Powder ESR Spectra Research Articles

Chiral Benzene Triimide (BTI) Radical Anions for Probing the Interplay of Unpaired Electron Spin and Chirality.

Herein a series of chiral BTI radical anions bearing different chiral substituents were efficiently prepared by chemical reduction. X-ray crystallography revealed finely-tuned packing and helix assemblies of the radicals by the size of chiral substituents in crystalline state. In accordance with the crystalline-state packing, the powder ESR spectra indicate that 4 a- ⋅CoCp2 + and 4 c- ⋅CoCp2 + π-dimers exhibit thermally excited triplet states arising from strong spin-spin interactions, while discrete 4 b- ⋅CoCp2 + shows a broad doublet-state signal reflecting weak spin-spin interactions. The interplay between the unpaired electron spin and chiral substituents was studied by UV-Vis-NIR spectra, electronic circular dichroism (ECD) and TD DFT calculations. Different NIR absorptions of the radicals attributing to isolated SOMO→LUMO+1 (~889 nm) transitions were recorded. The emergence of Cotton effects (CEs) at the NIR region for 4 c- ⋅CoCp2 + radical enantiomers suggest the interplay between chirality and unpaired electron spin. The origin of the different circularly polarized light absorptions regarding SOMO derived transitions (around 880 nm) was attributed to chiral substitutes regulated electric and magnetic transition dipole moments of the unpaired electron participated transition.

Spectroscopic Studies of Aminoacids Complexes with Biometals

The [Cu(L)2]·H2O, [Co(L)2]·2H2O, [Zn(L)2]·H2O complexes with methionine (L) as ligand, were synthesized in water solution and analyzed by means of: elemental analysis, atomic absorption spectroscopy, thermogravimetry, FT-IR, UV-VIS and EPR spectroscopies. The atomic absorption spectroscopy and elemental measurements confi rm the ratio 1:2 metal ion: methionine composition for the synthesised compounds.The IR spectra show that amino acids act as bidentate ligands with coordination involving the carboxylic oxygen and the nitrogen atom of the amino group. Spectral UV-VIS data confi rmed the covalent metal-ligand bonds, the pseudotetrahedral symmetry around the copper and zinc ions and the octahedral environment for the cobalt ion. Powder ESR spectra at room temperature are typically for monomeric species.

Synthesis, spectroscopic and redox properties of the copper(II) complexes of N-(di-methylphenyl)-3,5- [formula omitted]-salicylaldimines

A series of copper(II) complexes ( Cu L 2 x ) with new N-di-methylphenyl-3,5- B u 2 t -salicylaldimines (L x H) were prepared and characterized by IR, UV/vis, 1H NMR, ESR, cyclic voltammetry techniques and chemical oxidation. L x H ligands have been found selectively bind to a Cu II, rather than to Ni II, Co II, Mn II, VO IV, Zn II and Cd II. ESR examinations of the Cu L 2 x complexes demonstrate that they exist in magnetically diluted mononuclear or coupled triplet-state structures in the solid. The temperature dependent (113–283 K) intensity of the powder ESR spectra for some Cu L 2 x is characteristic of ferromagnetic coupling ( J > 0). The reduction potentials of Cu L 2 x in DMSO are sensitive to aniline moieties. Chemical oxidation of Cu L 2 x with (NH 4) 2[Ce(NO 3) 6] in CHCl 3 and MeCN solutions at 300 K affords gradually disappearance of their ESR signals and dramatic changes in the electronic spectra as well as the appearance of new maximum bands at 530–672 (CHCl 3) and 670–700 nm (MeCN), suggesting generation of Cu II–phenoxyl radical species.

Copper(II) complexes of tetradentate thioether-oxime ligands

Two dinuclear copper(II) thioether-oxime complexes ([Cu(DtdoH)] 2(ClO 4) 2 and [Cu(DtudH)] 2(ClO 4) 2 · 2CH 3OH) have been synthesized. [Cu(DtdoH)] 2(ClO 4) 2 reacted with excess BF 3 · OEt 2 to yield [Cu(Thyclops)]ClO 4, a BF 2 + -macrocyclized di-oxime. [Cu(DtdoH)] 2(ClO 4) 2 and [Cu(DtudH)] 2(ClO 4) 2 · 2CH 3OH are the first representatives of copper(II) thioether oximes which exhibit the classical out-of-plane oximate oxygen-metal dimer structure. [Cu(DtdoH)] 2(ClO 4) 2 and [Cu(Thyclops)]ClO 4 have been structurally characterized by single-crystal X-ray diffraction. The geometry about each copper(II) in [Cu(DtdoH)] 2(ClO 4) 2 is a distorted square pyramid ( τ = 0.14). The average copper–nitrogen(oxime) bond length is 1.984 Å longer (∼0.03 Å) than the average copper–nitrogen(oxime) bonds in copper(II) bis-glyoximates. The geometry of [Cu(Thyclops)]ClO 4 reveals an almost perfect square pyramid ( τ = 0.03) of N 2S 2O donors. Solution, cryogenic glass, and powder ESR spectra show a typical axial pattern, except for the powder spectrum of [Cu(DtudH)] 2(ClO 4) 2 · 2CH 3OH which displays a small rhombic distortion. Variable-temperature magnetic susceptibility measurements indicate very weak ferromagnetic interactions in [Cu(DtdoH)] 2(ClO 4) 2, where J = +0.52 cm −1 and very weak antiferromagnetic interactions in [Cu(DtudH)] 2(ClO 4) 2 · 2CH 3OH, where J = −0.59 cm −1. Electrochemical measurements reveal that the mixed thioether-oxime coordination environment tends to stabilize Cu(II), as all electrochemical reductions were quasi-reversible or irreversible. [Cu(Thyclops)]ClO 4 is more oxidizing than [Cu(DtdoH)] 2(ClO 4) 2 by 0.14 V.

Synthesis, characterization and electrochemical properties of copper(II) complexes with novel bidentate salicylaldimines derived from 3,5-di-t-butyl-2-hydroxybenzaldehyde

Mononuclear copper(II) complexes of novel bidentate salicylaldimines (L x H) have been synthesized by the addition of Cu(Ac)2·2H2O to a mixture of 3,5-di-t-butyl-2-hydroxybenzaldehyde (3,5-DTB) and biologically active amines, 4-(3-aminopropyl)morpholine, 1-(3-aminopropyl)-2-pyrrolidinone and 1-(3-aminopropyl)-2-methylpiperidine. In this study N-[1-(3-aminopropyl)imidazole]-3,5-di-t-butylsalicylaldimine (L1H) was synthesized by reaction of 3,5-DTB and 1-(3-aminopropyl)imidazole followed by complexation with copper(II). The complexes were characterized by FTIR, UV–VIS, ESR, MS, 1H and 13C NMR spectroscopy, magnetic susceptibility measurements and thermogravimetric analysis (TGA) and also by electrochemistry. The room-temperature powder ESR spectra of these complexes are similar and exhibit axially symmetric g-tensor parameters with g ‖ > g ⊥ > g e suggesting that the copper(II) atom has a ground state characteristic of square-planar or square-pyramidal stereochemistry. Thermal analysis indicated that Cu(L3)2 had the highest thermal stability of the complexes and Cu(L2)2 the lowest. Cyclic voltammetric experiments showed that all of the Cu(II) complexes underwent one-electron transfer, mainly diffusion controlled, as indicated by the dependence of the peak current on the square root of the scan rate.

A new type of charge compensating mechanism in Ca 5(PO 4) 3F:Eu 3+ phosphor

The X-ray powder diffraction, reflectance, photoluminescence, photoluminescence excitation and ESR spectra of Ca 5(PO 4) 3F:Eu 3+ phosphor have been studied. Three distinct variants of calcium substitutional Eu 3+-sites have been observed in this host and the charge compensating species related to each of these sites has been identified. It is noted that the host related trace impurities those have prospects of acting as charge compensator, and the reaction environment that exists during the preparation of the material, greatly influence the preferential substitution of different Ca 2+-sites by the Eu 3+ ions. It is also noted that the charge compensating species in a suitable case, takes part in the photophysical process of luminescence of the Eu 3+.

Synthesis, characterisation and magnetic properties of cobalt(II) complexes with picolinic acid derivatives: the crystal and molecular structures of [Co(MeC 5H 3NCOO) 2(H 2O) 2] and [CoCl 2(C 5H 4NCOOPr i) 2

The reaction of Co(AcO) 2 with 6-methyl-2-pyridinecarboxylic acid, and that of CoCl 2 with the isopropyl ester of 2-pyridinecarboxylic acid, both with a 1:2 metal to ligand molar ratio, afford optimum yields for the synthesis of cis-[Co(MeC 5H 3NCOO) 2(H 2O) 2] and cis-[CoCl 2(C 5H 4NCOOPr i) 2], respectively. According to X-ray crystallography they both consist of mononuclear discrete molecules with octahedral coordination around Co(II). The ESR powder spectra of the related Zn phases doped with 0.25% Co(II) show the strong anisotropy of the g and A tensors. The magnetic behaviour of the solid complexes is characteristic of Co(II) systems with important spin–orbit coupling and weak antiferromagnetic interactions. Electronic UV–Vis and magnetic data indicate that these complexes, as well as the already known trans-[Co(C 5H 4NCOO) 2(H 2O) 2], have a high-spin octahedral geometry in solution.

The First Tetranuclear Complex with a (μ-CrO4-O,O′,O″) Bridge: Crystal Structure and Ferromagnetic Behavior of [{Cu(bpy)2}3(μ-CrO4)](ClO4)4·H2O

A novel tetranuclear complex [{Cu(bpy)2}3(μ-CrO4)](ClO4)4·H2O (1) with a (μ-CrO4-O,O′,O′′) bridge has been synthesized by the reaction of K2CrO4 with Cu(ClO4)2·6H2O and bpy in CH3CN/H2O solution (bpy = 2,2′-bipyridine). A single crystal X-ray diffraction analysis showed that the chromate ion bridges three copper(II) ions showing a pesudo-C3v symmetry. The coordination sphere of each copper(II) ion is best described as trigonal bipyramidal, implying that the magnetic orbital of copper(II) ion is d, which is also confirmed by the powder ESR spectra. Variable-temperature magnetic studies verify the validity of the chromate bridging unit to link the tricopper system with ferromagnetic coupling, with 2J = +1.8 cm−1. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Copper(II) complexes of new unsymmetrical NSN thioether ligands

The reactions of 2-(mercaptoethyl)benzimidazole with 2-vinylpyridine and 2-picolyl chloride (in basic medium) yield the new unsymmetrical ligands 1-(2-benzimidazolyl)-5-(2′-pyridyl)-3-thiapentane (Biptp) and 1-(2-benzimidazolyl)-4-(2′-pyridyl)-3-thiabutane (Biptb), respectively. Copper(II) complexes of these ligands with differing anions were prepared. Crystal structures are reported for [Cu(Biptp)](CF 3SO 3) 2·2H 2O and [Cu(Biptb)](CF 3SO 3) 2·0.5(C 7H 8)·H 2O, in which the Cu(II) ions exhibit distorted square-pyramidal geometries. Powder ESR spectra of the copper compounds are rhombic and the degree of rhombicity is related to the identity of the anions. Charge-transfer bands and intense absorption in the visible region are observed in the electronic spectra. Electrochemical studies indicate that one-electron reductions are involved, the reductions occurring at relatively high potentials.

Dynamic nuclear polarization by photoexcited-triplet electron spins in polycrystalline samples

It is shown that the large electron spin polarization created in the photoexcited triplet species can be transferred to the nuclear spins even in a polycrystalline sample by utilizing a partial area of the extremely broad ESR powder spectrum for cross polarization (CP). The proton polarization 3160 times as large as the thermal equilibrium value was obtained in 0.018 mol% pentacene-doped naphthalene at 100 K in a field of 0.319 T. The influence of the proton spin–lattice relaxation and the sample thickness on the attained polarization is discussed.

Synthesis, spectroscopic characterization and ESR studies on electron transfer reactions of bis[ N-(2,6-di- tert-butyl-1-hydroxyphenyl)salicylaldiminato]-copper(II) complexes with PbO 2 and PPh 3

New bis[ N-(2,6-di- t-butyl-1-hydroxyphenyl)salicylideneminato]copper(II) complexes bearing HO and CH 3O substituents on the salicyaldehyde moiety were prepared, and their spectroscopic properties, as well as redox reactivity towards PbO 2 and PPh 3, examined by ESR and UV spectroscopy. In the process of synthesis of HO complexes unlike CH 3O the oxidative CC coupling of coordinated salicylaldimine ligands does not takes place. The powder ESR spectra of CH 3O substituted complexes unlike of HO analogues are typical of a triplet state Cu(II) dimers with a half-field forbidden (Δ M=±2) transition and the allowed transitions (Δ M=±1) dimeric form of the complexes at 300 and 113 K. The one-electron oxidation of 3-CH 3O and all of the OH complexes with PbO 2 to give indophenoxyl type secondary radicals which are significantly different from those observed for analogues Cl, Br and NO 2 substituted chelates. The presented complexes unlike their electron-withdrawing analogues are readily reduced by PPh 3 via intramolecular electron transfer from ligand to copper(II) to give various radical intermediates as well as Cu(I) radical ligand compounds. The analysis of ESR spectra all of the complexes and radical intermediates are presented.

IR and ESR studies on some dimeric copper(II) complexes

The copper(II) p-chlorobenzoates [Cu 2R 4·CH 3OH·2H 2O] (I) and [Cu 2R 4·CH 3COCH 3·2H 2O] (II) dimeric complexes, where R=( p-ClC 6H 4CO 2), as well as their monomeric species which occur at 77 K have been investigated by IR and ESR spectroscopy. The coordination of the copper(II) ions at the carboxylic -COO group arises from the appearance in the IR spectra of studied complexes of the stretching vibration ν(Cu–O) at 475 cm −1 and the combination frequencies ν(Cu–O)+ δ ring at 690 cm −1, ν(Cu–O)+ δ(O–CO) at 770–800 cm −1. The room temperature powder ESR spectra of the both copper(II) complexes correspond to a randomly oriented triplet state ( S=1) for coupled Cu(II) ions with short Cu–Cu distance (∼2.64 Å). The 77 K spectra indicate the coexistence of monomeric and dimeric species. The complex (I) presents two monomeric magnetic nonequivalent species, one (I′) with square-planar local symmetry D 4h (g ∥=2.301, g ⊥=2.067, A ∥=174×10 −4 cm −1, A ⊥=21.4×10 −4 cm −1) and the other (I″) with tetragonal–octahedral O h distorted symmetry due to the coordination of two water molecules along the Oz axis of Cu 2+ ion (g ∥=2.327, g ⊥=2.046, A ∥=162×10 −4 cm −1, A ⊥=43×10 −4 cm −1). Only the tetragonal–octahedral distorted species ( g ∥=2.324, g ⊥=2.044, A ∥=165×10 −4 cm −1, A ⊥=43×10 −4cm −1) occurs in the complex (II).

SYNTHESIS AND SPECTROSCOPIC STUDIES OF SOME NEW REDOX-ACTIVE BENZYLAMINE COMPLEXES OF COPPER(II) AND ESR STUDIES OF THEIR OXIDATIONREDUCTION PRODUCTS

New Cu(II) complexes Cu(L′x)2, where L′x=L′1, L′2, L′3, L′4 are monoanion of unsubstituted, 5-Cl, 5-Br and 3,5-di-Br-substituted 2-hydroxybenzylamines of redox-active N-(3,5-di-tert-butyl-1-hydroxyphenyl)-2-hydroxybenzylamines were synthesized. Each compound of L′xH and Cu(L′x)2 as well as products of their oxidation and reduction by PbO2 and PPh3, respectively, was characterized by IR, UV-visible and ESR spectroscopy. ESR results showed that one-electron oxidation of mononuclear tetrahedrally distorted Cu(L′x)2 chelates with PbO2, via C-C coupling of the Cu(II)-stabilized ligand radical intermediates and by the oxidative dehydrogenation of amine-chelates, produce new Cu(II) complexes with square-planar geometry. The powder ESR spectra of these new Cu(II) complexes exhibit a triplet-state type pattern with the zero-field splitting due to interaction between the copper(II) pairs. Interaction of Cu(L′x)2 with PPh3 via intramolecular ligand-metal electron transfer results in the formation of radical species and reduction of the metal center. All radical intermediates were characterized by ESR parameters.

The resolution-enhanced ESR powder spectrum of γ-ray and UV-light irradiated unbound- and silicone-bound-alanine and its satellite lines

From power saturated and resolution-enhanced ESR powder patterns of irradiated alanine it was possible to discern between the octet of satellite and allowed lines of these patterns. Additionally, differences between ESR spectra of γ-ray irradiated silicone-bound- and unbound-alanine free radicals are also observed when the induced free radicals are subjected to UV-light. These spectral differences and those from power saturated spectra are correlated in such a way that the existence of secondary free radicals and crystal defects may be needed to explain present results.

Dimetallic complexes derived from a novel dinucleating chelating symmetric triazole ligand; crystal structure, magnetic properties and ESR study of bis[μ-3,5-diacetylamino-1,2,4-triazolato-O ′,N 1,N 2,O ″]bis[(nitrato)(aqua)copper(II)] ‡

Download options Please wait... Supplementary files Rotatable 3-D crystal structure diagram of compound 1 XYZ (4K) Structural and magnetic parameters DOC (25K) Crystal structure data TXT (35K) X- and Q-band powder ESR spectra of compound 1 DOC (103K) Article information DOI https://doi.org/10.1039/A907740E Article type Paper Download Citation J. Chem. Soc., Dalton Trans., 1999, 4269-4276 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Dimetallic complexes derived from a novel dinucleating chelating symmetric triazole ligand; crystal structure, magnetic properties and ESR study of bis[µ-3,5-diacetylamino-1,2,4-triazolato-O′,N 1,N 2,O″]bis[(nitrato)(aqua)copper(II)]‡ S. Ferrer, P. J. van Koningsbruggen, J. G. Haasnoot, J. Reedijk, H. Kooijman, A. L. Spek, L. Lezama, A. M. Arif and J. S. Miller, J. Chem. Soc., Dalton Trans., 1999, 4269 DOI: 10.1039/A907740E To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Sacramento Ferrer Petra J. van Koningsbruggen Jaap G. Haasnoot Jan Reedijk Huub Kooijman Anthony L. Spek Luis Lezama Atta M. Arif Joel S. Miller

ESR evidence for chemically assisted thermal incorporation of Mn 2+ centres into aluminium fluoride lattices

The incorporation of Mn 2+ ions into the bulk of polycrystalline AlF 3 is reported for the first time as a result of combined chemical and thermal treatments. 55Mn-hyperfine (hfs) and 55Mn– 19F-superhyperfine (shfs) structures appear to be sensitive tools to indicate structural reorganization processes. ESR spectroscopic X-band in situ investigations of powder samples in the temperature range 4 K≤ T≤1473 K led to well defined ESR spectra even at 1473 K as a result of specific chemical and physical processes taking place at distinct intervals of the temperature range. Two coupled conditions appear to be necessary prerequisites for the appearance of the well resolved 55Mn– 19F shfs structure of MnF 6 4− subunits: (i) temperature treatments covering the range above 673 K, and (ii) the presence of water traces in the educts. In addition to X-band, Q-band measurements were performed to verify the coordination of Mn 2+ ions by six F − ions using the better spectral resolution at this frequency. Finally, it can be stated that the formation and stabilization of regular MnF 6 4− units critically depend on the state of the order of the matrix. Therefore, the shfs pattern can advantageously be used as an order parameter. All experimental ESR powder spectra could be simulated by diagonalization of the spin hamiltonian matrix for the S=5/2 and I=5/2 spin problem (Mn 2+).

Antitumour copper(II) salicylaldehyde benzoylhydrazone (H 2sb) complexes: physicochemical properties and the single-crystal X-ray structures of [{Cu(H 2sb)(CCl 3CO 2) 2} 2] and [{Cu(Hsb) (ClO 4) (C 2H 5OH)} 2] and the related salicylaldehyde acetylhydrazone (H 2sa) complex, [Cu(Hsa)Cl(H 2O)]·h 2O

Copper(II) complexes of the antitumour ligand salicylaldehyde benzoylhydrazone (H 2sb) have been prepared. In the presence of strong acids, complexes of the neutral ligand were isolated: [{Cu(H 2sb)X 2} 2]· nH 2O (X = Br, n X = CCl 3CO 2, n = 0) and [Cu(H 2sb)Cl 2(H 2O)]. In weakly acid or neutral media, monoanionic compounds separated: Cu(HsB)X 2· nH 2O] (X = Cl,Br, NO 3, 0.3SO 4, n = 0; X = ClO 4, n = 1). With base only the highly insoluble dianionic complex [{Cu(sb)} 2] was isolated. Also prepared was the related anionic ligand complex [Cu(Hsa)Cl(H 2O)]·H 2O (H 2sa = salicylaldehyde acetylhydrazone). The complexes have been characterised by a range of physicochemical techniques and the crystal and molecular structures of [{Cu(H 2sb)(CCl 3CO 2) 2} 2], [{Cu(Hsb)ClO 4(C 2H 5OH)} 2] and [Cu(Hsa)Cl(H 2O)]·H 2O, determined by single-crystal X-ray diffraction studies. Crystals [{Cu(H 2sb)(CCl 3CO 2) 2} 2] are triclinic, space group P 1 , with = 10.130(2), b = 11.660(2), c = 11.876(2)r α = 67.07(2), β = 109-09(2) γ = 107.84(2)° and Z = 2. The complex is a centrosymmetric dimer, the monomeric units being bridged through the phenol oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate ‘ONO’ donor ligand and the symmetry-related phenol oxygen. The more weakly bound axial donor oxygens are from the coordinated trichloroacetates. Crystals of [Cu(Hsb)ClO 4(C 2H 5OH) 2] are monoclinic, space group P2 1/ c, with a = 11.2281(8), b = 7.9129(4), c = 21.043(1) ;rA β = 98.560(6)°✓ and Z = 4. This complex is also a centrosymmetric dimer, the monomeric units being bridged through the phenoxy oxygen. The copper coordination is tetragonal with the equatorial donor atoms coming from the tridentate ‘ONO’ ligand and the symmetry related phenoxy oxygen. The more weakly bound axial donor oxygens are supplied by the ethanol and perchlorato moieties. Crystals of [Cu(Hsa)Cl(H 2O)]·H 2O are monoclinic, space group P2 1/ c, with a = 7.4877(4), b = 15.5806(7), c = 10.5208(3) A ̊ , β = 103.56(4)° and Z = 4 . The complex is monomeric with the copper(II) adopting a square-pyramidal coordination. The four in-plane donors are provided by the tridentate ‘ONO’ donor Hsa and an oxygen from a coordinated water molecule; the axial site is occupied by the chloride ion. Most of the complexes have low magnetic moments and are assigned dimeric side-by-side structures. Powder ESR spectra have g 1 and g ✓ resolved often with ΔM = 2 transitions present.

Spectroscopic properties of the vanadium(III) tris(metaphosphate), V(PO 3) 3

A vanadium(III) tris(metaphosphate) compound has been synthesized and characterized. The compound crystallises in the monoclinic space group Ic with lattice parameters a= 10.615(2), b= 19.095(4), c= 9.432(1) Å, β= 97.94(1) °. IR and UV-V studies confirm a chain structure for this compound. The ESR powder spectrum shows a weak signal belonging to the V 3+ ions. The D parameter value has been estimated between 2 and 8 cm −1.

Synthesis, structural characterisation and magnetic behaviour of three new dinuclear end-to-end thiocyanato bridged copper(II) compounds derived from tridentate amines

The compounds [Cu 2(μ-SCN) 2(Et 3dien) 2(ClO 4) 2] ( 1), [Cu 2(μ- SCN) 2(Me 5dien) 2](ClO 4) 2 ( 2) and [Cu 2(μ-SCN) 2(ept) 2(ClO 4) 2] ( 3), where Et 3dien is 1,4,7-triethyldiethylenetriamine, Me 5dien is 1,1,4,7,7-pentamethyldiethylenetriamine and ept is N-(2-aminoethyl)-1,3-propanediamine, were synthesised and characterised. The crystal structures of 1, 2 and 3 were determined by single-crystal X-ray analysis. 1: chemical formula C 22H 50Cl 2Cu 2N 8O 8S 2, M=816.80, monoclinic, space group P2 1/ c, a=12.623(4), b=8.708(3), c=17.150(3) Å. β=110.31(2)°, V=1767.9(9) Å 3, D x=1.534 g cm −3, Z=2, F(000)=852, μ(Mo Kα)=15.25 cm −1, λ(Mo Kα)=0.71069 Å, 293(2) K. 2: chemical formula C 20H 46Cl 2Cu 2N 8O 8S 2, M=788.76, monoclinic, space group C2/ c, a=22.701(3), b=13.826(2), c=14.039(2) Å, β=127.55(2)°, V=3493.4(8) Å 3, D x=1.829 g cm −3, Z=4, F(000)=2056, μ(Mo Kα)=27.30 cm −1, λ(Mo Kα)=0.71069 Å, 293(2) K. 3: chemical formula C 12H 30Cl 2Cu 2N 8O 8S 2, M=676.54, orthorhombic, space group Pbca, a=15.169(2), b=13.842(2), c=12.071(2) Å, V=2534.5(6) Å 3, D x=1.773 g cm −3, Z=4, F(000)=1384, μ(Mo Kα)=21.07 cm −1, λ(Mo Kα)=0.71069 Å, 293(2) K. The magnetic susceptibility data of 1, 2 and 3 recorded from 290 to 4 K show that all three are virtually uncoupled compounds. The polycrystalline powder ESR spectra of 1, 2 and 3 recorded at 4, 77, 180 and 298 K remain unchanged, with g ‖=2.18 and g ⊥=2.06 for 1 and a broad signal at g=2.10 for 2 and 3.

Ribose, galactose and glucose bis(thiosemicarbazone) complexes of copper(II) and nickel(II)

The bis(thiosemicarbazones) of glucose (GluTSCH 2), galactose (GalTSCH 2) and ribose (RibTSCH 2) were prepared and characterized by spectroscopic ( 1H and 13CNMR, UV, IR) methods. A complete assignment of the NMR signals was made using 1H 1H COSY; 13C 1H COSY; 13C COLOC and NOEDIF techniques, complemented with theoretical calculations. Metal complexes with the general formula [M( bis TSC)], where M = Cu II, Ni II and bisTSC = anion of the monosaccharide bis(thiosemicarbazones) were prepared and characterized. The X-band ESR powder spectra of the copper(II) complexes show a rhombic distortion and the solution (DMF) ESR spectra indicate significant axial interaction with solvent molecules. The presence of the monosaccharide residue enhances the complexes' water solubility and increases their biological potential