bpyNO)2](PF6)2 having highly planar chelate rings showed considerably strong ferromagnetic exchange couplings J/kB = 202 and 192 K, respectively, across the direct radical oxygen coordination bonds (the spin Hamiltonian is defined as -2JSi.Sj).     

Crystal structures and magnetic properties of nitroxide radical-coordinated copper(II) and cobalt(II) complexes

Transition Metal Chemistry - The crystal structures and magnetic properties of three coordination compounds constructed from various nitroxide radicals L and MII(hfac)2(H2O)2 building blocks...     

Cobalt(II), nickel(II) and copper(II) complexes of 1-hydroxy-2-naphthyl(4-X-styryl)ketones

Summary Metal(II) bis-chelates of the type ML₂nB [M=Co^II, Ni^II, and Cu^II, L=1-hydroxy-2-naphthyl(4-X-styryl)ketone, (X=H, Me, Cl, MeO), B=H₂O, Py; n=0, 2] have been prepared and characterised by element analyses, i.r., ligand field spectra, magnetic moments and thermal studies. The copper(II) chelates are anhydrous monomers oftrans-square-planar configuration. The cobalt(II) and nickel(II) chelates, obtained as dihydrates, possess a high-spintrans-octahedral structure. Their anhydrides are polymeric. All the pyridine adducts have high-spintrans-octahedral geometry. The (M–O), order, namely Cu >Ni>Co, parallels the Irving-Williams order. The weak ligand field strength of 1-hydroxy-2-naphthyl(4-X-styryl)ketones is ascribed to inhibition of extensive conjugation arising from deviation of the naphthoyl group from planarity.     

Synthesis and crystal structures of cobalt(II) and nickel(II) complexes containing nitronyl nitroxide radical and dicyanamide

Two new complexes [Co(NIT-1′-MeBzIm)₂(Dca)₂] (I) and [Ni(NIT-1′-MeBzIm)₂(Dca)(H₂O) · NO₃ · H₂O (II) (NIT-1′-MeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; Dca = N(CN)₂) were prepared and structurally characterized by single-crystal X-ray diffraction. Relevant crystallographic parameters are as follows: monoclinic, P2_1/c space group, Z = 4; crystal data: C₃₄H₃₈N₁₄O₄Co, M = 765.71, a = 14.343(4), b = 14.322(4), c = 18.626(5) Å, β = 105.956(3)° for I. Orthorhombic Pna2₁ space group, Z = 4; crystal data: C₃₂H₄₂N₁₂O₉Ni, M = 797.49, a = 24.426(4), b = 11.0326(18), c = 13.980(2)Å for II. The X-ray analysis reveals that Co²⁺ ion and Ni²⁺ ion resides in a approximate sdistorted octahedron center. In I, the complex was linked by intermolecular hydrogen bonds, resulting in a 1D chain configuration. In II, the complex was linked by intermolecular hydrogen bonds, resulting in a 2D network configuration.     

Geometric isomerism of copper(II) with monochlorobenzhydrazide chelate complexes

Summary Chelate complexes having a 12 Cu^II ion:(singly deprotonated ligand ratio, formed from Cu^II including 2-, 3- and 4-chlorobenzhydrazides, (ClC₆H₄C(O)NHNH₂) have been studied in the pH > 10 region. With the 2-chloro substituted derivative the cis-isomer is formed, whereas with the 3- and 4-chloro substituted derivatives trans-isomers are formed. The complexing schemes are described.     

Structure of bis(2-methylimino-3-penten-4-onato) nickel(II). properties of nickel(II) ketoiminates

A new volatile complex Ni(mi-aa)₂ [mi-aa = CH₃C(NCH₃)CHC(O)CH₃)] is synthesized and its crystal structure is determined (APEX DUO diffractometer with a 4C CCD detector, λMoK _α, graphite monochromator, T = 100 K). Crystallographic data for Ni(mi-aa)₂ are as follows: space group Pbca, a = 5.4058(3) Å, b = 11.8684(6) Å, c = 19.8472(10) Å, V = 1273.4(1) ų, Z = 4. The Ni(II) atom is coordinated by the O and N atoms of two ligands. The Ni-O and Ni-N distances are 1.8390(9) Å and 1.926(1) Å; the chelate ONiN angle is 92.52(4)°. The complex has the molecular structure formed from the isolated molecules of Ni(mi-aa)₂ bound by van der Waals interactions. For some complexes, the TG study is performed and the intermolecular interaction energy in the crystals is calculated.     

Four-coordinate nickel(II) and copper(II) complexes of 7-amino-4-methyl-5-aza-3-heptene-2-one

Summary The condensation of acetylacetone with ethylenediamine yields 7-amino-4-methyl-5-aza-3-heptene-2-one (AEH). This terdentate (N₂O) Schiff base forms various types of ternary complexes, depending on the nature of the second ligand. Examples of five- and six-coordination have been previously reported. The present paper points to the possibility of preparing a less common type of complex,i.e. [M^II(AE)Py]⁺ (M=Ni or Cu) in which the use of a monodentate ligand (pyridine) favours a square planar geometry.     

Convenient synthesis of 2-(2-pyridyl)-1, 3-diaminopropane,and its copper(II), nickel(II), and cobalt(III) complexes

Summary 2-(2-Pyridyl)-1, 3-propanediol was converted into the diacetate, which was then condensed with phthalimide. The product was hydrolyzed with hydrochloric acid to give 2-(2-pyridyl)-1, 3-diaminopropane. The free amine gave 12 complexes with copper(II), nickel(II), and cobalt(III), which were characterized spectroscopically and magnetically. Features of the amine as a ligand are discussed. A few related complexes were also studied.