Structural Analysis of a Series of Copper(II) Coordination Compounds and Correlation with their Magnetic Properties

The chemistry of copper(II) is widely described in the literature due to its importance in various fields of research and because of the relative ease in the synthesis of new compounds. The magnetochemistry is one of these fields. However the results obtained with \u27the magnetic methods\u27 e. g. EPR and magnetic susceptibility, that may enable important insight in the properties of the compounds, are very often ambiguous. The structural correlation of the wide range of copper(II) complexes with the magnetic analysis can fulfil some gaps in this area. A series of copper(II) complexes, synthesized in our lab during the last decade, is discussed

Synthesis, Characterization and Thermal Decomposition of [Cu(H2O)2(nia)2S04], nia = Nicotinamide

[Cu(H20)2(nia)2S04], nia = nicotinamide, was prepared by the reaction between aqueous solutions of CuS04 • 5H20 and nicotinamide, and was characterized by standard chemical and physical methods. Thermal behaviour of the sample in inert atmosphere proceeds in several steps. The dehydration of the sample (330—445 K) with 8.3% of mass loss (theoretical value 8.2%) is followed by a strong exothermal peak in DTA curve at 462 K, which is not accompanied by any significant mass change. Changes in electronic spectra and powder patterns of residues indicate a recrystallization process. This suggestion was confirmed by the EPR spectra of powder samples recorded in the temperature range from 295 K to 473 K. Changes of g values reflect modifications of the coordination sphere around copper(II) in the temperature range from 295 K to 423 K. In this temperature range, the symmetry type of the complex should have remained the same. However, above 423 K EPR spectra reflect major structural alternations. Significant changes of IR spectra in 900-1250 cm-1 region, where characteristic bands of S042- are present, indicate changes in the coordination mode of sulfate anion. All the observed results can be interpreted by slightly modified anation reaction in the solid state [Cu(H20)2(nia)2S04](s)—^->[Cu(nia)2S04](s) + 2 H20(g)

Interplay between the structural and magnetic probes in the elucidation of the structure of a novel 2D layered V_4O_4(OH)_2(O_2CC_6H_4CO_2)_4·DMF

The title compound has been synthesized under solvothermal conditions by reacting vanadium(V) oxytriisopropoxide with terephthalic acid in N,N-dimethylformamide. A combination of synchrotron powder diffraction, infrared spectroscopy, scanning and transmission electron microscopy, thermal and chemical analysis elucidated the chemical, structural and microstructural features of new 2D layered inorganic-organic framework. Due to the low-crystallinity of the final material, its crystal structure has been solved from synchrotron X-ray powder diffraction data using a direct space global optimization technique and subsequent constraint Rietveld refinement. [V_4O_4(OH)_2(O_2CC_6H_4CO_2)_4•DMF] crystallizes in the monoclinic system (space group P2/m (No. 10)); cell parameters: a = 20.923(4), b = 5.963(4), c = 20.425(1)Å, β = 123.70(6)º, V = 2120.1(9)Å^3, Z = 2. The overall structure can be described as an array of parallel 2D layers running along [-101] direction, consisting of two types of vanadium oxidation states and coordination polyhedra: face-shared trigonal prisms (V^4+) and distorted corner-shared square pyramids (V^5+). Both configurations form independent parallel chains oriented along the 2-fold symmetry crystallographic b-axis mutually interlinked with terephthalate ligands in a monodentate mode perpendicular to it. The morphology of the compound exhibits long nanofibers, with the growth direction along the layered [-101] axis. The magnetic susceptibility measurements show that the magnetic properties of V_4O_4(OH)_2(O_2CC_6H_4CO_2)_4•DMF can be described by a linear antiferromagnetic chain model, with the isotropic exchange interaction of J = −75 K between the nearest V^4+ neighbours of S = 1/2

Two Types of Pyridine Ligands in Mononuclear and Dinuclear Copper(II) Carboxylates

Copper(II) acetate [Cu(OOCCH3)2(L1)2] (L1 = 2,6-diaminopyridine) (1), [Cu(OOCCH3)2(L2)2] (L2 = 2-amino-6-methylpyridine) (2) and benzoate compounds [Cu2(OOCC6H5)4(L1)2]·2CH3CN (3), [Cu2(OOCC6H5)4(L1)2] (4), [Cu2(OOCC6H5)4(L2)2] (5), [Cu(OOCC6H5)2(L2)2] (6), were synthesized and characterized. X-ray structure analysis revealed monomeric structure in 1 and 6. In 1, cis arrangement of the ligands was found, and trans in 6, in an elongated octahedral CuO4N2 chromophore. The basal plane in 1 and 6 is formed by one co-ordinated oxygen atom from both carboxylates (Cu–O 1.9560(12)–2.007(3) Å) and pyridine nitrogen atom from two pyridine ligands (Cu–N 2.013(3)–2.282(14) Å), forming a CuO2N2 plane, while the second carboxylate oxygen atoms are more distant (Cu–O 2.488(3)–2.7648(16) Å). The dinuclear paddle- wheel central core was found in 5 (Cu–O 1.942(6)–1.992(6) Å), with pyridine nitrogen atoms in the axial positions (Cu–N 2.283(7), 2.284(7) Å). All compounds were characterized by magnetic measurements, electronic and vibrational spectroscopy and tested for fungal growth retardation activity

Two Types of Pyridine Ligands in Mononuclear and Dinuclear Copper(II) Carboxylates

Copper(II) acetate [Cu(OOCCH3)2(L1)2] (L1 = 2,6-diaminopyridine) (1), [Cu(OOCCH3)2(L2)2] (L2 = 2-amino-6-methylpyridine) (2) and benzoate compounds [Cu2(OOCC6H5)4(L1)2]·2CH3CN (3), [Cu2(OOCC6H5)4(L1)2] (4), [Cu2(OOCC6H5)4(L2)2] (5), [Cu(OOCC6H5)2(L2)2] (6), were synthesized and characterized. X-ray structure analysis revealed monomeric structure in 1 and 6. In 1, cis arrangement of the ligands was found, and trans in 6, in an elongated octahedral CuO4N2 chromophore. The basal plane in 1 and 6 is formed by one co-ordinated oxygen atom from both carboxylates (Cu–O 1.9560(12)–2.007(3) Å) and pyridine nitrogen atom from two pyridine ligands (Cu–N 2.013(3)–2.282(14) Å), forming a CuO2N2 plane, while the second carboxylate oxygen atoms are more distant (Cu–O 2.488(3)–2.7648(16) Å). The dinuclear paddle- wheel central core was found in 5 (Cu–O 1.942(6)–1.992(6) Å), with pyridine nitrogen atoms in the axial positions (Cu–N 2.283(7), 2.284(7) Å). All compounds were characterized by magnetic measurements, electronic and vibrational spectroscopy and tested for fungal growth retardation activity

Strong Antiferromagnetism in Isolated Anionic Dicopper(II) Methanoato Paddle-wheel Complex

A new ionic compound (C5H6NO)2[Cu2(μ-O2CH)4(O2CH)2], 1 formed of 4-hydroxy-pyridinium cations and a complex anion was synthesized. The anion is a paddle-wheel dicopper carboxy-late complex with four syn,syn-bridging and two axial anionic methanoato ligands. The XRD structure de-termination of 1 reveals that the molecular structure is stabilized by two H-bonds between the cations and the axial paddle-wheel anions (N–H···O 2.755(3), O–H···O 2.489(2) Å). The compound exhibits a very strong (2J = 500 cm–1) intra-binuclear antiferromagnetic interaction noticed already at room temperature attributed to the methanoato intra-binuclear bridges. The typical EPR S = 1 spin system signals of the dicopper paddle-wheel complexes at 90 and 450–700 mT are found in the room temperature spectrum, but they are poorly seen in the 110 K spectrum. These signals are of very low intensity and are accompanied by a dominant signal at 320 mT, all closely related to a very strong antiferromagnetic interaction present in 1

Synthesis and Characterization of Fatty Acid Copper(II) Carboxylates with N,N-Diethylnicotinamide

A series of new fatty acid copper(II) carboxylates of the composition [(Cu2(O2CCnH2n+1)4(Et2nia)2)] (Et2nia = N,N-diethylnicotinamide; n = 6 to 11) were synthesized, characterized and tested for fungicidal activity. The compounds were synthesized and crystallized from aqueous solution only because their solubility in organic solvents is too high. Dimeric structure for ali compounds was proposed (μeff at room temperature = 1.43-1.48 BM; UV-Vis λmax at 350-400 nm; IR, Δν(COO-) = 185-199 cm-1). A binuclear paddlewheel cage structure was found for the compound [(Cu2(O2CC7H15)4(Et2nia)2)] by X-ray diffraction. Screening for fungicidal activity against the woodrotting fungi Trametes versicolor and Antrodia vaillantii shows that the compounds dissolved in DMSO stop mycelium growth completely at a concentration of 1.0 × 10-3 mol L-1. Some of them show strong activity also in more diluted Solutions; however, stronger retardation for Antrodia vaillantii was noticed for all substances

Dichloridotetra­kis­(1H-1,2,4-triazole-κN 4)copper(II)

The central CuII atom of the molecular title complex, [CuCl2(C2H3N3)4], is situated on a site with symmetry 2.22. It is six-coordinated in an elongated octa­hedral geometry, with the equatorial plane defined by four N atoms of four 1,2,4-triazole ligands and the axial positions occupied by two Cl atoms situated on a twofold axis. The mol­ecules are connected via N—H⋯Cl hydrogen bonds and the crystal consists of two inter­penetrating three-dimensional hydrogen-bonded frameworks

Fatty Acid Copper(II) Carboxylates with Nicotinamide - Characterization and Fungicidal Activity. Crystal Structures of Two Heptanoate Forms and Nonanoate

Several new compounds of the composition Cu2(OOCCnH2n+1)4 (nia)2 (nia = nicotinamide; n = 6 to 11) were synthesized, characterized and tested for fungicidal activity. Crystal structure determinations revealed dinuclear structures of the copper(II) acetate hydrate type for compounds [Cu2(OOCC6H13)4(nia)2]-A (1A), [Cu2(OOCC6H13)4(nia)2]-B (1B) and [Cu2(OOCC8H17)4(nia)2] (3). Other applied characterization methods indicate dimeric structures for ali synthesized compounds [μeff (298 K) = 1.43-1.50 BM; characteristic band in UV-Vis spectra in the region λ = 350-400 nm]. The same conclusion may also be deduced from the IR (Δ = νasym(COO-) - νsym(COO-) = 183-189 cm-1) and EPR spectra, though some differences were observed for heptanoate modification 1A, probably due to a different hydrogen bonding scheme. Screening for fungicidal activity against the wood-rotting fungus Trametes versicolor (L. ex Fr.) Pilat shows that the compounds dissolved in DMSO completely stop mycelium growth at a concentration of 1.0 × 10-3 mol L-1. Some of them (n = 8, 9, 10) show strong activity also in more diluted Solutions (1.0 × 10-4 mol L-1)

Fatty Acid Copper(II) Carboxylates with Nicotinamide - Characterization and Fungicidal Activity. Crystal Structures of Two Heptanoate Forms and Nonanoate

Several new compounds of the composition Cu2(OOCCnH2n+1)4 (nia)2 (nia = nicotinamide; n = 6 to 11) were synthesized, characterized and tested for fungicidal activity. Crystal structure determinations revealed dinuclear structures of the copper(II) acetate hydrate type for compounds [Cu2(OOCC6H13)4(nia)2]-A (1A), [Cu2(OOCC6H13)4(nia)2]-B (1B) and [Cu2(OOCC8H17)4(nia)2] (3). Other applied characterization methods indicate dimeric structures for ali synthesized compounds [μeff (298 K) = 1.43-1.50 BM; characteristic band in UV-Vis spectra in the region λ = 350-400 nm]. The same conclusion may also be deduced from the IR (Δ = νasym(COO-) - νsym(COO-) = 183-189 cm-1) and EPR spectra, though some differences were observed for heptanoate modification 1A, probably due to a different hydrogen bonding scheme. Screening for fungicidal activity against the wood-rotting fungus Trametes versicolor (L. ex Fr.) Pilat shows that the compounds dissolved in DMSO completely stop mycelium growth at a concentration of 1.0 × 10-3 mol L-1. Some of them (n = 8, 9, 10) show strong activity also in more diluted Solutions (1.0 × 10-4 mol L-1)