Vibrational Behavior of Transition Metal Cupferronato Complexes: Raman Studies on Cobalt(II) Cupferronato Derivatives

The FT-Raman spectrum of cupferron, [PhN₂O₂]NH₄ and the micro-Raman spectra of the new corresponding cobalt(II) cupferronato complexes, CoL₂A₂, L = PhN₂O₂, a = H₂O, MeOH, o-C₆H₄(NH₂)₂, p-C₆H₄(NH₂)₂ and CoL₂A, a = (-C₆H₄NH₂-p)₂ were recorded and discussed. All the complexes show a Raman band at about 1302 cm¹ and the characteristic v(N-N) and δ(ONNO) modes of the anionic ligand. the vibrational analysis of the title compounds reveals the electron delocalisation over the N-nitroso-N-hydroxylaminato (ONNO) unit, as well as the bidentate coordination of the cupferronato ligand to the metal center through the oxygen atoms.     

Analysis of the ESR Spectrum of a Rhodium (II) Complex

Abstract

Rh(II) complexes are rather scarce¹ and often form dimeric structures, which are diamagnetic. The ESR spectra of definite Rh(II) species have so far been claimed for Rh in ZnWO₃ ², [Rh S₄C₄(CN)₄]^{2 ?}, ^3′4 [Rh(π-C₅H₅)₂]⁵, [(π-C₅H₅)Rh(π-C₂H₄)₂]⁺⁶, and an irradiation produced [RhCπ₂(CN)₄]^{2 ?} complex.⁷ A detailed analysis has been performed on the first², the second⁴ and the last⁷ complexes. The first system shows an almost axial symmetry and the unpaired electron has been assigned to the d_xy orbital² (the x,y,z axes are defined along the octahedral metal-ligand directions). The sulfur ligand complex and the dichlorotetracyano system have their unpaired electron in the d_Z ² orbital. ^4,7 In the course of studies ^8-10 on oxygenation of a Rh(I) complex, [RhCπ(C₈H₁₄)₂]₂, we observed ¹⁰ that a well defined ESR spectrum develops during the reaction in N,N′-dimethylacetamide (DMA) - lithium chloride media. For experimental detail, reference 10 should be consulted. The data summarized in the table refer to the spectrum B in that reference and are attributed to a Rh(II) species.     

Laser Raman Spectra of Crystalline Chloromercurate(II) Complexes

Abstract

The laser Raman spectra of crystalline [(CH₃)₄N] HgCl₃ and [(CH₃)₄N]₂HgCl₄ have been studied in the 400–20 cm^?1 region. All expected Raman active modes for the HgCl₃ ^? and HgCl₄ ^?2 ions are observed and assignments of the vibrational frequencies are made in relation to the structure of the anions.     

Copper(II) and nickel(II) complexes of tetradentate Schiff base ligand: UV-Vis and FT-IR spectra and DFT calculation of electronic,vibrational and nonlinear optical properties

The experimental fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectra of copper(II) and nickel(II) complexes of the deprotonated tetradentate Schiff base ligand N,N′-bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine (H₂L) are compared with their corresponding theoretical ones. The applied theoretical method is based on the density functional theory and time-dependent density functional theory at the UPBE0/PBE0 levels using Def2-TZVP basis set. The computational optimised geometric parameters of the complexes are in good agreement with their corresponding experimental data. The FT-IR and UV-Vis spectra of the complexes were reproduced on the basis of their optimised structures. The vibrational assignments of some fundamental modes of the complexes are performed. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies are calculated. The analyses of the calculated electronic absorption spectra of the complexes are carried out to elucidate the electronic transitions assignments and their characters. Second-order nonlinear optical property of the complexes is evaluated by the above-mentioned theoretical method that implies much greater values for the complexes in comparison with the corresponding value of urea.     

Far Infrared and Raman Spectra of Some Crystalline Iodomercurate Complexes

Abstract

Vibrational spectra of crystalline powders of [Nien₂] [HgI₃]₂ and [Men₂] [HgI₄] (where en = ethylene-diamine chelated to M = Ni(II), Pd(II) or Pt(II)) have been measured at room and liquid-nitrogen temperatures. The bands observed in the low frequency region 200–10 cm^?1 are interpreted in terms of mainly internal vibrations of the anions and external lattice modes. Raman and far infrared spectra are compared in order to make structural deductions. In comparison with present knowledge of the stereochemistry and vibrational spectroscopy of other iodomercurates, the triiodo-mercurate salt seems to contain nearly planar trigonal anions, while the tetraiodomercurates contain discrete tetrahedra. Probable site symmetries of the anions which may explain the spectra are discussed.     

Spectra-Structure Correlations in 2,2′-Bipyridine Mercury(II) Saccharinate: Comparison With Mercury(II) Saccharinate And Chloromercury(II) Saccharinate∗

Abstract

The infrared spectrum of 1:1 complex of mercury(II) saccharinate with 2,2′-bipyridine, [Hg(C₇H₄NO₃S)₂(C₁₀H₈N₂)], was studied in the CO and SO₂stretching regions. The appearance of the spectrum in the region of the carbonyl stretching modes was correlated with the number of non-equivalent CO groups in the structure. The spectral and structural characteristics of the CO groups in the title compound were compared with the corresponding ones in the mercury(II) saccharinate and chloromercury(II) saccharinate. It was found that the frequency of the CO stretchings in the spectrum of Hg(bpy) (sac)₂ is significantly lower (1630 and 1615 cm^?1) than the frequency of the corresponding modes in the spectra of covalently bonded mercury(II) saccharinate (1705 and 1680 cm^?1) and chloromercury saccharinate (1694 cm^?1). An attempt was also made to assign the bands which are mainly due to the symmetric and the antisymmetric SO₂ stretching vibrations.

     

Synthesis and Antitumor,Antioxidant Effects Studies of N-Ethylpiperazine Substitute Thiourea Ligands and Their Copper(II) Complexes

A series of N-ethylpiperazine substitute thioureas [C₆N₂H₁₃NHCSNHR], where R = -C₃H₅ (L ₁ ), -C₁₀H₇ (L ₂ ), and -C₇H₇ (L ₃ ), and their copper (II) complexes have been synthesized. These ligands and complexes have been characterized by elemental analyses, IR, ¹H and ¹³C-NMR spectra, UV-Vis, magnetic susceptibility, thermogravimetrical analyses, and MALDI-TOF MS. In vitro antitumor activity of ligands and their complexes has been screened toward several tumor cell lines. The effects on these complexes of the growth of L1210 and MCF7 were studied comparatively with that of free ligands. Antioxidant and radical scavenging activities of synthesized compounds were determined by various in vitro assays including 1,1-diphenyl-2-picryl-hydrazyl free radicals (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid radicals (ABTS+), and ferrous ion (Fe²⁺) chelating activities. Moreover, these activities were compared to synthetic and standard antioxidant trolox. The results showed that the synthesized compounds had effective antioxidant power.     

A Study on the Spectra Characterization of Ruthenium(Ii) Complexes

Abstract

A series of Ru(II) complexes have been synthesized, and their electronic spectra and NMR spectroscopy properties were characterized. the chemical shifts of aromatic protons of [Ru(bpy)₃] (PF₆)₂, [Ru(phen)₃](ClO₄)₂ and [Ru(bqdi)₃](PF₆) move downfield, but the resonance peaks of cis-Ru(bpy)₂Cl₂ shift upfield. Within the visible spectra of the ruthenium(II) complexes appear a relatively high oscillator strength which is referred to as the π(Ru)→? (ligands) transition.     

The effect of ligands on the first hyperpolarizabilities of rich d electron molecular system: iridium clusters,a TDDFT study

A systematically varied series of tetrahedral iridium clusters have been studied using a TDDFT method focusing on their electronic and nonlinear optical properties. The clusters W₂Ir₂(CO)₁₀(η⁵-C₅H₄Me)₂ (1), WIr₃(μ-dppe)(CO)₉(η⁵-C₅H₄Me (2), W₂Ir₂(μ-L)(CO)₈(η⁵-C₅H₄Me)₂(L = dppe 3, dppf 4), Ir₄(μ-L)(CO)₁₀(L = dppm 5, dppe 6, Ph₂P(CH₂)₃PPh₂ 7, Ph₂P(CH₂)₄PPh₂ 8, (Ph₂P)₂CHMe 9), Ir₄(CO)₁₀(phen)(phen = 1,10-phenanthroline) (10) exhibit the first static hyperpolarizabilities of medium magnitude (β _tot ～ 10 × 10^?30esu). The origination of β is discussed in terms of the electronic structure calculation and the expanded orbital decomposition scheme. The result suggests the origination of β for all the clusters are mainly d–d electron transitions intra metal skeleton, and d–π* electron transitions from metals to carbonyls. For cluster 5, which contains the ferrocenyl group, the main origination of β involves charge transfer from d orbitals of ferrocene to d orbirals of Ir and W.     

A Spectroscopic Study of Alkylamine Complexes of Copper(II) Succinimide

Abstract

The vibrational and electronic spectra of eleven complexes of copper(II) succinimide [CuSu²Am₂] (Su = succinimide ion; Am = variously substituted primary aliphatic amines) show that metal-imide co-ordination occurs through the imide nitrogen atom. The electronic effects of the amine substituents on the carbonyl stretching frequencies and on the electronic spectra are used to infer the probable mechanism of metal-imide bonding.     

Comparison of the ht Ultraviolet-Visible Spectra of the Copper(Ii) Complexes of Bidentate Schiff Base Ligands

Abstract

The bis(salicylaldiminato)copper(II) complexes of the ligand series of salicylaldimines derived from the condensation of n-alkyl or n-alkyloxy substituted aromatic amines with 2,4-dihydroxybenzaldehyde were synthesized. a series of Schiff base ligands with the general formula 4-X-N-(2,4-dihydroxybenzylidene)-aniline and differing only in substituents were synthesized. Some of these compounds have already been reported in literature. X=OCH₃[1],OC₂H₅[2],C₄H₉[1]. the copper(II) complexes of these ligands having the general formula, copper, bis[o-[N-(p-X-phenyl) formimidoyl]-4-hydroxyphenolato] were also synthesized. the ligands and their complexes, a total of 24 in number, are studied systematically with ultraviolet-visible spectroscopy to examine the effect of various n-alkyl- and n-alkyloxy substituents on the ligands and on their complexes. in the electronic spectrum of these compounds, the bands observed in the 200-450 run region which involve charge transfer π-π? transition were interpreted.     

Study of vibronic interactions in impurity centers by conjugate fluorescence and absorption spectra with a poorly resolved vibrational structure

The conjugate fluorescence and fluorescence excitation spectra of recently synthesized substituted arylpolyene (C₆H₅-[CH=CH]₂-C₆H₄-NH₂) are studied in solid n-octane at a temperature of 4.2 K. The spectra exhibit a weakly pronounced vibrational structure. A method of determination of the vibronic interaction parameters responsible for the shape of the spectra is developed. The method is based on the modeling of the spectra by series of vibronic bands, each of which consists of a narrow zero-phonon line and a broad phonon wing (phonon sideband). This makes it possible to calculate the fluorescence and fluorescence excitation spectra with the weakly pronounced vibrational structure and compare them with the measured spectra. The deviations from the mirror symmetry between the measured fluorescence and fluorescence excitation conjugate spectra are explained by the combined effect of the Franck-Condon and Herzberg-Teller interactions. The parameters of these interactions are determined.     

Fine band structure of the vibrational spectra of fullerite C<Subscript>60</Subscript> and enhancement of intermolecular interaction in high-temperature phase

The fine structure of the fundamental vibrational bands and some combination tones of fullerite C₆₀ in its IR absorption and reflection spectra, as well as in Raman spectra, has been studied. This structure is due to the overlapping components of Davydov and isotopic splittings and the removal of vibrational degeneracy with symmetry lowering. It is shown that for IR F _u (i) bands (i = 1–4) and low-frequency H _g (1) and A _g (1) bands in the Raman spectrum the splittings at room temperature exceed those for the low-temperature phase. The enhancement of intermolecular interaction at elevated temperatures is explained by the nonequilibrium vibrational excitation of the medium as a result of nonlinear interaction of vibrational modes and by the change in the electronic states.     

Sonochemical effect on two new Ruthenium(II) complexes with ligand (E)-N-((6-bromopyridin-2-yl)methylene)-4-(methylthio)aniline precursors for synthesis of RuO2 nanoparticles

Two novel Ru(II) complexes [(η⁶-p-cymene)RuCl(L2)]PF₆ (R2) and [(η⁶-C₆H₆)RuCl(L2)]PF₆ (R4), with ligand (E)-N-((6-bromopyridin-2-yl)methylene)-4-(methylthio)aniline (L2), were synthesized and characterized by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy. Based on X-ray crystallography studies, complexes R2 and R4 have coordination environments with formulated (η⁶-p-cymene)Ru(N₂Cl) and (η⁶-C₆H₆)Ru(N₂Cl), respectively. The thermal stabilities of compounds R2 and R4 were studied by thermal gravimetric (TG) and differential scanning calorimetry (DSC). Thermal decomposition of these complexes was at 280 °C and 260 °C under air atmosphere respectively. The interaction of these complexes with calf thymus DNA (CT-DNA) was explored through electronic absorption spectra, fluorescence and redox behavior studies. The results showed that the complexes bind to CT-DNA with electrostatic interactions. Nanoparticles of RuO₂ were prepared by calcination of R2 and R4. Also the role of the ultrasound waves on the characteristics of the RuO₂ nanoparticles was studied. The nanoparticles were characterized by IR spectroscopy and X-ray diffraction (XRD). Also size and morphology of nanoparticles were studied by scanning electron microscopy (SEM).     

Theoretical and spectroscopic studies of 5‐aminoorotic acid and its new lanthanide(III) complexes

The complexes of cerium(III) and neodymium(III) were synthesized by reaction of the respective inorganic salts with 5‐aminoorotic acid (H₄L) in amounts equal to the metal:ligand molar ratio of 1:3. The structures of the final complexes were determined by means of spectral (IR, Raman, ¹H NMR and ¹³C NMR) and elemental analysis. Significant differences in the IR spectra of the complexes were observed as compared to the spectrum of the ligand. A comparative analysis of the Raman spectra of the complexes with that of the free H₄L allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. The geometry of H₄L was computed and optimized for the first time with the Gaussian03 program using the B3PW91/6‐311++G**, B3PW91/LANL2DZ, B3LYP/6‐311++G** and B3LYP/LANL2DZ methods. The experimental IR and Raman bands of the ligand were assigned to normal modes on the basis of DFT calculations. The vibrational analysis performed for the studied species, H₄L and its complexes, helped to explain the vibrational behavior of the ligand vibrational modes sensitive to interaction with the lanthanides. The vibrational study gave evidence for the coordination mode of the ligand to lanthanide ions and was in agreement with the other theoretical prediction. Copyright © 2006 John Wiley & Sons, Ltd.     

The assignment of Co-C bond stretching vibrational frequency of CH3Co(DH)2H2O in IR and Raman spectra

Abstract

In order to aid assignment of Co-C bond stretching vibrational frequency of CH₃Co(DH)₂H₂O (DH=dimethylgIyoximato monanion) in IR and Raman spectra, its isotopic substitution CD₃Co(DH)₂H₂O has been synthesized and normal coordinate analyses on the two complex have been made. The bands were assigned in terms of potential energy distribution. The results provide definitive band assignment of the Co-C bond and Co-N bond stretching modes which are coupling at 511 cm^?1.     

The structural transformation of monoclinic [(R)-C5H14N2][Cu(SO4)2(H2O)4]·2H2O into orthorhombic [(R)-C5H14N2]2[Cu(H2O)6](SO4)3: crystal structures and thermal behavior

Single crystals of [(R)-C₅H₁₄N₂][Cu(SO₄)₂(H₂O)₄]·2H₂O (1) were grown through the slow evaporation of a solution containing H₂SO₄, (R)-C₅H₁₂N₂ and CuSO₄·5H₂O. These crystals spontaneously transform to [(R)-C₅H₁₄N₂]₂[Cu(H₂O)₆](SO₄)₃ (2) over the course of four days at room temperature. The same single crystal on the same mounting was used for the determination of the structure of (1) and the unit cell determination of (2). A second single crystal of the transformed batch has served for the structural determination of (2). Compound 1 crystallizes in the noncentrosymmetric space group P2₁ (No. 4) and consists of trimeric [Cu(SO₄)₂(H₂O)₄]^2? anions, [(R)-C₅H₁₄N₂]²⁺ cations and occluded water molecules. Compound 2 crystallizes in P2₁2₁2 (No. 18) and contains [Cu(H₂O)₆]²⁺ cations, [SO₄]^2? anions and occluded water molecules. The thermal decompositions of compounds 1 and 2 were studied by thermogravimetric analyses and temperature-dependent X-ray diffraction.     

Influence of N‐Substitution on Electron Spin Resonance (ESR) Behavior of 2‐(2‐Nitrophenyl)‐1H‐benzimidazole Derivatives

Abstract

The synthesis of 2‐(2‐nitrophenyl)‐1H‐benzimidazole (1), 1‐benzoyl‐2‐(2‐nitrophenyl)‐1H ‐benzimidazole (2), and 1‐acetyl‐2‐(2‐nitrophenyl)‐1H‐benzimidazole (3) is reported. Stable radical anions (1 ^·?, 2 ^·?, and 3 ^·?) were generated by chemical reduction in DMSO and studied by ESR spectroscopy. The interpretation of the ESR spectra was done by means of computational simulation process. Hyperfine coupling constants were assigned by comparison with related compounds, and on the basis of calculation based on SCF INDO MO method in the unrestricted Hartree–Fock scheme.     

Proton Nuclear Magnetic Resonance Spectroscopy: Significant Barriers to Rotation About N-N Bonds in 3-Acylaminoquinazolin-4(3H)-One Derivatives

Abstract

The proton NMR spectra of several 3-acylaminoquinazolin-4(3H)-one derivatives have been studied as a function of temperature. The changes, which were found to occur in the spectra at high temperatures, are discussed in terms of hindered rotation about the nitrogen-nitrogen bond. The free energies of activation for the rate-determining stereochemical process were calculated to be as high as (14.7～20.6 Kcal mol^?1) for hydrazine derivatives.     

High pressure 17O NMR study of solvent exchange on square planar complexes: Water exchange on [Pd(dien)H2O]2+

Abstract

The water exchange reaction of [Pd(dien)H₂O]²⁺ (dien = diethylenetriamine) was studied as function of temperature (268-308 K) and pressure 0.1-197 MPa) using ₁₇O NMR techniques. The rate and activation parameters are: k_cx = 5100 s^?1 at 298 K; ΔH^# =38 kJ mol^?1; ΔS^# = -47 JK^?1 mol^?1; ΔV^# = -2.8 cm³ mol^?1 at 296 K. The results are discussed in reference to solvent exchange data for other Pt(II) and Pd(II) complexes, and are interpreted in terms of an associatively activated substitution process.