IR Spectral Measurements Research Articles

Investigations of Co(II), Ni(II) and Cu(II) (2,2´:6´,2"2"-Terpyridine) Complexes With Sulfur Donor Ligands

The ‘complexes as metal’ strategy has been used to prepare new mixed ligand complexes containing Co(II), Ni(II) and Cu(II) terpyridine (terpy) with dithiooxamide (dto) and thiosemicarbazide (tsc). Characterization of the complexes has been accomplished by elemental analysis, molar conductance, thermal analysis, as well as electronic and IR spectral measurements. It is deduced that the coordination mode of the terpyridine is changed from tridentate in the binary complex to bidentate in the ternary one where the uncoordinated pyridine exists in the protonated form. The dto and tsc act as neutral bidentate ligands coordinating through either sulfur or sulfur and nitrogen atoms respectively, forming chelate ring systems.

<I>In-situ</I> Photoluminescence, Raman, and IR Spectral Study of Porous Silicon during Exposure to Thermoelectrons/H atoms, /H<SUB>2</SUB>O and /O<SUB>3</SUB>

Photoluminescence (PL), Raman, and transmission IR spectral measurements of porous silicon (PS) have been carried out during exposure to thermoelectrons and also subsequent exposure to H atoms, H 2 O and O 3 . The PL band of as-anodized PS was significantly decreased by the first exposure to thermoelectrons accompanied by the intensity reduction of the IR bands due to hydrogenated Si species (Si-H x ; x = 1-3). Upon subsequent exposure to H atoms the PL band intensity was almost recovered but never exceeded its original intensity. This PL recovery was accompanied by re-generation of Si-H x bottds. In contrast, an overshooting recovery in the PL intensity took place when thermoelectron-treated PS was exposed to H 2 O or O 3 . The obtained IR spectra showed that Si-O and/or Si-OH bonds were formed at the PS surface. These results demonstrate that the PL of the PS is quite sensitive to the oxygen-included surface bonds.

TRANSITION METAL COMPLEXES OF HETEROCYCLIC LIGANDS. PART VI. COMPLEXES OF 5-HYDROXY-6-MERCAPTO-BENZO[a]PHENAZINE WITH Co(II), Ni(II), Cu(II), Zn(II) AND Cd(II)

The paper reports the conclusions about the structure of jive new romp/exes of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the heterocyclic ligand, 5-hydroxy-6-mercapto- benzo[a] phenazine (H2L). These were obtained by elemental analysis, IR, UV-VIS and EPR spectral analysis, conductivity and magnetic susceptibility measurements, and thermal analysis. Bacteriological studies revealed that the ligand and the complexes possess moderate antimicrobial activity.

A Novel Bis(trans-thiocyanate)iron(II) Spin-Transition Molecular Material with Bidentate Triaryltriazole Ligands and Its Bis(cis-thiocyanate)iron(II) High-Spin Isomer

Two novel complexes trans-[Fe(MBPT)2(NCS)2] (1) and cis-[Fe(mMBPT)2(NCS)2] (2) have been synthesized and their structure characterized at 293 K by single-crystal X-ray crystallography [MBPT (or mMBPT) = 4-p(or m)-methylphenyl-3,5-bis(pyridin-2-yl)-1,2,4-triazole]. Complexes 1 and 2 are isomers, and 1 crystallizes in the triclinic space group P1̄ with Z = 1, a = 9.120(3) Å, b = 9.2563(18) Å, c = 11.576(2) Å, α = 76.256(15)°, β = 76.405(18)°, γ = 84.983(19)°, and V = 922.1(4) Å3 in contrast to 2 in the monoclinic space group C2/c with Z = 4, a = 21.851(3) Å, b = 13.4113(15) Å, c = 16.859(3) Å, β = 128.153(9)°, and V = 3885.0(9) Å3. Both complexes have a similar pseudo-octahedral [FeN6] core with the NCS- groups in the trans arrangement in 1 but cis in 2. Variable-temperature magnetic susceptibility and IR spectral measurements reveal that 1 shows an abrupt high-spin ↔ low-spin (HS ↔ LS) transition centered at T1/2 around 231 K, in contrast to 2 staying in a high-spin state in the observed temperature range of 75−300 K. The extended X-ray absorption fine structures (EXAFS) spectra confirm that the average Fe−N distance for the HS state in 1 is ≈0.2 Å longer than that of the LS state. Complex 1 represents the first spin-crossover iron(II) complex with triaryltriazole and trans-thiocyanate ligands.

SYNTHESIS AND CHARACTERIZATION OF COPPER(I) COMPLEXES OF N-CARBOETHOXY-4-CHLOROBENZENE AND N-CARBOETHOXY-4-BROMOBENZENE THIOAMIDES (Hcct AND Hcbt)

ABSTRACT Reactions of [Cu(EPh3)3X] with the title ligands yield [Cu(EPh3)2(LH)X] (LH=Hcct and Hcbt). Twelve complexes have been prepared and characterized on the basis of analytical, IR, electronic and NMR spectral and magnetic measurements. These complexes have a tetrahedral structure with the aromatic ligand bonded to copper(I) through sulfur.

Synthesis and Characterization of O,O′ Dialkyl and Alkylene Dithiophosphates of Lanthanum(III) and their Adducts with Nitrogen and Phosphorus Donor Bases

Lanthanum(III) tris(dithiophosphates), [La{S2P(OR)2}3] (where R=-CH2CH2CH3 or -C6H5) and [La{S2PO2G}3] [where G=-C(CH3)2CH2CH(CH3)-, -CH2C(CH3)2CH2-, -C(CH3)2C(CH3)2- and -CH2CH2CH(CH3)-] were prepared in methanolic solutions of anhydrous LaCl3 and ammonium dithiophosphates. Addition complexes of the type [La{S2P(OR)2}3·nL] and [La{S2PO2G}3·nL] [where n = 1, L = N2C10H8 or N2C12H8 and n = 2, L = P(C6H5)3] were prepared by reaction of lanthanum(III) tris(dithiophosphates) and nitrogen or phosphorus donor bases in benzene. These newly synthesized derivatives have been characterized by elemental analyses, molecular weights, IR, 1H and 31P NMR spectral measurements. Coordination numbers of six and eight are suggested for lanthanum(III) in these derivatives.

Synthesis and Characterization of Nitrato-Triamine-Metal(II) Complexes. Conglomerate Crystallization Part 55. Crystal Structure of [Ni(dien)(O2NO)(ONO2)] (I), {[Cu(dien)-(μ-ONO2)]NO3}∞ (II), [Zn(dien)(O2NO)(ONO2)] (III), [Ni(Medpt)(O2NO)(ONO2)] (IV) and [Cu(Medpt)(ONO2)2] (V)

In absolute ethanol and in the presence of triethylorthoformate, reactions of metal(II) nitrates with linear tridentate amines afforded metal complexes of the formula M(NNN)(NO3)2, where M = Ni2+, Cu2+ and Zn2+, and NNN = dien and Medpt. The compounds fall into three categories in accordance with their stereochemistry and mode of binding of the nitrato ligands. Compounds I, [Ni(dien)(O2NO)(ONO2)] and III, [Zn(dien)(O2NO)(ONO2)] are isomorphous and isostructural. They crystallize in the monoclinic space group P21/n with nearly identical cell constants. The stereochemistry of these two compounds is such that the terdentate dien ligand forms a fac MN3 moiety with the two oxygens of the bidentate nitrato ligand trans to the terminal NH2. These ligands form the base of the octahedral arrangement in which the sixth position, trans to the secondary nitrogen of the dien, is an oxygen of the monodentate nitrato ligand. Compound IV, [Ni(Medpt)(O2NO)(ONO2)] falls into the same category as I and III despite the fact that the two rings in the Ni-Medpt moiety are six-membered rings, unlike those in compounds I and III which are five-membered rings. Nevertheless, the nickel-amine arrangement is fac. The bidentate nitrato-oxygens are trans to the terminal NH2 of the amine ligand, and the oxygen of the monodentate nitrato ligand is trans to the tertiary amine-nitrogen. Such stereochemistry is prevalent for nickel and zinc compounds. Interestingly, compound IV crystallizes as a conglomerate (space group P212121). Compound II, {[Cu(dien)(μ-ONO2)]NO3}∞ belongs to the second category and has a polymeric structure. The repeating fragment in the polymeric chain is a Cu(dien)-O fragment with the monodentate nitrato ligand occupying an equatorial position of the base. A second oxygen of the equatorial nitrate becomes an axial ligand for an adjacent Cu-N3O fragment. In this way the substance propagates into an infinite chain. The repeating unit has an effective square pyramidal, five-coordinate, configuration. Finally, the compound crystallizes as a racemate. The second nitrate necessary for charge compensation of this copper(II) compound is ionic and its function is to hold the infinite chains of the lattice. The third category represented by compound V, [Cu(Medpt)(ONO2)2] contains two molecules in the asymmetric unit of the racemic lattice (monoclinic, space group P21/a). The structure of Cu-Medpt is unlike that of IV in that both species present in the asymmetric unit have the amine ligand in a mer configuration which together with a monodentate oxygen of a nitrato ligand form a base plane of a square pyramid. The fifth ligand of both Cu2+ ions is a second monodentate nitrato ligand. The stereochemical differences between the two Cu2+ ions are insignificant for the Cu-Medpt fragment, which share the same conformation and configuration. The major difference between the two species is the torsional angles defined by the Cu-O-N-O angles. The difference arises from variation in the hydrogens of the primary amine moieties selected by nitrato-oxygens to form intramolecular hydrogen bonds. Finally, there is a little variation in the equatorial Cu-ONO2 stereochemistry because of steric hindrance, imposed by the Medpt, preventing large torsional angles by these nitrato ligands. This is evident by comparing the two copper species shown in Finally, nitrate-to-Br ligand exchange was found to take place when KBr pellets are prepared for IR spectral measurements.

THE SYNTHESIS OF SUBSTITUTED BIS-(AMINOPHENYLGLYOXIME)METHANES AND THEIR POLYMERIC METAL COMPLEXES WITH Cu(II), Ni(II), AND Co(II) SALTS

In this study, 4,4′-bis(chloroacetyl)diphenylmethane (HL) has been synthesized from chloroacetylchloride and diphenylmethane. Subsequently, its keto oxime (H2L) and glyoxime (H4L) derivatives have been prepared. Then, seven new substituted bis(aminophenylglyoxime)methanes (H4Lx) have been synthesized from bis(chlorophenylglyoxime)methane and the corresponding amines. The Ni(II), Cu(II) and Co(II) complexes of these ligands were prepared. The structures of these ligands and their complexes were identifed by IR and 1H NMR spectral data, elemental analyses and magnetic measurements.

Spectrophotometric study on the adduct formation of nickel (II)-di(2,4-dimethylphenyl)carbazonate with heterocyclic nitrogen bases

The study of the adduct formation of Ni(II)di(2,4-dimethylphenyl)cabazonate has been undertaken by synthesising and characterising it by magnetic susceptibility, IR and 1H-NMR spectral measurements. The Ni(II) chelate forms adducts with heterocyclic nitrogen bases, spectrophotometeric method has been employed for the study of the adduct formation in a monophase chloroform. Both bidentate and unsaturated monodenate heteronuclear nitrogen bases form hexa-coordinated adducts with 1:1 stoichiomety (metal chelate, base). However, the saturated nitrogen bases form penta-coordinated adducts with 1:1 stoichiometry. The results are discussed in terms of basicity and steric factors of the bases.

Estimation of excited state dipole moments of di(4-methylphenyl)carbazone and its Co(II), Cu(II), Zn(II) complexes from the solvent effect on their ultraviolet absorption spectra

The solvent effect on the ultraviolet absorption spectra of di(4-methylphenyl)carbazone and its Co(II), Cu(II), Zn(II) complexes have been studied by synthesizing and characterizing them by magnetic moment, IR, 1H NMR, ESR and Fluorescence spectral measurements. The electric dipole moments of these compounds in the first electronically excited state have been determined. The results indicate that the observed band systems in these compounds may be attributed to π ∗←π transition.

DMA−FTIR Creep−Recovery Study of a Poly(ester urethane) Elastomer with Molecular-Level Viscoelastic Modeling

The combination of a research-grade DMA (dynamic mechanical analyzer) and an FTIR (Fourier transform infrared) spectrometer is demonstrated in simultaneous mechanical analysis and dynamic IR spectral measurement. In such a study, molecular-level responses to the deformation can be observed in the dynamic IR spectra and used to better understand the macroscopic viscoelastic behavior of the polymer sample characterized by monitoring the stress and strain. The measurements are performed on polymer films, with the DMA in the tensile geometry and IR measurement in the transmission mode. The DMA−FTIR technique is demonstrated in the creep−recovery study of an industrially important elastomer, Estane 5703. Differential orientation of various segments of the macromolecule during the creep and recovery process is observed. In a novel molecular-level application, Burger's model, a viscoelastic model that is often used to explain the bulk properties of materials, is applied to the analysis of the orientation of individual infrared dipoles. By replacing strain with orientation functions, contributions from separate molecular moieties to the macroscopic elasticity and viscosity are differentiated. Permanent damage observed after a large displacement is attributed to the irreversible alteration of the microscopic network structure of the elastomer and is discussed in light of IR spectral changes during the creep−recovery process.

The solvent effect and electronic spectral studies for the estimation of excited state dipole moments of di(4-ethylphenyl) carbazone and its Ni(II), Cu(II), Pd(II) complexes

Di(4-ethylphenyl)carbazone and its Ni(II), Cu(II) and Pd(II) metal complexes have been synthesized and characterized by magnetic moment, IR, ESR and 1H NMR spectral measurements. The solvent effect in a series of polar and non-polar solvents of varying dielectric constants and refractive indices are estimated by recording electronic spectra (S 1 band) of the above compounds. These data are used to determine the magnitude and direction of the electric dipole moments in the first electronically excited states. The results indicate that the observed band systems in these compounds may be attributed to π ∗←π transition.

THE SYNTHESIS AND CHARACTERIZATION OF NEW UNSYMMETRICAL vic-DIOXIMES AND THEIR COMPLEXES WITH SOME TRANSITION METALS

In this study, three new unsymmetrical vic-dioimes, N-(4-methoxy-phenyl)aminomethylglyoxime (L1H2), N-(5-chloro-2-methoxyphenyl)amino-methylglyoxime (L2H2) and N-(3-chloro-4-methoxyphenyl)aminomethylglyoxime (L3H2) have been synthesized from chloromethylglyoxime and the corresponding substituted aromatic amines. Mononuclear metal complexes of these ligands have been synthesized with Co(II), Ni(II) and Cu(II) salts. The structures of these new compounds are proposed based upon elemental analyses, 1H NMR, IR spectral data and magnetic measurements.

Crystal structure and physico-chemical properties of diaquabis(1,10-phenanthroline)manganese(II) disaccharinate monohydrate

A novel manganese complex, [Mn(phen)2(H2O)2](sac)2·H2O, was synthesized by the reaction of [Mn(sac)2(H2O)4]·2H2O with 1,10-phenantroline in aqueous solution and characterized by elemental analysis, IR spectral evidence, magnetic measurements, thermal analysis and single crystal X-ray diffraction. The compound crystallizes in triclinic system, space group P-1, with Z=2. The saccharinate ions do not coordinate the central metal, instead are present as the complementary anions. In the complex cation, Mn(II) is coordinated by two phen and two aqua ligands, and exhibits a distorted octahedral coordination with a high-spin configuration. The presence of lattice and coordinate water molecules are also confirmed by thermal analysis and IR spectroscopy.

A study of adduct formation of heterocyclic nitrogen bases with nickel(II) chelate of di(6-chloro-2-methylphenyl)carbazone

The study of the adduct formation of Ni(II) di(6-chloro,2-methylphenyl)carbazonate has been undertaken by synthesising and characterizing it by magnetic susceptibility, UV-VIS, IR and 1H-NMR spectral measurements. The distorted square planar Ni(II) chelate forms adducts with heterocyclic nitrogen bases; spectrophotometric method has been employed for the study of the adduct formation in a monophase chloroform. Both bidentate and unsaturated monodentate heteronuclear nitrogen bases form hexacoordinated adducts with 1:1 and 1:2 stoichiometry, respectively (metalchelate:base). However, the saturated nitrogen bases form pentacoordinated adducts with 1:1 stoichiometry. The results are discussed in terms of basicity and steric factors of the bases.

Metal Complexes of 22-Niembered Mononuclear Tetraimine-Tetraamide Macrocycles: Synthesis and Characterization

Template condensation reaction of succinic acid or phthalic acid with hydrazine hydrate and 2,4-pentanedione resulted in the formuation of a new series of 22-membered tetraiminetetraamide macrocyclic complexes: dichloro/dinitrato (8, 11, 19, 22-tetraone-3, 5, 14, 16-tetramethyl-1, 2, 6, 7, 12, 13, 17, 18-octaazacyclodocosane-2, 5, 13, 16-tetraene)metal(II), [ML1X2] [M = Mn(II), Co(II), Ni(II) and Zn(II); X = CI or NO3]; (8, 11, 19, 22-tetraone-3, 5, 14, 16-tetramethyl-1, 2, 6, 7, 12, 13, 17, 18-octaazacyclodocosane-2, 5, 13, 16-tetraene)copper(II) dichloride/dinitrate [CuL1]X2; dichloro/dinitrato(9, 10, 20, 21-d ibenzo-8, 11, 19, 22-tetraone-3, 5, 14, 16-tetramethyl-1, 2, 6, 7, 12, 13, 17, 18-octaazacyclodocosane-2, 5, 13, 16-tetraene)metal(II), [ML2X2] [M = Mn(II), Co(II), Ni(II) and Zn(II); X = CI or NO3) and (9, 10, 20, 21-dibenzo-8, 11, 19, 22-tetraone-3, 5, 14, 16-tetramethyl, 2, 6, 7, 12, 13, 17, 18-octaazacyclodocosane-2, 5, 13, 16-tetraene)copper(II) dichloride/dinitrate, [CuL2]X2. These complexes have been characterized by IR, 1H NMR, EPR and electronic spectral studies, conductivity and magnetic susceptibility measurements. An octahedral geometry has been suggested for the manganese, cobalt, nickel and zinc complexes, while a square-planar geometry is proposed for the copper complexes. All complexes are stable to air.

Dynamic photoluminescence change of porous Si upon exposure to thermoelectrons/D atoms and D2O

In situ photoluminescence (PL) and transmission IR spectral measurements have been carried out for porous Si (PS) after exposure to thermoelectrons and subsequent exposure to D atoms or D2O. Upon exposure to thermoelectrons the PL band (765 nm) of the PS almost diminished accompanied by the intensity reduction of the IR bands due to Si-Hx (x=1–3) species. A subsequent D atom exposure resulted in a recovery of the PL band with the formation of Si-Dx bonds. In contrast, D2O exposure gave rise to a new PL band at 650 nm in addition to a 745 nm band accompanied by the emergence of IR bands due to Si-OD and Si-D bonds: the integrated PL intensity after the D2O exposure is 1.2 times larger than the PL intensity of the as-anodized PS. These results suggest that the PL of the PS contains an important contribution from the surface Si-O bonds.

SYNTHESIS AND SPECTROSCOPIC STUDIES OF P,O′ ALKYLENE DITHIOPHOSPHATO COMPLEXES OF METALLOCENES; CP2ML2[M = Ti OR Zr

Complexes of the type Cp2,M[S2POGO[,2 [where Cp = C5H5, M=Ti or Zr; G = -C{CH3)CH2CH(CH3), -CH2C(CH3)2CH2-, -C(CH3)2C(CH3)2 and CH2CH2CH(CH3)-] were prepared by reaction of Cp2MCl2 and NH4[S2POGO] in 1:2 molar ratio in CH2Cl2. These newly synthesized compounds have been characterized by molecular weights, IR, 1H and 31P NMR spectral measurements. An octahedral geometry for both the metals have been proposed.

Isolation and characterisation of a ropy Lactobacillus strain producing the exopolysaccharide kefiran.

A capsular-polysaccharide-producing strain, LM-17, was isolated from kefir grains and was identified as a slime-forming, rod-shaped Lactobacillus. According to 1H- and 13C-NMR spectral data, the exopolysaccharide produced by the isolated bacterial strain is identical to the glucogalactan extracted from kefir grains and therefore known as kefiran. The kefiran produced was characterised by means of viscosity, optical rotatory power, circular dichroism and IR spectral measurements. A batch procedure was set up for the culture and extraction of the exopolysaccharide in laboratory conditions, resulting in a yield of 2 g/l purified kefiran from the culture supernatant of the LM-17 strain.

Dicarboxylic Acid Hydrazide Complexes of Magnesium Tetrafluoroborate

New magnesium tetrafluoroborate complexes with oxalic (ODH), malonic (MDH), succinic (SDH), adipic (ADH), phthalic (PDH) and terephthalic (TDH) dihydra-zides have been synthesised and investigated by elemental analyses, magnetic, conductance and IR spectral measurements. The complexes are diamagnetic with some evidence of polarisation paramagnetism. They have been assigned octahedral stereochemistry with any two of the carbonyl, amino and amide groups as the possible coordination sites.