Inorganic Chemistry

Zinc oxide nanoparticles (nZnO) are one of the most highly produced nanomaterials and are used in numerous applications including cosmetics and sunscreens despite reports demonstrating their cytotoxicity. Dissolution is viewed as one of the main sources of nanoparticle (NP) toxicity, however dissolution studies can be time-intensive to perform and complicated by issues such as particle separation from solution. Our work attempts to overcome some of these challenges by utilizing new methods using UV/vis and fluorescence spectroscopy to quantitatively assess nZnO dissolution in various biologically relevant solutions. All biological buffers tested induce rapid dissolution of nZnO. These buffers, including HEPES, MOPS, and PIPES, are commonly used in cell culture media, cellular imaging solutions and to maintain physiological pH. Additional studies using X-ray diffraction, FT-IR, X-ray photoelectron spectroscopy, ICP-MS and TEM were performed to understand how the inclusion of these non-essential media components impacts the behavior of nZnO in RPMI media. From these assessments, we demonstrate that HEPES causes increased dissolution kinetics, boosts the conversion of nZnO into zinc phosphate/carbonate and, interestingly, alters the structural morphology of the complex precipitates formed with nZnO in cell culture conditions. Cell viability experiments demonstrated that the inclusion of these buffers significantly decreases the viability of Jurkat leukemic cells when challenged with nZnO. This work demonstrates that biologically relevant buffering systems dramatically impact the dynamics of nZnO including dissolution kinetics, morphology, complex precipitate formation, and toxicity profiles.

Laboratory Information System (LIS) streamlines workflow in the laboratory and eliminates time-consuming paperwork. The business today is getting increasingly pressured to be more productive and efficient with less traditional resources. If we look at a typical production process, for instance, the level of automation and optimization that has permeated into the production floor is quite astounding. Many industries have had a tremendous impact in bringing to the market the automation and optimization solutions to streamline -the production floor. The other ends of the spectrum are the back-office transaction oriented processes like Inventory Management, Materials Management, Financials and so on, Therefore a lab’s ability to process data quickly and its ability to disseminate that information efficiently throughout the plant is vital for the success of the production process. Laboratory Information Management System (LIMS) can help in managing the information flow within the lab and can be the modus operandi of connecting the lab with the rest of the organization. For instance, imagine all the information that is generated in a lab.

The spectra of iron(I1) phthalocyanine polymer complexes (FePcL), with bispyridinato bridging ligands, where L = 44'-bipyridine (bpy), trans-1,2-(4-pyridyl)ethylene (bpe), 1,2-bis-(4-pyridyl)ethane (bpa), are discussed in comparison with the spectra of Fe"Pc and FePcL;, where L' = pyridine, 4-cyanopyridine (4CNpy), in reference to the n backdonation to the macrocycle.

High-level composite, ab initio and density functional theory (DFT) procedures have been employed to study O–H bond dissociation energies (BDEs), as well as radical stabilization energies (RSEs) in the oxygen-centred radicals that are formed in the dissociation of the O–H bonds. Benchmark values are provided by Wn results up to W3.2 and W4.x. We are able to recommend revised BDE values for FO–H (415.6 ± 3 kJ mol–1), MeC(O)O–H (459.8 ± 6 kJ mol–1) and CF3CH2O–H (461.9 ± 6 kJ mol–1) on the basis of high-level calculations. We find that Gn-type procedures are generally reliable and cost-effective, and that some contemporary functionals and double-hybrid DFT procedures also provide adequate O–H BDEs/RSEs. We note that the variations in the O–H BDEs are associated with variations in the stabilities of not only the radicals but also the closed-shell precursor molecules. Most substituents destabilize both species, with σ-electron-withdrawing groups having larger destabilizing effects, whil...

This is to certify that the dissertation entitled "Synthesis and characterization of silica coated magnetite nanoparticle" being submitted by Miss Ranjana Panigrahi to the Department of Chemistry, National Institute of Technology, Rourkela, Orissa, for the award of partial fulfillment of the degree of Master of Science is a record of the research training carried out by her under my supervision and guidance. This work is a scale-up synthesis process of silica coated magnetite following the procedure earlier reported. The matter embodied in the dissertation has not been submitted to any other University / Institute for the award of any Degree or Diploma.

Desulfovibrio vulgaris Hildenborough cytochrome c 3 contains four hemes in a low-spin state with bis-histidinyl coordination. Highspin forms of cytochrome c 3 can be generated by protonation of the axial ligands in order to probe spin equilibrium (low-spin/high-spin). The spin alterations occurring at acid pH, the associated changes in redox potentials, as well as the reactivity towards external ligands were followed by the conjunction of square wave voltammetry and UV-visible, CD, NMR and EPR spectroscopies. These processes may be used for modelling the action of enzymes that use spin equilibrium to promote enzyme activity and reactivity towards small molecules.

The preparation of three new examples of water insoluble host/guest assemblies of the general composition:[(R4N)(Me3Sn) 2M (CN) 6· zH2O](R= n-propyl or n-pentyl, M= Fe or Co, 0≤ z≤ 2) from likewise polymeric super-Prussian-blue derivatives [(Me3Sn) 3M (CN) ...

We applied ab initio phonon analysis to layered titanium-oxypnictides, Na 2 Ti 2 Pn 2 O (Pn = As and Sb), and found a clear contrast between the cases with lighter/heavier pnictogen in comparison with experiments. The result completely explains the experimental structure at low temperature, C2/m for Pn = As, within the conventional charge density wave, while there arise discrepancies when the pnictogen gets heavier. Our phonon calculation using the GGA-PBE functional predicts that a Cmce polymorph is more stable than the experimentally observed one (Cmcm) for Pn = Sb. On the basis of further quantitative analysis, we suggest the possibility that the GGA-PBE functional does not properly reproduce the electron correlation effects for Pn = Sb, and this could be the reason for the present discrepancy.

The synthesis of four novel cobalt(I1) cyclidene complexes with long polymethylene bridges is described. These complexes have been found to reversibly bind dioxygen in a manner similar to that of their shorter bridged analogs. Dioxygen affinities are reduced for bridge lengths exceeding that of octamethylene, an effect which has been correlated with the width of the cavity surrounding the dioxygen-binding site. Structural effects on small-molecule binding that are associated with the long bridge have been examined by comparison of the X-ray crystal structure of the undecamethylene-bridged cobalt(II1) complex with the shorter bridged analogues. Bis(isothiocyanato)(2,3,15,16,17,24hexamethyl-3,15,19,23,26,30-hexaazabicyclo-[ 15.7.7lhentriaconta-1,16,18,23,25,30-hexaene-K4N)cobalt(III) hexafluorophosphate crystallizes in space group P21 with a = 13.699(6) A, b = 9.515(3) A, c = 14.726(7) A, and j3 = 97.40(4)', and the structure was solved by the heavy-atom method to R = 0.053, R, = 0.058. The thiocyanate that is coordinated within the cavity is bent through steric interaction with the ligand and has bond lengths and angles closer to those of the externally bound thiocyanate than is true of analogous complexes with shorter bridges. The cavity width of the six-coordinate undecamethylene-bridged cobalt(II1) complex is similar to that of the octamethylene-bridged complex, in contradistinction to the previous observation that the widths of vacant cavities decrease as the bridge length increases beyond (CHZ)~. This clearly shows that that the longer bridged complexes are flexible enough to expand their cavities when a small molecule is coordinated to the metal center. The autoxidation of these cobalt(I1) complexes has been found to depend on the dioxygen partial pressure and the axial base in a manner analogous to that of the shorter bridged derivatives. However, the rate of autoxidation is significantly greater for the complexes having longer bridges.

This paper discusses the sorption properties for U(VI) by alginate coated CaSO 4. 2H 2 O sepiolite and calcined diatomite earth (Kieselguhr) (ACSD). The removal of U(VI) from aqueous solution by sorption onto ACSF in a single component system with various contact times, pH, temperatures, and initial concentrations of U(VI) was investigated. The sorption patterns of uranium on the composite adsorbent followed the Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherms. The Freundlich, Langmuir, and D-R models have been applied and the data correlated well with Freundlich model and that the sorption was physical in nature (sorption energy, E a = 17.05 kJ/mol). The thermodynamic parameters such as variation of enthalpy ∆H, variation of entropy ∆S and variation of Gibbs free energy ∆G were calculated from the slope and intercept of lnK 0 vs. 1/T plots. Thermodynamic parameters (∆H ads = 31.83 kJ/mol, ∆S ads = 167 J/mol. K, ∆G°a ds (293.15 K) = −17.94 kJ/mol) showed the endothermic heat of sorption and the feasibility of the process. The thermodynamics of U(VI) ion/ACSD system indicates the spontaneous and endothermic nature of the process. It was noted that an increase in temperature resulted in a higher uranium loading per unit weight of the adsorbent.

Supporting Information 1 Powder XRD patterns of hydrothermal products in the system of NaF-LnF 3 [Ln=(a) Pr, (b) Nd, (c) Sm, (d) Eu, (e) Cd, (f) Tb, (g) Dy, and (h) Ho]. Supporting Information 2: TEM images and an electron diffraction pattern of the NaSmF 4 nanostructure. (a) Low magnification TEM image, (b) [0 1 0] SAED pattern, and (c) [0 1 0] HRTEM image. The forbidden 00l reflections with l = 2n+l appear in the [0 1 0] SAED pattern, but the intensity is systematically weak or extinctive when the crystal is rotated along the c-axis. Supporting Information 3 SEM (upper row) and typical TEM (lower row) images of (a) NaEuF 4 , (b) NaGdF 4 , (c) NaTbF 4 , and (d) NaDyF 4. The arrows point to the sections with solid interiors that initially serve as seeds. All images in upper row are at the same scale, as annotated in (b).

A series of silicon-centered connecting units, Me n Si(p-C 6 H 4 CO 2 H) 4-n (n ) 0, 1, 2), have been prepared and their coordination polymers with Zn(II) metal atoms studied. The tetra-acid L1 (n ) 0) acts as a tetrahedral node and reacts with Zn(II) centers to give 1, a novel interpenetrating 3D network containing distorted tetrahedral bimetallic secondary building units (SBUs). The triacid L2 (n ) 1) acts as a trigonal pyramidal node and forms an intercalated 2D layered network, 2, with Zn(II) ions, containing distorted octahedral tetranuclear SBUs. Last, the bent diacid L3 (n ) 2) reacts with Zn(II) centers to give 3, a corrugated 2D layered structure containing 1D zinc hydroxo chains. Together these three new coordination polymers demonstrate the potential versatility of tetravalent silicon containing connecting ligands for metal-organic framework construction.

Nanocrystalline zinc oxide-thin films have drawn the attention of researchers due to its attractive properties like transparency in visible region, abundance in nature and gas sensitivity. Nanostructured Zinc oxide (ZnO) thin films were grown on silicon, alumina and glass substrates at various substrate temperatures using a 6 kW electron beam evaporation technique. The effects of film thickness, growth temperature and substrate on the crystallinity of deposited ZnO films were investigated using X-ray diffraction, scanning electron microscopy, optical absorption and photoluminescence studies. Our studies show that good quality films are obtained for silicon substrate for a growth temperature of 2508 8 8 8 8C. Film thickness plays an important role on the evolution of the nanostructures. SEM studies combined with XRD analysis reveal that ultrathin nanorods are grown with (002), (101) and (102) orientations. All the ZnO films show room temperature photoluminescence emission bands at 394 nm and 468 nm. Optical absorption studies show strong absorption at 377 nm. Details of the structure and optical properties correlation will be presented and potential of a simple technique such as e-beam deposition to grown ZnO nanostructures suitable for optoelectronic application will be assessed.

The preparation and characterization of Rh I , Pd II , and Pt II through conformational equilibration of the chelate ring, and/or inversion of configuration at the stereogenic sulfur. In complexes with chiral C 2 -symmetrical dithioether ligands derived from 1,1Ј-binaphthalene-2,2Ј-dithiol (BINAS) are re-the solid state the palladium derivative of Me 2 BINAS shows a twisted chair conformation of the chelate ring, with both ported. All complexes are fluxional in solution at room temp. Interconversion between the stereoisomers can take place methyl groups in equatorial positions.

We report here two series of [M(II)(ox)(L) 2 ] n coordination polymer chains: the first being [M(II)(ox)(bnz) 2 ] n (M = Mn 1, Fe 2, Co 3, Ni 4, Cu 5 and Zn 6; ox = oxalate C 2 O 4 2− ; bnz = benzimidazole) and the second [M(II)(ox)(btz) 2 ] n (M = Mn 7, Fe 8, Co 9, Ni 10, Cu 11 and Zn 12; btz = benzotriazole). The first series displays an unusual homometallic [−M i −M ii −M ii −] n chain topology and the second series is isostructural to [Fe(II)(ox)(btz) 2 ] n , originally reported by Jia et al. 1 These two series allow us to make comparisons between the spin state of each metal and the magnetic coupling interaction within an isostructural series spanning the full range of spin states available in 3d metals and to investigate which models are the best to use in each case. Additionally, we have synthesised a two-dimensional coordination polymer {[Zn(II)(bnz) 4 ][Zn(II) 2 (ox) 3 ]} n (13), in which distorted hexagonal [Zn(II) 2 (ox) 3 ] n 2n− layers are hydrogen bonded by [Zn(II)(bnz) 4 ] 2+ cations to give an interlayer separation of 12.001(2) Å.

Several pentahalophenylplatinate complexes with Pt-Sn metal-metal bonds have been synthesized by facile insertion of SnCl 2 into Pt-Cl bonds of the starting platinum substrates. The complexes have been characterized spectroscopically and, in the case of (NBu 4 ) 2 [trans-Pt(SnCl 3 ) 2 (C 6 F 5 ) 2 ] and (NBu 4 ) 2 [trans-Pt 2 (l-Cl) 2 (SnCl 3 ) 2 (C 6 F 5 ) 2 ], the structures have been analyzed by X-ray diffraction. The reactivity of these derivatives towards neutral ligands has been explored. The electronic spectra of some selected derivatives have also been examined.

Ultrasonic irradiation effectively promotes the Diels-Alder reaction of substituted furans with reactive dienophiles (i.e., dimethyl acetylenedicarboxylate (DMAD) and dimethyl maleate). Regiospecific furano Diels-Alder cycloaddition of 2-vinylic furans with DMAD furnished functionalized oxabicyclic alkenes in good yield under ultrasonication condition.

A green template route for the synthesis of mesoscale solid ZnO spheres was ascertained. The protocol involves a double coating of the carbonaceous spheres with successive layers of zinc-containing species by alternating a non-ultrasound and ultrasound-assisted deposition, followed by calcination treatments. The composites were characterized by FTIR spectroscopy, thermal analysis, scanning electron microscopy while the obtained ZnO spheres by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, N 2 adsorption-desorption isotherms and photoluminescence investigations. A growth mechanism of the solid spheres is advanced based on these results. While the spheres' diameters and the mean size values of ZnO are independent on deposition order, the surface area and the external porosity are fairly dependent. The photoluminescence measurements showed interesting emission features, with emission bands in the violet to orange region. The spheres present high photocatalytical activity towards the degradation of phenol under UV irradiation, the main reaction being its mineralization.

A series of intramolecular hetero-Diels-Alder reactions of iminium and imine dienophiles has been explored with density functional theory using the B3LYP functional and 6-31+G* basis set. Aqueous solvation energies were calculated with the CPCM method. DFT predicts that these reactions are concerted but involve highly asynchronous transition states. Stereochemical preferences of imine cycloaddition transition states arise from electron repulsion of the nitrogen lone pair with electron density from the butadiene moiety. Protonation of the nitrogen leads to a highly asynchronous transition state. The iminium dienophiles are predicted to have a 17 kcal/mol lower barrier than the corresponding imines, even in aqueous solution.

Macrocyclic complexes of Mn(II) were synthesized by template condensation using 2,6-diaminopyridine and diethylenetriamine with malonic, succinic, glutaric and adipic acids. The reaction proceeded smoothly to completion. These 16- to 24-membered N(6), but behaving as tetradentate, macrocyclic complexes were characterized by elemental analyses, molecular weight determinations, infrared, electronic, mass and X-ray spectral analyses. The elemental analyses are consistent with the formation of complexes [Mn(N(6)L(n))Cl(2)]. All the complexes are stable and monomeric in nature, as indicated by the molecular weight determinations. The spectral studies confirmed the proposed framework of the new macrocyclic complexes and indicated an octahedral geometry around the central metal atom. The complexes were screened in vitro against a number of pathogenic fungi and bacteria to assess their growth-inhibiting potential. The testicular sperm density, sperm morphology, sperm motility, density of ca...

The triethylamine-catalyzed addition reactions of benzenethiol to 2-cyclopenten-1-one and its 2and 3-methyl derivatives have been found to be appreciably reversible in chloroform solution. Rates and equilibria have been carefully measured at 25°C in order to assess the negative influence on addition exerted by methyl groups substituted on the carbon-carbon double bond. 2-Methyl-2cyclopenten-1-one has been found to react with benzenethiol under kinetic control to give the cis adduct as the sole detectable product in a highly stereoselective anti addition process. However, on prolonged reaction times the system slowly evolved toward a new state of equilibrium in which the more stable trans adduct, derived from a syn addition mode, was the predominant isomer.

Two porous organic polymers decorated with the amide functionality were synthesized mechanochemically and their properties were compared with the ones prepared by conventional solution mediated method. All the POPs were subjected to gas and water vapor sorption studies. The mechanochemically synthesized POPs have less surface area and show moderate adsorption properties compared to the solution mediated POPs. The amide based POPs show remarkable stability in water and concentrated acids.

Objective: Biodegradable polycaprolactone/starch composites can be used for bone tissue engineering applications. The effect of the ratio of components on composite properties is of tremendous importance. Methods: Polycaprolactone/starch composite of 80/20 and 70/30 ratios were fabricated by dissolving them in chloroform followed by evaporation of the solvent. Results: The composites were characterized by fourier transform infrared spectroscopy. Their bioactivity was evaluated by studying the apatite formation ability after immersing the specimens in simulated body fluid. The results of compressive test on samples showed that the composite's modulus and strength approximated that of human trabecular bone. Mass loss in distilled water and starch degradation rate in PBS was evaluated, which showed that the starch ratio was effective in composite degradation. MTT analysis and alkaline phosphatase levels showed that this composite had no toxicity and could increase G-299 cell line osteoblastic activities. Conclusion: The increase in cellular osteoblastic activities and the ability for apatite formation on the composite surface, in addition to the polycaprolactone/starch samples' mechanical properties shows their capability to be used as substitutes for bone. Because this composite degradation rate is controlled by changing the starch ratio, it has the potential for use in bone tissue engineering applications. Samples that have a 70/30 ratio are considered optimal due to their enhanced cellular response and better mechanical properties.

The solid solution of vanadium in hexagonal molybdenum oxide has never previously been completely studied; no information has been given about the solubility limit or the thermal stability of the system. In this work, we have determined that the solubility limit is reached with the following composition: (NH 4 ) 0.13 V 0.13 Mo 0.87 O 3 . Our samples have been obtained by a soft chemistry method. The obtained precipitates have been processed and analyzed with several techniques. We have shown that the introduction of vanadium in the h-MoO 3 structure has several e4ects, on the thermal stability of the metastable mixed oxide, on the morphology, as well as on the lattice parameters.

A series of Prussian blue analogues, Rb x Mn[Fe(CN) 6 ] y ·zH 2 O with different stoichiometries have been synthesized. Elemental analyses reveal a quasilinear decrease in x and y when z increases. Some of these samples present a first-order phase transition between the Mn II -Fe III and Mn III -Fe II electronic states with large thermal hysteresis loops observed in the magnetic susceptibility. The phase-transition temperatures correlate with the stoichiometry, but quantitative predictions cannot be made because of the disordered nature of the compounds. Contrary to previous literature reports, [a]

The real industrial establishment of MOFs requires significant advances in economic and chemical sustainability. This work describes a novel and simple method to prepare one of the most widely studied MOF material, i.e. MIL-100(Fe), which significantly improves the sustainability of the conventional process in several aspects. Interestingly, the only difference in the preparation method of MIL-100(Fe) compared with that of semi-amorphous Fe-BTC (MOF material commercialized as Basolite F300 having the same metal and linker, and which can be also prepared under similar sustainable conditions), is to start from Fe(II) or Fe(III) sources, respectively, which opens certain versatility options in the room temperature synthesis procedures of MOF materials. The prepared samples were characterized using XRD, TGA, N 2 adsorption/ desorption isotherms, Cs-aberration corrected STEM and UV-Vis DRS. These two room-temperature-made Fe-BTC materials were tested in the industrially-demanded photocatalytic degradation of methyl orange under both ultraviolet and solar light radiation. MIL-100(Fe) was a very active photocatalyst in comparison with its homologue. That difference was mainly attributed to the presence of larger cavities within its structure.

Organovanadium compounds have been shown to be insulin sensitizers in vitro and in vivo. One potential biochemical mechanism for insulin sensitization by these compounds is that they inhibit protein tyrosine phosphatases (PTPs) that negatively regulate insulin receptor activation and signaling. In this study, bismaltolato oxovanadium (BMOV), a potent insulin sensitizer, was shown to be a reversible, competitive phosphatase inhibitor that inhibited phosphatase activity in cultured cells and enhanced insulin receptor activation in vivo. NMR and X-ray crystallographic studies of the interaction of BMOV with two different phosphatases, HCPTPA (human low molecular weight cytoplasmic protein tyrosine phosphatase) and PTP1B (protein tyrosine phosphatase 1B), demonstrated uncomplexed vanadium (VO ) in the active site. Taken together, these findings support phosphatase inhibition as a mechanism for insulin sensitization by BMOV 4 and other organovanadium compounds and strongly suggest that uncomplexed vanadium is the active component of these compounds. 

This commentary concentrates on corrole complexes with the three metal ions that are most relevant to oxidation catalysis: chromium, manganese, and iron. Particular emphasis is devoted to the only recently introduced meso-triarylcorroles and a comparison with the traditionally investigated b-pyrrole-substituted corroles. Based on a combination of spectroscopic methods, electrochemistry, and X-ray crystallography, it is concluded that in most high-valent metallocorroles the corrole is not oxidized. Both experimental (for (oxo)chromium(V) corrole) and computational (for (oxo)manganese(V) corrole) evidence indicate that the stabilization of high-valent metal ions by corroles originates from a combination of short metal-nitrogen bonds and large metal out-of-plane displacements in the corrole, which lead to quite unexpected interactions of the oxo-metal p* orbitals with the in-plane orbitals of the corrole.

The reaction of gold with thiosaccharin ligand and additional phosphorous coligands is studied. Four new Au(I) complexes with thiosaccharinate as coordinating counteranion: [Au(tsac)(PPh 3)], [Au 2 (tsac) 2 (dppm)]ÁEtOH, Au 2 (tsac) 2 (dppe)ÁEtOH, and Au(tsac)(Htsac) 2 Á0.25 EtOH (tsac: thiosaccharinate, C 6 H 4 C(S)NSO 2 À , dppm: bis(diphenylphosphino)methane, dppe: bis(diphenylphosphino)ethane) were synthesized and characterized by means of spectroscopic techniques (IR, UV-Vis, and 1 H, 13 C and 13 P NMR). The crystal structure of two of them, [Au(tsac)(PPh 3)] and [Au 2 (tsac) 2 (dppm)]ÁEtOH, were solved applying single crystal X-ray diffraction and studied using the density functional theory (DFT) formalism. In the latter, the aurophilic interaction between the two gold centers was analyzed and theoretically confirmed.

The [2,3]-sigmatropic rearrangement of a variety of configurationally stable diastereomeric allylic sulfinyl dihydropyrans, produced by base-promoted cyclization of sulfinyl dienols, has been studied. In some cases, the efficient transformation of these substrates into dihydropyranols required an in-depth study of reaction conditions, with the preferred protocol relying on the use of DABCO in warm toluene. This methodology has been applied to the syntheses of the cores of ent-dysiherbaine and deoxymalayamicin A by means of efficient tethered aminohydroxylations.

The compound NazRu(CN),N0.2H20 has been synthesized from ruthenium trichloride and sodium cyanide by oxidation with nitric acid. The orange prismatic crystals belong to the orthorhombic space group Pnmm with a = 6.303 (2) A, b = 12.084 (4) A, c = 15.833 (5) A, and Z = 4. The structure was refined with use of the initial atomic coordinates from the isostructural sodium nitroprusside, NazFe(CN)SNO-2Hz0, to R = 0.030, R , = 0.028, for 1588 independent reflections; hydrogen atoms were then located in a difference Fourier synthesis and refined with use of constraints in bond lengths R = 0.024, R , = 0.023). Important bond lengths and angles are as follows: RuN = 1.773 (3) A, NO = 1.130 (4) a , Ru-C(trans) = 2.051 (4) A, Ru-C(cis) = 2.053 (3), 2.064 (3) A, C-N(trans) = 1.136 (5) A, C-N(cis) = 1.145 (4), 1.149 (4) A, LRuNO = 174.4 (3)O. The structure, together with data from infrared and electronic absorption spectra, is discussed in terms of ?r-acceptor and r-donor capabilities of the ligands and the Ru central atom, respectively. The electrophilic reactivity of the anionic complex has also been studied by its reaction with OH-, SH-, SO:-, NH3, and N2H4. They form addition intermediates, which further decay to generate final products, one of them presumably RU(CN)~H,O", an important precursor to other related Ru(CN),X" complexes.

In the reaction of Co(NO 3) 2 AE 6H 2 O with 4-acetyl-3-amino-5-methylpyrazole (aamp) two octahedral Co(II) complexes, [Co(aamp) 2-(H 2 O) 4 ](NO 3) 2 , 1, and [Co(ampf)(MeOH) 2 NO 3 ]NO 3 (ampf = N,N 0-bis(4-acetyl-5-methylpyrazole-3-yl)formamidine), 2, were obtained, depending on the reaction conditions. The presence of water in the reaction system leads to incorporation of water molecules into the crystal lattice and 1 was formed. In an anhydrous environment, due to addition of CH(OEt) 3 , the fusion of two aamp was induced through their NH 2-groups, incorporating the methine group of CH(OEt) 3. As a result, complex 2, containing an adenino-mimetic NNO pharmacophore ligand, was obtained. The crystal and molecular structure of both compounds was determined. The coordination of aamp in 1 was achieved through N2 of the pyrazole ring. On the contrary, in 2, an unusual coordination mode of pyrazole is found: one of the pyrazole moieties, due to steric hindrance, coordinates through the oxygen atom of the acetyl group instead of N2. The complexes were characterized by elemental analysis and electronic spectra. For 2 a comprehensive IR spectral analysis is given. The metalligand interactions in 2 are analyzed by quantum chemical computations. The desolvation mechanism of both compounds is discussed in detail.

Uranium-and Th-series radionuclides have been analyzed in C-~2-rich geothermal waters and their associated iron hydroxide and carbonate deposits from the French Massif Central. A geochemical budget for U and Ra in water and solid deposits has been estimated. Most of the U (> 75%) remains in solution, probably because of the presence of soluble U-carbonate complexes. In contrast, a large fraction of Ra (> 50%) is scavenged by both deposit types. The distribution coefficient of U and Ra in calcite are 0.2 and 0.4 respectively. The DRa value is much higher than the experimentally determined coefficients and represents a non-equilibrium value that might be applicable to natural systems with high CaCO 3 precipitation rates.