X-ray diffraction,spectroscopic (IR,Raman) and DSC studies of bis(betainium) p-toluenesulfonate monohydrate crystal

Bis(betainium) p-toluenesulfonate monohydrate (abbreviated as BBTSH) was studied at various temperatures by X-ray diffraction, differential scanning calorimetry and vibrational spectroscopy methods. DSC curves of BBTSH show a peak at about 349 K which corresponds to water escape from the crystal, and reveal the “cold crystallization” phenomenon. BBTSH crystallizes in the P2₁/c space group of monoclinic system. After heating above 349 K the compound dehydrates, the crystal system changes to triclinic, the monocrystalline samples become non-merohedral twins. The BBTSH crystal comprises p-toluenesulfonic anions, monoprotonated betaine dimers and water molecules. Three kinds of hydrogen bonds are present in the crystal: strong, asymmetric and almost linear OH⋯O hydrogen bond (R(O⋯O) = 2.463(2) Å), weak O_wH⋯O hydrogen bonds (R(O_w⋯O) = 2.820(2) − 2.822(2) Å) and weak CH⋯O hydrogen bonds (R(C⋯O) = 3.295(2) − 3.416(2) Å). The ν_aOHO vibration of the strongest hydrogen bond in the crystal gives rise to an intense broad absorption with numbers of transmission windows in the low wavenumber region of the infrared spectra. Coupling between νCO stretching vibrations of two COO groups of the betaine dimer was detected. The process corresponding to the loss of water is accompanied by the breakage of strong OH⋯O hydrogen bonds in betaine dimers and rearrangement inside half of the betaine dimers. This rearrangement results in formation of the new betaine dimers with OH∙∙∙O hydrogen bond of similar strength as corresponding bond in the hydrated form (BBTSH).     

Mechanochemical and solution synthesis, X-ray structure and IR and 31P solid state NMR spectroscopic studies of copper(I) thiocyanate adducts with bulky monodentate tertiary phosphine ligands

A number of adducts of copper(I) thiocyanate with bulky tertiary phosphine ligands, and some nitrogen-base solvates, were synthesized and structurally and spectroscopically characterised. CuSCN:PCy3 (1:2), as crystallized from pyridine, is shown by a single crystal X-ray study to be a one-dimensional polymer ...(Cy3P)2CuSCN(Cy3P)2CuSCN... (1) with the four-coordinate copper atoms linked end-on by S-SCN-N bridging thiocyanate groups. A second form (2), obtained from acetonitrile, was also identified and shown by IR and 31P CPMAS NMR spectroscopy to be mononuclear, with the magnitude of the dν(Cu) parameter measured from the 31P CPMAS and the ν(CN) value from the IR clearly establishing this compound as three-coordinate [(Cy3P)2CuNCS]. Two further CuSCN/PCy3 compounds CuSCN:PCy3 (1:1) (3), and CuSCN:PCy3:py (1:1:1) (4) were also characterized spectroscopically, with the dν(Cu) parameters indicating three- and four-coordinate copper sites, respectively. Attempts to obtain a 1:2 adduct with tri-t-butylphosphine have yielded, from pyridine, the 1:1 adduct as a dimer [(Bu(t)3P)((SCN)(NCS))Cu(PBu(t)3)] (5), while similar attempts with tri-o-tolylphosphine (from acetonitrile and pyridine (= L)) resulted in solvated 1:1:1 CuSCN:P(o-tol)3:L forms as dimeric [{(o-tol)3P}LCu((SCN)(NCS))CuL{P(o-tol)3}] (6 and 8). The solvent-free 1:1 CuSCN:P(o-tol)3 adduct (7), obtained by desolvation of 6, was characterized spectroscopically and dν(Cu) measurements from the 31P CPMAS NMR data are consistent with the decrease in coordination number of the copper atom from four (for 6) (P,N(MeCN)Cu,S,N) to three (for 7) (PCuS,N) upon loss of the acetonitrile of solvation. These results are compared with those previously reported for mononuclear and binuclear PPh3 adducts which demonstrate a clear tendency for the copper centre to remain four-coordinate. The IR spectroscopic measurements on these compounds show that bands in the far-IR spectra provide a much more definitive criterion for distinguishing between bridging and terminal bonding than does an often-used empirical rule based on ν(CN) in the mid-IR, which leads to the wrong conclusion in some cases.     

Vibrational spectroscopic studies of metal(II) halide benzimidazole

Infrared spectra (4000–200 cm⁻¹) are reported for metal halide(II) benzimidazole complexes of the following stoichiometries: M(benz)X₂ [M=Cd, Cu; X=Cl, Br; BENZ=benzimidazole], Co(benz)₂, and Co(benz)₂X₂ [X=Cl, Br, I]. Vibrational assignments are given for all the observed bands. The analysis of the vibrational spectra indicates that there are some structure–spectra correlations. For a given series of isomorphous complexes the sum of the difference between the values of the vibrational modes of uncoordinated benzimidazole and coordinated to metal ion benzimidazole was found to increase in the order of the second ionization potentials of metals.     

Synthesis,spectroscopic and X-ray structural studies of mercury(II) halide complexes of 4-methoxybenzoylmethylenetriphenylphosphorane

The reactions of the title ylide {(C₆H₅)₃PCHCOC₆H₄OCH₃)} (MBPPY) with mercury(II) chloride and mercury(II) bromide in equimolar ratios using methanol as the solvent produces crystals of [(MBPPY) · HgCl₂]₂ (1) and [(MBPPY) · HgBr₂]₂ (2), respectively. Single crystal X-ray analyses reveal the presence of centrosymmetric dimeric structures containing the ylide and HgX₂ (X = Cl or Br) in both cases. The IR and NMR data of the product [(MBPPY) · HgI₂]₂ (3), formed by the reaction of mercury(II) iodide with the same ylide, are similar to those of 1 and 2. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products.     

Chemisorption of copper(II) at zinc and cadmium dialkyldithiocarbamates: EPR and X-ray diffraction studies

Chemisorption of Cu²⁺ cations at zinc and cadmium dialkyldithiocarbamates was studied. According to EPR data, in the first step, the zinc and cadmium atoms are partially replaced by copper in the starting molecular structure to form heterobinuclear and heteropolynuclear complexes. In the second step, copper replaces up to 90 to 97% of the total number of the metal atoms, yielding binuclear and polynuclear copper(II) complexes. The possibility of the existence of heterobinuclear complexes in the individual state was demonstrated with [CuCd{S₂CN(C₂H₅)₂}₄] as an example. Its molecular and crystal structures were determined from X-ray diffraction data.     

X-ray diffraction and IR spectral characteristics of zinc(II)tetra-tert-butylphthalocyanine

According to well-known procedures, alpha- and beta-crystal polymorphic modifications of zinc(II)tetra-tert-butylphthalocianine (Zn(t-Bu)4Pc) were prepared and X-ray analysis of their powders was carried out. It was found that four tert-butyl groups in Zn(t-Bu)4Pc molecule do not prevent the formation of the alpha- and beta-polymorphs. The alpha- and beta-polymorphs differ from each other mainly by a mutual arrangement of neighboring metallophthalocyenine molecules in pi-stacking. Comparison of IR spectra of the alpha- and beta-polymorphs of ZnPc and Zn(t-Bu)4Pc was carried out. It was indicated that new bands appear at 670-690, 1256 and 1362 cm(-1) in the spectrum of Zn(t-Bu)4Pc in comparison with that of ZnPc. The appearance of new band at 1256 cm(-1) is assigned to rocking C-CH(3) vibrations and the band at 1362 cm(-1) to symmetrical deformational C-H vibrations of methyl groups of the peripheral substitutes. The main spectral characteristics for identification of the polymorphic modifications of Zn(t-Bu)4Pc are listed.     

Structural and spectroscopic studies of some copper(I) halide tert-butyl isocyanide adducts

Single-crystal structural characterizations confirm the existence of the unusual 1 : 4 copper(I) halide : unidentate ligand adducts [Cu(CNt-Bu)4]X for X = Cl, Br (two forms), I (the chloride and one form of the bromide being solvated) with crystal packing dominated by stacks of interleaving cations. Cu-C range between 1.941(2) and 1.972(4) A. The structure of the 1 : 2 chloride complex is also recorded, being [ClCu(CNt-Bu)2], with the copper(I) atom environment trigonal planar, while CuCN : (CNt-Bu) (1 : 1) is a single-stranded polymer which spirals about a crystallographic 3-axis (CN scrambled), the ligands being pendant from the ...CuCNCuCN... string. The (5Cu static broadline NMR spectra of [Cu(CNt-Bu)4]I and [Cu(CNt-Bu)4]Br.H2O in the solid state exhibit dominant, narrow -1/2 <--> +1/2 central transition resonances and associated +/-1/2 <--> +/-3/2 satellite transition resonances which are characteristic of first-order quadrupole broadened systems, while associated high-resolution 65Cu MAS NMR data provide accurate measurement of the 65Cu isotropic chemical shifts. Both approaches provide complete data on the quadrupole and chemical shift interactions which contribute to these spectra. Far-IR spectra of products of reactions involving a range of CuX : t-BuNC ratios reveal the existence of 1 : 1.5 adducts for X = Br, I. Metal-carbon and metal-halogen bands are assigned in the far-IR spectra, which indicate a binuclear double halogen-bridged structure for the 1 : 1.5 complexes.     

IR and EXAFS spectroscopic studies of glyphosate protonation and copper(II) complexes of glyphosate in aqueous solution

The varying degrees of protonation of N-(phosphonomethyl)glycine (PMG, glyphosate) were investigated with infrared (IR) spectroscopy and ab initio frequency calculations. The zwitterionic nature of PMG in solution was confirmed, and intramolecular hydrogen bonding was identified. Successive protonation of the PMG molecule follows the order amine, phosphonate, carboxylate. Intramolecular hydrogen bonding is indicated to exist at all stages of protonation: between both RCO(2-) and RNH(2)(+) and RPO(3)(2-) and RNH(2+) in HL(2)(-) (where L represents the ligand PMG); between RCO(2)(-) and RNH(2)(+) in H(2)L(-); predominantly between RPO(3)(2-) and RNH(2)(+) in H(3)L. There are strong indications that the zwitterion is intact throughout the pH range investigated. Results from IR and extended X-ray absorption fine structure (EXAFS) spectroscopies provide new evidence for structures of N-(phosphonomethyl)glycinecopper(II) complexes. The structures of 1:1 complexes, CuL(-) and CuHL, are essentially the same, differing only in protonation of the phosphonate group. Copper(II) lies at the center of a Jahn-Teller distorted octahedron with all three donor groups (amine, carboxylate, phosphonate) of PMG chelating with copper(II) to form two five-membered chelate rings oriented in the equatorial plane. EXAFS indicates that oxygen (most likely a water molecule) is a fourth ligand, which would thus occupy the fourth corner in the equatorial plane of the elongated octahedron. CuL(2)(4-) most probably forms an isomeric mixture in solution, and there are indications that this mixture is dominated by complexes where two PMG ligands are bound to copper(II) via equatorial and axial positions, with both phosphonate and carboxylate donor groups responsible for chelation at axial positions.     

IR spectroscopic studies on substituted pyridine N-oxide complexes of tin(IV) chloride in acetonitrile

Complexes of eleven substituted pyridine N-oxide donors with stannic chloride in acetonitrile solution were investigated ultizing IR spectroscopy. Two distinct types of behaviour were noted: (1) Pyridine N-oxide donors containing electron releasing substituents generally form strong complexes with SnCl₄ and exhibit maxima in continuous variation plots at a 2:1 ligand-to-metal ratio. Little or no free ligand is detected in these solutions until this ratio is exceeded. Ligands exhibiting this behaviour include the 2-methyl-, 3-methyl-, 4-methyl-, 4-methoxy- and 4-phenylpyridine N-oxides.(2) Pyridine N-oxide donors containing electron neutral to electron with-drawing substituents generally form weaker complexes with SnCl₄ aM exhibit maxima in continuous variation plots at a 1:1 ligand-to-metal ratio. Free ligand is evident in these solutions even at ligand-to-metal ratios as low as 1:3. Formation plots for these complexes indicate the possibility that 1: 2 and 1:1 ligand to metal complexes exist in the concentration ranges studied. Ligands exhibiting this behaviour include the 4-chloro-, 4-nitro-, 3 and 4-acetyl-pyridine N-oxides and 2-pyridine methanol N-oxide.The complex of 2,6-1utidine N-oxide with SnCl₄ exhibits behaviour characteristic of the 1:1 complexes even though the substituents are electron releasing. This ligand contains the most sterically crowded N-O group in the series, however, and steric factors are invoked to explain this behavior.These results are rationalized in terms of an equilibrium model which includes the postulated existence of oxygen bridged dimers comprising a dominant species in solutions containing the 1:1 complexes. Some supporting ¹H NMR and polarographic data are also presented and discussed.     

Nickel(II) complexes of new polydentate carboxyamide: spectroscopic,kinetics of thermal decomposition and X-ray powder diffraction studies

Complexes of Ni^II with new ligands N′,N′′-bis(3-carboxy-1-oxoprop-2-enyl), 2-Amino-N-arylbenzamidine (C₂₁H₁₇N₃O₆), N′,N′′-bis(3-carboxy-1-oxopropanyl) 2-Amino-N-arylbenzamidine (C₂₁H₂₁N₃O₆) and N′,N′′-bis(3-carboxy-1- oxophenelenyl) 2-Amino-N-arylbenzamidine (C₂₉H₂₁N₃O₆) have been synthesized and characterized by elemental analyses, vibrational spectra, electronic spectra, TOF-mass spectra, magnetic susceptibility measurements, thermal studies and X-ray powder diffraction studies. Vibrational spectra indicate coordination of amide and carboxylate oxygen of the ligands along with two water molecules giving a MO₆ weak field octahedral chromophore. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for Ni^II complexes. The elemental analyses and mass spectral data have justified the ML complexes. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The crystal data: C₂₁H₁₉N₃O₈ Ni is orthorhombic, space group P_mmm, a = b = 9.015360(Å), c = 10.554430(Å), V = 572.11A³; C₂₁H₂₃N₃O₈Ni is monoclinic, space group P_2/m, a = 15.08206(Å), b = 5.358276(Å), c = 9.898351(Å), V = 671.58A³; C₂₉H₂₃N₃O₈Ni is tetragonal, space group P_4/m, a = b = 6.328104(Å), c = 9.82213(Å), V = 393.33A³. Molecular structures of the complexes have been optimized by MM2 calculations and supported octahedral arrangements around Nickel(II) ions.     

Dinuclear copper(II) complexes of Fenoprofen: synthesis,spectroscopic, thermal,and SOD-mimic activity studies

Three dinuclear copper(II) complexes with the anti-inflammatory drug Fenoprofen [Hfen, 2-(3-phenoxyphenyl)propionic acid] and nitrogen donors of general formula [Cu₂(fen)₄(L)] _n were prepared from [Cu₂(fen)₄(dmf)₂]·2H₂O (1) [dmf?=?N,N′-dimethylformamide; L?=?4,4′-bipyridine (2), pyrazine (3), and 2,5-dimethylpyrazine (4)]. The new complexes were characterized by chemical analysis, spectroscopic, and thermogravimetric techniques. Antioxidant properties of 1–4 were evaluated for superoxide-dismutase-mimic activity employing the XTT method. Complex 2 presented the highest antioxidant activity (IC₅₀?=?0.260?µmol?L^?1). Anti-inflammatory properties of 2 were evaluated employing carrageenan-induced paw edema in mice, revealing that the Fenoprofen–copper(II) complex containing 4,4′-bipyridine does not present enhanced anti-inflammatory activity compared to the uncomplexed parent drug Fenoprofen calcium salt.     

Cobalt(II) silanethiolato complexes with dimethylpyridines: crystal structures and spectroscopic studies

Cobalt(II) tri-tert-butoxysilanethiolates with 2,5-dimethylpyridine, 3,4-dimethylpyridine and 3,5- dimethylpyridine co-ligands have been synthesized by reaction of bimetallic [Co{μ-SSi(O ^t Bu)₃}{SSi(O ^t Bu)₃}(NH₃)]₂ with the appropriate pyridines. The complexes were characterized by elemental analysis, single-crystal X-ray structure determination, IR and UV–Vis spectroscopy. These complexes are tetra- or penta-coordinated with CoN₂S₂ and CoNO₂S₂ cores, respectively.     

Synthesis,characterization and anticancer studies of bis-(N-methyl-1-phenyldithiocarbamato) Cu(II), Zn(II), and Pt(II) complexes: single crystal X-ray structure of the copper complex

Abstract

Cu(II), Pt(II), and Zn(II) complexes of N-methyl-1-phenyldithiocarbamate were synthesized and characterized by FTIR, NMR, UV-visible spectroscopy and elemental analysis. The complexes were formulated as [Cu(L)₂], [Zn(L)₂] and [Pt(L)₂] (where L?=?N-methyl-1-phenyldithio­carbamate) in which two molecules of the ligands coordinate to the metal ions in a bidentate chelating fashion. This is confirmed by elemental analysis and the presence of strong single bands at 952, 951, and 955?cm^?1 for Cu(II), Pt(II), and Zn(II) complexes, respectively, in the FTIR spectra. The electronic spectra of Pt(II) and Cu(II) complexes are consistent with four-coordinate square planar geometry. Single crystal X-ray of [Cu(N-mpDTC)₂] confirmed square planar structural arrangement (CuS₄) in which the ligands are asymmetrically bonded to the Cu(II) ion building a centrosymmetric monomer entity. The S-Cu-S bite angle is 77.95° (3) whereas the intramolecular N–C bond length is 1.318 Å and trans S1¹-Cu-S1?=?S2¹-Cu-S2 is 180°, which are consistent with reported copper thiolates in square planar environment. In vitro antiproliferative activity of the complexes against three human cancer cell lines showed that the zinc complex has better activity compared to Cu and Pt complexes, with IC₅₀ values of 14.28, 22.74 and 20.10?μM against TK10, UACC62, and MC7 cell lines, respectively.     

Thermodynamics and phase equilibrium studies of silver halide-cobalt(II) halide systems

Phase diagrams for the systems AgCl-CoCl₂ and AgBr-CoBr₂ were determined by differential scanning calorimetry. The systems are of the eutectic type. Eutectic points are at 271±2 K, 19.5 mol% CoCl₂ and 653±2 K, 17.0 mol% CoBr₂, respectively. The solid solubility does not exceed 2 and 4 mol% in the systems AgCl-CoCl₂ and AgBr-CoBr₂, respectively. Thermodynamic activities of components in molten mixtures and molar free enthalpies of mixing were determined for both systems on the basis of liquidus curves. Deviations from ideality were not found to be considerable.     

An X-ray photoelectron spectroscopic study of some copper(II) tetraaza complexes

A selected series of copper(II) tetraaza complexes, involving open-chain and macrocyclic ligands, has been studied by X-ray photoelectron spectroscopy. The binding energy data obtained are interpreted in terms of the structures of these complexes with particular reference to the existence of π-electron delocalisation over metal and ligand, peripheral ring substituents, cation-anion interaction and hydration water. It is apparent that the degree of cation-anion interaction and photoreduction is a function of the existing experimental conditions.     

17O-ligand hyperfine structure in single crystal ESR spectra of copper(II)hydroxyquinolinate: phthalimide and copper(II)picolinate:zincpicolinate tetrahydrate

K-band ESR spectra of ¹⁷O labelled Copper(II)oxyquinolinate (CuOX₂) substituted in phthalimide single crystals and of Copper(II)picolinate (Cupic₂) substituted in single crystals of Zinc picolinate tetrahydrate are reported. The spectra were analyzed as a superposition of spectra of 3 isotopic ¹⁶O, ¹⁷O species, yielding anisotropic hyperfine coupling tensors for the ¹⁷O ligands of the two complexes. The magnetic data will then be used for derivation of bonding parameters in a one hole MO scheme and of spin densities at oxygen ligands by two different approaches π^o values of 0.13 and 0.085 (per oxygen atom) for CuOx₂ and Cupic₂ were found. f⁰_p/f⁰_s ratios amount to 11.0 and 8.7 for the two systems, respectively, thereby ranging considerably higher then found hitherto.     

Guanine-containing copper(II) complexes: synthesis, X-ray structures and magnetic properties

Three new compounds of formula {[Cu(gua)(H(2)O)(3)](BF(4))(SiF(6))(1/2)}(n) (1), {[Cu(gua)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(n) (2) and [Cu(gua)(2)(H(2)O)(HCOO)]ClO(4).H(2)O.1/2HCOOH] (3) [gua = 2-amino-1H-purin-6(9H)-one] showing the unprecedented coordination of neutral guanine, have been synthesised and structurally characterized. The structures of the compounds 1 and 2 contain uniform copper(II) chains of formula [Cu(gua)(H(2)O)(3)](n)(2n+), where the copper atoms are bridged by guanine ligands coordinated via N(3) and N(7). The electroneutrality is achieved by uncoordinated tetrafluoroborate and hexafluorosilicate (1) and triflate (2). Each copper atom in 1 and 2 is five-coordinated in a distorted square pyramidal environment: two water molecules in trans positions and the N(3) and N(7a) nitrogen atoms of two guanine ligands build the basal plane whereas a water molecule fills the axial position. The values of the copper-copper separation across the bridging guanine ligand are 7.183(1) (1) and 7.123(1) A (2). is an ionic salt whose structure is made up of mononuclear [Cu(gua)(2)(H(2)O)(HCOO)](+) cations and perchlorate anions plus water and formic acid as crystallization molecules. The two guanine ligands in the cation are coordinated to the copper centre through the N(9) atom. The copper atom in 3 is four-coordinated with two monodentate guanine molecules in the trans position, a water molecule and a monodenate formate ligand building a quasi square planar surrounding. Magnetic susceptibility measurements for 1 and 2 in the temperature range 1.9-300 K show the occurrence of significant intrachain antiferromagnetic interactions between the copper(ii) ions across the guanine bridge [J = -9.6(1) (1) and -10.3(1) cm(-1) (2) with H = -J summation operator(i)S(i).S(i+1)].     

X-ray crystal and molecular structure of sulphato aquotris(benzotriazole) copper(II)benzotriazole

The complex “Cu(SO₄)(btaH)₄·2H₂O” (btaH = benzotriazole) deposited as deep blue crystals from aqueous CuSO₄·5H₂OH₂SO₄btaH solutions been shown by X-ray diffraction methods to be a monohydrate [Cu(SO₄)(H₂O)(btaH)₃·btaH]. The crystals contain five-coordinate, tetragonal pyramidal Cu(SO₄)(H₂O)(btaH)₃ units and bridging btaH molecules linked together by a three-dimensional array of H-bonding interactions.     

X-ray crystal structure of phenylglycine hydrazide: synthesis and spectroscopic studies of its transition metal complexes

Phenylglycine hydrazide was synthesized and investigated by X-ray crystallography. It crystallizes in the monoclinic space group P121/c with cell parameters a=5.9459 (18) Angstrom, b=5.1940 (16) Angstrom, c=26.7793 (83) Angstrom and Z=2. Its conformational changes, on complexation with transition metal ions Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) has been studied on the basis of elemental analysis, magnetic moment and spectral (IR, (1)H NMR, UV-vis) studies. The bidentate nature of the ligand was confirmed on the basis of a comparative IR and NMR spectral studies. The trigonal bipyramidal geometries were observed for Cu(II), Ni(II) and Co(II) complexes, while it is octahedral for the remaining complexes. The conductivity data suggest them to be non-electrolytes.