bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses, Structures, and Magnetic Properties of Two 1D, Mixed‐Ligand, Metal Coordination Polymers, [M(C4O4)(dpa)(OH2)] (M = CoII, NiII, and ZnII; dpa = 2,2'‐dipyridylamine) and [Cu(C4O4)(dpa)(H2O)]2·(H2O)
Authors: Wang Chih‐Chieh , Yang Cheng‐Han , Lee Gene‐Hsiang , Tsai Hui‐Lien 
Published: April 2005

AbstractTwo metal coordination polymers with general formula [M(dpa)(C4O4)(H2O)] [M = Co (1), Ni (2), Zn (3); dpa = 2,2'‐dipyridylamine] and [Cu(dpa)(C4O4)(H2O)]2·H2O (4) have been synthesized under hydrothermal conditions. The single‐crystal X‐ray analyses reveal that compounds 1–3 are isostructural and possess distorted octahedral metal centers coordinated by two squarates, one dpa, and two water molecules. A 1D two‐legged ladder‐like framework is formed by interconnection of the water‐bridged [M(dpa)(μ2‐OH2)]24+ dimeric fragments and μ1,2‐squarate ligands. Intra‐ and intermolecular hydrogen bonds between squarate, water, and dpa ligands, as well as the π‐π stacking interaction of the pyridyl ring in the dpa ligands, provide extra forces to stabilize the extended network. Conversely, the molecular structure of compound 4 contains two distorted square‐pyramidal CuII centers coordinated by two squarates, one dpa ligand, and one water molecule. The squarates adopt a μ1,2‐binding mode to link the Cu centers and form a 1D helical chain. For compound 2, the magnetic exchange couplings between metal centers are analyzed with a binuclear magnetic model. The resulting negative magnetic exchange coupling constant indicates an antiferromagnetic interaction within the dimers. The magnetic behavior of compound 4 is typical of paramagnetic CuII ions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Photocontrol of Complexation of Neutral and Cationic Species by p‐tert‐Butylcalix[4]arene Tetraethyl Ester
Authors: Creaven Bernadette S. , Deasy Mary , McKenna Catherine , Murray Brian A. , Tobin Darren 
Published: April 2005

AbstractA number of sodium salt complexes of p‐tert‐butylcalix[4]arene tetraethyl ester (1) were isolated both with and without upper‐rim encapsulated acetonitrile or methanol. Upon dissolution in CDCl3, 1 remained largely complexed to the sodium cation but ca. 90 % of the upper‐rim bound solvent was released, reflecting the relative values of the binding constants for complexation of the two guest species. Selective decomplexation of lower‐rim bound sodium cations could be successfully achieved using low‐pressure light sources, triggering the immediate expulsion of the upper‐rim bound solvent. The extent of decomplexation at both rims is controlled both by the oxidation of the counter‐anionic species at the lower rim and by the fate of the photoproducts generated. The calixarene host molecule, 1, remains intact during the decomplexation process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
[H2bpy]2[{Cu(btepy)2}Mo5P2O23]·4H2O: A Three‐Dimensional Framework Built from Transition‐Metal Coordination Polymer Sheets Pillared by Polyoxomolybdophosphate Clusters
Authors: Lu Ying , Li Yangguang , Wang Enbo , Lü Jian , Xu Lin , Clérac Rodolphe 
Published: April 2005

Abstract[H2bpy]2[{Cu(bpy)2}Mo5P2O23]·4 H2O (1; bpy = 4,4'‐bipyridine) contains the first three‐dimensional framework based on two‐dimensional transition metal coordination polymer sheets pillared by polyoxomolybdophosphate clusters. It crystallises in the C2/c monoclinic space group with a = 17.630(4) Å, b = 13.670(3) Å, c = 25.111(5) Å, and β = 106.61(3)°. Thermogravimetric analysis shows that guest molecules (H2O and free bpy ligands) can be easily removed from 1 by simple heat treatment without losing the three‐dimensional framework. Moreover, the paramagnetic properties of the {Cu(bpy)2} arrays, make this material an interesting magnetic solid based on polyoxometallate clusters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Thermal Properties of [M10Se4(SePh)12(PR3)4] (M = Zn, Cd, Hg)Cluster Molecules – Synthesis and Structure of[Cd32Se14(SePh)36(L)4]; L = OPPh3, OC4H8
Authors: Eichhöfer Andreas 
Published: April 2005

AbstractA series of four different M10 selenide cluster molecules of the general formula [M10Se4(SePh)12(PR3)4] (M = Zn, Cd, Hg; R = organic group) have been synthesized by the reaction of metal chlorides MCl2 (M = Zn, Cd, Hg) with phosphanes PR3, Se(SiMe3)2 and PhSeSiMe3 in organic solvents. The investigations of the thermal properties by thermogravimetric analysis (TGA) reveal that [Zn10Se4(SePh)12(PnPr2Ph)4], [Cd10Se4(SePh)12(PEt3)4], [Cd10Se4(SePh)12(PnPr3)4] and [Hg10Se4(SePh)12(PnPrPh2)4] form the corresponding bulk chalcogenides in mainly two‐ or three‐step processes. From the intermediate product of the first step of the vacuum thermolysis of [Cd10Se4(SePh)12(PnPr3)4] we were able to obtain in solution the larger cluster molecule [Cd32Se14(SePh)36‐(OC4H8)4] and upon addition of OPPh3 its homologue [Cd32Se14(SePh)36(OPPh3)4]. The structures of both molecules have been determined by single‐crystal XRD. Obviously, the smaller Cd10 cluster grows upon thermal treatment in the solid state to form larger cluster cores. However, optical spectra and dynamic light scattering of the dissolved residues reveal that this growth is not totally specific. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Pyrazole‐Tethered Heteroditopic Ligands and Their Transition Metal Complexes: Synthesis, Structure, and Reactivity
Authors: Mukherjee Anuradha , Subramanyam U. , Puranik Vedavati G. , Mohandas Thekke P. , Sarkar Amitabha 
Published: April 2005

AbstractVarious pyrazole‐based P,N (2a–c) and N,N (3a–b) ligands have been synthesized. Using representative ligands, NiII, CoII, CuII, and CuI complexes have been prepared and structurally characterized by crystallography. During complexation of CoII and CuII salts, the phosphane part of the P,N ligand oxidized to phosphane oxide. For N,N donor ligands, a dimeric chloro‐bridged NiII complex was obtained. NiII complex 4 is an active catalyst for ethylene oligomerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Trinuclear Oxo‐Centered Iron and Iron/Nickel Clusters – Ligand‐Controlled Homo/Hetero Valency
Authors: Saalfrank Rolf W. , Scheurer Andreas , Pokorny Klaus , Maid Harald , Reimann Uwe , Hampel Frank , Heinemann Frank W. , Schünemann Volker , Trautwein Alfred X. 
Published: April 2005

AbstractCleavage of the all‐iron(III) μ2‐O2–‐linked dimer [FeIII3O(L)2‐(OAc)4]2O (3) with lithium chloride yields [FeIII3O(L)2(OAc)4]Cl (4) and with sodium benzoate, in combination with complete acetate‐to‐benzoate coligand exchange, gives [FeIII3O(L)2‐(OBz)4]OBz (5). Reduction of the all‐FeIII complex 5 [Fe/L/OBz = 3:2:(4+1)] with sodium iodide affords the homonuclear mixed‐valent cluster [FeIIFeIII2O(L)3(OBz)3] (6) (Fe/L/OBz = 1:1:1) and requires fundamental coligand‐to‐ligand exchange. Likewise, when the all‐FeIII dimer [FeIII3O(L)2(OAc)4]2O (3) (Fe/L/OAc = 3:2:4) is cleaved with nickel acetate, the mixed‐valent heteronuclear complex [NiIIFeIII2O(L)3(OAc)3] (7) (M/L/OAc = 1:1:1) is formed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Di‐ and Trivalent Lanthanide Complexes Stabilized by Sterically Demanding Aminopyridinato Ligands
Authors: Scott Natalie M. , Kempe Rhett 
Published: April 2005

AbstractDeprotonation of Ap*H {Ap*H = (2,6‐diisopropylphenyl)‐[6‐(2,4,6‐triisopropylphenyl)pyridin‐2‐yl]amine} and Ap'H {Ap'H = (2,6‐diisopropylphenyl)‐[6‐(2,6‐dimethylphenyl)pyridin‐2‐yl]amine} using KH leads to polymeric [Ap*K]n and [Ap'K]n which undergo clean salt metathesis reactions with NdCl3 in THF forming [Nd(Ap*)Cl2(THF)2]2 and [Nd(Ap')2‐Cl(THF)], respectively. Ethylene polymerization activities of the two chloro complexes (after activation with MAO) were studied. Derivatization of the chloro compounds proceeds without ate complex formation, for instance the reaction of [Nd(Ap')2Cl(THF)] with one equiv. of [K{N(SiMe3)2}] leads to the “THF‐free” silylamide [Nd(Ap')2{N(SiMe3)2}]. Furthermore rare examples of heteroleptic amido‐iodo complexes of selected divalent lanthanides can be stabilized by deprotonated Ap*H. Reaction of [Ap*K]n with [LnI2(THF)3] (Ln = Yb, Sm) in THF leads, after workup in hexane, to [Yb(Ap*)I‐(THF)2]2 and [Sm(Ap*)I(THF)2]2. All lanthanide complexes, four of them are paramagnetic, were characterized by X‐ray crystal structure analysis. These compounds exhibit an excellent solubility in nonpolar solvents like hexane. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Endohedral Metallocenophanes of Rhodium and Cobalt
Authors: Schaefer Carsten , Scholz Gerald , Gleiter Rolf , Oeser Thomas , Rominger Frank 
Published: April 2005

AbstractThe synthesis of seven endohedral metallocenophanes of rhodium (7b, 8b) and cobalt (1d−h) with a cyclopentadienyl unit as one of the π‐systems and a cyclobutadiene or cyclopentadienone unit as the second π‐system is described, including the synthesis of the unsubstituted parent compound of the [CpCo(cbd)]‐derived endohedral phanes, [3.3]‐η5‐(1,1',3,3')‐cyclopentadienyl–η4‐(cyclobutadienophane)co‐balt(I) (1h). This compound could be obtained by deprotection of the corresponding trimethylsilyl‐substituted endohedral phane 1g. The X‐ray structures of 7b, 1e, 1g and 1h could be obtained. This paper compares their structural properties to the complexes reported in previous short communications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Heteroditopic Imino N‐Heterocyclic Carbenes and Their Sulfur, Selenium, and Tungsten Tetracarbonyl Derivatives
Authors: Steiner Georg , Kopacka Holger , Ongania Karl‐Hans , Wurst Klaus , Preishuber‐Pflügl Peter , Bildstein Benno 
Published: April 2005

AbstractNew heterditopic imino N‐heterocyclic carbenes for use as chelating ligands in homogeneous catalysis are the focus of this contribution. The synthesis of the corresponding imid‐azolium precursors is accomplished in three steps by alkylation of imidazole with ketoalkyl bromides, imination of the carbonyl functionality with anilines, either by conventional methods or by an aluminum‐assisted condensation, and methylation using highly electrophilic methyl triflate. Deprotonation of the imidazolium triflates with potassium hydride gives a different outcome depending on the substitution pattern of the iminomethyl moiety: iminomethyl N‐heterocyclic carbenes containing a methylene group between the imino moiety and the N‐heterocycle are unstable because of tautomerization to the corresponding methylene‐deprotonated ylides. In contrast, iminoisopropyl N‐heterocyclic carbenes, where the acidic site of the methylene group is blocked by two methyl groups, are stable in solution, as proven by 1H and 13C NMR spectroscopy. First derivatives of these new [N,C]‐ligands include their sulfur and selenium oxidation products (iminoisopropylimidazolin‐2‐thione and ‐selenone, respectively) as well as a tungsten tetracarbonyl complex with a six‐membered [N,C] chelating moiety. All new products were fully characterized by multinuclear NMR (1H, 13C, 77Se, 183W) and IR spectroscopy, mass spectrometry, as well as by X‐ray single crystal structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Zinc Thiolate Complexes of (N,N,S)‐Tridentate Ligands for the Modeling of Thiolate Alkylating Enzymes
Authors: Ji Mian , Vahrenkamp Heinrich 
Published: April 2005

AbstractZinc thiolate complexes of three tridentate (N,N,S) ligands were prepared as models for the structure and function of thiolate alkylating zinc enzymes. N‐(2‐Mercaptoisobutyl)(2‐pyridin‐2‐yl‐methyl)amine (L1) forms isobutylthiolate‐bridged dinuclear complexes with ZnN2S3 coordination. N‐(2‐Mercaptoisobutyl)(2‐pyridin‐2‐yl‐ethyl)amine (L2) yields isobutylthiolate‐bridged dinuclear complexes in which the pyridine donor is not coordinated to zinc, resulting in a ZnNS3 coordination. Only N‐(2‐mercaptoisobutyl)(2‐pyridin‐2‐yl‐ethyl)methylamine (L3) forms the desired mononuclear complexes with ZnN2S2 coordination. The latter react with the alkylating agents CH3I and PO(OCH3)3 in a two‐step process. In the first step the isobutylthiolate function is methylated and its position in the ligand sphere of zinc is taken by I– or OPO(OCH3)2–, respectively, and in the second step the additional thiolate ligand is methylated and replaced by a second iodide or dimethyl phosphate anion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Reduction of CCl4 by Iron Powder in Aqueous Solution
Authors: Rusonik Irena , Cohen Haim , Meyerstein Dan 
Published: April 2005

Abstract·CCl3 radicals formed in the first step of the CCl4 degradation react with iron powder to form an intermediate with an Fe–C σ bond. In the absence of iron powder, ·CCl3 radicals formed by γ‐irradiation react with 2‐propanol in a chain reaction toward dechlorination. When the irradiated solution contains iron powder, the iron scavenges the ·CCl3 radicals, thus inhibiting the chain reaction. The minor product of the dechlorination of CCl4 by iron powder in aqueous solution is CH4, contrary to the results reported in the literature for the electrochemical reduction of CCl4 on iron electrodes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Si‐, Ge‐, and Sn‐Centered Free Radicals: From Phantom Species toGrams‐Order‐Scale Materials
Authors: Lee Vladimir Ya. , Sekiguchi Akira 
Published: April 2005

AbstractRecent developments in the field of the stable free radicals of heavier group 14 elements are reviewed, covering both neutral and charged radical species. The electronic and crystal‐structural features of these radicals, both in the solid state and in solution, are compared with each other. The most important parameters affecting the stability, geometry and electronic configuration of the radicals are discussed on the basis of the latest experimental and computational data. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Sediment budget for an eroding peat‐moorland catchment in northern England
Authors: Evans Martin , Warburton Jeff 
Published: April 2005

AbstractThis paper describes a detailed contemporary sediment budget from a small peat‐covered, upland catchment in Upper Teesdale, northern England. The sediment budget was constructed by measuring: (1) sediment transfers on slopes, (2) sediment flux on the floodplain and through the main stream channel and (3) sediment yield at the catchment outlet. Measurements were taken over a four‐year monitoring period between July 1997 and October 2001 when interannual variations in runoff were relatively small. Three sites were selected to represent the major erosion subsystems within the catchment: an area of bare peat flats, a pair of peat gullies, and a 300 m channel reach. Collectively the sites allow detailed characterization of the main patterns of sediment flux within the catchment and can be scaled up to provide an estimate of the sediment budget for the catchment as a whole. This constitutes the first attempt to provide a complete description of the functioning of the sediment system in eroding blanket peatlands. Results demonstrate that fluvial suspended sediment flux is controlled to a large degree by channel processes. Gully erosion rates are high but coupling between the slopes and channels is poor and therefore the role of hillslope sediment supply to catchment output is reduced. Consequently contemporary sediment export from the catchment is controlled primarily by in‐channel processes. Error analysis of the sediment budgets is used to discuss the limitations of this approach for assessing upland sediment dynamics. A 60 per cent reduction in fluvial suspended sediment yield from Rough Sike over the last 40 years correlates with photographic evidence of significant re‐vegetation of gullies over a similar period. This strongly suggests that the reduced sediment yields are a function of increased sediment storage at the slope–channel interface, associated with re‐vegetation. Copyright © 2005 John Wiley & Sons, Ltd.
Predictability of river flow and suspended sediment transport in the Mississippi River basin: a non‐linear deterministic approach
Authors: Sivakumar Bellie , Wallender Wesley W. 
Published: April 2005

AbstractAs the Mississippi River plays a major role in fulfilling various water demands in North America, accurate prediction of river flow and sediment transport in the basin is crucial for undertaking both short‐term emergency measures and long‐term management efforts. To this effect, the present study investigates the predictability of river flow and suspended sediment transport in the basin. As most of the existing approaches that link water discharge, suspended sediment concentration and suspended sediment load possess certain limitations (absence of consensus on linkages), this study employs an approach that presents predictions of a variable based on history of the variable alone. The approach, based on non‐linear determinism, involves: (1) reconstruction of single‐dimensional series in multi‐dimensional phase‐space for representing the underlying dynamics; and (2) use of the local approximation technique for prediction. For implementation, river flow and suspended sediment transport variables observed at the St. Louis (Missouri) station are studied. Specifically, daily water discharge, suspended sediment concentration and suspended sediment load data are analysed for their predictability and range, by making predictions from one day to ten days ahead. The results lead to the following conclusions: (1) extremely good one‐day ahead predictions are possible for all the series; (2) prediction accuracy decreases with increasing lead time for all the series, but the decrease is much more significant for suspended sediment concentration and suspended sediment load; and (3) the number of mechanisms dominantly governing the dynamics is three for each of the series. Copyright © 2005 John Wiley & Sons, Ltd.
Estimation and propagation of error in measurements of river channel movement from aerial imagery
Authors: Mount Nicholas , Louis John 
Published: April 2005

AbstractRates of river channel migration or widening are only valid if it can be demonstrated that the amount of change in the measured parameters exceeds the measurement errors. However, it is still uncommon to see estimates of errors presented alongside rates of river channel change measured from aerial photography. Here, detailed methods are presented for the estimation of errors in quantifying channel migration rates that can be easily applied to GIS‐based analysis of planform change. In addition, the impact of relaxing assumptions regarding error independence between image dates and systematic registration errors is presented and discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Contrasting flow pathways within tropical forest slopes of Ultisol soils
Authors: Chappell Nick A. , Sherlock Mark D. 
Published: April 2005

AbstractThere are very few experimental studies identifying hydrological pathways within rain forest slopes. Such knowledge is, however, necessary to understand why forest disturbance affects rainfall–riverflow response and nutrient migration. This study examines flow pathways within lowland rain forest slopes comprising Udults of the Ultisol soil order. Experimentation was conducted on four SE Asian hillslope units (each 5 × 5 m in plan) in the Bukit Timah catchment (Singapore Island), and in the W8S5 catchment (Sabah, Borneo Island). The flow pathways were identified by artificial tracer experiments. We evaluated how well hydrometric calculations based on tensiometry and permeametry measurements predicted the tracer patterns.The tracer work indicated much faster subsurface flows at Bukit Timah than W8S5 for the storms studied. Some explanation of the greater subsurface waterflows at Bukit Timah in comparison to W8S5 is afforded by the less steep moisture release curves which maintain hydraulic conductivity as the soil dries. Vertical flow of the tracer through the upper 1 m of soil predominated (>90 per cent of percolation) in the Bukit Timah slopes. In some contrast, a major component (approximately 60 per cent) of the tracer percolation was directed laterally within the W8S5 slopes. The flow vectors calculated using the hydrometric methods did, however, grossly under‐estimate the degree of lateral deflection of waterflow generated at W8S5 and to a lesser extent over‐estimated it at Bukit Timah. In part, these errors may relate to the inability of traditional hydrometric techniques to fully characterize the effect of the large and small ‘natural soil pipes’ present within both catchments. In conclusion, the study indicates that marked variations in flow vectors exist within the Udult great group of SE Asian soils and hydrometric calculations may be poor predictors of these dominant pathways. Copyright © 2005 John Wiley & Sons, Ltd.
Solution of the planar Newtonian stick–slip problem with the singular function boundary integral method
Authors: Elliotis M. , Georgiou G. , Xenophontos C. 
Published: April 2005

AbstractA singular function boundary integral method (SFBIM) is proposed for solving biharmonic problems with boundary singularities. The method is applied to the Newtonian stick–slip flow problem. The streamfunction is approximated by the leading terms of the local asymptotic solution expansion which are also used to weight the governing biharmonic equation in the Galerkin sense. By means of the divergence theorem the discretized equations are reduced to boundary integrals. The Dirichlet boundary conditions are weakly enforced by means of Lagrange multipliers, the values of which are calculated together with the singular coefficients. The method converges very fast with the number of singular functions and the number of Lagrange multipliers, and accurate estimates of the leading singular coefficients are obtained. Comparisons with the analytical solution and results obtained with other numerical methods are also made. Copyright © 2005 John Wiley & Sons, Ltd.
Corroboration of a familial chordoma locus on chromosome 7q and evidence of genetic heterogeneity using single nucleotide polymorphisms (SNPs)
Authors: Yang Xiaohong (Rose) , Beerman Michael , Bergen Andrew W. , Parry Dilys M. , Sheridan Eamonn , Liebsch Norbert J. , Kelley Michael J. , Chanock Stephen , Goldstein Alisa M. 
Published: April 2005

AbstractChordoma, a rare bone tumor originating from notochordal remnants, has a genetic predisposition in some families. Previously, we performed linkage analysis using microsatellite (STR) markers on 3 unrelated chordoma kindreds (16 patients with chordoma) and reported significant evidence for linkage to chromosome 7q33 (Zmax = 4.78) with a minimal disease gene region of 11 cM. In our present study, we performed linkage analysis in these 3 families using chromosome 7 single nucleotide polymorphisms (SNPs). Parametric and nonparametric multipoint analyses showed significant linkage to 7q markers with p < 0.001 and Zmax = 2.77, respectively. The minimal disease gene region was not reduced by combined SNP and STR haplotype analysis compared to the previous STR haplotype analysis alone. We genotyped members of a fourth chordoma family with SNP and STR markers for chromosome 7q and for 1p36, the location of a previously reported chordoma locus. Affected members of this family did not share a common haplotype on 7q, and the family did not show evidence of linkage to 1p36. Thus, we corroborated a chordoma locus on chromosome 7q in the 3 original families and demonstrated evidence for genetic heterogeneity in the fourth family. Our study also provided insights into some limitations and analytical complexities associated with using a dense SNP marker set in linkage analysis of complex pedigrees. © 2005 Wiley‐Liss, Inc.