bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of tripod Ligands Containing Mixed Donor Sets with Phosphane and Pyrazole Donors − Bidentate Chelate Binding Modes and Dynamic Behaviour of tripod Ligands in d8‐Metal Complexes (NiII, PdII, PtII)
Authors: Faissner Ralf , Huttner Gottfried , Kaifer Elisabeth , Kircher Peter , Rutsch Peter , Zsolnai Laszlo 
Published: June 2003

AbstractThe synthesis of a series of tripod ligands MeOCH2C(CH2X)(CH2Y)(CH2Z) (X = PR2; Y, Z = PR′2 or pz; pz = 1‐pyrazolyl) based on the 3,3‐difunctionalized oxetane Oa[CH2]2Ca(CH2OMs)(CH2Br)(Oa−Ca) as the starting material is described. With their mixed donor sets these ligands coordinate to d8‐metal ions in a bidentate binding mode. One of the three donors remains uncoordinated in each case. Coordination of phosphane donors is generally preferred over coordination of pyrazole donors. With bulky phosphanes such as −CH2PMes2, however, pyrazole may compete with PR2, depending on the kind of the d8 fragment. Dynamic exchange between coordinated and noncoordinated pyrazole donors is observed. Tetracoordinate complexes of the general type L2MR2 are formed (L2 symbolizes the tripod ligand in its bidentate chelate binding mode with two donors functions coordinating and the third one serving as a dangling arm; M = NiII, PdII, PtII). With nickel(II) as the d8 species, tetrahedral or square‐planar coordination geometries ensue, depending on the kind of donor functions and on the kind of co‐ligands R. With palladium(II) and platinum(II) as the d8 centres, square‐planar coordination is observed throughout. The size of the chelate cycles varies from six to eight depending on the number of pyrazole entities within the cycle. The conformations and the conformational flexibility characterizing the chelate cycles have been analysed by X‐ray analyses and by variable‐temperature NMR. The classes of conformations observed may be formally reduced to chair, half‐chair and twist‐boat conformations. Dynamic exchange between these conformations is observed. In one case, the same compound forms two different types of crystals that differ by the conformation adopted by their chelate cycles. All compounds have been fully characterized by standard analytical techniques including X‐ray structure analysis of 14 chelate compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Nickel(II) Compounds Derived from tripod Ligands: Efficient Catalysts for the Stereoselective Heterodimerization of Styrene and Propene
Authors: Faissner Ralf , Huttner Gottfried 
Published: June 2003

AbstractThe tripod ligands RCH2C(CH2X)(CH2Y)(CH2Z) form tetracoordinate compounds with NiHal2. If two of the donor functions X, Y, Z are phosphanes, square‐planar coordination is observed. In contrast, donor sets X,Y,Z = P,N,N or N,N,N form tetrahedral compounds, by P,N or N,N coordination, that are active in the catalysis of olefin oligomerization with MAO as a co‐catalyst. These catalyst systems are also active in the stereoselective heterodimerization of olefins. The co‐dimerization of styrene and propene by these systems leads to 4‐phenyl‐2‐pentene almost exclusively, with regioselectivities up to 98% and (E)/(Z) ratios of up to 95:5, surpassing other reported catalysts for this process. The products of these catalytic transformations have been fully characterized by GC/MS techniques as well by isolation, NMR and MS characterization of the pure compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Crystal Structures and Third‐Order Nonlinear Optical Properties of Two Novel Ferrocenyl Schiff‐Base Complexes [Ag(L)2](NO3)⋅(MeOH)⋅(EtOH) and [HgI2(L)] {L = 1,2‐Bis[(ferrocen‐l‐ylmethylene)amino]ethane}
Authors: Hou Hongwei , Li Gang , Song Yinglin , Fan Yaoting , Zhu Yu , Zhu Lu 
Published: June 2003

AbstractTwo novel ferrocenyl complexes [Ag(L)2](NO3)·(MeOH)· (EtOH) (1) and [HgI2(L)] (2) {L = 1,2‐bis[(ferrocen‐l‐ylmethylene)amino]ethane} have been prepared and structurally characterized by means of X‐ray single crystal diffraction. The central ion, silver(I) or mercury(II), has a distorted tetrahedral environment, the silver(I) ion coordinates with two L, and the mercury(II) ion binds one L and two iodine atoms. Their third‐order nonlinear optical (NLO) properties were determined by Z‐scan techniques in DMF solution. The results indicate that the two complexes exhibit very strong NLO absorption and strong self‐focusing effects. The third‐order NLO absorptive coefficients α2 are 1.34 × 10−8 m W−1 for 1 and 3.1 × 10−9 m W−1 for 2. The refractive indexes n2 for the two complexes are 1.15 × 10−18 and 8.02 × 10−19 m2 W−1, respectively. The hyperpolarizability γ values are calculated to be 2.68 × 10−30 esu for 1 and 1.44 × 10−30 esu for 2. The γ values are several orders of magnitude larger than those of the reported aryl and vinyl derivatives of ferrocene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Reduction of [(C5Me5)2Mo2O5] and [(C5Me5)2Mo2O4] in Methanol/Water/Trifluoroacetate Solutions Investigated by Combined On‐Line Electrochemistry/Electrospray‐Ionization Mass Spectrometry
Authors: Gun Jenny , Modestov Alexandre , Lev Ovadia , Poli Rinaldo 
Published: June 2003

AbstractComplexes [Cp*2Mo2O5] (Cp* = η5‐C5Me5) and [Cp*2Mo2O4] were investigated by combined on‐line electrochemical (EC) reduction and electrospray‐ionization mass spectrometry (ESI‐MS) techniques in a trifluoroacetic acid buffered water/methanol solution. The reduction products at the larger negative potentials are identical for both compounds. The studies reveal the existence of a wide range of previously unknown di‐ and trinuclear MoV, MoIV, MoIII, and mixed‐valence complexes that were identified on the basis of their masses and characteristic isotope patterns. The structures of the initial compounds and the product of electroreduction with m/z = 713−729 were supported by in situ MSn experiments that allowed the elucidation of the fragmentation pathway for the collision‐induced dissociation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ternary Mononuclear and Ferromagnetically Coupled Dinuclear Copper(II) Complexes of 1,10‐Phenanthroline and N‐Salicylidene‐2‐methoxyaniline that Show Supramolecular Self‐Organization
Authors: Reddy Pattubala A. N. , Nethaji Munirathinam , Chakravarty Akhil R. 
Published: June 2003

AbstractThe ternary copper(II) complex [Cu(phen)(L)](ClO4) (1) and dinuclear copper(II) complex [Cu2(phen)3(L)(O2CMe)](ClO4)2 (2) have been prepared and characterized structurally by X‐ray crystallography (HL: N‐salicylidene‐2‐methoxyaniline; phen: 1,10‐phenanthroline). The crystal structure of 1 displays a square‐pyramidal [4+1] coordination geometry in which the basal plane has three nitrogen donor atoms and the phenolate oxygen atom of the Schiff base. The methoxy oxygen atom exhibits axial coordination in the CuN3O2 chromophore. Complex 2 has a dinuclear copper(II) core in which the Cu(phen)22+ and Cu(phen)(L)+ units are linked by an acetate ion showing equatorial/axial modes of bonding. In the bis(phen) unit, the basal plane has three nitrogen atoms and the acetate oxygen atom with one phen nitrogen atom occupying the axial site. In the mono(phen) unit, the basal plane has three nitrogen atoms and one phenolate oxygen atom. The acetate oxygen atom occupies the axial site. The equatorial/axial bridging mode of the acetate ion makes the dicopper(II) unit weakly ferromagnetic (2J = +22 cm−1) and the complex in CH2Cl2 glass at 77 K shows an axial EPR spectrum [g|| = 2.23 (A|| = 150 × 10−4 cm−1); g⊥ = 2.03] corresponding to a ΔMs = ±1 transition and a half‐field signal due to a ΔMs = ±2 transition. Complex 1 displays an axial EPR spectrum with g|| > g⊥ indicating a {d−}1 ground state. The complexes show a d−d band near 650 nm and a charge‐transfer band at ca. 415 nm in methanol. The complexes are redox‐active and exhibit a CuII/CuI couple near 0.0 V versus SCE in DMF and CH2Cl2/0.1 M TBAP. Complex 1 is catalytically active in the oxidation of ascorbic acid by dioxygen in aqueous methanol. Complex 2 also shows similar catalytic activity, but the core is susceptible to cleavage under the reaction conditions. The complexes show π−π stacking interactions. Complex 1 forms a one‐dimensional chain through intermolecular π−π stacking interactions involving phen and the phenolate ring of the Schiff base. Complex 2 displays intramolecular and intermolecular π−π stacking interactions involving phen ligands leading to the formation of a supramspectrum with g|| > g⊥ indicating a {d−}1 ground state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Photophysical and Energy‐Transfer Properties of (Salen)zinc Complexes and Supramolecular Assemblies
Authors: Splan Kathryn E. , Massari Aaron M. , Morris Gregory A. , Sun Shih‐Sheng , Reina Eduardo , Nguyen SonBinh T. , Hupp Joseph T. 
Published: June 2003

AbstractThe absorption, emission, and energy‐transfer properties of monomeric and supramolecular (salen)Zn complexes (square and rectangular assemblies) are reported. The monomeric complexes fluoresce in solution, displaying photophysical behavior similar to typical (porphyrin)zinc complexes. Rhenium coordination chemistry is used to assemble molecular rectangles and squares that largely retain the photophysical properties of the parent compounds. Host‐guest assemblies obtained by binding a fifth (salen)Zn complex to a tetrakis(salen) square are capable of efficient salen‐to‐salen electronic energy transfer. Energy transfer flow through these systems can be manipulated by modification of the salen building‐block structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Crystal Structure, and Electrical Properties of Novel Radical Cation Salts of Iodine‐Substituted TTF‐Derived Donors with the Nitroprusside Anion Exhibiting Strong ‐I···NC‐ Interactions
Authors: Ueda Kazumasa , Sugimoto Toyonari , Faulmann Christophe , Cassoux Patrick 
Published: June 2003

AbstractRadical‐cation salts of iodine‐substituted TTF derivatives [diiodoethylenedithiotetrathiafulvalene (1) diiodoethylenedithiodiselenadithiafulvalene (2), or iodoethylenedithiotetrathiafulvalene (3)] with the [Fe(CN)5NO]2− nitroprusside anion, namely, 14·[Fe(CN)5NO], 24·[Fe(CN)5NO] and 33·[Fe(CN)5NO], were synthesized by electrocrystallization from solutions of the appropriate TTF derivative in CH2Cl2 with bis(tetraphenylphosphonium)nitroprusside [(PPh4)2{Fe(CN)5NO}] as electrolyte. An X‐ray structure analysis indicates that the crystal structures of 14·[Fe(CN)5NO] and 24·[Fe(CN)5NO] are very similar. In both cases, molecules 1 and 2 are stacked along the c direction, with their long molecular axis parallel to each other. By contrast, in 33·[Fe(CN)5NO], molecules 3 are stacked in triad units in which two of the molecules are arranged in a face‐to‐face fashion and the remaining molecule is arranged in a head‐to‐tail fashion with respect to its neighboring molecules. In all cases, several effective iodine‐nitrogen contacts between donor molecules and [Fe(CN)5NO]2− anions are observed. The room temperature electrical conductivities of 14·[Fe(CN)5NO], 24·[Fe(CN)5NO] and 33·[Fe(CN)5NO] are <10−6, 2.2 × 10−2 and 5 S cm−1, respectively. The temperature dependence of the electrical conductivity of 33·[Fe(CN)5NO] reveals semiconducting behavior with a small activation energy of 30 meV. The temperature dependence of the electrical conductivity of 24·[Fe(CN)5NO] also reveals a semiconducting behavior, but with two regimes: above 200 K the activation energy is 60 meV and becomes much smaller — 0.2 meV — below this temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Solvothermal Synthesis and Structure of Anhydrous Manganese(II) Formate, and Its Topotactic Dehydration from Manganese(II) Formate Dihydrate
Authors: Viertelhaus Martin , Henke Henning , Anson Christopher E. , Powell Annie K. 
Published: June 2003

AbstractRecrystallization of manganese(II) formate dihydrate from formic acid under solvothermal conditions results in single crystals of anhydrous manganese(II) formate Mn(O2CH)2, and the structure of this phase has been determined by X‐ray diffraction. The same product can be obtained by solid‐state dehydration of single crystals of manganese formate dihydrate, giving crystals that, although of poor quality, still allow for a single crystal structure determination. The structural relationship between the hydrated and anhydrous phases and the nature of the transformation have been determined. Given the nature of the rearrangement involved in the solid‐state reaction, it is remarkable that a crystalline product is obtained. Magnetic measurements of the anhydrous manganese(II) formate show it to be a three‐dimensional antiferromagnet. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Polymeric, Molecular, and Cation/Anion Arrangements in Chloro‐, Bromo‐, and Iododiruthenium(II,III) Carboxylate Compounds
Authors: Barral M. Carmen , González‐Prieto Rodrigo , Jiménez‐Aparicio Reyes , Priego J. Luis , Torres M. Rosario , Urbanos Francisco A. 
Published: June 2003

AbstractThe synthesis and characterization of the anhydrous compounds [Ru2X(μ‐O2CR)4] [R = CH2CH2OPh, X = Cl (1a), Br (2a), I (3a); R = CMePh2, X = Br (5a), I (6a)] and of the solvated complexes [Ru2X(μ‐O2CR)4(H2O)] [R = CH2CH2OPh, X = Cl (1b), I (3b); R = CMePh2, X = Cl (4b), Br (5b), I (6b)] are described. Thermogravimetric analyses have been used to confirm the anhydrous or solvated natures of the complexes. The crystal structures of 1b·2MeOH, 3b·0.5H2O, and 4b have been investigated by X‐ray diffraction and none of them shows the usual polymeric arrangement reported for tetracarboxylatodiruthenium(II,III) compounds. The structure of 3b·0.5H2O consists of cationic and anionic units, [Ru2(μ‐O2CCH2CH2OPh)4(H2O)2][Ru2I2(μ‐O2CCH2CH2OPh)4], and represents the first reported crystal structure of a tetracarboxylato(iodo)diruthenium(II,III) derivative. The structures 1b·2MeOH and 4b each show the presence of discrete dinuclear molecules. The crystal structure of [Ru2Cl(μ‐O2CCMePh2)4(H2O)] demonstrates that diruthenium compounds with the same halide and carboxylate ligands may adopt polymeric or discrete molecular dispositions. Magnetic susceptibility measurements of the complexes in the 2−300 K range have been carried out. Complex 2a shows a strong antiferromagnetic coupling, consistent with the existence of linear chains in the solid state. The complexes [Ru2X(μ‐O2CR)4(H2O)] show weak through‐space antiferromagnetic coupling, in accordance with non‐polymeric structures. The magnetic behaviour of 1a, 3a, 5a, and 6a suggests a mixture of arrangements. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of Oxalato‐Bridged (Oxo)vanadium(IV) Dimers Using L‐Ascorbic Acid as Oxalate Precursor: Structure and Magnetism of Two Systems
Authors: Baruah Bharat , Golub Vladimir O. , O’Connor Charles J. , Chakravorty Animesh 
Published: June 2003

AbstractThe reaction of an aqueous solution of NH4VO3 with L‐ascorbic acid and Et4NBr has afforded [Et4N]2[(VO)2(C2O4)3‐(H2O)2]·4H2O (3). A similar reaction, in which malonic acid is also added, has furnished [Et4N]2[(VO)2(C2O4)(C3H2O4)2(H2O)2]·2H2O (4). In these syntheses the oxalate ion is derived from L‐ascorbic acid. In both the complexes the dinuclear anion is centrosymmetric. In 3 the metal atoms are displaced from the plane of the bridging oxalate anion by 0.05 Å, the corresponding displacement in 4 being 0.17 Å. The terminal oxalato chelate ring in 3 is roughly planar but the malonato chelate ring in 4 has a distorted boat conformation. The V−O distances in 4 are systematically shorter than the corresponding distances in 3 by 0.02−0.06 Å. The V···V distance within the dimer is 5.616(2) Å in 3 and 5.529(2) Å in 4. The two uncoordinated water molecules in the asymmetric unit of 3 constitute a hydrogen‐bonded dimer and the lattice consists of a supramolecular anionic assembly held by five different types of O···O hydrogen bonds. The anionic assembly in 4 involves three types of O···O hydrogen bonds. The Et4N+ cations reside between the anionic layers. The magnetic susceptibility data of both 3 and 4 fit excellently with the Heisenberg dimer model in the temperature interval 2−300 K. The species are antiferromagnetic and the J values are −6.50 cm−1 for 3 and −6.25 cm−1 for 4. The two opposing factors — V−O(bridge) bond length and the displacement of the metal atom from the oxalate plane — appear to have more or less balanced each other resulting in virtually equal J values for the two complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Syntheses of Dimetallamacrocycles by Intramolecular Oxidative Couplings of Dinuclear Bis(1,3‐butadiynyl) Complexes: A New Approach to Steric Shielding in (sp‐Carbon chain)dirhenium Complexes [(η5‐C5Me5)Re(NO)(PR3)(C≡CC≡CC≡CC≡C)(R3P)(ON)Re(η5‐C5Me5)] (Eur. J. Inorg. Chem. 12/2003)
Authors: Horn Clemens R. , Gladysz John A. 
Published: June 2003

AbstractThe cover picture shows the first example of an isolated organometallic compound containing two terminal alkynes undergoing an intramolecular oxidative coupling. Twenty‐two‐ and twenty‐six‐membered rings or “metallamacrocycles” are obtained in 18−41 % yields. The intramolecular oxidative coupling of organic compounds containing two terminal alkynes has played a critical role in the development of macrocycle chemistry, particularly with annulenes and dehydroannulenes, and macrocyclizations are playing an increasingly important role in organometallic chemistry, particularly as attention turns to architecturally novel types of target molecules that may have applications in materials chemistry or nanotechnology. Details are discussed in the article by J. A. Gladysz et al. on p. 2211 ff.
The Use of Ultrasound for the Degradation of Pollutants in Water: Aquasonolysis – A Review
Authors: Lifka J. , Ondruschka B. , Hofmann J. 
Published: June 2003

AbstractThe degradation of organic compounds in water is the subject of a number of fundamental and applied investigations. Aquasonolysis of organic compounds is an advanced technology for the purification of contaminated water. The process is based on the phenomenon of acoustic cavitation. Dominant reactions of volatile compounds are: cavitative high‐temperature gas‐phase reactions and thermal‐oxidative decay in bubbles. Nonvolatile compounds are mainly decomposed by OH radicals in the aqueous solution (sonolytical cleavage of water). This article reviews mechanisms and kinetics of pollutant decomposition in water and discusses the influence of different experimental parameters. An overview of the application spectrum of aquasonolysis is provided, analyzing results gathered in experiments completed in our group as well as results reported in the literature.
Analysis of multilocus models of association
Authors: Devlin B. , Roeder Kathryn , Wasserman Larry 
Published: June 2003

AbstractIt is increasingly recognized that multiple genetic variants, within the same or different genes, combine to affect liability for many common diseases. Indeed, the variants may interact among themselves and with environmental factors. Thus realistic genetic/statistical models can include an extremely large number of parameters, and it is by no means obvious how to find the variants contributing to liability. For models of multiple candidate genes and their interactions, we prove that statistical inference can be based on controlling the false discovery rate (FDR), which is defined as the expected number of false rejections divided by the number of rejections. Controlling the FDR automatically controls the overall error rate in the special case that all the null hypotheses are true. So do more standard methods such as Bonferroni correction. However, when some null hypotheses are false, the goals of Bonferroni and FDR differ, and FDR will have better power. Model selection procedures, such as forward stepwise regression, are often used to choose important predictors for complex models. By analysis of simulations of such models, we compare a computationally efficient form of forward stepwise regression against the FDR methods. We show that model selection includes numerous genetic variants having no impact on the trait, whereas FDR maintains a false‐positive rate very close to the nominal rate. With good control over false positives and better power than Bonferroni, the FDR‐based methods we introduce present a viable means of evaluating complex, multivariate genetic models. Naturally, as for any method seeking to explore complex genetic models, the power of the methods is limited by sample size and model complexity.Genet Epidemiol25:36–47, 2003. © 2003 Wiley‐Liss, Inc.
Evolutionary‐based association analysis using haplotype data
Authors: Seltman Howard , Roeder Kathryn , Devlin B. 
Published: June 2003

AbstractAssociation studies, both family‐based and population‐based, can be powerful means of detecting disease‐liability alleles. To increase the information of the test, various researchers have proposed targeting haplotypes. The larger number of haplotypes, however, relative to alleles at individual loci, could decrease power because of the additional degrees of freedom required for the test. An optimal strategy would focus the test on particular haplotypes or groups of haplotypes, much as is done with cladistic‐based association analysis. First suggested by Templeton et al. ([1987] Genetics 117:343–351), such analyses use the evolutionary relationships among haplotypes to produce a limited set of hypothesis tests and to increase the interpretability of these tests. To more fully utilize the information contained in the evolutionary relationships among haplotypes and in the sample, we propose generalized linear models (GLM) for the analysis of data from family‐based and population‐based studies. These models fully account for haplotype phase ambiguity and allow for covariates. The models are encoded into a software package (the Evolutionary‐Based Haplotype Analysis Package, EHAP), which also provides for various kinds of exploratory data analysis. The exploratory analyses, such as error checking, estimation of haplotype frequencies, and tools for building cladograms, should facilitate the implementation of cladistic‐based association analysis with haplotypes. Genet Epidemiol 25:48–58, 2003. © 2003 Wiley‐Liss, Inc.
Remembering the contributions of Kenneth I. Howard: An introduction
Authors: Beutler Larry E. 
Published: June 2003

AbstractThis special issue of the Journal of Clinical Psychology recognizes the contributions of Kenneth I. Howard, one of the most influential and productive contemporary scholars in the domain of psychotherapy process and outcome. The articles address some of the major contributions by Dr. Howard and extend their implications to contemporary clinical practice and research. © 2003 Wiley Periodicals, Inc. J Clin Psychol.
What random assignment does and does not do
Authors: Krause Merton S. , Howard Kenneth I. 
Published: June 2003

AbstractRandom assignment of patients to comparison groups stochastically tends, with increasing sample size or number of experiment replications, to minimize the confounding of treatment outcome differences by the effects of differences among these groups in unknown/unmeasured patient characteristics. To what degree such confounding is actually avoided we cannot know unless we have validly measured these patient variables, but completely avoiding it is quite unlikely. Even if this confounding were completely avoided, confounding by unmeasured Patient Variable × Treatment Variable interactions remains a possibility. And the causal power of the confounding variables is no less important for internal validity than the degree of confounding. © 2003 Wiley Periodicals, Inc. J Clin Psychol.