Physicochemical Study of New Mono- and Binuclear Copper(II) Complexes with Sterically Hindered Acylhydrazones and Azomethines

Series of new binuclear copper(II) complexes with acylhydrazones and azomethines of substituted derivatives of salicylaldehyde containing bulky tert-butyl substituents were synthesized. The target dimerization of the monomeric fragments of the complexes caused by the steric factors was shown to predetermine the specific features of their magnetochemical behavior. The calculated exchange parameters for the complexes based on acylhydrazones range from –110 to –138 cm^–1 and those for the complexes based on azomethines lie in the interval from –400 to –500 cm^–1.     

Physico-Chemical Characteristics and Formation Constants of Mono- and Binuclear Co(II), Ni(II) and Cu(II) Chelates with Phthaleincomplexone

A series of Co(II), Ni(II) and Cu(II) complexes of the type [M(PC)]2H₂O and [M₂(PC)]4H₂O, where PC is phthaleincomplexone (metalphthalein), are synthesized. It is attempted to throw some light on (heir stoichiometry, structure and stability. The formation of 1:1 and 2:1 (M:L) complexes is confirmed by their elemental microanalysis. The compounds are characterized by IR, electronic absorption spectra, X-band ESR spectra, magnetic moments and TGA measurements. The conditional stability constants are also determined.     

Synthesis and Physicochemical Study of Binuclear Copper(II) Chelates Containing an Asymmetric Exchanged Fragment

Series of novel binuclear copper(II) chelate complexes containing an asymmetric exchanged fragment were synthesized for the first time. The ligands were the products of condensation of salicylaldehyde derivatives and 1,3-diaminopropan-2-ol or carbonohydrazide. The compositions and structures of the complexes obtained were proved by elemental analysis, IR and ¹H NMR spectroscopy, and magnetochemistry. The antiferromagnetic exchange parameters 2J were determined in terms of the isotropic-exchange HDVV model. The structural effects of exchange channels on these parameters are discussed.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 376–379.Original Russian Text Copyright © 2005 by Lukov, Kogan, Novotortsev, Tupolova, Gevorkyan.     

Mono- and Binuclear Copper(II) and Nickel(II) Complexes with the 3,6-Bis(picolylamino)-1,2,4,5-Tetrazine Ligand

Four new compounds of formulas [Cu(hfac)₂(L)] (1), [Ni(hfac)₂(L)] (2), [{Cu(hfac)₂}₂(µ-L)]·2CH₃OH (3) and [{Ni(hfac)₂}₂(µ-L)]·2CH₃CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN₂O₄ surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χ_MT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm⁻¹] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm⁻¹] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS₁·S₂). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties.     

3,5-Di(hydroxyorganyl)pyrazoles

The reaction of primary-tertiary and secondary-tertiary aliphatic diacetylenic -glycols with hydrazine hydrate leads to the formation of isomeric 3,5-di(hydroxyalkyl)pyrazoles in which the pyrazole ring is present both in the and in the position to the tertiary carbon atom to which the hydroxy group is attached. The structure of the hydrocarbon substituents connected with this atom substantially affects the ratio of the and isomers. The addition of hydrazine hydrate to aliphatic glycols and their monoethers is accompanied by the formation of individual -(hydroxyalkyl)pyrazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1538–1541, November, 1973.     

Copper(II) trimethylacetate complexes with 3,5-dimethylpyrazole

Specific features of the chemical behavior and structure of copper(II) trimethylacetate complexes with 3,5-dimethylpyrazole have been considered based on X-ray crystallographic data.     

Binuclear Copper(II) Complexes with Hydrazones Containing Spiropyran Fragment

New hydrazones were prepared by the reaction of new spiropyran of benzoxazine series and aliphatic acid hydrazides; their binuclear complexes were synthesized.     

Mono- and heteroligand iron(II) complexes with tris(3,5-dimethylpyrazol-1-yl)methane

Coordination compounds of iron(II) thiocyanate with tris(3,5-dimethylpyrazol-1-yl)methane (HC(3,5-Me₂Pz)₃), [Fe(HC(3,5-Me₂Pz)₃)₂](NCS)₂] (I) and [Fe(HC(3,5-Me₂Pz)₃)(Рhz)(NCS)₂] · H₂O (II), where Рhz is phthalazine, are synthesized. The complexes are studied by X-ray diffraction analysis, diffuse reflectance and IR spectroscopy, and static magnetic susceptibility measurements. The single crystals are obtained, and the molecular and crystal structures of complex II and compounds [Fe(HC(3,5-Me₂Pz)₃)(3,5-Me₂Pz)(NCS)₂] · С₂H₅OH (III), where 3,5-Me₂Pz is 3,5-dimethylpyrazole, and [Fe(HC(3,5-Me₂Pz)₃)₂][Fe(HC(3,5-Me₂Pz)₃)(NCS)₃]₂ (IV) are determined (CIF files CCDC 1415452 (II), 1415453 (III), and 1415454 (IV)). The study of the temperature dependence μ_eff(Т) in a range of 2–300 K shows exchange interactions of the antiferromagnetic character between the iron(II) ions in complexes I and II.     

Spectrophotometric Studies of Cobalt(II) and Copper(II) Chelates of 2-Picolylamine

Cobalt (II) and copper (II) chelates of 2-picolylamine have been studied spectrophotometrically in aqueous solution. Formation of 2-picolylamine chelates was pH dependent, and the optimum pH range of the cobalt (II) chelate was at pH 8.8-9.6, and copper(II) chelate at 4.7-6.8, respectively. The mole ratio of 2-picolylamine to both of metal(II) ions was found to be 2 to 1 stoichiometry. The spectrophotometric sensitivities are 0.23γ of Co/Cm² and 8.9γ of Cu/Cm³, at 373 mμ, pH 9.0 for Co(II) chelate and 588 mμ, pH 6.0 for Cu (II) chelate. The stability constants (logK) of the chelates CoL₂²⁺ and CuL₂²⁺ have been evaluated at a constant ionic strength of 0.10 at 20, 25, 30, 35 and 40°C. Enthalpy and entropy changes characterizing the formation of the chelates have been calculated at 25°C The results are collected as follows:      

Syntheses and Crystal Structures of Mono-and Binuclear Copper(Ⅱ) Mixed-ligand Complexes Involving Schiff Base

1 INTRODUCTION The chemistry of copper compounds has been extensively investigated and the relationship be- tween structure and reactivity, ranging from indus- trial catalysis to biochemistry activity, is of major importance. For binuclear copper(II) complexes equa- torially bridged by pair of hydroxide[1] or alkoxide[2, 3] groups, satisfactory linear correlation is found be- tween the Cu–O–Cu bridging angle and spin coupling between the metal centers. However, for binuclear copper(I…     

Multinuclear NMR Study of Cationic Binuclear Mono- and Trihydrido Platinum (II) Bisphosphine Complexes

Abstract

Magnitude and signs of J(Pt,Pt), J(Pt,P), J(Pt,H) and J(P,P) scalar couplings and hydride T₁ relaxation values characteristic for chelating systems are discussed.     

Syntheses and Crystal Structures of Mono- and Binuclear Copper( Ⅱ ) Mixed-ligand Complexes Involving Schiff Base

The mononuclear copper(Ⅱ) complex [Cu(L)(2-AP)] 1 and binuclear copper(Ⅱ)complex [Cu(L)(py)]2 2 (L = C1oH1 1O5NS, taurine o-vanillin, py = prydine, 2-AP = 2-aminopyridine)with mixed ligand have been synthesized and characterized by X-ray diffraction method. Crystal data for 1: orthorhombic, space group Pbca with a = 11.921(4), b = 15.816(6), c = 17.076(6) (A), V=3219.7(19) (A)3, C15H17CuN3O5S, Z = 8, Mr = 414.92, Dc = 1.712 g/cm3,μ(MoKα) = 1.520 mm-1,F(000) = 1704, the final R = 0.0300 and wR = 0.0705 for 2840 observed reflections with I ＞ 2σ(I);and crystal data for 2: monoclinic, space group P21/c with a = 7.929(3), b = 17.038(5), c = 11.734(4)(A), β = 98.162(6)°, V = 1569.1 (9) (A)3, C15H16CuN2O5S, Z = 4, Mr = 399.90, Dc = 1.693 g/cm3, F(000)= 820,μ(MoKα) = 1.554 mm-1, the final R = 0.0351 and wR = 0.0848 for 2767 observed reflections (I ＞ 2o(I)). The molecular structure of complex 1 consists of one tetra-coordinated Cu(Ⅱ) atom generating a slightly distorted square plane, and a one-dimensional chain structure is formed by intermolecular hydrogen bonds. Complex 2 consists of a diphenolic hydroxyl O-bridged binuclear copper(Ⅱ) structure. The crystal structures of complexes 1 and 2 reveal that the coordinate copper centers are bound to both nitrogen and oxygen atom donors. The usual N,O-trans arrangement of ligands is observed in both cases.     

3, 6-Di(tert-butyl)-o-benzoquinone fluoroalkylated derivatives

Russian Chemical Bulletin - A reaction of perfluoroalkyltrimethylsilanes with 3, 6-di(tert-butyl)-o-benzoquinone was used to obtain new perfluoroalkyl-substituted sterically hindered...     

Extraction of Unprotected Amino Acids by Mixed-Ligand Nickel(II) and Copper(II) Chelates

Summary.  Six mixed-ligand Nickel(II) and Copper(II) chelates with square-planar geometry of the formula [Ni/Cu(O-O)(S-tmpn)]B(C₆H₅)₄ were prepared, where O-O represents acetylacetonate, tropolonate, or hinokitiolate and S-tmpn is (S)-tetramethyl-1,2-propanediamine. The compounds were investigated with respect to their function as receptor for unprotected amino acids, taking advantage of their high solubilities in non-polar organic solvents. In liquid-liquid extraction experiments between a 1,2-dichloroethane phase containing the metal chelates and an aqueous phase containing amino acids (rac-phenylglycine, rac-phenylalanine, or rac-tryptophan), the nickel(II) chelates effectively extracted amino acids from the aqueous phases under neutral conditions, forming octahedral ternary chelates. Received February 19, 2001. Accepted April 2, 2001     

Copper(II), nickel(II) and cobalt(II) complexes of oxaldihydrazide and succindihydrazide Schiff bases with salicylaldehyde ando-hydroxyacetophenone

Summary Polymeric copper(II), nickel(II) and cobalt(II) complexes of the type M₂L where M = Cu^II, Ni^II or Co^II and H₄L = disalicylaldimine oxamide (H₄A), di(o-hydroxyacetophenoneimine)oxamide (H₄B), disalicylaldimine succinamide (H₄C) or di(o-hydroxyacetophenoneimine)succinamide (H₄D), have been synthesized and characterized by analysis, i.r. and electronic spectra and magnetic moment data. Copper(II) complexes and some of the nickel(II) and cobalt(II) complexes are planar while other nickel(II) complexes are distorted octahedral and other cobalt(H) complexes are square pyramidal. Anomalously low magnetic moments of some complexes have been related to M-M interactionsvia oxo-bridge structures.     

Endo and Exo Coordination to Cofacial Binuclear Copper(II) Complexes

A structural study of internal (endo) and external (exo) coordination to cofacial binuclear complexes is reported.Cu₂(NBA)₂(NBAH₂=3,3'-[2,7-naphthalenediylbis(methylene)]-bis(2,4-pentanedione)) is large enough to accommodate 2-methylpyrazine as an intramolecularly coordinated guest molecule Cu₂(NBA)₂((2Mepyz))4CH₂Cl₂Cu₂C₅₃H₅₈N₂O₈Cl₈, orthorhombic, space group Pnma (No. 62); a = 22.4674(11); b = 22.230(2); c = 11.4520(6) Å V = 5719.6(6) ų (at 100 K); Z = 4; R = 0.058; R _w = 0.167 for 344 parameters and 5339 reflections with I > 2(I). The Cu₂(NBA)₂(-(2-Mepyz)) molecules possess crystallographic m symmetry, with the CuCu vector (CuCu' 7.4801(8) Å) perpendicular to the mirror plane; this requires disorder in the 2-Mepyz guests. The two ``Cu(acac)₂' moieties (acacH = 2,4-pentanedione) are not quite parallel (dihedral angle between (acac)₂ planes = 3.93(7)^circ), forming a slightly wider opening on the side of the methyl group in the 2-Mepyz guest. On the other hand, the cavity in Cu₂(XBA)₂ (XBAH₂ = 3,3'-[1,3-phenylenebis(methylene)]-bis(2,4-pentanedione)) is smaller, so that CH₃CN must bind externally.Cu₂(XBA)₂(CH₃CN)₂1.5CH₃CNH₂O,Cu₂C₄₃H_52.5N_3.5O₉, monoclinic, space group P2₁/c (No. 14); a = 11.7361(16); b = 14.197(3); c = 13.299(3) Å; = 92.22(2)^{^}; V = 2214.3(7) ų (at 100 K); Z = 2; R = 0.044; R _w = 0.124 for 275 parameters and 4983 reflections with I > 2 (I). This structure contains centrosymmetric Cu₂(XBA)₂ units (CuCu' 4.8302(12) Å) with externally coordinated CH₃CN ligands. The crystal packing in Cu₂(NBA)₂((2Mepyz))4CH₂Cl₂,which contains close contacts between layers of Cu₂(NBA)₂(-(2-Mepyz)) moieties, is also similar to that in three other crystalline host–guest adducts M₂(NBA)₂(-G). Cu₂(XBA)₂(CH₃CN)₂1.5CH₃-CNH₂O does not contain similar layers of molecules, presumably because the adduct molecules do not have the same type of exposed flat surfaces.