Search

The K-edge X-ray absorption near-edge structure (XANES) spectra of 19 phosphorus-containing compounds have been measured in solution. The energy at maximum intensity of the primary phosphate peak, regardless of chemical species, is 2154.5 ± 0.4 eV. A few of the compounds studied feature XANES spectra which are conceivably characteristic enough to be used as positive identifiers in solution, including O,O-diethyldithiophosphate, (C2H5O)2PS(SH), triphenylphosphine oxide, (C6H5)3PO, and triphenylphosphite (C6H5O)3P. However, most spectra are near-identical or similar enough to another compound to prohibit any useful quantification analysis. The narrow range of absorption edge energy, and all phosphorus compounds studied have an absorption edge at higher energy than elemental phosphorus (red phosphorus). This shows that the electron density of phosphorus in these compounds is lower than in elemental phosphorus, and the conventional use of oxidation numbers cannot be applied.

Colloids and nanoparticles leached from agricultural land are major carriers of potentially bioavailable nutrients with high mobility in the environment. Despite significant research efforts, accurate knowledge of macronutrients in colloids and nanoparticles is limited. We used multi-elemental synchrotron X-ray fluorescence (XRF) microscopy with multivariate spatial analysis and X-ray atomic absorption near-edge structure (XANES) spectroscopy at the P and S K-edges, to study the speciation of P and S in two fractions of leached particles, >0.45 and

The structures of the solvated copper(II) ion in water and nine organic oxygen donor solvents with similar electron-pair donor ability, but with different space-demanding properties at coordination, have been studied by EXAFS. N,N′-Dimethylpropyleneurea and N,N,N′,N′-tetramethylurea are sufficiently space demanding at coordination to make the axial positions not accessible, resulting in square-planar copper(II) solvate complexes with an intense green color. The mean Cu–O bond distances in these two solvate complexes are 1.939(3) and 1.935(3) Å, respectively. The best fits of the remaining solvates, which are light blue in different hues, are obtained with a Jahn–Teller distorted-octahedral model consisting of four strongly bound solvent molecules in the equatorial positions at 1.96(2) Å and two in the axial positions but with different Cu–Oax bond distances: ca. 2.15 and 2.32 Å. This is in agreement with observations in solid-state structures of compounds containing hexaaquacopper(II) complexes crystallizing in noncentrosymmetric space groups and all reported crystal structures containing a [Cu(H2O)5(O-ligand)] complex with Jahn–Teller distortion. Such a structure is in agreement with previous EPR and EXAFS studies proving the hydrated copper(II) ion to be a noncentrosymmetric complex in aqueous solution. The refinements of the EXAFS data of the solids [Cu(H2O)6](ClO4)2, [Cu(H2O)6](BrO3)2, [Cu(H2O)6]SiF6, Cu(NO3)2·2.5H2O, and CuSO4·5H2O gave Cu–O bond distances significantly different from those reported in the crystallographic studies but similar to the configuration and bond distances in the hydrated copper(II) ion in aqueous solution. This may depend on whether the orientation of the axial positions is random in one or three dimensions, giving a mean structure of the solid with symmetry higher than that of the individual complexes. This study presents the very first experimental data from the new X-ray absorption spectroscopy beamline Balder at the MAX IV synchrotron radiation facility in Lund, Sweden, as well as the utilized properties of the beamline., The coordination chemistry of the solvated copper(II) ion has been studied in 10 solvents, including water. The copper(II) ion has a noncentrosymmetric Jahn−Teller distorted-octahedral geometry with the axial Cu−O bond distances differing by ca. 0.2 Å.

A very slow oxidation of dimethylsulfoxide (dmso) solvated tin(II) ions in solution results in the formation of a crystalline, structurally determined compound, [CH3Sn(OS(CH3)2)5](ClO4)3, whereas a similar reaction in N,N-dimethylthioformamide (dmtf) forms a crystalline solid with a proposed binuclear [Sn2(SH)2(SCHN(CH3)2)8]6+ entity but whose exact formula remains undetermined. Both solids precipitate with time in their respective mother liquids and constitute the first two tin(IV) and even tetravalent d10 metal ion solvate complexes ever reported. An EXAFS study showed that the structure of the [CH3Sn(OS(CH3)2)5]3+ complex is identical in solid state and dmso solution. While the exact chemical reaction pathways are unknown, the formation of these complexes constitute a novel way of obtaining solvated tin(IV) ions in standard, commonplace organic media.

Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated. Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching. Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha−1) > organic 1 (1.0 kg ha−1) > sand (0.3 kg ha−1) > loam (0.2 kg ha−1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)2) in water. The Langmuir maximum adsorption capacity (Qmax) of the coated biochar was 65.4 mg P g−1. Lysimeters produced mixed results, with a 74% (P

With recent developments in autonomous cars, route based optimisation is closer to reality. Penetration of such connected cars technology provides potential for optimisation of fuel consumption. In this paper, look ahead prediction is used along with lumped parameter based models to develop a supervisory controller for a light duty diesel engine. A supervisory interface proposed in earlier works for a light duty diesel engine with LNT-SCR aftertreatment system is used. The supervisory controller is designed with the objective of non-interference of local controllers. However, the ability to influence the subsystem with a system objective is maintained. The look ahead prediction comprises of vehicle speed and load trajectory. A set of discrete control actions are evaluated for the complete powertrain to determine the optimal action with respect to equivalent fuel consumption. The use of the simple models along with discrete control actions has low computational effort. After a full factorial simulation of the discrete actions carried out on-line, the optimal supervisory control action is chosen by selecting the action with least fuel consumption. The simulation results utilising the proposed controller is analysed for fuel equivalent consumption saving potential.

A very slow oxidation of dimethylsulfoxide (dmso) solvated tin(ii) ions in solution results in the formation of a crystalline, structurally determined compound, [CH3Sn(OS(CH3)2)5](ClO4)3, whereas a similar reaction in N,N-dimethylthioformamide (dmtf) forms a crystalline solid with a proposed binuclear [Sn2(SH)2(SCHN(CH3)2)8]6+ entity but whose exact formula remains undetermined. Both solids precipitate with time in their respective mother liquids and constitute the first two tin(iv) and even tetravalent d10 metal ion solvate complexes ever reported. An EXAFS study showed that the structure of the [CH3Sn(OS(CH3)2)5]3+ complex is identical in solid state and dmso solution. While the exact chemical reaction pathways are unknown, the formation of these complexes constitute a novel way of obtaining solvated tin(iv) ions in standard, commonplace organic media.

The coordination chemistry of oxotitanium(IV) or titanyl(IV), TiO2+, has been studied in solution by X-ray methods. The titanyl(IV) ion hydrolyzes easily in aqueous systems to solid titanium dioxide as long as it is not stabilized through complexation. In this study the structures of the hydrated bissulfatotitanyl(IV) complex and the dimethylsulfoxide (DMSO) solvated titanyl(IV) ions have been determined. In isolated monomeric titanyl complexes titanium(IV) binds strongly to a doubly bound oxo group at ca. 1.64 Å, to four ligands in the equatorial plane almost perpendicular to the Ti=O bond at ca. 2.02 Å, and there is one weakly bound ligand, trans to the Ti=O bond, at ca. 2.22 Å, for oxygen donor ligands; the O=Ti–Oeq bond angles are 95°–100°. The structure of the DMSO solvated titanyl(IV) ion in the solid state is maintained in DMSO solution. Electronic supplementary material The online version of this article (doi:10.1007/s10953-017-0581-3) contains supplementary material, which is available to authorized users.

A combined field and laboratory scale study of 10 European lakes treated between 2006 and 2013 with a lanthanum (La) modified bentonite (LMB) to control sediment phosphorus (P) release was conducted. The study followed the responses in sediment characteristics including La and P fractions and binding forms, P adsorption capacity of discrete sediment layers, and pore water P concentrations. Lanthanum phosphate mineral phases were confirmed by solid state (31)P MAS NMR and LIII EXAFS spectroscopy. Rhabdophane (LaPO4 · nH2O) was the major phase although indications of monazite (LaPO4) formation were also reported, in the earliest treated lake. Molar ratios between La and P in the sediments were generally above 1, demonstrating excess La relative to P. Lanthanum was vertically mixed in the sediment down to a depth of 10 cm for eight of the ten lakes, and recovery of La in excess of 100% of the theoretical aerial load indicated translocation of the LMB towards the deepest areas of the lakes. Lanthanum was generally recovered from bed sediment samples following sequential chemical extraction from the HCl fraction. Soluble reactive P (SRP) release experiments on intact sediment cores indicated conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment.

The solvation and coordination chemistry of the manganese(II) ion in water, methanol, dimethylsulfoxide (dmso), N,N’-dimethylpropylene urea (dmpu), acetonitrile and N,N-dimethylthioformamide (dmtf) have been studied from solvation thermodynamic, structural and complex formation ability point of view by calorimetry and EXAFS spectroscopy. The heats of transfer from water to methanol, dmso, acetonitrile and dmtf have been determined to −37.7, −71.6, –23.1 and −36.3 kJ mol−1, respectively, from the heats dissolution of anhydrous manganese(II) trifluoromethanesulfonate by ampoule calorimetry in the neat solvents. Refinement of the EXAFS data of the hydrated and methanol and dmso solvated manganese(II) ions in solution show octahedral configuration and mean Mn-O bond distances of 2.165(3), 2.161(2) and 2.157(3) A, respectively. The Mn-O bond distance is significantly shorter in dmpu solution, 2.087(3) A. As dmpu is a space-demanding solvent upon coordination, the manganese(II) ion is only allowed to bind five dmpu molecules in the solvate complex. The acetonitrile solvated manganese(II) ion is six-coordinate in octahedral fashion in solution with a mean Mn-N bond distance of 2.193(3) A. The relative permittivity of pyridine is too low to allow dissociation of salts of divalent metal ions and neutral pyridine solvated complexes are formed in pyridine solution. In concentrated manganese(II) trifluoromethanesulfonate dmtf solution a contact ion-pair is formed with one trifluoromethanesulfonate ion. In this complex manganese(II) binds five dmtf molecules and a trifluoromethanesulfonate oxygen with Mn-S and Mn-O bond distances of 2.598(6) and 2.16(1) A, respectively, in an octahedral complex. Complex formation studies performed by titration calorimetry of the manganese(II)-bromide system show significantly more stable complexes in dmpu than in solvents where the solvated manganese(II) ion has regular octahedral symmetry. The dmpu solvated MnBr2 complex in dmpu solution is five coordinate with mean Mn-Br and Mn-O bond distances of 2.494(3) and 2.076(3) A, respectively. The structure of the [MnBr2(dmpu)2] complex in solid state has distorted tetrahedral geometry with mean Mn-Br and Mn-O bond distances of 2.473(3) and 2.014(3) A, respectively, and a Br-Mn-Br bond angle of 116.3(1) degrees.

Look ahead information can be used to improve the powertrain’s fuel consumption while efficiently controlling exhaust emissions. A passenger car propelled by a Euro 6d capable diesel engine is studied. In the conventional approach, the diesel powertrain subsystem control is rule based. It uses no information of future load requests but is operated with the objective of low engine out exhaust emission species until the Exhaust After-Treatment System (EATS) light off has occurred, even if fuel economy is compromised greatly. Upon EATS light off, the engine is operated more fuel efficiently since the EATS system is able to treat emissions effectively. This paper presents a supervisory control structure with the intended purpose to operate the complete powertrain using a minimum of fuel while improving the robustness of exhaust emissions. A supervisory controller assisted by look ahead information, and using a supervisory control interface that works in concert with low level local controllers, can make subsystems operate near optimal. The look ahead parametrized supervisory control calculates the set-points for the subsystems: Internal Combustion Engine (ICE), Lean NOx Trap (LNT) and the Selective Catalytic Reduction (SCR) based on the Emission Equivalent Fuel Consumption minimization strategy (EEFC). The controller performance is analyzed for the World wide harmonized Light vehicles Test Cycle (WLTC) and randomly sequenced WLTCs under different initial conditions. This paper extends upon the earlier work where an LNT-SCR EATS supervisory control structure was proposed that optimizes based on the EEFC strategy. The future work will focus on extending the approach to more subsystems and characterizing the look ahead information.

The relationship between the structural and volumetric properties of ions in solvents with different physico-chemical properties has been studied for 19 cations and six anions in six solvents., The structures of the N,N-dimethylformamide (dmf), N,N-dimethylacetamide (dma), and N,N-dimethylpropionamide (dmp) solvated strontium and barium ions have been determined in solution using large angle X-ray scattering and EXAFS spectroscopy. The strontium ion has a mean coordination number (CN) between 6.2 and 6.8, and the barium ion has a mean CN between 7.1 and 7.8 in these amide solvents. The non-integer numbers indicates that equilibria between different coordination numbers and geometries exist in these systems. Structural information of the alkali, alkaline earth, and selected transition metal and lanthanoid(iii) ions, and the halide ions in water, methanol, ethanol, dimethylsulfoxide, formamide, dmf and dma has been combined with previously reported standard partial molar volumes, V0. The ionic radii and charge densities (charge/ionic volume), and corresponding V0 values have been used to gain information on the relationship between structural and volumetric properties. For the structure-breaking ions, i.e. the alkali metal and halide ions, there is an almost linear relationship between the ionic radius and V0. On the other hand, for the structure-making ions, here the alkaline earth, transition metal and lanthanoid(iii) ions, a linear relationship is observed between the charge density and V0. Solvents with a well-defined bulk structure through hydrogen bonding, specifically, water, methanol and ethanol, will be more contracted through solvation than aprotic solvents, as the space between the solvent molecules is lost as a result of the hydrogen bonding. In this respect, methanol stands out as the most compressed solvent participating in solvation compared to its bulk structure.

Densities and sound velocities at temperatures (298.15, 303.15, 308.15, 313.15 and 318.15) K of magnesium(II), calcium(II) and strontium(II) trifluoromethanesulfonates (triflates), as well as barium(II) perchlorate in N,N-dimethylformamide (dmf) and N,N-dimethylacetamide (dma) have been measured over the composition range studied. From these results, apparent molar volumes and apparent molar isentropic compressibilities at infinite dilution, as well as expansibilities have been evaluated. The results have been discussed in terms of ion–solvent interactions and coordination number.

International audience; Lytic polysaccharide monooxygenases (LPMOs) are a recently discovered class of enzymes that employ a copper-mediated, oxidative mechanism to cleave glycosidic bonds. The LPMO catalytic mechanism likely requires that molecular oxygen first binds to Cu(I), but the oxidation state in many reported LPMO structures is ambiguous, and the changes in the LPMO active site required to accommodate both oxidation states of copper have not been fully elucidated. Here, a diffraction data collection strategy minimizing the deposited x-ray dose was used to solve the crystal structure of a chitin-specific LPMO from Enterococcus faecalis (EfaCBM33A) in the Cu(II)-bound form. Subsequently, the crystalline protein was photoreduced in the x-ray beam, which revealed structural changes associated with the conversion from the initial Cu(II)-oxidized form with two coordinated water molecules, which adopts a trigonal bipyramidal geometry, to a reduced Cu(I) form in a T-shaped geometry with no coordinated water molecules. A comprehensive survey of Cu(II) and Cu(I) structures in the Cambridge Structural Database unambiguously shows that the geometries observed in the least and most reduced structures reflect binding of Cu(II) and Cu(I), respectively. Quantum mechanical calculations of the oxidized and reduced active sites reveal little change in the electronic structure of the active site measured by the active site partial charges. Together with a previous theoretical investigation of a fungal LPMO, this suggests significant functional plasticity in LPMO active sites. Overall, this study provides molecular snapshots along the reduction process to activate the LPMO catalytic machinery and provides a general method for solving LPMO structures in both copper oxidation states.

The coordination chemistry and the volumetric properties of three representative lanthanoid(III) ions--lanthanum(III), gadolinium(III), and lutetium(III)--have been studied in three amide solvents with gradually increasing spatial demand upon coordination: N,N-dimethylformamide (dmf)N,N-dimethylacetamide (dma)N,N-dimethylpropionamide (dmp). Large angle X-ray scattering (LAXS) and EXAFS have been used to determine the structure of the solvated lanthanoid(III) ions in solution, further supplemented with a crystallographic study on octakis(N,N-dimethylacetamide)lanthanum(III) triflate, [La(dma)8](CF3SO3)3. The selection of ions and solvents allows an estimate of the steric congestion effects on the resulting coordination number, CN, ranging from nine for lanthanum(III) ions in dmf to seven for the smaller lutetium(III) ion in space-demanding dma. The standard partial molar volumes of the solvated lanthanoid(III) ions in water and dmf are reflected in the CNs, as these solvent molecules are small enough to not interfere with each other upon coordination. However, the larger and more space-demanding dma displays a different pattern with an almost constant standard partial molar volume and a decreasing CN, counterbalancing the difference in ionic radius of the lanthanoid(III) ion.

The concentration and temperature dependencies of density of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) have been determined. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent molar isentropic compressibilities of lanthanum, gadolinium, lutetium and sodium trifluoromethanesulfonates in DMF and DMA have been calculated from sound velocity data obtained at 298.15 K. The results have been discussed in terms of ion–solvent interactions.

The coordination chemistry of d

Biochars are known to affect the environmental fate of pesticides when used as soil amendments and have been suggested to be useful as cheap adsorbents of organic contaminants. We studied the ability of a wood-based biochar produced by slow pyrolysis from a mixture of about 80 % hardwood (Betula sp.) and 20 % softwood (Picea abies) to adsorb pesticides in order to assess its potential use as a filter material to prevent point source pollution in agriculture. The pesticides bentazone, chlorpyrifos, diuron, glyphosate and (4-chloro-2-methylphenoxy)acetic acid (MCPA) were used as model compounds. Their adsorption and desorption to the biochar were tested before and after it had been subjected to treatments with heat and/or iron intended to enhance its adsorptive properties. The adsorption affinity of the native biochar, as indicated by the Freundlich K F value, varied greatly and decreased in the order diuron > chlorpyrifos > MCPA > bentazone > glyphosate. Activation with heat (t = 450 °C) increased the specific surface area and the wettability of the biochar, measured by a water drop penetration time assay, and increased the adsorption of bentazone and MCPA. Treatment with iron salts, which partially coated the biochar with an iron oxide identified as magnetite, decreased the specific surface area but increased the adsorption of glyphosate. Mixing biochar fractions subjected to different treatments was a successful approach for optimising the adsorption of all model compounds and could be a viable path for creating a versatile yet comparably cheap filter material.

An overview of published crystalline dimercury(I) hydrates, solvates, and complexes/compounds with O-donor ligands shows that there is virtually no correlation between the Hg—Hg bond distance and the overall Hg—O bonding conditions. Additionally, many structures feature different configurations for the individual mercury atoms in the dimercury(I) ion, Hg2 2+. To supplement these findings, the crystal structures of the perchlorate salts of hydrated and dimethylsulfoxide (dmso) solvated mercury(I), [Hg2(OH2)2](ClO4)2 (1) and [Hg10(OS(CH3)2)16](ClO4)10 (2), respectively, have been determined by single crystal X-ray diffraction. In compound 1, the perchlorate ions act as bridges between the almost linear [Hg2(OH2)2]2+ units forming infinite chains. The Hg—Hg bond distance is 2.500(1) Å and the Hg—O distance to the water molecule is 2.231(19) Å. Additional much weaker Hg—O bonds to the bridging perchlorate oxygens lie in the range 2.78–3.15 Å. Compound 2 consists of five crystallographically independent [Hg—Hg]2+ units solvated and bridged by dmso oxygens. These larger entities form chains through much weaker bridging perchlorate ions at longer distances, 3.0–3.3 Å, with a few remaining perchlorate ions isolated in the lattice. The mean Hg—Hg bond distance is 2.500(1) Å, while the Hg—Odmso bond distances are in the range of 2.15–2.92 Å. The dmso molecules are grouped into three types of coordination, strong κO-terminal, medium μ2 O-bridging, or medium/weak μ3 O-bridging, depending on which dimercury(I) ion(s) in the entity they coordinate to.

The structure of the N,N-dimethylthioformamide (DMTF)solvated gallium(III)ion has been determined in solution by means of extended X-ray absorption fine structure (EXAFS)spectroscopy. The gallium(III) ion is four-coordinate in tetrahedral fashion with a mean Ga-S bond distance of 2.233(2)angstrom in DMTF solution. At the dissolution of indium(III)perchlorate or trifluoromethanesulfonate in DMTF coordinated solvent molecules are partly reduced to sulfide ions, and a tetrameric complex with the composition [In4S4(SHN(CH3)(2))(12)](4+) is formed. The structure of the solid tetrameric complex in the perchlorate salt was solved with single crystal X-ray diffraction. Four indium(III)ions and four sulfide ions form a highly symmetric heterocubane structure where each indium binds three bridging sulfide ions and each sulfide ion binds three indium(III)ions with a mean In-S bond distance of 2.584(1)angstrom, and S-In-S angles of 90.3(1)degrees. Each indium(III)additionally binds three DMTF molecules at significantly longer mean In-S bond distance, 2.703(1)angstrom; the S-In-S angles are in the range 80.3-90.4 degrees. Large angle X-ray scattering data on a DMTF solution of indium(III)trifluoromethanesulfonate show that the same tetrameric species characterized in the solid state is also present in solution, whereas the EXAFS measurements only give information about the In-S bond distances due to the short core hole lifetime. (C) 2010 Elsevier B. V. All rights reserved.

A fundamental property of ions is their size, a known fact since before the acceptance of the modern atom model. The common way to describe the size of an ion is to determine its radius, defined as one of a pair of radii adding up to the bond distance between the centers of two nuclei. There are numerous factors that influence the ionic radius of a metal ion, where both valence and coordination number are essential when explaining reactivity, complexation, and chemical behavior. The similarity in ionic radii and chemical behavior between the elements in the lanthanoid and actinoid series is well-known and frequently used, making members of the former safe substitutes to avoid hazardous experiments with the radioactive actinoids. This review establishes reliable ionic radii for the nine-coordinate actinoid(III) ions, based on reported structural data, shedding light upon common misconceptions and clarifying the relationship between the ionic radii in the lantanoid and actinoid series.

A laboratory scale experiment was set up to test the effect of dissolved organic carbon (DOC) as well as ageing of the La-P complex formed during phosphorus (P) sequestration by a La modified clay (Phoslock(®)). Short term (7 days) P adsorption studies revealed a significant negative effect of added DOC on the P sequestration of Phoslock(®), whereas a long-term P adsorption experiment revealed that the negative effect of added DOC was reduced with time. The reduced P binding efficiency is kinetic, as evident from solid-state (31)P magic-angle spinning (MAS) NMR spectroscopy, who showed that the P binding did not change in the presence of DOC. (31)P MAS NMR also reveals that up to 26% of the sequestered phosphate is as loosely bound redox-sensitive P species on the surface of rhabdophane (LaPO4 · nH2O, n ≤ 3). The ratio between the loosely bound P and lanthanum phosphate did not change with time, however both NMR and La LIII-extended x-ray absorption fine structure (EXAFS) spectroscopy shows a transformation of lanthanum phosphate from the initially formed rhabdophane towards the more stable monazite (LaPO4). Furthermore, the effect of natural DOC on the P binding capacity was tested using water and pore water from 16 Danish lakes. Whilst DOC has an immediate negative impact on P binding in the lake water, with time this effect is reduced.

The coordination chemistry of d(10)s(2) metal ions is strongly affected by an (at least partially) occupied d(10)s(2) metal ion-ligand atom antibonding orbital, which may cause a void in the coordination sphere due to repulsion between the electrons in the antibonding orbital on the metal ion and those on the ligands. The character of the formed d(10)s(2) metal ion-ligand atom bond plays an important role in the electron density in the antibonding orbital and thereby also in the coordination chemistry. The hydrated tin(II) ion, [Sn(H2O)(3)](2+), and the trihydroxidostannate ion, [Sn(OH)(3)](-), have very different mean Sn-O bond lengths (2.21 and 2.08 angstrom, respectively) and O-Sn-O angles (ca. 78 and 90 degrees, respectively) both in the solid state and in solution. On increasing the covalency of the tin(II)-ligand bonds, the repulsion decreases and higher coordination numbers are obtained, as seen in the dimethylsulfoxide- and N,N-dimethylthioformamide-solvated tin(II) ions, both of which are five-coordinate with square-pyramidal structures.

The complex formation between iron(III) and bromide has been studied calorimetrically in N,N′-dimethylpropyleneurea (DMPU), and the structure of the DMPU solvated tribromoiron(III) complex has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS), and in solid state by EXAFS and single crystal X-ray diffraction. The calorimetric study showed that iron(III) forms three medium strong bromide complexes in DMPU, and the thermodynamic pattern strongly indicates that all complexes are formed in entropy driven substitution reactions. In DMPU solution, the tribromoiron(III) complex has a regular trigonal planar configuration with a mean Fe–Br bond distance of 2.36 A, and without any solvent molecules strongly bound to iron(III). In the solid state, however, the structure is a slightly distorted trigonal bipyramid, with one short and two slightly longer Fe–Br bonds, 2.37 and 2.44 A, respectively, in a somewhat distorted trigonal plane, and two DMPU solvent molecules (mean Fe–O bond distance 1.98 A) in the apical positions. The DMPU solution of iron(III) bromide and the [FeBr3(dmpu)2] crystals are both blackish red.

The structures of the solvated iron(II) and iron(III) ions have been studied in solution and solid state by extended X-ray absorption fine structure (EXAFS) in three oxygen donor solvents, water, dimethylsulfoxide (Me2SO), N,N′-dimethylpropyleneurea (DMPU), and one sulfur donor solvent, N,N-dimethylthioformamide (DMTF); these solvents have different coordination and solvation properties. In addition, the structure of hexakis(dimethylsulfoxide)iron(III) perchlorate has been determined crystallographically to support the determination of the corresponding solvate in solution. The hydrated, the dimethylsulfoxide and N,N-dimethylthioformamide solvated iron(II) ions show regular octahedral coordination in both solution and solid state with mean Fe–O, Fe–O, and Fe–S bond distances of 2.10, 2.10, and 2.52 A, respectively, whereas the N,N′-dimethylpropyleneurea iron(II) solvate is five-coordinated, d(Fe–O) = 2.06 A. The compounds vary in color from light green (hydrate) to dark orange or red (DMPU). The hydrated iron(III) ion in aqueous solution and the dimethylsulfoxide solvated iron(III) ions in solution and solid state show the expected octahedral coordination, the Fe–O bond distances are 2.00 A for both, whereas the N,N′-dimethylpropyleneurea iron(III) solvate is found to be five-coordinated with a mean Fe–O bond distance of 1.99 A. The N,N-dimethylthioformamide solvated iron(III) ion in the solid perchlorate salt is tetrahedrally four-coordinated, the mean Fe–S bond distance is 2.20 A. Iron(III) is reduced with time to iron(II) in N,N-dimethylthioformamide solution. The compounds vary in color from pale yellow (hydrate) to blackish red (DMPU).

Compared to the corresponding hydrate, the space-demanding solvent ligand N,N′-di­methyl­propyl­eneurea [dmpu; systematic name: 1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one] often lowers the coordination number of metal ions. For dmpu-solvated aluminium iodide, the resulting complex is a di-μ2-hydroxide dimer with AlO5 centres., The structure of the title compound, [Al2(OH)2(C6H12N2O)6]I4·4C6H12N2O (systematic name: di-μ2-hydroxido-bis­{tris­[1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one-κO]aluminium} tetra­iodide 1,3-di­methyl­tetra­hydro­pyrimidin-2(1H)-one tetra­solvate), is composed of two Al(C6H12N2O)3 moieties linked into a centrosymmetric dinuclear unit by a pair of bridging hydroxide ions. The aluminium cations show a distorted trigonal bipyramidal AlO5 coordination environment formed only by monodentate ligands. The Al—O bond lengths are in the range 1.789 (2)–1.859 (2) Å (mean bond length = 1.818 Å). The non-coordinating iodide anions compensate the charge of the complex cation. The remaining solvent mol­ecules and the iodide counter-anions inter­act with the complex cation by weak non-classical C—H⋯I and C—H⋯O hydrogen bonds.

Phosphate (Pi) sequestration by a lanthanum (La) exchanged clay mineral (La-Bentonite), which is extensively used in chemical lake restoration, was investigated on the molecular level using a combination of 31P and 139La solid state NMR spectroscopy (SSNMR), extended X-ray absorption spectroscopy (EXAFS) and powder X-ray diffraction (PXRD) and sorption studies. 31P SSNMR show that all phosphate was immobilized as rhabdophane (LaPO4·n H2O, n  3), which was further supported by 139La SSNMR and EXAFS. However, PXRD results were ambiguous with respect to rhabdophane and monazite (LaPO4). Adsorption studies showed that at dissolved organic carbon (DOC) concentration above ca. 250 M the binding capacity was only 50 % of the theoretical value or even less. No other La or Pi phases were detected by SSNMR and EXAFS indicating the effect of DOC is kinetic. Moreover, 31P SSNMR showed that rhabdophane formed upon Pi sequestration is in close proximity to the clay matrix.

Separation of trivalent actinoid (An(III)) and lanthanoid (Ln(III)) ions is extremely challenging due to their similar ionic radii and chemical properties. Poly-aromatic nitrogen compounds acting as tetradentate chelating ligands to the metal ions in the extraction, have the ability to sufficiently separate An(III) from Ln(III). One of these compounds, 6,6'-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-benzol[1,2,4]triazin-3-yl)-[2,2]bipyridine, CyMe4-BTBP, has proven to be resistant towards acidic environments and strong radiation from radioactive decomposition. EXAFS studies of the dicomplexes of CyMe4-BTBP with americium(III) and europium(III) in nitrobenzene, cyclohexanone, 1-hexanol, 1-octanol and malonamide (DMDOHEMA) in 1-octanol have been carried out to get a deeper understanding of the parameters responsible for the separation. The predominating complexes independent of solvent used are [Am(CyMe4-BTBP)(2)(NO3)](2+) and [Eu(CyMe4-BTBP)(2)](3+), respectively, which are present as outer-sphere ion-pairs with nitrate ions in the studied solvents with low relative permittivity. The presence of a nitrate ion in the first coordination sphere of the americium(III) complex compensates the charge density of the complex considerably in comparison when only outer-sphere ion-pairs are formed as for the [Eu(CyMe4-BTBP)(2)](3+) complex. The stability and solubility of a complex in a solvent with low relative permittivity increase with decreasing charge density. The [Am(CyMe4-BTBP)(2)(NO3)](2+) complex will therefore be increasingly soluble and stabilized over the [Eu(CyMe4-BTBP)(2)](3+) complex in solvents with decreasing relative permittivity of the solvent. The separation of americium(III) from europium(III) with CyMe4-BTBP as extraction agent will increase with decreasing relative permittivity of the solvent, and thereby also with decreasing solubility of CyMe4-BTBP. The choice of solvent is therefore a balance of a high separation factor and sufficient solubility of the CyMe4-BTBP ligand.

Position isomerism is ubiquitous in atmospheric oxidation reactions. Therefore, we have compared surface-active oxygenated amphiphilic isomers (1- and 3-pentanol) at the aqueous surface with surface- and chemically sensitive X-ray photoelectron spectroscopy (XPS), which reveals information about the surface structure on a molecular level. The experimental data are complemented with molecular dynamics (MD) simulations. A concentration-dependent orientation and solvation of the amphiphiles at the aqueous surface is observed. At bulk concentrations as low as around 100 mM, a monolayer starts to form for both isomers, with the hydroxyl groups pointing towards the bulk water and the alkyl chains pointing towards the vacuum. The monolayer (ML) packing density of 3-pentanol is approx. 70% of the one observed for 1-pentanol, with a molar surface concentration that is approx. 90 times higher than the bulk concentration for both molecules. The molecular area at ML coverage (approximate to 100 mM) was calculated to be around 32 +/- 2 angstrom(2) per molecule for 1-pentanol and around 46 +/- 2 angstrom(2) per molecule for 3-pentanol, which results in a higher surface concentration (molecules per cm(2)) for the linear isomer. In general we conclude therefore that isomers - with comparable surface activities - that have smaller molecular areas will be more abundant at the interface in comparison to isomers with larger molecular areas, which might be of crucial importance for the understanding of key properties of aerosols, such as evaporation and uptake capabilities as well as their reactivity.

The structures of the thallium(I) complexes with hydrotris(pyrazolyl)borate (TpTl, 2-Tl), and the modified Bp and Tp ligands dihydrobis(1,2,4-triazolyl)borate (3-Tl), hydrotris(imidazolyl)borate (6-Tl), dihydrobis(indazolyl)borate (7-Tl), and hydrotris(indazolyl)borate (8-Tl) are reported and discussed in terms of their (molecular) metal–ligand arrangement and their crystal packing. Compounds 2-Tl and 7-Tl feature molecular TpTl and Bp′Tl units with pronounced Tl⋯πazolyl interactions between neighboring molecules. In 8-Tl the molecular units are arranged in pairs through indazolyl π⋯π stacking. Complexes 3-Tl and 6-Tl form extended 3D and 1D structures, respectively, through the bridging action of the poly(azolyl)borate ligand between three symmetry related thallium centers. Compounds 2-Tl, 3-Tl, and 8-Tl crystallize in the chiral space groups P21, P212121, and C2, respectively.

The structure of the [Eu(CyMe(4)-BTBP)(2)(NO(3))(n)]((3-n)+) complex in 1-octanol solution and solid state has been determined by EXAFS and X-ray crystallography. The crystal structure shows that 1-octanol binds only to the europium(III)-coordinated BTBP molecules through weak van der Waals forces, making it the first indication of the role of the extraction solvent.

The coordination chemistry of hydrated and solvated vanadium(III), oxovanadium(IV), and dioxovanadium(V) ions in the oxygen-donor solvents water, dimethyl sulfoxide (DMSO), and N,N'-dimethylpropyleneurea (DMPU) has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large-angle X-ray scattering (LAXS) and in the solid state by single-crystal X-ray diffraction and EXAFS. The hydrated vanadium(III) ion has a regular octahedral configuration with a mean V-O bond distance of 1.99 Å. In the hydrated and DMSO-solvated oxovanadium(IV) ions, vanadium binds strongly to an oxo group at ca. 1.6 Å. The solvent molecule trans to the oxo group is very weakly bound, at ca. 2.2 Å, while the remaining four solvent molecules, with a mean V-O bond distance of 2.0 Å, form a plane slightly below the vanadium atom; the mean O═V-O(perp) bond angle is ca. 98°. In the DMPU-solvated oxovanadium(IV) ion, the space-demanding properties of the DMPU molecule leave no solvent molecule in the trans position to the oxo group, which reduces the coordination number to 5. The O═V-O bond angle is consequently much larger, 107°, and the mean V═O and V-O bond distances decrease to 1.58 and 1.97 Å, respectively. The hydrated and DMSO-solvated dioxovanadium(V) ions display a very distorted octahedral configuration with the oxo groups in the cis position with a mean V═O bond distance of 1.6 Å and a O═V═O bond angle of ca. 105°. The solvent molecules trans to the oxo groups are weakly bound, at ca. 2.2 Å, while the remaining two have bond distances of 2.02 Å. The experimental studies of the coordination chemistry of hydrated and solvated vanadium(III,IV,V) ions are complemented by summarizing previously reported crystal structures to yield a comprehensive description of the coordination chemistry of vanadium with oxygen-donor ligands.

The acid-base properties of two raw and purified mixed clays from Burkina Faso were studied, as well as their potential to remove copper(II), lead(II) and chromium(III), and thereby their ability to be used to purify water from heavy metals. The purification procedure of the clays involved removal of carbonates, iron oxides and organic matter. A determination of the elemental composition of the mixed clays revealed the presence of aluminum, iron and silicon as main constituents. The high alkaline pH in one of the samples is attributable to the presence of carbonate in the raw clay. The point of zero charge (pH pzc ) values of the clays, as determined by potentiometric titrations, were 6.79 and 9.52 for the raw clays, while after purification they were 6.87 and 6.76, respectively. Metal adsorption to the clay surfaces started at pH values below pH pzc , strongly indicating formation of inner-sphere complexes. With contact time of 48 h, complete removal of copper(II) was achieved at pH 8 for all samples. More than 90% of the lead(II) removal was attributed to adsorption while for chromium(III), it was 85%. Adsorption to organic matter and iron oxides, and precipitation of metal hydroxides gave significant contributions to the removal of metal ions in aqueous systems. Key words: Mixed clays, potentiometric titration, heavy metals, pH pzc .

The coordination chemistry of lead(II) in the oxygen donor solvents water, dimethylsulfoxide (dmso, Me(2)SO), N,N-dimethylformamide (dmf), N,N-dimethylacetamide (dma), N,N'-dimethylpropyleneurea (dmpu), and 1,1,3,3-tetramethylurea (tmu), as well as in the sulfur donor solvent N,N-dimethylthioformamide (dmtf), has been investigated by extended X-ray absorption fine structure (EXAFS) and/or large angle X-ray scattering (LAXS) in solution, and by single crystal X-ray diffraction and/or EXAFS of solid hydrates and solvates. Lead(II) may either form hemidirected complexes with large bond distance distribution and an apparent gap for excess electron density, or holodirected ones with a symmetric coordination sphere with normal bond distance distribution, depending on the strength of antibonding lead 6s/ligand np molecular orbital interactions and ligand-ligand interactions. The crystallographic data show that the solid lead(II) perchlorate and trifluoromethanesulfonate hydrate structures are hemidirected, while the solid lead(II) solvates of dma and dmpu have regular octahedral configuration with holodirected geometry and mean Pb-O bond distances in the range 2.50-2.52 Å. EXAFS data on the hydrated lead(II) ion in aqueous solution show broad bond distance distribution and a lack of inner-core multiple scattering contributions strongly indicating a hemidirected structure. The Pb-O bond distances found both by EXAFS and LAXS, 2.54(1) Å, point to a six-coordinate hydrated lead(II) ion in hemidirected fashion with an unevenly distributed electron density. The results obtained for the dmso solvated lead(II) ion in solution are ambiguous, but for the most part support a six-coordinate hemidirected complex. The mean Pb-O bond distances determined in dmf and dma solution by LAXS, 2.55(1) and 2.48(1) Å, respectively, indicate that in both solvate complexes lead(II) binds six solvent molecules with the former complex being hemidirected whereas the latter is holodirected. The dmpu and tmu solvated lead(II) ions have a regular holodirected octahedral configuration, as expected given their space-demanding characteristics and ligand-ligand intermolecular interactions. The dmtf solvated lead(II) ion in solution is most likely five-coordinate in a hemidirected configuration, with a mean Pb-S bond distance of 2.908(4) Å. New and improved ionic radii for the lead(II) ion in 4-8-coordination in hemi and holodirected configurations are proposed using crystallographic data.

Solid octaaqua(κ2O-perchlorato)thorium(IV) perchlorate hydrate, [Th(H2O)8(ClO4)](ClO4)3·H2O, 1, and aquaoxonium hexaaquatris(κO-trifluoromethanesulfonato)thorium(IV) trisaquahexakis(κO-trifluoromethanesulfonato)thorinate(IV), H5O2[Th(H2O)6(OSO2CF3)3][Th(H2O)3(OSO2CF3)6], 2, were crystallized from concentrated perchloric and trifluoromethanesulfonic acid solutions, respectively. 1 adopts a severely distorted tricapped trigonal prismatic configuration with an additional oxygen from the perchlorate ion at a longer distance. 2 consists of individual hexaaquatris(κO-trifluoromethanesulfonato)thorium(IV) and trisaquahexakis(κO-trifluoromethanesulfonato)thorinate(IV) ions and an aquaoxonium ion bridging these two ions through hydrogen bonding. The hydrated thorium(IV) ion is nine-coordinated in aqueous solution as determined by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS). The LAXS studies also showed a second hydration sphere of about 18 water molecules, and traces of...

The structures of the N,N'-dimethylpropyleneurea (dmpu) solvated lanthanoid(III) ions have been studied in dmpu solution (La-Nd, Sm-Lu) and in solid iodide salts (La-Nd, Sm, Gd-Lu) by extended X-ray absorption fine structure (EXAFS), and single crystal X-ray diffraction (La, Pr, Nd, Gd, Tb, Er, Yb, and Lu); the EXAFS studies were performed on both K and L(III) absorption edges. Because of the space-demanding properties of dmpu upon coordination, dmpu solvated metal ions often show coordination numbers lower than those found in corresponding hydrates and solvates of oxygen donor solvents without steric requirements beyond the size of the donor atom. All lanthanoid(III) ions are seven-coordinate in solution, except lutetium(III) which is six-coordinated in regular octahedral fashion, whereas in the solid iodide salts the dmpu solvated lanthanoid(III) ions are all six-coordinate in regular octahedral fashion. A comparison of Ln-O bond lengths in a large number of lanthanoid(III) complexes with neutral oxygen donor ligands and different configurations shows that the metal ion-oxygen distance is specific for each coordination number with a narrow bond distance distribution. This also shows that the radius of the coordinated oxygen atom in these compounds can be assumed to be 1.34 A as proposed for coordinated water, while for ethers such as tetrahydrofuran (thf) it is somewhat larger. Using this atomic radius of oxygen in coordinated water molecules, we have calculated the ionic radii of the lanthanoid(III) ions in four- to nine-coordination and evaluated using the bond lengths reported for homo- and heteroleptic complexes in oxygen donor solvates in solution and solid state. This yields new and revised ionic radii which in some instances are significantly different from the ionic radii normally referenced in the literature, including interpolated values for the elusive promethium(III) ion.

The structures of the N,N'-dimethylpropyleneurea (DMPU) solvated gallium(III) and indium(III) ions have been determined in DMPU solution by means of EXAFS. The gallium(III) ion is five-coordinate with a mean Ga-O bond distance of 1.924(5) angstrom, while the larger indium(III) ion is octahedrally coordinated with a mean In-O bond distance of 2.146(3) angstrom. The complex formation equilibria in DMPU for the gallium(III) and indium(III) bromide systems have been studied calorimetrically at 298 K. Three relatively strong complexes are formed in the indium(III) bromide system in DMPU, whereas no stability constants could be established in the gallium(III) bromide system as the heats of complex formation were very close to zero. Gallium(III) bromide is present as DMPU solvated GaBr3 complexes in solution with three equatorial Ga-Br bonds at 2.328(3) angstrom, and two Ga-O bonds at 1.92(3) angstrom in the apical positions of a distorted trigonal bipyramid. The DMPU solvated indium(III) bromide has the same configuration with a mean In-Br bond distance of 2.510(3) angstrom, and two In-O bonds at 2.201(6) angstrom. Indium(III) binds three bromides and three Me2SO molecules through the oxygen atoms in octahedral fac-configuration with mean In-Br and In-O bond distances of 2.630(3) and 2.211(15) angstrom, respectively. (C) 2009 Elsevier B.V. All rights reserved.

Solid octaaqua(kappa(2)O-perchlorato)thorium(IV) perchlorate hydrate, [Th(H(2)O)(8)(ClO(4))](ClO(4))(3).H(2)O, 1, and aquaoxonium hexaaquatris(kappaO-trifluoromethanesulfonato)thorium(IV) trisaquahexakis(kappaO-trifluoromethanesulfonato)thorinate(IV), H(5)O(2)[Th(H(2)O)(6)(OSO(2)CF(3))(3)][Th(H(2)O)(3)(OSO(2)CF(3))(6)], 2, were crystallized from concentrated perchloric and trifluoromethanesulfonic acid solutions, respectively. 1 adopts a severely distorted tricapped trigonal prismatic configuration with an additional oxygen from the perchlorate ion at a longer distance. 2 consists of individual hexaaquatris(kappaO-trifluoromethanesulfonato)thorium(IV) and trisaquahexakis(kappaO-trifluoromethanesulfonato)thorinate(IV) ions and an aquaoxonium ion bridging these two ions through hydrogen bonding. The hydrated thorium(IV) ion is nine-coordinated in aqueous solution as determined by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS). The LAXS studies also showed a second hydration sphere of about 18 water molecules, and traces of a 3rd hydration sphere. Structural studies in aqueous solution of the hydrolysis products of thorium(IV) have identified three different types of hydrolysis species: a mu(2)O-hydroxo dimer, [Th(2)(OH)(2)(H(2)O)(12)](6+), a mu(2)O-hydroxo tetramer, [Th(4)(OH)(8)(H(2)O)(16)](8+), and a mu(3)O-oxo hexamer, [Th(6)O(8)(H(2)O)(n)](8+). Detailed structures of these three hydrolysis species are given. A compilation of reported solid state structures of actinoid(IV) compounds with oxygen donor ligands show a strong correlation between the An-O bond distance and the coordination number. The earlier reported U-O bond distance in the hydrated uranium(IV) ion in aqueous solution, confirmed in this study, is related to nine-coordination. The hydrated tri- and tetravalent actinoid ions in aqueous solution all seem to be nine-coordinated. The trivalent ions show a significant difference in bond distance to prismatic and capping water molecules in assumed tricapped trigonal prismatic configuration, while the tetravalent ions seem to form more regular structures, probably because of higher polarization.

The structures of the N , N ′-dimethylpropyleneurea (DMPU) solvated zinc(II) and cadmium(II) ions have been studied in solution by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS), and in solid state as the trifluoromethanesulfonate salts by EXAFS and crystallography. The DMPU solvated zinc(II) ion is four-coordinated in a tetrahedral fashion with a mean Zn–O bond distance of 1.925(6) A in solid state, while the mean Zn–O bond distance is much longer in solution, 1.99(2) A, suggesting that a five-coordinated solvate complex is dominating. As this Zn–O bond distance is somewhat shorter than expected for a five-coordinated zinc(II) complex the presence of a transient four-coordinated solvate complex in small amounts is possible. The DMPU solvated cadmium(II) ion is six-coordinated in an octahedral fashion in the solid state with a mean Cd–O bond distance of 2.260(9) A. The crystal structure displays severe disorder of both the hexakis( N , N ′-dimethylpropyleneurea)cadmium and trifluoromethanesulfonate ions. In this case, the mean Cd–O bond distance is slightly shorter in solution, 2.24(1) A, which may indicate the existence of a transient dissociative five-coordinated species.

The asymmetric unit of the title compound, C20H18O6 (systematic name: 1β,3β-dihydroxy-2β-methoxyfuro[4′,3′,2′:4,5,6]-18-norandrosta-8,11,13-triene-7,17-dione), a dihydro derivative of the fungal steroid viridin, contains two molecules with similar conformations. The rings bearing the hydroxy groups adopt boat conformations. The absolute structure was assigned based on the known chirality of a precursor compound. In the crystal, molecules are linked by O—H...O hydrogen bonds, generating a three-dimensional network and weak C—H...O interactions consolidate the packing.

Using lanthanoid(III) ions as non-radioactive substitutes for the actinoid(III) ions in model compounds is commonplace in many nuclear research areas. For instance, highly radioactive americium(III) ions are often replaced by europium(III) ions, found at the same position in the lanthanoid series. There is, however, no structural evidence to support this replacement, a fact that proponents in many fields do not consider. By carefully comparing the available data sets, it becomes obvious that the visual overlap in the periodic table does not reflect the true ionic radii of these elements at all. Here, using structural data from both solution and solid state, we present a comparative study of the ionic radii of the two inner transition metal series.

The title compound, [CdI2(C6H12N2O)2], displays distorted tetra­hedral coordination at the CdO2I2 centre. Intra­molecular C—H⋯O inter­actions appear to be present.