Nitrito Group Research Articles

Influence of Donated Pair of Electrons by a Nitrito-Group Ligand on the Solid-State Properties of Lead Sulfide Thick Films

In general, thick and thin films are developed to provide special properties that range from electrical properties, optical, mechanical and chemical properties that can satisfy the needs for specific applications in technology. Lead sulfide (PbS) is an example of such films. Lead sulfide thin films have been synthesized on glass substrates. Some of the advantages of PbS thin film in olar cell applications include low material consumption, shorter energy payback period, large area modules, monolithic integration, tuneable material properties, low-temperature processes, and transparent modules. PbS thin films help also help in preventing corrosion of metallic parts of many devices. They are also used to offer protection against wear in moving parts. Materials such as jewelry, wrist watches, and knives are often coated to avoid corrosion. For deposition of PbS thin films, lead acetate is used as lead precursor and for sulfur source thiourea, has been was used in many studies.in this study, three samples of lead sulphide thick films were deposited on microscope glass slides at varying nitrito-group ligand concentrations at room temperature using solution method. The nitrito group ligand has a capacity to coordinate a central metal {Pb) atom using two different sites. First, it can use the nitrogen (N) atom as donor atom (nitrito group) and the oxygen (O) as donor atom (nitrito group). Secondly, it can use a sulphur (S) atom as donor atom ( in a thiocyanate group) and nitrogen (N) atom as donor atom ( as in a isothiocyanate). The influence of nitrito-group ligand on the solid-State properties of PbS thin films deposited by chemical bath technique were investigated and characterized using UV-VIS spectrophotometer and Four-Point Probe (FPP) technique. They were analyzed graphically, and the results show that, the donated pair of electrons from the nitrito group ligand caused absorption edge to decreases towards longer wavelength region while band gap energy increase from 1.61eV to 3.71eV with increase concentration. On the sampled films, there was a consistent increase in the sheet resistance and electrical conductivity as the concentration of Nitrito-group ligand increases.

A critical evaluation of [ML(ONO)]n+ (M = Fe, Ru, Os) as nitric oxide precursor influenced by spin multiplicity and geometrical parameters (M-O-NO and MO-N-O) for the NO release: A theoretical study

In cell biology, the physiological functions control blood pressure by the production of nitric oxide, and the exploitation of metal complexes such as [ML-ONO] (M = Fe2+, Ru2+, Os2+) has been motivated to study the photolytic liability of NO. The structural and electronic properties of the complexes of 1,4,8,11-tetrakis-(1-methyl-pyridyl)-1,4,8,11-tetraazacyclotetradecane were analyzed theoretically. The results show that β-cleavage of nitrito group in the complex [ML-ONO]n+ (M = Fe, Ru, Os; n = 1 or 2) favors the NO release, and observed the role of spin multiplicity. The M(II)-O-NO angle is associated with the degree of activation of the M(II)O—NO bond, relying on the excitations (S = 1 or S = 2), and it is corelated to the reduction of the bond angle ONO (~133° at S = 0) to ~ 105° at S = 1 or 2, favoring the nitrito β-cleavage for the complexes. This is consistent with orbital energy (dx2-y2) stabilizing the axial M(III)-O bond greater than that in M(II)-O [Fe < Ru ~ Os] as the excitation of singlet to triplet or to quintet prompts the NO delivery according to Gibbs free energy, agreeing with the transition state energy. However, at high spin state like 3/2 or 5/2, irrespective of bond angle M(III)-O-NO or ONO, the bond O-NO was broken spontaneously, resulting relatively a greater bond distance. Natural Transition Orbitals (NTOs), Molecular orbital (MO) Electron density contour on molecular orbital surface were also studied to understand the M-ONO bonding nature, and observed its performance in the TD-DFT electronic spectra.

Photocrystallographic Studies on Transition Metal Nitrito Metastable Linkage Isomers: Manipulating the Metastable State.

ConspectusThe design of solid-state materials whose properties and functions can be manipulated in a controlled manner by the application of light is an important objective in modern materials chemistry. When the material changes property or function, it is helpful if a simple measurable response, such as a change in color, can be detected. Potential applications for such materials are wide ranging, from data storage to smart windows. With the growing emphasis on solid-state materials that have two or more accessible energy states and which exhibit bistability, attention has turned to transition metal complexes that contain ambidentate ligands that can switch between linkage isomeric forms when activated by light. Suitable ligands that show promise in this area include nitrosyls, nitro groups, and coordinated sulfur dioxide molecules, each of which can coordinate to a metal center in more than one bonding mode. A nitrosyl normally coordinates through its N atom (η1-NO) but when photoactivated can undergo isomerism and coordinate through its O atom (η1-ON). At a molecular level, converting between these two configurations can act as an “on/off” switch. The analysis of such materials has been aided by the development of photocrystallographic techniques, which allow the full three-dimensional structure of a single crystal of a complex, under photoactivation, to be determined, when it is in either a metastable or short-lived excited state. The technique effectively brings the dimension of “time” to the crystallographic experiment and brings us closer to being able to watch solid-state processes occur in real time.In this Account, we highlight the advances made in photocrystallography for studying solid-state, photoactivated linkage isomerism and describe the factors that favor the switching process and which allow complete switching between isomers. We demonstrate that control of temperature is key to achieving either a metastable state or an excited state with a specific lifetime. We draw our conclusions from published work on the formation of photoactivated metastable states for nitrosyl and sulfur dioxide complexes and from our own work on photoactivated switching between nitro and nitrito groups. We show that efficient switching between isomers is dependent on the wavelength of light used, on the temperature at which the experiment is carried out, on the flexibility of the crystal lattice, and on both the electronic and steric environment of the ambidentate ligand undergoing isomerism. We have designed and prepared a number of nitro/nitrito isomeric metal complexes that undergo reversible 100% conversion between the two forms at temperatures close to room temperature. Through our fine control over the generation of the metastable states, it should be possible to effectively “dial up” a suitable temperature to give a metastable or an excited state with a desired lifetime.

Nitrogen dioxide reactivity of a Nickel(II) complex of tetraazacyclotetradecane ligand

Reaction of a Ni(II) complex of ligand L (L=meso-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) (1) in methanol with NO2 has been studied. Addition of equivalent amount of NO2 resulted in the reduction of Ni(II) to Ni(I). The reduction was monitored by UV-visible, EPR spectroscopy. The Ni(I) intermediate reacted with further equivalent of NO2 to form Ni(II)-O-nitrito complex, [NiII(L)(η1-ONO)2] (2). Structural characterization confirmed the formation of 2. Subsequent equivalent of NO2 resulted in the oxo transfer from NO2 to the metal bound nitrito group leading to the formation of O-nitrato complex, [NiII(L)(η1-ONO2)]+ (3) with simultaneous release of NO. The release of NO in the reaction was evidenced by spin trapping experiment. Complex 3 was isolated and characterized structurally.

Formation of a dinuclear and a trinuclear Ni(II) complex on slight variation of experimental conditions: Structural analysis and magnetic properties

A diphenoxido bridged dinuclear Ni(II) complex [Ni2L2(NO2)2] (1) and a μ2 and μ3-phenoxido, μ3-hydroxido, and μ2-nitrito (1κO:2κN) bridged trinuclear Ni(II) complex [Ni3L3(OH)(NO2)]·ClO4 (2), have been synthesized using a tridentate reduced Schiff base ligand HL (HL=2-[(2-dimethylamino-ethylamino)-methyl]-phenol). Both complexes were characterized by X-ray structure determination and variable-temperature magnetic susceptibility measurements. In both complexes the nickel atoms are six-coordinated with a distorted octahedral environment. The interesting feature of the trimeric complex 2 is that the three mononuclear units are assembled around a μ3-hydroxido ion in such a way that the three phenoxido groups and one nitrito group form a cyclic bridge that markedly modify the magnetic properties. Complex 1 presents a moderate antiferromagnetic Ni–Ni coupling (J=−39cm−1) through the phenoxido bridges with a wide Ni–O–Ni bond angle of 101.77(6)° whereas the lower Ni–O–Ni bond angles, in the range 86.66(6)–96.07(7)°, lead to a moderate ferromagnetic coupling (J=+18.2cm−1) in the trimeric complex 2 with a weak antiferromagnetic contribution (J′=−0.51cm−1) via the 1κO:2κN nitrito bridge.

Oxo Transfer from Nitrogen Dioxide to Nitrito Group in a Copper(II) Complex

Reaction of Cu(II) complex [Cu(II)(LH)(O2CCH3)2] (1) [LH = 4,6-ditert-butyl-2-((2-picolyl(isopropyl)amino)methyl)phenol] with equivalent amount of NO2 leads to the reduction of Cu(II) to Cu(I) with concomitant nitration at the phenol ring of the ligand. This resulted in the in situ formation of intermediate Cu(I) complex of the nitrated ligand (L'H). Additional equivalent of NO2 coordinates to the Cu(I) complex to form corresponding O-nitrito Cu(II) complex [Cu(II)(L'(η(1)-ONO)] (2). Subsequent addition of NO2 led to the corresponding O-nitrato complex, [Cu(II)(L')(η(1)-ONO2)] (3) with concomitant formation of NO. Complexes 2 and 3 were isolated and structurally characterized. The formation of NO in the reaction was established by spin-trapping experiment. Isotopic labeling experiment revealed that the oxo transfer takes place from NO2 to the coordinated η(1)-ONO group.

Experimental and Theoretical Studies of the Vibrational and Electronic Spectra of a Lanthanide Ion at a Site of Th Symmetry: Pr3+ in Cs2NaPr(NO2)6

The Pr(3+) ion in Cs(2)NaPr(NO(2))(6) is situated at a site of T(h) symmetry with 12-coordination to O atoms of bidentate nitrito groups. First-principles calculations of the vibrational modes of the complex were carried out using the density functional theory with the generalized gradient approximation Perdew-Burke-Ernzerhof exchange-correlation functional. The calculations that treated the Pr(3+) 4f electrons as valence electrons showed better agreement with the experimental vibrational assignments compared with those treating the 4f electrons a part of the inner core. The (1)D(2) → (3)H(4) emission spectra of Cs(2)NaPr(NO(2))(6) at 7 K enabled assignments to be made for the crystal-field (CF) levels of the ground-state multiplet. The emission of the dilute system Cs(2)NaY(NO(2))(6):Pr(3+) was dominated by NO(2)(-) triplet emission, which was quenched at elevated temperatures by energy transfer to trace Eu(3+) impurity. From magnetic dipole calculations and the vibronic fingerprint, detailed assignments are given for the complex 10 K electronic absorption spectrum of Cs(2)NaPr(NO(2))(6) between 3940 and 18800 cm(-1), and the derived Pr(3+) 4f(2) energy-level data set has been fitted by calculation. By comparison with Cs(2)NaPrCl(6), the fourth-order CF parameter in Cs(2)NaPr(NO(2))(6) is relatively small so that interaction with a 4fnp configuration is not important. From the NO(2)(-) absorption bands above 20,000 cm(-1), the N-O bond length change upon excitation is small, whereas the angle O-N-O opens by more than 10° in the triplet state. By contrast to the NO(2)(-) internal vibration frequencies, which except for the wagging mode show only minor changes with the environment, the triplet-state energy shows a linear decrease with an increase of the lanthanide (Ln(3+)) ionic radius in Cs(2)NaLn(NO(2))(6). Using the eigenvectors from the energy-level fit, the variation of the inverse magnetic susceptibility with temperature has been calculated between 1 and 100 K and the values are somewhat lower than those from experiment.

The trans influence in the modulation of platinum anticancer agent biology: the effect of nitrite leaving group on aquation, reactions with S-nucleophiles and DNA binding of dinuclear and trinuclear compounds.

To examine the effect of leaving group and trans influence on the general reactivity of polynuclear platinum antitumor agents we investigated substitution of the chloride leaving groups with nitrite ion, which forms strong bonds to Pt. It was of interest to explore whether nitrite could be used to modulate biological properties of these agents, in particular the deactivating reactions that occur on reaction with S-nucleophiles, involving loss of the linking diamine under the trans influence of sulfur. Reported herein is a study of the synthesis, aquation, DNA binding and reactions with glutathione (GSH), methionine (Met) and acetylmethione (AcMet) of nitrito derivatives of di- and trinuclear platinum antitumor compounds: [{trans-PtNO(2)(NH(3))(2)}(2)(mu-NH(2)(CH(2))(6)NH(2))](NO(3))(2) (1-NO(2)) and [{trans-PtNO(2)(NH(3))(2)}(2)(mu-trans-Pt(NH(3))(2){NH(2)(CH(2))(6)NH(2)}(2))](NO(3))(4) (1'-NO(2)). {(1)H,(15)N}-HSQC NMR studies revealed that 1-NO(2) is inert to aquation reactions, even after prolonged incubation at physiological pH. Monitoring of the interaction of 1-NO(2) with the duplex 5'-d(ATATGTACATAT)(2) (I) showed only unreacted complex, consistent with activation by aquation being a requirement for covalent DNA binding. The reaction of 1-NO(2) with GSH was studied by (1)H, (195)Pt, (15)N and {(1)H,(15)N}-HSQC NMR spectroscopy. For the parent dichlorido compounds (1 and 1') substitution of chloride by GS(-) leads to drug degradation involving liberation of the diamine linker. While the same final products trans-[Pt(SG)(2)(NH(3))(2)] (5) and trans-[{Pt(SG)(NH(3))(2)}(2)-mu-SG] (6) are formed, different mechanisms are involved, consistent with the trans influence NO(2)(-) > Cl(-); the half-life is slightly longer for 1-NO(2) (1.8 h) compared with 1 (1.3 h). Identification of the intermediate trans-[Pt(NH(3))(2)(NO(2))(SG)] (4) shows that the nitrito group remains coordinated while the linker amine is substituted by coordination of GS(-), and then trans labilization of the nitrito group occurs leading to 5 and 6. Reaction of the trinuclear 1'-NO(2) with GSH follows essentially the same reaction pathway. Reaction of 1-NO(2) with Met and AcMet is much slower and only 20 % liberated amine was observed after reaction with Met for 24 h at 37 degrees C. The final product from reaction with AcMet is trans-[Pt(NH(3))(2)(NO(2))(AcMet)], as in this case coordination of the S-nucleophile does not lead to trans labilization of the nitrito group.

Synthesis and structural characterization of nitrite-coordinating CoII and CoIII complexes as models for the reaction center of Co-substituted nitrite reductase

CoII and CoIII complexes containing nitrite and tridentate aromatic amine compounds [bis(6-methyl-2-pyridylmethyl)amine (Me2bpa) and bis(2-pyridylmethyl)amine (bpa)] have been prepared as models of the catalytic center in Co-substituted nitrite reductase: [CoII(Me2bpa)(NO2)Cl]2 · acetone (2), CoII(Me2bpa)(NO2)2 (3), CoII(bpa)(NO2)Cl (4), CoII(bpa)(NO2)2 (5), CoIII(Me2bpa)(NO2)(CO3) (6), and CoIII(bpa)(NO2)3 (7). The X-ray crystal structure analyses of these CoII and CoIII complexes indicated that the geometries of the cobalt centers are distorted octahedral and the Me2bpa and bpa with three nitrogen donors exhibit mer- (2, 3, and 7) and fac-form (4 and 6). The coordination mode of nitrite depends on the cobalt oxidation state, to CoII through the oxygen (nitrito coordination, O- and O,O-coordination) and to CoIII through nitrogen (nitro coordination, N-coordination mode). These findings are consistent with the results of their IR spectra, except that another oxygen of the O-coordinated nitrito group in 3 might interact weakly with CoII according to its IR spectrum. Reductions of the nitrite in 2, 3, 4, and 5 to nitrogen monoxide were not accelerated in the presence of proton, perhaps due to the nitrito coordination in these CoII complexes.

Tailored synthesis, spectroscopic, catalytic, and antibacterial studies of dinuclear ruthenium (II/III) chloro sulfoxide complexes with 5-nitro-o-phenanthroline as a spacer

A dinucleating spacer incorporating o-phenanthroline has been synthesized and characterized. The reaction of this spacer with ruthenium precursors resulted in formation of dinuclear complexes, [cis,fac-RuCl2(SO)3 (μ-nphen)cis,cis-RuCl2(SO)2], [trans,mer-RuCl2(SO)3 (μ-nphen)trans, cis-RuCl2(SO)2], and [X]+[trans-RuCl4(SO)(μ-nphen)mer-RuCl3(SO)]−, where SO = dimethylsulfoxide/tetramethylenesulfoxide, nphen = 5-nitro-o-phenanthroline, and X+ = [(dmso)2H]+, Na+, and [(tmso)H]+. These complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility, FT-IR, FAB-Mass, 1H-NMR, 13C{1H}-NMR, and electronic spectroscopy. [trans,mer-RuCl2(dmso)3(μ-nphen)trans,cis-RuCl2(dmso)2] was also characterized on the basis of 1H–1H COSY NMR. The coordination of one ruthenium is through heterocyclic nitrogen of the o-phenanthroline and the second is through the oxygen of the nitrito group. Catalytic activity of these complexes has been investigated in hydrolysis of benzonitrile. All the complexes possess antibacterial activity against Escherichia coli and are compared to Chloramphenicol.

Reversible nitro–nitrito inter-conversion in a simple mono-nuclear nickel(II) complex [Ni II{C 6H 4(NH 2) 2} 2(NO 2) 2] in the solid state

A simple mono-nuclear nickel(II) complex [Ni II{C 6H 4(NH 2) 2} 2(NO 2) 2] ( 1) has been synthesized from an aqueous solution containing nickel chloride, sodium nitrite and ortho-phenylenediamine (opda). When crystals of compound 1 are heated in the temperature range of 110–120 °C for 5 min, their brown color changes to blue, that is accompanied by the conversion of nitro group (N-coordinated) in compound 1 into nitrito group (O-coordinated) in compound [Ni II{C 6H 4(NH 2) 2} 2(ONO) 2] ( 2). On cooling, the nitrito compound 2 goes back to parent nitro-compound 1.

Crystal structures and electronic properties of three fluxional [Cu(di-2-pyridylamine)2(OXO)]Y complexes

The crystal structures of three bis(dpyam)copper(II) complexes, [Cu(dpyam)2(ONO)](SO4)0.5(H2O) (I), [Cu(dpyam)2(O2CCH3)](ClO4) (II) and [Cu(dpyam)2(O2CCH2CH3)](ClO4) (III) (dpyam = di-2-pyridylamine) have been determined at room temperature by single-crystal X-ray methods. The complexes involve a CuN4O2 chromophore with a symmetric cis-distorted octahedral stereochemistry for I, and an asymmetric cis-distorted octahedral stereochemistry for II and III. In I the copper atom and the oxygen donor atoms of the symmetrically bonded nitrito group lie on a crystallographic C 2 axis. This is the first reported example in the literature of such a complex with this type of stereochemistry, involving the [Cu(dpyam)2(OXO)][Y] series as a whole, where (OXO)− involves an oxoanion. In contrast, complexes II and III involve a distortion of the CuN4O2 chromophore towards a square pyramidal (4 + 1 + 1) stereochemistry. Here, the stereochemistries of I, II and III are compared with other closely related complexes. The highly asymmetric geometry of the CuN4O2 chromophores of II and III suggests that both complexes appear to be static in nature. Electronic spectra of the three complexes involve two bands of similar intensity corresponding to cis-distorted octahedral copper(II) stereochemistry.

Structure determination of nitrito- and thiocyanato-copper(II) complexes: X-ray structures of [Cu(Medpt)(ONO)(H 2O)]ClO 4 ( 1), [Cu(dien)(ONO)]ClO 4 ( 2) and [Cu 2(Medpt) 2(μ N,S-NCS) 2](ClO 4) 2 ( 3) (Medpt = 3,3′-diamino- N-methyldipropylamine and dien = diethylenetriamine)

The synthesis and characterization of the monomeric nitrite complexes [Cu(Medpt)(ONO)(H 2O)]ClO 4 ( 1) and [Cu(dien)(ONO)]ClO 4 ( 2) as well as the new dinuclear bridged thiocyanato complex [Cu 2(Medpt) 2(μ N,S-NCS) 2](ClO 4) 2 ( 3) (Medpt = 3,3′-diamino- N-methyldipropylamine and dien = diethylenetriamine) are described. In complex 1, the copper center is penta-coordinated by the three N atoms of the Medpt, an oxygen atom O(1) from nitrito group and oxygen atom O(3) of a water molecule whereas in complex 2, the penta-coordinate geometry is achieved by copper bonds to the three N atoms of the dien ligand, a short bond to oxygen O(1) and a long one to the second oxygen atom O(2) of the nitrito group. In the bridged thiocyanato complex 3, the two copper centers are linked by two thiocyanate groups in an end-to-end bonding fashion where the copper ions are penta-coordinated by three N-atoms of the Medpt ligand, one N atom from the bridging thiocyanato group and the fifth coordination site is occupied by S atom from the second bridging thiocyanate ligand. The structure consists of three crystallographically independent dinuclear [Cu 2(Medpt) 2(μ N,S-NCS) 2] 2+ cations. The coordination polyhedron around the Cu(II) ions in these complexes may be described as an axially elongated square pyramid geometry (SP). The intradimer Cu⋯Cu distance in this complex ranges from 5.429(2) to 5.516(2) Å. Variable-temperature magnetic susceptibility studies for complex 3 indicate weak antiferromagnetic coupling between the Cu 2+ centers with J = −1.8 cm −1. The IR stretching frequencies of the nitrito, ν ( NO 2 - ) and thiocyanato, ν(NCS −) groups in the 1470–1100 and 2030–2120 cm −1 regions, respectively, are discussed in relation to other related species. The visible spectra of the complexes studied in different solvents were in agreement with the assigned predominant SP stereochemistry.

Photoinduced Oxygen Transfer and Double‐Linkage Isomerism in a cis‐(NO)(NO2) Transition‐Metal Complex by Photocrystallography, FT‐IR Spectroscopy and DFT Calculations

Photocrystallographic experiments show that laser exposure of crystals of [Ru(bpy)2(NO)(NO2)](PF6)2 at 90 K produces a double isonitrosyl-nitrito linkage isomer and provide the detailed geometry of the metastable species generated. The analysis indicates that the isomerization is accomplished through an intramolecular redox reaction involving oxygen transfer from the nitro to the nitrosyl group. At 200 K only a single (nitrito) linkage isomer is formed with a U-shaped conformation of the nitrito group rather than the Z conformation observed at 90 K. A mechanism for the isomerization is proposed based on the crystallographic results and FTIR data collected at low temperatures during the isomerization process. The study presents the first structural evidence for double linkage isomerization in transition-metal complexes.

Bidentate bonding mode of tetrahydroborate and nitrite towards copper(II) in open-faced macrocyclic complexes

Novel seven-coordinate complexes formulated as [CuL(BH4)2], [CuL(BH4)(NO2)] and [CuL(NO2)2] (L = 1,4,7-triazacyclononane) have been prepared and structurally characterized by elemental analyses, spectroscopic data (u.v., i.r. and e.p.r.), magnetic susceptibility and conductivity measurements. The results reveal that the complexes are non-electrolytic. The coordination geometry around the copper(II) ion is a seven coordinated square pyramidal structure with three nitrogen atoms of the 1,4,7-triazacyclononane and either four hydrogen atoms of two bidentate tetrahydroborate groups or two hydrogen atoms of the bidentate tetrahydroborate group and two oxygen atoms of the bidentate nitrite group or four oxygen atoms of two bidentate nitrito groups. A cyclic voltammetric study on the complexes indicates an irreversible redox couple (CuII/CuI) in DMF, giving a voltage of ca. −0.37 V versus s.c.e.

The crystal structure and electronic properties of a cis-distorted octahedral CuN 4O 2 chromophore: [Cu(dpyam) 2(OXO)] +, OXO=ONO −, O 2CH − and ONO 2−

The crystal structures of three bis(dpyam)copper(II) complexes, [Cu(dpyam) 2(NO 2)](NO 2) ( I) and [Cu(dpyam) 2(O 2CH)](ClO 4) ( II) and [Cu(dpyam) 2(ONO 2)](BF 4) ( III) have been determined by X-ray analysis. In I, the copper atom and the asymmetrically bonded nitrito group lie on a crystallographic C 2-axis. The nitrito group is clearly disordered about the C 2-axis giving a square pyramidal cis-distorted octahedral (4+1+1 *) chromophore rather than a pseudo-regular cis-distorted octahedral chromophore. In II and III, a distortion of the cis-distorted CuN 4O 2 chromophore towards a square pyramidal (4+1+1 *) stereochemistry is also present. The polycrystalline EPR spectra of I– III together with the high asymmetry in geometry of the CuN 4O 2 chromophores are suggesting that all complexes appear to be near the static distortion limit of the fluxional CuN 4O 2 chromophore geometry. The electronic reflectance spectra of the three complexes involve two bands at the same intensity corresponding to a cis-distorted octahedral geometry.

Polymeric fullerene oxide films produced by decomposition of hexanitro[60]fullerene

A new poly(fullerene oxide) thin film material has been fabricated by thermal activation and electron bombardment on hexanitro[60]fullerene (HNF) film deposited on a Au substrate, all under vacuum conditions. The reaction products in the polymerization process are analyzed by XPS, UPS, IR, TGA-MS and LDI-MS techniques. It is found that the main effect of thermal and radiation treatments is to induce cleavage of –NO bonds from HNF molecules resulted in the release of nitric oxide gas and the formation of fullerene-bound oxyradicals, C 60–O 6. Spectroscopic evidence strongly suggests that rearrangement of fullerenic nitro moieties into nitrito groups is involved in the HNF decomposition process prior to the generation of reactive oxyradical intermediates. Consequently, the intermolecular coupling reaction of these oxyradicals leads to carbon polymer networks containing oxygen-bridged fullerenes. The thermally generated polymeric thin film is stable up to 900 K. Electron bombardment is also effective in both the decomposition of –NO 2 groups and the removal of –OH groups present in HNF films. UV irradiation at 365 nm alone is shown to be not as efficient for the polymer formation.

Differential Thermal and Thermogravimetric Studies of Carbonatodiphenanthrolinecobalt(III) Complexes

The [CoPhen2CO3]X ·nH2O complexes, where Phen, phenanthroline; X · nH2O = Cl · 5H2O, Br · 4H2O, I · 4H2O, NCS · 3H2O, NO2 · 5H2O, NO3 · 3H2O, ClO4, and ClO3, are studied by the differential thermal and thermogravimetric methods. After the endoeffect of complete dehydration of the complexes, the DTA curves exhibit effects of the СоIII reduction to СоII by the outer-sphere chloride, bromide, and iodide anions. In the case of the outer-sphere nitrite anion, the endoeffect of the reduction of СоIII with the nitrito group is followed by the exoeffect of oxidation of the organic ligand with the nitrogen dioxide formed. In the case of the outer-sphere chlorate and perchlorate anions, the complexes are decomposed at temperatures of 250 and 310°С, respectively, without preliminary СоIII reduction.

Stable poly(fullerene oxide) thin films derived from hexanitro[60]fullerene

A new approach for the fabrication of poly(fullerene oxide) thin films that are stable up to 800 K and above by thermal treatment of hexanitro[60]fullerene is described. The reaction proceeds via the rearrangement of fullerenic nitro moieties and cleavage of the –O–NO bond in the nitrito groups; spectroscopic and mass spectrometric evidence for the oligomeric structure is presented.

The coordination chemistry of mono and bis(di-2-pyridylamine)copper(II) complexes: preparation, characterization and crystal structures of [Cu(L)(NO 2) 2], [Cu(L)(H 2O) 2(SO 4)], [Cu(L) 2(NCS)](SCN)·0.5DMSO and [Cu(L) 2(SCN) 2

The crystal structures of two mono(dpyam)copper(II) complexes, [Cu(dpyam)(NO 2) 2] ( 1) and [Cu(dpyam)(H 2O) 2(SO 4)] ( 2) and two dithiocyanate compounds containing bis(dpyam)copper(II) units, [Cu(dpyam) 2(NCS)](SCN)·0.5DMSO ( 3) and [Cu(dpyam) 2(SCN) 2] ( 4) have been determined by X-ray crystallography. The second orthorhombic form of the monomeric Cu(II) complex 1 was obtained by the reaction of di-2-pyridylamine (dpyam) with CuCl and NaNO 2 in water–methanol solution. Each copper(II) ion in 1 exhibits a tetrahedrally-distorted square base of the CuN 2O 2 chromophore, with off-the- z-axis coordinated nitrito groups weakly bound in approximately axial positions. Complex 2 is an example of a polymeric copper(II) derivative containing the bidentate bridging sulfate ligand in the long-bonded axial positions. Each copper(II) ion in 2 shows an elongated tetragonal octahedral stereochemistry. The CuN 4N′ chromophore of 3 involves a square-based pyramidal structure, slightly distorted towards a trigonal bipyramidal stereochemistry, τ=0.13. One of the SCN − anions is bonded to the copper(II) ion via the N atom in the axial position of the square pyramid. Complex 4 is centrosymmetric and octahedrally elongated, with the SCN − anions coordinating in axial positions via the S atom. The structures of complexes 1– 4 and their ESR and electronic reflectance spectra are compared with those of related complexes.