Publications by authors named "Ad M J van der Eerden"

20 Publications

  • Page 1 of 1

Nature of cobalt species during the in situ sulfurization of Co(Ni)Mo/AlO hydrodesulfurization catalysts.

J Synchrotron Radiat 2019 May 26;26(Pt 3):811-818. Epub 2019 Apr 26.

Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

The evolution in local structure and electronic properties of cobalt was investigated during in situ sulfurization. Using a combination of 1s X-ray absorption (XAS) and 1s3p resonant inelastic X-ray scattering (RIXS), the valence, coordination and symmetry of cobalt ions were tracked in two cobalt-promoted molybdenum oxide precursors of the hydrodesulfurization catalyst system, namely Co-Mo/AlO and Co-Ni-Mo/AlO. Extended X-ray absorption fine structure shows that the Co-O bonds were replaced with Co-S bonds as a function of reaction temperature. The cobalt K pre-edge intensity shows that the symmetry of cobalt was modified from Co O and Co O to a Co ion where the inversion symmetry is broken, in agreement with a square-pyramidal site. The 1s3p RIXS data revealed the presence of an intermediate cobalt oxy-sulfide species. This species was not detected from XAS and was determined from the increased information obtained from the 1s3p RIXS data. The cobalt XAS and RIXS data show that nickel has a significant influence on the formation of the cobalt oxy-sulfide intermediate species prior to achieving the fully sulfided state at T > 400°C.
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http://dx.doi.org/10.1107/S1600577519002546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510205PMC
May 2019

X-Ray Absorption Near Edge Structure Spectroscopy of a Solid Catalyst using a Laboratory-Based Set-up.

ChemCatChem 2019 Feb 11;11(3):1039-1044. Epub 2019 Jan 11.

Inorganic Chemistry and Catalysis Debye Institute for Nanomaterials Science Utrecht University Universiteitsweg 99 Utrecht 3584 CG The Netherlands.

An laboratory-based X-ray Absorption Near Edge Structure (XANES) Spectroscopy set-up is presented, which allows performing long-term experiments on a solid catalyst at relevant reaction conditions of temperature and pressure. Complementary to research performed at synchrotron radiation facilities the approach is showcased for a Co/TiO Fischer-Tropsch Synthesis (FTS) catalyst. Supported cobalt metal nanoparticles next to a (very small) fraction of cobalt(II) titanate, which is an inactive phase for FTS, were detected, with no signs of re-oxidation of the supported cobalt metal nanoparticles during FTS at 523 K, 5 bar and 200 h, indicating that cobalt metal is maintained as the main active phase during FTS.
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http://dx.doi.org/10.1002/cctc.201801822DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6471006PMC
February 2019

Capturing the Genesis of an Active Fischer-Tropsch Synthesis Catalyst with Operando X-ray Nanospectroscopy.

Angew Chem Int Ed Engl 2018 Sep 17;57(37):11957-11962. Epub 2018 Aug 17.

Inorganic Chemistry and Catalysis group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584, CG, Utrecht, The Netherlands.

A state-of-the-art operando spectroscopic technique is applied to Co/TiO catalysts, which account for nearly half of the world's transportation fuels produced by Fischer-Tropsch catalysis. This allows determination of, at a spatial resolution of approximately 50 nm, the interdependence of formed hydrocarbon species in the inorganic catalyst. Observed trends show intra- and interparticular heterogeneities previously believed not to occur in particles under 200 μm. These heterogeneities are strongly dependent on changes in H /CO ratio, but also on changes thereby induced on the Co and Ti valence states. We have captured the genesis of an active FTS particle over its propagation to steady-state operation, in which microgradients lead to the gradual saturation of the Co/TiO catalyst surface with long chain hydrocarbons (i.e., organic film formation).
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http://dx.doi.org/10.1002/anie.201806354DOI Listing
September 2018

In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites.

Phys Chem Chem Phys 2014 Nov;16(41):22651-8

Department of Inorganic Chemistry and Heterogeneous Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de- and re-hydrogenation of nanoconfined lithium borohydride (LiBH4) and therefore we can possibly identify the de- and re-hydrogenation pathways. In the XRS of nanoconfined LiBH4 at different points in the de- and re-hydrogenation, we identified phases that lead to the conclusion that de- and re-hydrogenation pathways in nanoconfined LiBH4 are different from bulk LiBH4: intercalated lithium (LiCx), boron and lithium hydride were formed during de-hydrogenation, but as well Li2B12H12 was observed indicating that there is possibly some bulk LiBH4 present in the nanoconfined sample LiBH4-C as prepared. Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH4-C nanocomposites can be partially rehydrogenated to about 90% of Li2B12H12 and 2-5% of LiBH4 at a mild condition of 1 bar H2 and 350 °C. This suggests that re-hydrogenation occurs via the formation of Li2B12H12. Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications.
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http://dx.doi.org/10.1039/c4cp02918fDOI Listing
November 2014

X-ray nanoscopy of cobalt Fischer-Tropsch catalysts at work.

Chem Commun (Camb) 2013 May;49(41):4622-4

Inorganic Chemistry and Catalysis Group, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

Transmission X-ray microscopy has been used to investigate individual Co/TiO2 Fischer-Tropsch (FT) catalyst particles in 2-D and 3-D with 30 nm spatial resolution. Tomographic elemental mapping showed that Co is heterogeneously concentrated in the centre of the catalyst particles. In addition, it was found that Co is mostly metallic during FT at 250 °C and 10 bar. No evidence for Co oxidation was found.
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http://dx.doi.org/10.1039/c3cc00160aDOI Listing
May 2013

Transition-Metal Nanoparticle Oxidation in a Chemically Nonhomogenous Environment Revealed by 2p3d Resonant X-ray Emission.

J Phys Chem Lett 2013 Apr 25;4(7):1161-6. Epub 2013 Mar 25.

‡Paul Scherrer Institut (PSI), Swiss Light Source, CH-5232 Villigen, Switzerland.

X-ray absorption spectroscopy (XAS) is often employed in fields such as catalysis to determine whether transition-metal nanoparticles are oxidized. Here we show 2p3/2 XAS and 2p3d resonant X-ray emission spectroscopy (RXES) data of oleate-coated cobalt nanoparticles with average diameters of 4.0, 4.2, 5.0, 8.4, and 15.2 nm. Two particle batches were exposed to air for different periods of time, whereas the others were measured as synthesized. In the colloidal nanoparticles, the cobalt sites can have different chemical environments (metallic/oxidized/surface-coordinated), and it is shown that most XAS data cannot distinguish whether the nanoparticles are oxidized or surface-coated. In contrast, the high-energy resolution RXES spectra reveal whether more than the first metal layer is oxidized based on the unique energetic separation of spectral features related to the formal metal (X-ray fluorescence) or to a metal oxide (d-d excitations). This is the first demonstration of metal 2p3d RXES as a novel surface science tool.
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http://dx.doi.org/10.1021/jz4002696DOI Listing
April 2013

Heterogeneities of the nanostructure of platinum/zeolite y catalysts revealed by electron tomography.

ACS Nano 2013 Apr 29;7(4):3698-705. Epub 2013 Mar 29.

Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.

To develop structure-performance relationships for important catalysts, a detailed characterization of their morphology is essential. Using electron tomography, we determined in three dimensions the structure of Pt/zeolite Y bifunctional catalysts. Optimum experimental conditions enabled for the first time high-resolution 3D imaging of Pt particles as small as 1 nm located inside zeolite micropores. Semiautomated image analysis of 3D reconstructions provided an efficient study of numbers, size distributions, and interparticle distances of thousands of Pt particles within individual zeolite crystals. Upon extending this approach to a number of zeolite crystals of one batch of Pt/zeolite Y catalyst, heterogeneities were revealed. The Pt loading, an important parameter for catalyst performance, varied between zeolite crystals up to a factor of 35. This discovery calls for re-evaluation of catalyst preparation methods and suggests potential for lowering the nominal loading with noble metals.
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http://dx.doi.org/10.1021/nn400707pDOI Listing
April 2013

Structural properties of subnanometer thick Y layers in extreme ultraviolet multilayer mirrors.

Appl Opt 2012 Dec;51(36):8541-8

Fundamental Research on Matter Institute, Dutch Institute for Fundamental Energy Research, Nieuwegein, The Netherlands.

We studied the structure and optical properties of B(4)C/Mo/Y/Si multilayer systems. Using extended x-ray absorption fine structure measurements at the Y and Mo K-edge, the structure of the subnanometer thick Y layer and the underlying Mo layer were analyzed. It was found that even a 0.2 nm thick Y layer significantly reduced silicon diffusion toward Mo, thus reducing Mo silicide formation. Hard x-ray reflectometry showed that the difference in average interface roughness of the B(4)C/Mo/Y/Si multilayer structure compared to Mo/Si and B(4)C/Mo/B(4)C/Si multilayer structures was negligible. Soft x-ray reflectometry showed optical improvement of B(4)C/Mo/Y/Si with respect to Mo/Si and B(4)C/Mo/B(4)C/Si multilayer structures.
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http://dx.doi.org/10.1364/AO.51.008541DOI Listing
December 2012

In situ X-ray Raman spectroscopy of LiBH4.

Phys Chem Chem Phys 2012 Apr 16;14(16):5581-7. Epub 2012 Mar 16.

Department of Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 23584 CG Utrecht, The Netherlands.

X-Ray Raman Spectroscopy (XRS) is used to study the electronic properties of bulk lithium borohydride (LiBH(4)) and LiBH(4) in porous carbon nano-composites (LiBH(4)/C) during dehydrogenation. The lithium (Li), boron (B) and carbon (C) K-edges are studied and compared with calculations of the starting material and intermediate compounds. Comparison of the B and C K-edge XRS spectra of the as-prepared samples with rehydrogenated samples shows that the B and C electronic structure is largely regained after rehydrogenation. Both Li and C K-edge spectra show that during dehydrogenation, part of the Li intercalates into the porous carbon. This study shows that XRS in combination with calculations is a promising tool to study the electronic properties of nano-crystalline light-weight materials for energy storage.
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http://dx.doi.org/10.1039/c2cp24025dDOI Listing
April 2012

Implementation of a combined SAXS/WAXS/QEXAFS set-up for time-resolved in situexperiments.

J Synchrotron Radiat 2008 Nov 3;15(Pt 6):632-40. Epub 2008 Oct 3.

KU Leuven, DUBBLE CRG/ESRF, F-38043 Grenoble, France.

It has previously been shown that there are many benefits to be obtained in combining several techniques in one in situ set-up to study chemical processes in action. Many of these combined set-ups make use of two techniques, but in some cases it is possible and useful to combine even more. A set-up has recently been developed that combines three X-ray-based techniques, small- and wide-angle X-ray scattering (SAXS/WAXS) and quick-scanning EXAFS (QEXAFS), for the study of dynamical chemical processes. The set-up is able to probe the same part of the sample during the synthesis process and is thus able to follow changes at the nanometre to micrometre scale during, for example, materials self-assembly, with a time resolution of the order of a few minutes. The practicality of this kind of experiment has been illustrated by studying zeotype crystallization processes and revealed important new insights into the interplay of the various stages of ZnAPO-34 formation. The flexibility of this set-up for studying other processes and for incorporating other additional non-X-ray-based experimental techniques has also been explored and demonstrated for studying the stability/activity of iron molybdate catalysts for the anaerobic decomposition of methanol.
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http://dx.doi.org/10.1107/S0909049508023327DOI Listing
November 2008

Monitoring the coordination of aluminium during microporous oxide crystallisation by in situ soft X-ray absorption spectroscopy.

Chem Commun (Camb) 2006 Nov 6(42):4410-2. Epub 2006 Sep 6.

Inorganic Chemistry and Catalysis group, Department of Chemistry, Utrecht University, Sorbonnelaan 16, 3508 TC, Utrecht, The Netherlands.

An in situ cell, which is capable of obtaining time resolved soft X-ray data (200 eV < E < 3000 eV) under hydrothermal conditions has been developed and used to study the self-assembly processes occurring during microporous aluminophosphate crystallization.
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http://dx.doi.org/10.1039/b610080eDOI Listing
November 2006

A combined SAXS/WAXS/XAFS setup capable of observing concurrent changes across the nano-to-micrometer size range in inorganic solid crystallization processes.

J Am Chem Soc 2006 Sep;128(38):12386-7

Inorganic Chemistry and Catalysis, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.

A novel combined SAXS/WAXS/XAFS setup for studying the self-assembly processes occurring during the crystallization of porous materials, such as ZnAlPO-34, is described. In a single experiment, it has been possible to obtain congruent and time-resolved information on aggregation processes in the synthesis gel, the incorporation process of Zn2+ ions in the framework, and the formation of the crystalline material.
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http://dx.doi.org/10.1021/ja062580rDOI Listing
September 2006

Synchrotron radiation effects on catalytic systems as probed with a combined in-situ UV-vis/XAFS spectroscopic setup.

J Phys Chem B 2005 Mar;109(9):4042-7

Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.

UV-vis spectroscopy was used in a combined in-situ UV-vis/XAFS spectroscopic setup to study the synchrotron radiation effect on aqueous homogeneous copper solutions. Two different systems were studied. In the first study, the focus was on a copper bipyridine-catalyzed oxidation of benzyl alcohol to benzaldehyde with 2,2,6,6- tetramethylpiperidinyl-1-oxy and base as cocatalysts. It was found that when the reaction mixture is exposed to the X-ray beam, the features present in the in-situ UV-vis spectrum develop differently compared to the situation when the reaction mixture is not exposed to the X-ray beam. Besides a temperature effect of the X-ray beam, both the UV-vis analysis and the XAFS analysis showed a reducing influence of the X-ray beam on the sample. To investigate this in more detail, we studied a series of dilute aqueous copper solutions from different precursor salts, viz., Cu(NO3)2.3H2O, CuSO4.5H2O, CuCl2, and CuBr2. It was found that the different aqueous copper solutions have different stabilities under the influence of the X-ray beam. Especially the solution from the CuCl2 precursor salt was found to be unstable and to be subjected to reduction. These examples illustrate the need for a second technique, such as in-situ UV-vis spectroscopy, to evaluate the effect of synchrotron radiation used to measure in-situ XAFS on catalytic systems.
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http://dx.doi.org/10.1021/jp045206rDOI Listing
March 2005

Promotion effects in the oxidation of CO over zeolite-supported Pt nanoparticles.

J Phys Chem B 2005 Mar;109(9):3822-31

Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.

Well-defined Pt-nanoparticles with an average diameter of 1 nm supported on a series of zeolite Y samples containing different monovalent (H+, Na+, K+, Rb+, and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations have been used as model systems to investigate the effect of promotor elements in the oxidation of CO in excess oxygen. Time-resolved infrared spectroscopy measurements allowed us to study the temperature-programmed desorption of CO from supported Pt nanoparticles to monitor the electronic changes in the local environment of adsorbed CO. It was found that the red shift of the linear Pt-coordinated CO vibration compared to that of gas-phase CO increases with an increasing cation radius-to-charge ratio. In addition, a systematic shift from linear (L) to bridge (B) bonded CO was observed for decreasing Lewis acidity, as expressed by the Kamlet-Taft parameter alpha. A decreasing alpha results in an increasing electron charge on the framework oxygen atoms and therefore an increasing electron charge on the supported Pt nanoparticles. This observation was confirmed with X-ray absorption spectroscopy, and the intensity of the experimental Pt atomic XAFS correlates with the Lewis acidity of the cation introduced. Furthermore, it was found that the CO coverage increases with increasing electron density on the Pt nanoparticles. This increasing electron density was found to result in an increased CO oxidation activity; i.e., the T(50%) for CO oxidation decreases with decreasing alpha. In other words, basic promotors facilitate the chemisorption of CO on the Pt particles. The most promoted CO oxidation catalyst is a Pt/K-Y sample, which has a T(50%) of 390 K and a L:B intensity ratio of 2.7. The obtained results provide guidelines to design improved CO oxidation catalysts.
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http://dx.doi.org/10.1021/jp044767fDOI Listing
March 2005

Adding a third dimension to operando spectroscopy: a combined UV-Vis, Raman and XAFS setup to study heterogeneous catalysts under working conditions.

Chem Commun (Camb) 2005 Jun 27(24):3015-7. Epub 2005 May 27.

Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3508 TC, Utrecht, The Netherlands.

The potential of combined operando UV-Vis/Raman/XAFS has been explored by studying the active site and deactivation mechanism of silica- and alumina-supported molybdenum oxide catalysts under propane dehydrogenation conditions.
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http://dx.doi.org/10.1039/b504027bDOI Listing
June 2005

Atomic XAFS as a tool to probe the electronic properties of supported noble metal nanoclusters.

J Am Chem Soc 2005 Mar;127(10):3272-3

Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands.

Atomic XAFS is a very attractive technique for probing electronic properties of supported metal nanoclusters. For platinum nanoparticles on different supports, the technique is found to be in good agreement with infrared CO adsorption measurements. The advantages of AXAFS, however, are that no probe molecule is required and that real-time measurements under reaction conditions are possible.
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http://dx.doi.org/10.1021/ja043107lDOI Listing
March 2005

Local structure of the zeolitic catalytically active site during reaction.

J Am Chem Soc 2004 Apr;126(14):4506-7

Swiss Federal Institute of Technology (ETH) Zurich, CH-8093, Zurich, Switzerland.

The structural changes of the catalytic active site that occur during catalytic reaction in an acidic zeolite are detected. The local structure of the zeolitic Brønsted active site is a distorted tetrahedrally coordinated aluminum that has three short and one long aluminum-oxygen bond. Using in situ Al K edge X-ray absorption spectroscopy, the adsorption of a reactive intermediate in the oligomerization of ethene changed the local structure of the catalytic active site; the long aluminum oxygen bond is partially relaxed. At increasingly higher temperature, extensive coking of the catalyst frees the Brønsted acid site from the reactive intermediate, restoring the asymmetric coordination. These measurements show that application of in situ Al K edge spectroscopy provides fundamental insight into the structure of zeolitic catalytically active sites during catalytic action.
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http://dx.doi.org/10.1021/ja031755jDOI Listing
April 2004

Three-coordinate aluminum in zeolites observed with in situ x-ray absorption near-edge spectroscopy at the Al K-edge: flexibility of aluminum coordinations in zeolites.

J Am Chem Soc 2003 Jun;125(24):7435-42

Institute for Chemical and Bioengineering, ETH Hönggerberg, CH-8093 Zurich, Switzerland.

Application of in situ X-ray absorption near-edge spectroscopy (XANES) at the Al K-edge provides unique insight into the flexibilty of the aluminum coordinations in zeolites as a function of treatment or during true reaction conditions. A unique, previously not observed, pre-edge feature is detected in zeolites H-Mordenite and steamed and unsteamed H-Beta at temperatures above 675 K. Spectra simulations using the full multiple scattering code Feff8 identify the unique pre-edge feature as three-coordinate aluminum. The amount of three-fold coordinated aluminum is a function of temperature and pretreatment of a zeolite: a steamed zeolite Beta contains more three-coordinate aluminum than an unsteamed sample. No clear differences between zeolites H-Mordenite and H-Beta were observed. Octahedrally coordinated aluminum forms in zeolites H-Mordenite and H-Beta at room temperature in a stream of wet helium. This octahedrally coordinated aluminum is unstable at temperatures higher than 395 K, where it quantitatively reverts to the tetrahedral coordination.
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http://dx.doi.org/10.1021/ja0292905DOI Listing
June 2003

Deactivation processes of homogeneous Pd catalysts using in situ time resolved spectroscopic techniques.

Chem Commun (Camb) 2003 Jan(1):128-9

Debye Institute, Dept. Inorganic Chemistry and Catalysis, P.O. Box 80083, 3508 TB Utrecht, The Netherlands.

UV-Vis, combined with ED-XAFS shows, for the first time, the evolution of inactive Pd dimers and trimers, that are a possible first stage in the deactivation process of important palladium catalysed reactions, leading to larger palladium clusters and eventually palladium black.
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http://dx.doi.org/10.1039/b206758gDOI Listing
January 2003

Structure-performance relations in homogeneous Pd catalysis by in situ EXAFS spectroscopy.

J Am Chem Soc 2002 Dec;124(50):14814-5

Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, P.O. Box 80083, 3508 TB Utrecht, The Netherlands.

X-ray absorption fine structure (XAFS) spectroscopy is used to unravel the structure of homogeneous catalysts in their catalytically active phase (solution), for which other characterization techniques failed in providing detailed structural information. Application of in situ EXAFS shows that the conformation of the allylic fragment of (P-P)Pd(1,1-dimethylallyl) catalytic intermediate complexes in solution (i.e., reaction medium) differs from that in the solid state, dependent on the bidentate ligand. The change in orientation directly explains differences in regioselectivity in the allylic alkylation reaction, displayed by the distinct complexes.
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http://dx.doi.org/10.1021/ja026604fDOI Listing
December 2002
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