V. V. Minin

Magnetic properties of spacer-armed dinuclear copper(II) complexes

The results of static magnetic susceptibility studies of spacer-armed dinuclear copper(II) complexes with dicarboxylic acid acylhydrazones are described. Weak exchange coupling between paramagnetic centers has been detected with an exchange parameter value of −2J ∼ 1–7 cm−1. Short intermolecular contacts give rise to additional weak antiferromagnetic exchange coupling between copper cations comparable in terms of energy with superexchange inside the dinuclear complex (−zJ′ ∼ 0.6–5.0 cm−1).

Structure and magnetic properties of the copper(II) complexes with diacyl hydrazides of salicylic acid

The structures and results of the static magnetic susceptibility investigation of the copper(II) binuclear complex with salicylic acid diacyl hydrazide (H2L), [Cu2(L)(Py)4] (I), and the copper(II) trinuclear complex with diacyl dihydrazide of salicylic and glutaric acids (H6L′), [Cu3(L′)(Py)4] · 2Py (II), are described. The exchange antiferromagnetic interactions between the paramagnetic centers with the exchange interaction parameter −2J = 119 cm−1 for dimer I and 14 cm−1 for trinuclear complex II are detected.

Binuclear copper(II) complexes with acyldihydrazones of 4-formyl-5-hydroxy-3-methyl-1-phenylpyrazoles

The synthesis of copper(II) binuclear complexes with acyldihydrazones of saturated carboxylic acids and 4-formyl-5-hydroxy-3-methyl-1-phenylpyrazoles in which the coordination polyhedra are connected by polymethylene chains of different length (two to five units) is described. The complexes were studied by chemical and thermal analysis, IR spectroscopy, and EPR. The molecular and crystal structure of the copper(II) complex with glutaric acid and 1-(4′-chlorophenyl)-4-formyl-5-hydroxy-3-methylpyrazole acyldihydrazone (H4L) described as [Cu2L·2Py] · Py · 4H2O was determined by X-ray diffraction. The crystals are orthorhombic: a = 24.789(7) Å, b = 39.319(9) Å, c = 4.6336(14) Å, space group Pnma, Z = 4. The number of symmetrically unrelated reflections is 4716, R = 0.0606, Rw = 0.1307. The central atoms are separated by a chain of eight σ bonds and are located at a distance of 8.939 Å. The copper coordination polyhedron is a square. A specific feature of the crystal structure is the stacking interaction involving chelate rings and the pyrazole ring, resulting in stacks of molecular complexes. The EPR spectrum of a solution of the complex based on the acyldihydrazone of succinic acid and 4-formyl-5-hydroxy-3-methyl-1-phenylpyrazole recorded at room temperature exhibits seven HFS lines with an intensity ratio of 1: 2: 3: 4: 3: 2: 1 and a constant of 33.3 G as a result of exchange coupling of the unpaired electrons to the two equivalent copper nuclei. An increase in the length of the polymethylene chain to 3–5 units or introduction of the para-chlorine atom into the benzene ring hampers the exchange interactions, and the EPR spectrum shows a signal of four HFS lines with a constant of 55–70 G typical of monomeric copper(II) complexes.

Neutral and monocationic dinuclear (carbonyl)(cyclopentadienyl)(phenylchalcogenate) iron complexes of the general formulas [(RC5H4)Fe(CO)EPh]2 and [(RC5H4)Fe(CO)EPh]2PF6 (E = S or Te; R = H or Me): Synthesis, molecular structures, and EPR spectra

Heating of the compounds (RC5H4)Fe(CO)2TePh (R = H (I) and Me (II)) in heptane afforded the dinuclear complexes [(RC5H4)Fe(CO)TePh]2 (III and IV, respectively). By oxidation with Fc+PF6−, these complexes were transformed into the paramagnetic cationic complexes [(RC5H4)Fe(CO)TePh]2PF6 (V and VI, respectively). Structures III–V and [(C5H5)Fe(CO)SPh]2PF6 (VII) were characterized by X-ray diffraction.

Structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acids and trifluoroacetylacetone

Binuclear copper(II) complexes with acyldihydrazones of benzenedicarboxylic acid and trifluoroacetylacetone have been synthesized and studied. The structure of the copper(II) complex with diacylhydrazone of 1,3-benzenedicarboxylic acid (H4L) of composition [Cu2L · 2LPy] has been studied by X-ray diffraction. The crystals are triclinic: a = 9.2298(4) Å, b = 11.8510(6) Å, c = 13.8314(7) Å, α = 90.780(3)°, β = 96.124(3)°, γ = 99.264(3)°, space group

Spacer-armed binuclear copper(ii) complexes with salicylidene hydrazones of N-benzoylaminodicarboxylic acids

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Binuclear copper(II) complexes with acyldihydrazones of 1,4-cyclohexanedicarboxylic acid

, Z = 2. The number of symmetry-unrelated reflections with I > 2σ(I) 5941; R = 0.0357, Rw = 0.0589. The complex contains two equivalent copper atoms at a distance of 9.56 Å from each other in the square-planar coordination environment. The high-temperature EPR spectra of the complexes show a signal of seven HFS lines indicating the coupling of unpaired electrons to two equivalent copper nuclei (g = 2.113−2.116, aCu = 37.0−37.2 × 10−4 cm−1).

Rhenium(VI) compounds in the reactions with hydroxylamine

The structure and EPR spectra of copper(II) complexes with bis(salicylidene)hydrozones of N-benzoyl-L-aspartic and N-benzoyl-L-glutamic acids have been described. The compounds have been studied by chemical and thermal analyses, IR spectroscopy, and EPR spectroscopy. The molecular and crystal structure of the copper(II) complex with bis(salicylidene)hydrozone of N-benzoyl-L-aspartic acid (H4L) of composition [Cu2L · 2Py] · 2CH3OH · H2O has been determined by X-ray single-crystal diffraction. The crystals are monoclinic: a = 10.3316(7) Å, b = 16.7552(9) Å,c = 11.0137(6) Å, β = 105.758(3)°, space group P21, Z = 2. The complex has a polymeric structure composed of alternating copper-containing binuclear fragments bound to each other either via phenoxy bridges or via an aliphatic spacer (the Cu…Cu distances are 3.471 Å and 8.939 Å, respectively). The EPR spectra of the solutions of the complexes under study shows an isotropic signal comprising seven HFS lines due to two equivalent copper nuclei with the spin Hamiltonian parameters g = 2.115–2.122 and aCu = (36.1–36.9) × 10−4 cm−1, which indicates the reaization of weak exchange coupling of the paramagnetic centers.

Binuclear copper(II) complexes with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid

The binuclear copper(II) complexes with acyldihydrazones formed by 1,4-cyclohexanedicarboxylic acid and salicylaldehyde or 2-hydroxyacetophenone were synthesized and studied. The structure of the complex with 1,4-cyclohexanedicarboxylic acid bis(salicylidene)hydrazone (H4L1) [Cu2L1(Py)2] was studied by X-ray diffraction. The crystals are triclinic: a = 8.1852(4) Å, b = 8.5157(5) Å, c = 11.6553(7) Å, α = 80.678(3)°, β = 70.041(4)°, γ = 74.803(3)°. Space group

Trinuclear copper(II) complexes with diacylhydrazines of aliphatic dicarboxylic acids and salicylic acid

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